Blue side video board noise (2009-March-30)

The video processor board on the left most CCD of LRIS Blue failed and was replaced with a spare. The spare board exhibits low level noise as seen in this bias image. The stddev in the bias is 2.7 in the noisy amp relative to 2.1 for the right most amplifiers. We are in the process of repairing or replacing the old video board. The failed board was sent to the manufacturer for assessment.

Red Side Halos Problem fixed (2009-March-20)

We removed the LRIS red camera and found some condensation on both sides of the dewar window. The dewar window was cleaned, and the dewar was pumped out. Following cool down, the halos reported on 2009-Feb-15 were no-longer detected.

Starlists Now Allow PA Info (2009-Feb-20)

For years, observers have been forced to provide their position angle information to the OA verbally. The new starlist file format now permits you to enter the position angle for your target using the ROTMODE and ROTDEST keywords. Here is an example of how to specify the position angle:

# slitmask with specified rotator position
PA_targ_name    00 24 00.00 +16 00 00.00 2000.0 rotdest=123.45 rotmode=pa

# target observed at parallactic angle
VA_targ_name    12 34 56.78 +01 23 45.67 2000.0 rotdest=0.0 rotmode=vertical

Red Side Halos (2009-Feb-15) -Fixed 2009 March 20

Images of point sources on the red side only have halos at a level of 1% of the source peak flux. An image of the grid of holes mask shows clearly this effect. This effect is also present in spectra on the red side. We suspect at this time that condensation is present on the red side dewar window. The Red side camera will be removed in early March to address this problem.

New Slit Guider Camera commissioned. (2009-Feb-15)

A new slit guiding camera was commissioned for use during engineering nights on 12 and 14 Feb. The new slit guider is rotated such that the slit is 29.5 degrees relative to the columns on the detector. The new camera is sensitive enough to reach a signal-to-noise of 10 in 1s on a star of v-mag=19.5. The unvignetted FOV is expected to be 1.6 arcmin diameter, and at 40% vignetting, the FOV is expected to be 2.2 arcmin. For observers who use pickoff mirrors, the new default pixel location on the guide camera for a pickoff mirror guide star is 459 618. A new slitb pointing origin was also defined to move the star away from a bad column on the red side detector. An image of M13 is available here. The dark line going through the field is a 1.0 arcsec wide long slit.

New Hatch Commissioned but has light leaks (2009-Feb-15)

All observers are advised to acquire internal calibrations after the dome lights are turned off because the hatch has light leaks. As part of the new guider upgrade, a new hatch was needed to house all the new guider optics. The new hatch was tested during engineering nights on 12 and 14 Feb, and it was determined that it has light leaks. An internal G filter pseudo-flat acquired with all internal lamps off, hatch closed, and dome lights on revealed the light leaks seen in the image here. The peak flux from the light leaks is ~3000 ADU, and it varies as a function of rotator position, telescope elevation, and telescope azimuth. This problem will be address in either early or late March.

831/8200 Grating available (2009-Jan-22)

We received and commissioned a new 831/8200 grating. The grating is available for general use, and there is an option to select the grating in the LRIS configuration form.

LRIS slit guider upgraded (2008-Dec-23)

We have commissioned a new slit guide camera and electronics for LRIS. This was an emergency commissioning of a new guider camera because the old slit guider camera was flooded with glycol after a coolant connector seal failed. The old camera was a Photometrics CH250. The new camera is a Photometrics CH350. New electronics are part of the commissioning and the electronics are not inside the electronics bay. The new camera has a wider FOV with significant vignetting in the corners (see image). It is also a more sensitive camera with a higher gain and less readnoise than the old camera by a factors of 3 and 4, respectively. With the old guider, objects were centered at pixel 191, 143. Last night's commissioning result show that objects should now be centered at pixel 277, 290. In the MAGIQ software, Observing Assistants should see two cameras: one for LRIS lris50m (as before), and another called lrisSlit for the slit-guider. Both MAGIQ and XGUIDE were updated and released for use.

831/8200 Grating status (2008-Nov-13)

A new 831/8200 grating was ordered and is scheduled to arrive in January 2009. It was determined that the old grating could not be used inside LRIS due to the risk of additional fracturing. The new grating will be made from the same master grating as the original LRIS 831/8200 grating.

Desktop Menu Returns (2008-Nov-13)

The desktop menu or background menu is now used to run the instrument, replacing the LRIS workspace menu that appeared in the upper left corner of every display.

New IRAF tasks make LRIS mask alignment more convenient (2008-Nov-03)

Three new tasks are now available in the keck.lris package to assist observers with aligning masks:

• do_check_boxesb will wait until the image is written (if one is in progress), then will read the image name and run check_boxesb on it.
• do_xboxb will wait until the image is written (if one is in progress), then will read the image name and run xboxb on it.
• get_seeing will estimate the current seeing by measuring the profiles of the stars in the boxes on a slitmask alignment image.

All three tasks presume that the file listing the box coordinates is named slitmask.box, where slitmask is the name of the slitmask as shown in the SLITNAME keyword.

Grating 831/8200 damaged and unavailable (2008-Oct-9)

The 831/8200 grating is damaged and has been temporarily taken out of service. Three fragments, each roughly one cubic inch in size, were found in the corners of the grating. We are in the process of assessing the grating substrate to determine the risk of future fragmentation, and we are exploring options for repairing and replacing the grating. If we determine that the only solution is to replace the grating, the time frame for replacing it is 10 weeks. If we determine that the damage will not impact science and there is no risk of future fragmentation, then the time frame for repair is 6 weeks.

Web page makeover (2008-Aug-19)

All LRIS web documentation was updated to the new instrument page format. If you find content or pages missing, please contact your support astronomer.

New I band filter installed (2008-Jul-11)

A new I band filter is available for use with LRIS. This filter is an interference type filter with a relatively square passband with FWHM from 6986-8204 Angstroms. Please see the filters on-line documentation to view the transmission curve.

NB4000 filter has a long-wavelength leak (2008-Jul-10)

Observers noted that the NB4000 filter has developed a long-wavelength leak past roughly 7000 Angstroms. Engineering data of this filter was acquired on 8 July 2008 to characterize the long wavelength leak. Spectroscopic flats of the internal halogen lamp using the 1 arcsecond long-slit and 150/7500 grating tuned to 7000 angstroms were acquired with and without the filter in beam. The filter spectrum was divided by the flat to produce a relative transmission spectrum. Please see filters to view the plot.

New MAGIQ Guider Software released (2008-Jul-7)

We are in the process of upgrading the acquisition and guide cameras on all WMKO instruments, and LRIS has been selected as the next instrument to receive a hardware upgrade. An important element of our upgrade strategy is to first deploy the MAGIQ software for operation with the two existing LRIS guide cameras. The new software provides all of the functionality of the existing acquisition and guiding software while improving routine tasks such as star list management, field identification, acquisition, and guiding. Successful testing of MAGIQ software with the existing slit viewing and offset guiders was completed on May 27 and June 27, respectively. The MAGIQ software is released for use, and you are encouraged to use MAGIQ during your observing sessions. The hardware portion of the guider upgrade will take place at a later date.

Slitmask Design Software (2008-Apr-18)

At this time, it is recommended that observers use the Autoslit software to design slitmasks for LRIS. Dr. Arjun Dey and his observing team compared the mask designs that were output from both autoslit and the ucsc lris package and found significant difference in the slit locations. The specific recommendation by the author of the UCSCLRIS package is that observers use the AUTOSLIT field mapping until the UCSCLRIS software is updated.

FVWM with LRIS (2007-Aug-29)

FVWM is a multiple virtual desktop window manager for the X windows system which is now in use with all LRIS accounts. With the switch from open-windows to FVWM, a couple of other changes were required. Most instrument operations are now found on the "LRIS workspace menu" which is automatically launched on startup and will be located in the upper left corner of each display. The "LRIS workspace menu" replaces the open-windows background menu, and is similar to the "DEIMOS workspace menu." Second, clicking on the virtual desktop will bring up a FVWM background menu which is used mostly to start VNC, start local xterms, start browsers, and instrument menus. The FVWM is not used to run the LRIS software, and there are no options provided on that menu to run the instrument. The web documentation has been updated with these changes, but please let your SA know of any inconsistencies.

Blue Side compass rose (2007-Aug-29)

A compass rose that works with the blue side figdisp display is released for observer use.

Grating offsets applied (2007-Aug-08)

Grating offsets are now in use so that the actual central wavelength is closer to the desired central wavelength. Each grating and port combination requires a different offset. All gratings in all ports have been mapped. For most grating and port combinations, the accuracy to which the grating is positioned is better than 10 angstroms. Gratings in port 3 may exhibit larger offsets of up to 50 A. In the past, observers' noted offsets from 100 to 1000 Angstroms. If you notice a large offsets of > 20 Angstroms in the desired central wavelength compared to the actual central wavelength, please inform you support astronomer and add a comment to your post observing comments form.

I filter broke. (2007-July-20)

On 18 July, the I filter was found broken inside the instrument. One of the largest pieces was lodged in the grism mechanism and was preventing movement of the grism mechanism. There is a 3-4 mm gouge in the back surface of the 600 line grism. Fortunately, the gouge is located at the very edge of the grism and this should not alter the grisms optical performance. Because the filter pieces tumbled inside LRIS for at least half a night, we are taking the time to inspect all optical surfaces that may have been exposed to filter fragments. In the long term, we expect to have LRIS ready for operation by the start of the next LRIS observing session which begins 8 Aug. LRIS will be without an I band filter on the red side until a suitable replacement is acquired.

ADC and LRIS together at last (2007-July-09)

Please see the ADC docs.

LRIS-ADC MODE: The default observing mode for LRIS as of semester 2007B is to use LRIS with the new Keck I Atmospheric Dispersion Compensator (ADC), regardless of what you requested on your observing proposal. The presence of the ADC changes the focal plane scale of LRIS by a small but measureable amount, meaning that:

(a) old slitmasks designed for use without the ADC should not be used with the ADC, and

(b) new slitmasks must be designed with software that accounts for the ADC.

If you plan to use LRIS slitmasks, then you must download the new, ADC-compatible version of Judy Cohen's AUTOSLIT software (v3.09) or the similar FABMASK package by Drew Phillips. Please contact your support astronomer for ADC-related questions.

LRIS Blue side shutter fixed, and CCD readout problem fixed (2007-May-6)

The blue side shutter was fixed between 31 April and May 5. A bushing on the shutter was worn. and galling in the bushing was causing the shutter to stick. A dry lube was applied to the bushing.

The CCD can be read-out using all four amplifiers following a repair of the CCD signal cable. The ccd readout problem experienced was that the second amplifier did not see the signal. This meant that the detector had to be read-out in single amp mode, which is slower. During the shutter repair, technicians discovered that the CCD cable had a busted wire. Re-soldering the wire to the connector has fixed the readout problem.

LRIS Blue side CCD readout problem (2007-April-18)

As of April 17, one of the amplifiers on the "left" CCD of the blue-side mosaic is failing to read out properly. Troubleshooting suggests that the problem is a bad cable between the dewar and the saddlebag. Since we have no spare for the cable, we are unable to repair this fault until the run is over. In the meantime, the workaround is to read out both blue CCDs using the "right" amplifiers only. The command to put the blue side into this mode is:

mb amplist=2,4,0,0

Readout times will be double the usual for two-amp mode on the blue side.

LRIS Blue side shutter is stuck open (2007-April-16)

The LRIS blue channel shutter has failed again, and work to replace the shutter will begin on 23 April 2007. The LRIS blue channel shutter should be available in time for the next run which starts 7 May 2007.

For now, the trapdoor may be used as a shutter for the blue side.In this mode, red side data may still be acquired simultaneously. Your SA will review the scripts with you upon your arrival, but please see trapdoor_as_shutter.html for a brief description of the observing scripts.

Observers who used LRIS during April 2007 should carefully examine blue side data to ensure the shutter was not stuck open during their observations.

LRIS Red channel missing columns (2007-April-13)

LRIS Troughput Measurements (2007-Mar-12)

To regularly monitor the throughput of LRIS, observers will be asked for permission to take spectrophotometric observations of a designated standard star during twilight. A script called observe_flux_ standard: verifies that the telescope is pointed to a known LRIS flux standard star by checking DCS keyword TARGNAME; checks the current grating and build appropriate exposure list; saves current LRIS configuration; checks that SKYPA is correct for this star; sets the correct pointing origin (SLITB); configures for slitless spectroscopy; acquires exposures; and restores the observer's configuration. Before running the script the observer should be set up to acquire spectroscopic measurements on the red side (blue side optional) and the OA should point to one of the standards in the target list called 0000_throughput_standards.

ADC status (2007-March-7)

For a description of the current status on the ADC please see: ADC Current Status

LRIS Blue side shutter replaced (2006-Sept-7)

The blue channel dewar is installed in LRIS following the replacement of the blue channel shutter. The shutter that was replaced failed due to ware between a pivot pin and arm used to open and close the shutter. The new shutter was tested and is operating normally.

As a result of the shutter replacement, the blue channel dewar was realigned. As a result of the realignment, the FOV is shifted slightly along rows and columns. This shift along the horizontal axis for LRIS is roughly 70 pix. The shift is benefits LRIS observers because it moves the bar closer to the center of the gap between the blue channel ccds. Observer's may notice that slits fell in the gap during May to Aug because the dewar was slightly misaligned.

The dewar is rotated 0.1-0.3 degrees such that the edges of the imaging FOV are not parallel to the horizontal and vertical array axis.

Grating station 3 is still unavailable. Observers will be limited to three grating choices until the grating station three is fixed. Thus, the fourth grating listed in an observer configuration form will not be installed as it is assumed to have the lowest priority.

LRIS Blue side shutter is stuck open (2006-Aug-29)

The LRIS blue channel shutter has failed again, and work to replace the shutter began on 28 Aug 2006. The LRIS blue channel should be available in time for the next run which starts 15 Sept. 2006. The shutter that recently failed was a rebuilt shutter. We are replacing it with a new shutter. We are replacing the shutter this week, and the blue channel dewar will be re-aligned next week.

Observer who used LRIS during 21-27 Aug. 2007 should carefully examine blue channel data to ensure the shutter was not stuck open during their observations.

Blue channel FOV is slightly misaligned (2006-Aug-18)

The dichroics used to redirect light toward the blue channel are slightly misaligned. The misalignment results in all slits being shifted roughly six arcseconds to the right as seen on the CCD mosaic. This means that some portion of a slit very near the slitmask bar will fall in the gap between the two Blue channel CCDs. If this shift significantly disrupts the primary science with your slitmasks for the run starting 21 August, you may redesign and submit a slitmask for milling.

Grating station three Fixed (2006-Aug-10)

Grating station 3 is back in action. The encoder used to help define the position of the grating tilt failed. The failure mode was that the encoder could not find home. The encoder was replaced with a spare. Observers should find that the wavelength offsets for grating station three that were measured during past runs may no longer apply. Observers may again select up to four different gratings for their run.

Grating station three failed (2006-Jul-18)

Grating station 3 is temporarily out of service. The grating station failed 18 July, and has been taken out of service. Observing teams are limitted to 3 gratings until the grating station is fixed.

Dewar Service and Focus Change (2006-Jul-18)

The LRIS dewar was removed from the instrument so that summit staff could install a new dewar window, replacing the original which was broken during the shutter repair in May. The new window appears to work as desired. Following the work, we've been adjusting the "tilt" position of the LRIS blue dewar to improve the uniformity of focus across the field of view. Currently the unformity in the blue CCD Y direction (along CCD columns) is good, but the CCD X direction (along rows) shows a gradient of about 100 microns from side to side. We judge this to be an insignificant amount of defocus. Observers should be aware that the nominal blue-side focus value has changed significantly and is now approximately -2450. This should be used as the central focus value when acquiring focus images with the focus loop script.

New Web Pages Released (2006-May-15)

There is a new look and feel to the LRIS instrument web pages. The new web pages include information on the LRIS blue channel that was previously lacking with the old pages. Procdures were updated, conflicts in the information or procedures were resolved, and the page information was re-organized. The LRIS documatation is grouped into three primary stages: Pre-Observing when you will require information for preparing proposals and materials in advance of an observing run; Observing when you will be at the telescope, and Post-Observing when you will need to process and analyze data in preparation for publishing.

The old web documenttion is obsolete and is no longer available. Please report any errors, missing information, clarification requests, and any problems with the pages to the lris instrument master.

LRIS Blue side shutter is stuck open! (2006-Apr-25)

The LRIS blue side shutter has failed and work to replace the shutter will begin on 5 May 2006. The shutter is stuck open which permits observing. Several new scripts are available to observers for use during afternoon setup and science acquisition. The trapdoor is currently being used as a shutter for the blue side. Red side data may still be acquired simultaneously. Your SA will review the scripts with you upon your arrival, but please see trapdoor_as_shutter.html for a brief description of the observing scripts.

LRIS Configuration Form Updated (2005-Nov-16)

A new version of the LRIS configuration form is available at http://www2.keck.hawaii.edu/inst/siastng/release/web/ObsConf/welcomeScreenEh.php . The new form is customized to the number of nights in your observing run, links to the slitmask database, and populates dropdown lists with facility and user masks. For LRIS, the blue side elements are listed, and a default configuration is presented. When prepairing for upcoming LRIS and DEIMOS runs, please use the new configuration forms.

IRAF script updates (2005-May-19)

A new version of lrisbias.cl is available in the keck.lris package to handle the 4-amp case (old version only worked with 1 or 2 amps). The script was tested with both red and blue images. Please report any problems with the script to the LRIS master. Chris Fassnacht is the author of the new version of lrisbias.cl.

IRAF Changes (2004-Oct-12)

LRIS accounts have now been upgraded to use v2.12. Also, the tasks previously found in the ucsclris package have now been moved to the keck.lris package. Simply type keck and then lris to load the new package.

July 28, 2004 New telescope focus procedures  (MIRA)

A new MIRA script will be released for the August 2004 run. The script, which allows more flexibility, error checking and greater efficiency on sky, will be run by the OA or by the SA at least once per night. In addition, one of the MIRA runs of the night, preferably the first, will involve taking focus mode images on red and blue side simultaneously and running a double side focus mode with before and after stacked images. The MIRA analysis will be performed using the images of one side only, red if the scientific program is exclusively using the red side, blue if the scientific program uses the blue arm or both arms. The extra time required to run this script is gained back by the ability to configure LRIS while the telescope is slewing to the target star. Subsequent MIRA runs will be done with the minimal amount of reconfiguration and number of exposures.

An additional advantage of the new MIRA script is the possibility for the astronomer to specify a user setup to reconfigure LRIS after the MIRA run: the old MIRA script used to reconfigure LRIS as it was before running the MIRA script, which in most cases was not ideal. In order to specify a custom post-MIRA instrument setup follow the following steps:

1. In the afternoon, after the UT date has changed, configure LRIS as you need for your first post-MIRA observations (example for slitmask alignment in the blue and spectroscopy in the red).
2. In a punaluu xterm type setMira
3. The script will generate the file ~lriseng/open2users.user.save_state.2004-Mmm-dd (e.g user.save_state.2004-Aug-10)
4. After sky focussing, when you have the correct focus values for the red and blue side, you can edit the file.

Do not hesitate to ask your SA in case of questions. The new MIRA script and its features are being tested for the first time: we encourage feedback from the users.

July 13, 2004 New Instrument focus procedures:

During the June run we have collected evidence of focus variations during the night. We are investigating the problem and the July 13 Engineering night will be partly devoted to the problem. In the meantime, we strongly encourage observers to follow our recommendation for instrument focus:

• Dome focus: data will be collected by the support astronomer in the late afternoon as close as possible to opening time.
• Sky focus: the support astronomer or the observer will collect a sky focus sequence with  both red and blue arms with dichroic 560, red filter: R, blue filter: G. Different setups may be used if beneficial to the science program. Please consult your support astronomer.
• Set the  focus values determined on sky using the XLRIS GUI and issue the following command on the punaluu window:

  •  focus_table > focus_yymmdd_RG560
  •  lpr -P lw4 focus_yymmdd_RG560

• Use the printed set of focus for your science setups.

June 12, 2004 - The LRIS red side has been repaired and will be available during the June run. Noise and conversion factor have been determined for both amplifiers. Please check the new values on the CCD specs page.

 

June 8, 2004 -  URGENT MESSAGE: THE RED SIDE WILL PROBABLY NOT BE AVAILABLE FOR THE JUNE RUN.

 The red side electronics problems (see below) has recently worsened. Despite our efforts to fix it, it is unlikely that June observers will be able to use the red side.

            Please contact the Instrument Scientist if you have questions. 

 

Red Side electronics problems (January 2004 - ongoing) 

Since January 2004 the red side electronic is not working properly. The problem, dubbed " The red side saturation", which usually manifests itself after a power-cycle of the instrument red side electronics, generates completely saturate images (including pre and post pixel areas). We have not yet found a way to fix the problem. We know that it clears itself after a period of time. This period, which initially was of 2-3 hours, has, since April, lengthened: it takes now more than 12 hours to get the red side back. We have been working to fix this problem since it appeared, but till now we have failed to find a permanent cure. The observers are advised that they may loose the red side capability at any time, but especially in these situations:

                            1) First day of the run - When LRIS has to be power cycled for installation on the telescope.

                  2) Every time a red electronics power-cycle is needed. 

        As a temporary measure, till the problem is fixed, we will anticipate LRIS installation at the telescope as early as possible and we have advised all personnel to limit the chances of      events by minimizing the power-cycling of the electronics. Astronomers are requested NOT to attempt any power-cycling without talking to their SA.

 

Blue camera oil leak (May  2004)

During the May 2004  run a new oil leak in the blue camera was discovered. The effects of the leak (partly smeared images) could only be seen during MIRA acquisition,  when the telescope in PMFM mode. The leak from the back of the first triplet affected only the edge of the lenses. No effects were noticed in the images taken at PMFM=0. During the on-deck period at the beginning of June, the camera was taken off the instrument, disassembled and cleaned. The leaking seal has also been replaced. On June 4 the blue camera was back on-board. 

 

New LRISB pointing origin (19 November 2003) 

A new pointing origin named LRISB has been defined. It is meant for users who want to do imaging in the blue side.  The LRIS pointing origin can is still available and puts the object at the center of the red side detector, which falls in the gap on the blue side. This LRISB pointing origin puts the object at approximate (x,y) coordinates as listed in the table below

        

Blue detector	Red detector
2177, 2192	870,1135

 

Changes to the XFOCUS widget (31 Oct. 2003)

Minor changes to the XFOCUS GUI and procedures:

1) The GUI can still be started from the background menu from the Xfocus menu: this menu now has two entries, one for the red side and one for the blue side. The GUI will automatically set the correct number of holes to be looked for in the focus images (44 in the blue, 68 on the red side).

2) The focus procedure now uses the correct pixel scale for the blue side (0.135"). This result in a smaller average FWHM for a well focused point (~0.23)

Blue images shifted on the blue side (Sep-Oct. 2003)

During the late September run a horizontal shift (right-to-left) of approximately 135 pixels was noticed on the blue CCD. The problem affected only the MOS observers, who had slits close to the right hand side of the gap. The problem was due to a camera misalignment The blue camera had been taken out to repair the blue shutter which had broken in August and to fix a couplant-oil leak . The installation of the camera is a difficult procedure which may be prone to errors. The camera was re-aligned in time for he start of the late October run. 

 

Adjustment to Pickoff Mirror Coordinates (9 Oct 2003)

Observers who design slitmasks with pickoff mirrors using the UCSC software package need to be aware of a change. This software provides the pixel location onto which you should place the alignment star in order to get your objects into the slits. During a recent engineering night we re-measured the offset between the predicted and actual location of stars on the guider. Until further notice, observers should apply the following offset to their pickoff star coordinates:

• deltaX=+7
• deltaY=-23

These represent only a small change from the last measurement made 3 years ago.

Changes to LRIS Slitmask Submission Process and Deadlines (October 2003)

The procedures and deadlines for submitting LRIS slitmasks are changing effective 2003-Oct-04 due to the onset of DEIMOS slitmask milling at the Keck summit. Key points:

• The existing FTP-based submission system is being eliminated in favor of a web-based slitmask database system which offers numerous advantages for both observers and the observatory. Observers will need to register with the database in order to submit slitmasks.
• Due to the heavy increase in slitmask milling workload anticipated with the inclusion of DEIMOS masks, the deadline for submitting both DEIMOS and LRIS slitmasks will increase from 3 to 4 weeks, effective for all LRIS and DEIMOS observing runs starting in October 2003. Particularly complex masks (200 or more slits) must be submitted 8 weeks in advance.

Please see http://www2.keck.hawaii.edu/realpublic/inst/lris/lris_slitmask_changes.html for complete information on the changes.

The change will affect all LRIS users whose run starts after Oct. 20 2003.

LRIS-R saddlebag electronics repaired (Sep 15, 2003 )

The red side electronic failed during some test while LRIS was on the deck. It turned out that one of the amplifiers on the analog board was the cause of the malfunction. The electronic has been repaired. We believe that the gain, the saturation level, the bias levels and CTE have been restored to their previous values. New measurements will be done ASAP.

LRIS-B shutter REPAIRED (September 13, 2003)

The blue shutter broke again during the August-September run. It has since been repaired using available spare parts.  The shutter is now working nominally.

Status of the blue side mechanisms (August 2003)

The LRIS servicing mission has started. The blue side mechanisms have been inspected and partially serviced.

• Grism: the grism transport mechanism suffers from vibration and bar-stooling problems. A temporary solution has been implemented and will allow normal operations of the mechanism in the near future. A complete repair mission is being prepared.
• Dichroic and Filter have been partially serviced. No major problems have been found. In June the dichroic latch mechanism caused some sky-time loss. The filter failure during the engineering night of July 2 was caused by a loose screw trapped between a filter cell and its retainer. Both mechanisms have been repaired.

LRIS red side detector electronics problems - July 2003 - During the engineering night of July 2nd we collected data to generate transfer curves for the CCDs. The red side curve showed that blooming effects were affecting the images as soon as the ~34,000 ADU limit was passed. A repair mission was initiated immediately and a temporary patch allowed observations with close to nominal performance for the CCD at the end of July. During the August on-deck time the repairs where completed and as of August 7th the red CCD is working nominally. Refer to the specs page for further details.

 

LRIS-B shutter REPAIRED - January 22, 2003 The broken blue shutter was replaced at the end of the January run with the available spare. The shutter is now working nominally.

LRIS-B shutter failure

Currently (Dec. 29) the blue shutter in LRIS has failed. It is partially open, and we may be able to force it completely open. It is not expected to be fully repaired until after the current LRIS run ends. In the meantime, observers may want to consider changes to their observing programs. A Web page describing some workarounds and extra calibrations can be consulted for ideas.

Electronic logs

The script PMlog allows to produce an observing log in electronic format. It can be called by any lris account from any machine (either local or punaluu). The script is very simple and produces either ths standard logsheet information (taken from the fits headers) or any custom combination of keywords. The print option generates a postscript file which can be printed with the lpr command. Users are encouraged to use it and give feedback.

Usage : PMlog directory [-p filename] [KEY1] [KEY2] ... [KEYn]

Examples: PMlog . RA DEC Ut TARGNAME object
                     PMlog /s/sdata223/lris2/9Sep2002 -p filename RA DEC Ut TARGNAME object
Options : -p filename prints to file filename.ps in the data directory

Focus Tables

With the NBC commissioning the focus tables for LRIS, both red and blue side, have changed. To facilitate the users, the new script "focus_table" has been made available on punaluu. The script calculates the focus table for the night, for each instrument configuration. It assumes that the correct focus was measured for the current instrument setup (by means of the usual focus loop procedure) and it calculates the focus for all the settings applying a list of recently calibrated offsets. It does NOT correct for the difference between dome focus ad sky focus (-20 microns, to be added to dome focus values).

LRIS update for september 2002 (18 Sep 2002)

LRIS update for august 2002 (15 Aug 2002)

IRAF mask alignment software updated

To support slitmask alignment using the New Blue Camera, Alice Shapely and Chuck Steidel of Caltech have generously provided CARA with an updated version of Drew Phillips's UCSCLRIS package for IRAF. The revised version is installed on the headquarters IRAF account; observers will get this new version (2.0) when they load UCSCLRIS. The package features three new tasks:

• xboxb performs slitmask alignment on blue images
• mshiftb performs offsets in pixel space on the blue mosaic
• check_boxesb is a front-end or xboxb allowing the observer to define or preview alignment box locations

These tasks account for the spatial gap between the two CCDs in the mosaic. Also, the default imtool buffer size for LRIS observers has been updated to 4096×4096 to support the new mosaic size. Please advise us of any problems you encounter in running this new software.

Changes with the LRIS New Blue Camera (NBC) (June 2002)

Efficiency curves with the LRIS New Blue Camera (NBC) (June 2002)

Gain and Focus measurements with the LRIS New Blue Camera (NBC) (June 2002)

Wavelength coverage and throughput with the LRIS New Blue Camera (NBC) (June 2002)

Efficiencies of LRIS 600-line Gratings

Plots and data showing the relative efficiencies of the three 600-line gratings available with LRIS are now available on the Red Gratings specifications page.

LRIS Update for February 2002 (21 Feb 2002)

LRIS Update for January 2002 (24 Jan 2002)

Enjoy Faster MALIGN (06 Jan 2002)

Changes to the data gathering component of MALIGN have sped up the procedure by about 1.5 minutes for each single-sided alignment and nearly 3 minutes for double-sided. The modifications are:

• only half as many CCD rows are read out
• images are read using dual-amp readout

Note that this requires that the telescope execute a small (30 arcsec) offset at the beginning and end of the procedure in order to center the image on the left amplifier.

LRIS Update for December 2001 (13 Dec 2001)

Movable Guider Repaired (26 Nov 2001)

The offset guider, which is used for guiding during imaging and multislit spectroscopy, failed during the November LRIS run due to a mechanical breakdown. The guider has now been repaired and is once again in full working order. Observers should bear the following in mind:

• Despite an active maintenance program, LRIS is a complex instrument with many moving stages which often experience mechanical problems.
• You can minimize the risk of losing time during observing runs by coming prepared with backup plans for imaging and longslit spectroscopy.
• Designing your slitmasks to use pickoff mirrors will help ensure that the loss of either guider does not impact your multislit observing program.

New Blue Camera Delayed (26 Nov 2001)

The deployment of the new UV-hot detector and dewar for the blue side of LRIS has been delayed. The target date for commissioning the system had been late November 2001, but recent technical problems have made it impossible to achieve that goal. Although a new schedule is not yet available, the system will not be available in December and perhaps not for some months afterward.

LRIS Update for November 2001 (01 Nov 2001)

New Tool Allows Observer Control of Dome Lamps (31 Oct 2001)

By using the new Dome Lamps tool developed by Bob Goodrich, observers can now turn the spectral and imaging flatfield dome lamps on or off remotely. The new GUI is available by clicking on the CMD... button on XLRIS and selecting the Control dome lamps option. This capability is intended to allow Observing Assistants (OAs) to leave the mountaintop as scheduled at the end of the night while still enabling observers to obtain calibrations. Please note the following:

• Assistance from the OA is still required to place the telescope at the dome flat position
• Observers must complete all calibrations by 8 a.m., at which time the day crew will begin to arrive.

A corresponding domelamps command allows control of the dome lamps from observer scripts.

LRIS Collimator Mirror Cleaned After Spill (25 Oct 2001)

Recent reports of vignetting of the LRIS imaging field were traced to a fluid spill on the LRIS collimator mirror. The mirror was removed from the instrument and successfully cleaned by summit staff without the loss of additional time, and performance of the mirror should once again be normal. It seems likely that the spilled fluid may be optical coupling fluid leaked from the LRIS blue camera; hence, we are investigating whether any changes in image quality are evident on the blue side of the instrument.

Slitmask Alignment Checklist Available (19 Oct 2001)

A new checklist which comprehensively describes the steps required to align a slitmask is now on-line. The procedure includes some operations to shave valuable time off the alignment process, and has been observer-tested. This checklist is designed for the most common slitmask alignment technique, which is:

• alignment boxes included on slitmask;
• no pickoff mirrors in use (coarse alignment via direct imaging);
• using xbox software for fine alignment.

Dewar Warming/Cooling Curves Available (1 Oct 2001)

Plots of the dewar temperature during warmup and cooldown phases have been posted online.

Ghost update (18 Sep 2001)

Chuck Steidel recently studied the ghosting problem on the blue side and reports some new findings: ``The brightest 'ghosts' on the blue side are not reflections from the back side of the dichroic as we previously thought. They are actually dispersed light from the red side (if the flat mirror is in on the red side then you get only single ghost images, if a grating is in then the ghost spectrum moves by the same amount as it does on the red side in responding to a change in the grating angle). The dispersion in the primary ghost spectrum suggests that it is second-order dispersed red-side light. All of this suggests that we may be able to improve this situation by improving the baffling internal to the instrument. Incidentally, the ghosts also depend on whether a grism is deployed on the blue side, suggesting that the reflections that are making it into the blue camera are 'channeled' there by the grism.''

Safeguard Added to 'xbox' (12 Sep 2001)

The xbox task used for LRIS slitmask alignment has been changed to account for the inability of the guider to operate properly when rotating the instrument. When you run xbox, it will now prompt you to have the OA disable guiding during the move, and re-enable it after the move completes. You must acknowledge that guiding has been turned on and off by pressing the <Enter> key; these additional prompts may cause longtime LRIS observers to believe that their moves have been sent when, in fact, the program is waiting for input. Please pay close attention to the messages you receive from xbox.

New Tool Aids Slitmask Alignment (11 Sep 2001)

Observers who use the xbox program for slitmask alignment will benefit from the new task check_boxes which provides an interface for defining and inspecting the pixel locations of the alignment boxes. The task allows you to generate a coordinate list rapidly and to see immediately whether the coordinates you gave agree with the box locations.

LRIS Low-level Software Repaired (08 Sep 2001)

Diligent work by Keck software staff has tracked down a bug which prevented the low-level software from functioning appropriately. Keywords should no longer lie, and XLRIS should now give accurate information about the state of the instrument. We will be disabling the monitor tasks which were needed to deal with the bugs, and which caused numerous spurious warnings which confused observers.

LRIS Update for September 2001 (06 Sep 2001)

Select Guider Filters Yourself (31 Aug 2001)

A new GUI allows observers to show or change the selected filter in each of the LRIS guider filter wheels. The GUI can be invoked from the CMD... menu on the XLRIS GUI; click on the item labeled Select guider filter.

LRIS Update for July 2001 (26 Jul 2001)

LRIS Update for May 2001 (17 May 2001)

Software Changes (26 Apr 2001)

Changes made to the LRIS software in early April are believed to have been responsible for some abnormal behavior of the instrument, including:

• XLRIS window freezing up every time a grating is changed
• watch_ccd occasionally freezing, preventing frame numbers from incrementing and causing loss of data

We have undone the change to the keyword library software which appears to have been responsible for the problems; however, this has had a side effect on XLRIS that prevents it from reporting clear when the dichroic, grism, or blue filter has been removed from the beam. Instead, the GUI will report the name of the currently selected element whether the elements is in the carousel or in the beam. To determine the position of the blue elements, you can bring up a window which reports the position of the transport mechanisms by selecting the item LRIS Transport Status on the LRIS Eavesdropping menu from the OpenWindows pulldown menu.

LRIS Update for April 2001 (19 Apr 2001)

A Better Way to Run Xfocusloop (13 Apr 2001)

It is no longer necessary to type the xfocusloop or xfocusloop.blue commands to acquire internal focus images for analysis with the Xfocus widget. Observers can now start a focus sequence on the red or blue side by going to the appropriate Xpose window and selecting the Focus loop option on the CMD... menu. Also, please note that red and blue focusloops can be run simultaneously to save time.

New Arc Lamps Aid Blue Wavelength Calibration (12 Apr 2001)

Arc lamps containing zinc (Zn) and cadmium (Cd) have replaced the previously-used krypton (Kr) and xenon (Xe) bulbs in the LRIS calibration lamp complement. The new lamps should provide sufficient wavelength coverage to enable accurate calibration of all blue spectra. Observers must bear in mind that these UV-emitting lamps take time to warm up: the Zn lamp reaches half-peak output in 150 sec, and the Cd lamp requires 250 sec to reach the half-peak-flux level. Neither lamp emits significant levels of UV flux in the first minute of operation!

G Filter Now Available (12 Apr 2001)

A new G-band filter was recently received and has been installed as a permanent addition to the blue side of the instrument. This filter has a transmission curve which is broader than the Gunn g' filter but has no color term relative to g'. See Steidel & Hamilton (1992, ApJ, 394, 81) for further discussion of this filter.

LRIS Software Changes (12 Apr 2001)

We took the opportunity during the last two weeks to complete several changes to the LRIS software. Changes of interest to observers include:

• XLRIS blue controls simplified. The dichroic, grism, and blue filter stages previously had separate controls for the transport and carousel. These have been replaced by the single control which indicates clear when the filter, grating, or dichroic is stowed and out of the beam. Also, the blue focus window slider bar now corresponds to the legal range of blue focus values.
• Keyword behavior changed. All queries for instrument keywords will now cause an enquiry to the corresponding instrument stage instead of looking up the value in a state table. This should fix most of the instances of "lying keywords" recently encountered.
• Blue optics now clamp reliably. The clamps which hold the blue optics in position in the blue beam have not always fired reliably on the first try. The motor control software has now been upgraded to check the status of the clamps and apply them up to 5 times as needed to ensure that the clamp is activated. This change should eliminate the problems seen previously with undefined blue optics.

New Warnings for Keywords and Clamps (21 Mar 2001)

LRIS is currently experiencing some problems with keywords and blue mechanisms:

• Lying keywords. Sometimes the LRIS keywords such as slitname (name of the current slitmask) or graname (name of the current grating) fail to update when the corresponding stage is moved. This can lead to confusion, because XLRIS will then display the wrong name for the current slitmask, filter, grating, etc. Furthermore, the keywords written to the image header will be wrong.

  As a stopgap measure, the LRIS software has been revised to check every 60 seconds for invalid keywords, and to warn observers via the TkLogger window when invalid keywords are found. Observers can then fix the problem by executing the fixkeywords command from a punaluu xterm window. We will investigate this problem more fully with help from Caltech software support in April.

• Undefined blue optics. The optical mechanisms on the blue side (dichroics, gratings, and blue filters) are held in position by pneumatically-driven clamps. Recently we have seen evidence that these clamps do not always activate, leaving the optics undefined mispositioned. This can produce shifting of the resulting images or spectra on the blue side, or on the red side if a dichroic is in use.

  We will update the motor control software to deal with this issue as soon as possible. Meanwhile, the LRIS software will check every 60 seconds for unclamped blue optics and will warn observers via the TkLogger window when any are found. Observers can then execute the check_clamps script from a punaluu window to activate the clamps.

LRIS Collimator Recoated (16 Mar 2001)

The collimator mirror at the heart of LRIS has received a new high-tech coating and been reinstalled into the instrument. Prior to the LRIS-B upgrade the collimator was coated with silver, but this was changed to aluminum in mid-2000 in order to provide better UV reflectance. During the two-week LRIS downtime in March, this mirror was coated with a hybrid silver-on-aluminum coating at Lawrence Livermore National Laboratory. The new coating melds the best of both worlds, providing better UV reflectance than Al and red response comparable to silver. The chief effects observers should see are:

• Improved throughput at all wavelengths.
• Possible changes in the plate scale and astrometric mapping of the LRIS field-of-view due to realignment of the optics.

We hope to redetermine the mapping from pixel space to the sky in the near future.

LRIS Guider Filters Changed (16 Mar 2001)

A new set of broadband filters is now installed in both the slit-viewing and offset guiders. The set includes clear, B, V, and R filters. See the guider filter page for details.

LRIS User Script Library (12 Mar 2001)

LRIS now has a complete library of commands which can be used to control the instrument and telescope from the command line as well as from user shell scripts in order to perform complex operations. For more information, see LRIS Shell Scripts.

LRIS Update for March 2001 (08 Mar 2001)

Blue Side Filter Changes (26 Feb 2001)

The V filter for LRIS-B has been temporarily returned from the manufacturer in order for us to verify that the filter delivers double images. It has been re-installed into LRIS but is not expected to provide scientifically useful imaging capability. We expect to return it to the vendor shortly. The blue filter list has been updated accordingly.

New LRIS-R&B Logsheet (26 Feb 2001)

A new logsheet suitable for simultaneous red- and blue-side operation is now available online. It and others can be accessed from the LRIS logsheets list.

Dichroic Data Posted (21 Feb 2001)

A list of LRIS dichroics is now available, featuring transmission data for the four LRIS dichroics installed as part of the blue-side upgrade.

LRIS Update for February 2001 (07 Feb 2001)

LRIS FAQ Available (30 Jan 2001)

Answers to some frequently asked questions have now been assembled on-line for your convenience. While still embryonic, this version may help shed light on certain issues related to LRIS-B.

Grism Data Posted (30 Jan 2001)

A list of LRIS-B grisms is now available, featuring wavelength coverage and efficiency data for the four LRIS-B grisms.

Blue Side Filter Changes (26 Jan 2001)

The blue side of LRIS has lost one filter and gained another. The V filter, which has been rendered scientifically useless by delamination of the filter sandwich, has been returned to the manufacturer for servicing and is expected to be gone for several months. However, Chuck Steidel has generously supplied his Palomar U filter and it is now available for use. Prospective observers should note that this U filter is undersized and will significantly vignette the beam, passing only about 57% of the light. Chuck also reports that the G filter he has ordered for public use on LRIS-B (4730/1100) is expected to arrive in time for use during the March LRIS run.

Single-sided MALIGN Working (17 Jan 2001)

MALIGN-ing the telescope using only one set of PMFM exposures (a.k.a. ``single-sided MALIGN'') should work again now that we have redetermined the appropriate correction factor, and will become the default mode for running MALIGN. Completing a single-sided MALIGN takes only about half as long as the 2-sided MALIGN which we have been running lately on LRIS. If the primary mirror stack is suspect, two-sided MALIGN should still be run. Observers who prefer two-sided MALIGN for reasons of security are still welcome to request that the OA use it.

LRIS-B Overview Available (15 Jan 2001)

An LRIS-B Overview is now available thanks to Chuck Steidel, LRIS-B P.I. It provides a succinct introduction to the characteristics and vagaries of the new blue side of the spectrograph.

Don't Rotate While Guiding (14 Jan 2001)

A simple test tonight confirmed what some slitmask observers have seen for some time: if you attempt to rotate the instrument while guiding, the guide box will not follow the object. Until further notice, follow these steps when aligning slitmasks:

• take your mask exposure
• determine the solution (e.g., run xbox but do NOT send moves if a rotation is suggested
• ask the OA to turn guiding OFF
• send the move involving rotation
• ask the OA to resume guiding
• check alignment again

We are investigating the reasons for the failure.

XLRIS-Generated Scripts OK (14 Jan 2001)

We believe that scripts generated using the WRITE button on XLRIS now work properly; i.e., they do not arbitrarily insert blue optical elements into the optical path.

LRIS Update for January 2001 (11 Jan 2001)

XLRIS Bugs (03 Jan 2001)

Observers should be aware that LRIS currently has two bugs in it that can affect observing:

• Script generated with the WRITE button currently do not function properly. The problem is that the script insert a dichroic, grism, and blue filter into the beam even if none was in the beam when the script was written. We are awaiting a software fix for this. (fixed as of 13 Jan 2001)
• XLRIS will sometimes stop updating some items, leading observers to conclude that the instrument is not set up correctly (for example, it may indicate that your latest slitmask change was not made). If you feel the information displayed may be in error, use the following commands in a punaluu window to check the status of various stages:

  s slitmask  # displays current slitmask number
  s grating   # displays current grating number
  s redfnum   # displays current red filter number
  

  You can then use the consort command to translate from number to name.

Update on Secondary Misalignment and Optical Issues (24 Dec 2000)

Further testing of optical alignment suggests that the secondary is not significantly decentered from LRIS. In fact, we suspect that the rotator compensations to secondary piston were incorrect, resulting in significant focus change of LRIS with rotator angle. The secondary piston corrections have now been disabled. Observers are advised to monitor guider focus frequently in order to determine whether focus has degraded since the last MALIGN.

Also, please be advised that single-sided MALIGN is currently not returning correct values for secondary piston; hence, only double-sided MALIGN is recommended for use on LRIS until further notice. (note: fixed as of 15 Jan 2001)

Observers have recently reported that LRIS images exhibit significant distortion, even after running MALIGN. The effect is most noticeable on the leftmost part of the images. If your program consists primarily of direct imaging, you should ask the OA to disable LRIS tilt compensations to obtain the best image quality. Note that with tilt compensations disabled, focus will be expected to degrade more quickly than normal as the LRIS physical rotator angle (ROTPPOSN) changes. Check focus carefully and be prepared to re-run MALIGN when the physical rotator angle changes by 45° or more.

Blue Side Unavailable for December LRIS Run (24 Dec 2000)

The LRIS blue dewar has a faulty limit switch on its focus stage, preventing the dewar from focusing properly. Unfortunately, removal of the red dewar is necessary in order to make the repair. Since we do not want to put the red side at any risk for this run, we will not repair the switch until after the end of the current LRIS run on 1 Jan 2001. We hope to complete the repair before the mid-January LRIS run begins.

New Utility for Writing Tapes (18 Dec 2000)

A new program called mktartape makes writing tapes of your data virtually foolproof. The program has many features designed to make the process easier and prevent observer mistakes, such as:

• verifies the existence of the data directories entered by user
• allows observer to select any tape drive on the current machine without needed to know the name of the tape drive
• allows user to append new files to those already on tape
• can write multiple data directory trees to tape in one pass, putting each into a separate tarfile
• after writing data to tape can (optionally) verify tape while creating a tape log
• optionally rewinds and ejects tape at completion of writing

The script can be run from any observing account by going to the Openwindows pulldown menu, selecting the submenu called Instrument Utilities, and clicking the item labeled Make tar tape.

LRIS Update for December 2000 (14 Dec 2000)

Keck I Shutter Fixed -- Restrictions Lifted (7 Dec 2000)

The Keck I dome shutter is now repaired and observers can once again gain unvignetted access to the zenith.

Policy on the use of LRIS-B during Semester 2000B (1 Dec 2000)

LRIS-B has essentially completed its commissioning phase and is expected to be ready for regular use by observers beginning with the 2001A semester in February 2001. However, the instrument is not yet in its final state:

• The collimator remains coated with Al; we hope to increase red throughput by applying a silver-on-aluminum coating in March 2001. Instrument throughput is expected to change at that time, increasing by 10% in the red.
• The need to remove the collimator for recoating means that the plate scale (for both the blue and red sides) could potentially change.
• The U filter has delaminated and been returned to the factory for repair with an unknown return date, leaving the blue side with only B and V filters at present.
• There is as yet no science-grade detector for the blue side. The current detector is a very good engineering-grade SITe 2048×2048 chip very similar to the long-standing red side detector but with a little bit more blue sensitivity. We do not know when a UV-optimized science grade detector will be available.

Furthermore, the instrument documentation has not yet been received and the Instrument Specialists are not all trained in the use of the blue side. However, the instrument should be simple to use and can prove quite useful to observers for slitmask alignment and other applications. Thus, our current policy on the use of the blue side of LRIS is that the instrument is available only on a SHARED RISK basis. In practice, this means that observers are allowed to operate the blue side mechanisms and detector, but that Keck cannot fully support the instrument. So if (for example) the detector system hangs or a blue-side mechanism fails, we will not take extraordinary measures to fix them during the night. Of course, once the instrument is documented and all personnel have been trained, we will begin supporting the instrument fully. We hope to institute full support by the end of Semester 2001A (end of July 2001) as scheduled. However, we can offer no assurance as to when any of the hardware problems -- collimator coating, U filter, or detector -- will be resolved.

LRIS-B U Filter Out of Order (1 Dec 2000)

The U filter delivered with LRIS-B was found during commissioning to have severe optical problems. The manufacturer evaluated the filter and determined that it had delaminated. A new filter is begin fabricated, but will require custom optics to be made in Germany. A realistic date for receiving a replacement is June 2001.

Rs Imaging Filter Available (27 Nov 2000)

A new public "Rs" filter is available for LRIS observers thanks to the generosity of Chuck Steidel (Caltech). This broadband filter features higher peak transmission than the standard LRIS R filter (96% vs. 78%) and a sharper transmission profile. Although inspired by the so-called "Spinrad Night Sky Filter" in use for many years at Lick, this particular filter (generally referred to as the "script R" or filter in the literature) was originally defined by Mark Dickinson and Chuck Steidel in order to cut off the substantial red tail inherent to the Spinrad filter. The Rs passband is intended to be a nice compromise between R and I while maintaining a dark sky background (21.0 AB mag/arcsec^2 under moonless conditions at most sites, including those with broad Na D problems like Lick and Palomar). Its transformation to standard systems is given in Steidel and Hamilton (1993). Thanks to Grant Hill, plots and transmission curves are accessible from the LRIS General Filter List.

Run Copymon Automatically with "Autocopy" (22 Nov 2000)

Bob Goodrich has kindly automated the process of starting the copymon routine for mirroring your LRIS images to a HQ disk. If you select the Autocopy option under the LRIS Widgets item on the OpenWindows menu, it will select the best scratch disk, start copymon writing to that disk, and optionally copy over existing images (copymon only grabs new images).

Secondary Misalignment and Telescope Focus (21 Nov 2000)

All observers should be aware that the K1 f/15 secondary remains out of adjustment. We discovered last month that the cams which support the secondary were loose, and hence the position of the secondary has been changed by an unknown amount and must be recentered. We've acquired some engineering data which should allow us to measure the severity of the effect, but in the meantime you must assume that the secondary is off center relative to the instrument rotator. This is particularly important to bear in mind for LRIS observing, because it means that the rotator-dependent correction factor to the telescope focus is likely to be inaccurate. Until further notice, observers are advised to run autofoc or MALIGN whenever the PHYSICAL rotator position changes by 30 degrees or more since the last calibration.

Arc Lamps and Movable Guider (20 Nov 2000)

LRIS observers who calibrate their data using the internal arc lamps should be aware that their wavelength solutions may depend on the position of the movable guider stage. The arc lamps are physically mounted on the same stage which holds the movable guider; hence, as the movable guider changes position, the line lamps move in the direction perpendicular to the slits (i.e., in the wavelength direction). The result is that the illumination of the slitmask by the arc lamps may depend on the movable guider position (header keyword TV1FPOS), although we have not yet quantified the effect. Observers who require accurate wavelength solutions should:

1. Ensure that the movable guider stage is always set to the same position when taking arc lamp exposures. The most uniform illumination is found when the guider is near the low end of its range (TV1FPOS=216).
2. Use night sky emission lines to verify wavelength solutions.

Slitmask Disposal (17 Nov 2000)

Space limitations at the summit have forced us to change our policy on keeping old LRIS slitmasks. Previously, we saved all slitmasks in case they were needed in the future. In practice, we've found that few of these masks were ever re-used. As of October 2000, we will begin discarding LRIS slitmasks immediately following a run unless the observer requests otherwise. Note that we will permanently maintain the design file used to manufacture the slitmask, allowing it to be re-milled if it is needed in the future. Observers wishing to have their slitmasks retained are welcome to request for them to be mailed to their home institution following the observing run.

LRIS Update for December 2000 (15 Dec 2000)

Keck I Dome Problems Limit Observations (6 Nov 2000)

We recently experienced another mechanical failure with the Keck 1 Dome Shutter, this time in one of the 8 cables that moves the top shutter. Although troubleshooting has been severely hampered by an extended bout of bad weather, we have determined that it is safe to open and close the Keck 1 top shutter, but with some restrictions on the range of movement. Until the damaged cable is replaced, we cannot fully open the top shutter. Movement is limited to a shutter position of 90 degrees, which means that the telescope beam starts to see the top shutter at a telescope elevation of about 75 degrees. Higher telescope elevations will of course see more of the shutter, and the effects will of course be most severe in the thermal IR.

We have a replacement cable on rush order. IF the weather cooperates, we hope to have the replacement cable installed and properly tensioned in about 2 weeks. Working on this problem requires opening the dome during the day, so any bad weather will cause a direct delay in the repair schedule. The shutter movement restrictions will be in force until the repairs are complete and tested. I will notify you again as soon as the repairs are complete.

Thanks for your cooperation and understanding during this problem.

David Sprayberry
Associate Director for Observing Support

New Version of UCSCLRIS IRAF Package Released (25 Oct 2000)

Version 1.0 of the IRAF package UCSCLRIS has been released for use. This package contains two tasks commonly used by observers during the slitmask alignment process:

• xbox will check the image header to determine whether images were taken with the red or blue camera (INSTRUME keyword) and will adjust the pixel scale accordingly to make accurate offsets for slitmask alignment. Also, the safety prompt will appear even if you run the task using the :go directive in the parameter editor.
• mshift has been updated to prompt the user for the camera name (red or blue) and to set the pixel scale appropriately. (Note: the movr and movb commands available from the punaluu command line provide similar capability and are recommended.) As with xbox, the safety prompt will now appear even if you run the task using the :go directive in the parameter editor.

New LRIS Widgets Available (25 Oct 2000)

Three new widgets are available from the LRIS OpenWindows pulldown menu under the heading LRIS Widgets:

• Xfocus analyzes focus data acquired with the focus_holes slitmask to determine the internal LRIS focus.
• Xarcplots produces arc line plots at any desired central wavelength and with any combination of line lamps.
• Xdither allows observers to define a series of spatial offsets and acquire images in a pattern. This widget was previously available from the LRIS IDL Tools menu.

LRIS Red & Blue Image Scales Measured (24 Oct 2000)

LRIS-B P.I. Chuck Steidel (Caltech) has made measurements of the new pixel scales on the red and blue sides. His estimates are:

• LRIS-R, w/dichroic: 0.2109 arcsec/pix
• LRIS-R, no dichroic: 0.2109 arcsec/pix
• LRIS-B, D560 dichroic 0.2151 arcsec/pix

The scripts movr and movb which move the telescope in red and blue pixel space, respectively, have been updated with the new pixel scales.

Adjustment to Pickoff Mirror Coordinates (16 Oct 2000)

Observers who design slitmasks with pickoff mirrors using the UCSC software package need to be aware of a change. This software provides the pixel location onto which you should place the alignment star in order to get your objects into the slits. Due to realignment of the slit-viewing guider, the field of view has shifted slightly and hence, the coordinates have changed. Until further notice, observers should apply the following offset to their pickoff star coordinates:

• deltaX=+3
• deltaY=-24

LRIS Red Image Scale Changed (25 Sep 2000)

Initial results suggest that the pixel scale of LRIS images has changed by about 1.9% since the summer refurbishment, which included adjustments to several elements in the optical path. The new pixel scale appears to be around 0.211 arcsec/px, versus 0.215 arcsec/px prior to the upgrade. This change has two important operational implications for LRIS users:

• Because it relies on exact knowledge of the LRIS imaging scale, the FIGDISP-based slitmask alignment software will no longer work. Observers should plan to use the xbox software package until we remap the image plane.
• Images acquired since the upgrade cannot be used with the coordinates software to produce slitmask designs. Observers must continue to use pre-upgrade images in order to generate accurate coordinates for slitmask designs.

We have not yet derived a new plate solution for the refurbished instrument, but will plan to do so after work on recoating the collimator mirror is completed late in 2000. We thank Judy Cohen for providing numbers on the pixel scale changes.

Dual-Amp Readout Mode Restored (25 Sep 2000)

Reprogramming of the Leach controller for the red side of LRIS appears to have eliminated the previous problems with freeze-up during dual-amp image readouts. Observers may now return to using dual-amp readout mode for all LRIS images.

Observations Restricted to Single-Amp Readout Mode (31 Aug 2000)

The new LRIS CCD system has proven to be very prone to getting stuck when operated in dual-amp readout mode. Although the recovery procedure is well defined and the recovery time should be short (5 minutes or less), the glitch results in losing part or all of the image. Since single-amp-mode images do not show this problem, observers are advised to use single-amp mode for all nighttime exposures while we work to diagnose and fix the problem.

'movr' Replaces 'imoffset xy xy' (28 Aug 2000)

The FIGARO command imoffset xy xy, long used by observers to move the telescope in LRIS red detector coordinates, has been replaced by a new script call movr. The syntax of the commands is essentially the same, the arguments being:

• current x coordinate of target [pixels]
• current y coordinate of target [pixels]
• desired x coordinate of target [pixels]
• desired y coordinate of target [pixels]

Once the blue side is commissioned, a corresponding movb command will enable moves in blue detector coordinates.

LRIS-B Upgrade Status (14 Aug 2000)

LRIS has been out of commission since early May for installation of the new blue side of the spectrograph. Work also included major changes to the electronics and computers associated with the instrument. Due to the diligent efforts of the LRIS-B team from Caltech and many staff members at CARA, the installation of all optical systems is complete and the red beam of LRIS is being prepared to return to regular service as scheduled on August 22. Long-time LRIS-R users will notice some minor changes in the instrument, but red-side operations should be mostly unchanged.

Although the LRIS-B optics are installed and working, the science-grade CCD array for the blue side has been returned to Caltech for servicing. It is still months away from being installed and will also take some time to commission and characterize. At this point, the likelihood of releasing the blue side for science during the 2000B semester is small; however, with luck we hope to have the blue side available for shared-risk observing in the 2001A semester.

See also the following items describing additional changes which will impact LRIS users in 2000B.

New LRIS Internal Focus Procedures (14 Aug 2000)

Recent testing during LRIS re-commissioning nights suggests that the internal LRIS focus on the red side can vary significantly (60 µm or more) on timescales of several hours. Although the source of the variation is not yet certain, it may be caused by temperature changes which affect the red camera. It is likely that this has always been the case, but we were previously unaware of this situation.

Furthermore, testing has shown that focus values obtained from images with internal or dome illumination do not correlate well with on-sky focus values; hence, we recommend that focus be checked on-sky, ideally during twilight. Until we have characterized the dependence of focus on temperature, all observers should plan to refocus the spectrograph during evening twilight and possibly at various times throughout the night.

Since the focus values for each filter will not be constant over time, we will no longer be posting recommended focus values for each filter on the bulletin board and the web pages; instead, we will post focus offsets for each observing mode and filter relative to the direct imaging R-band focus. Observers will be expected to measure the R-band focus and thus obtain correct focus in other modes based on these offsets.

New software now allows the internal focus to be checked in under 10 minutes during twilight illumination. However, using this method requires that you have the focus_holes.eng mask installed as part of your slitmask complement; thus, you will have room for only 8 other slitmasks.

To summarize the new recommendations:

• Observers will be responsible for measuring instrument focus.
• Plan to devote 10 minutes of twilight to checking the R-band focus, as dome and internal illumination do not adequately simulate the incoming beam from the sky.
• Request focus_holes.eng slitmask on your LRIS configuration form to enable use of new focus software

For further information, please or consult the LRIS web pages.

Throughput decreased due to collimator re-coating (14 Aug 2000)

In order to provide acceptable UV throughput with LRIS for using the blue side, we have replaced the old silver coating on the LRIS collimator mirror with a new aluminum coating. While this will help the blue/UV throughput of the instrument, it also decreases the red throughput by about 10%; hence, observers will require integrations lasting 10% longer in order to achieve the same S/N in the red as with the old LRIS collimator coating. By the beginning of the 2001A semester, we hope to have the collimator re-coated with a special silver-on-aluminum process which will provide uniformly high throughput from the atmospheric cutoff in the UV out past 1µm in the red.

Host Computer Upgraded (14 Aug 2000)

The downtime for LRIS-B allowed us to upgrade the LRIS host computer from an old SunOS workstation (manuka) to a much faster new Solaris-based workstation (punaluu). The following notable changes to software were also made:

• XLRIS has changed significantly, with control buttons now installed for blue-side mechanisms (dichroics, grisms, blue filters, and blue focus); however, during 2000B observers should not move these mechanisms unless given permission by the instrument specialist.
• Xpose has been upgraded but will work essentially the same as before.
• FIGDISP has been upgraded for use with Solaris and the old DataViews-based interface has been replaced with Tcl/Tk controls. Note: the key bindings for operations like FWHM measurements and row plots have changed; please see the FIGDISP help page for details on the new keybindings.

WMKOLRIS IRAF Package Release 1.0 (06 Jun 2000)

Release 1.0 of the wmkolris IRAF package is now available on the HQ network. The only major change is an update to the lrisbias task which subtracts overscan from images taken in either single- or dual-amp readout modes. The task did not treat properly the case of subwindowed data in dual-amp mode. Note that ESI observers can also use this task to de-bias their data. Release 1.0 is now available for downloading on the Keck FTP server.

LRIS Moves Back to Keck I (24 Feb 2000)

After a long sojourn on Keck II, LRIS has returned to operation on the Keck I side, providing a true dark-time instrument on both telescopes for the first time and enabling eventual silvering of the primary mirror on Keck II. The most was completed with only minor glitches affecting startup on Keck I. Observers should bear in mind that the western pointing limit required on Keck II no longer applies, but that an eastern limit now affects LRIS observations.

New Narrowband Filter Available (27 Jan 2000)

A new public filter is available for LRIS observers thanks to the generosity of Hy Spinrad (UCB). This narrowband filter features a 100 Å-wide passband which (unfortunately) varies radially, changing from a central wavelength of 8536 Å at the filter center to 8605 Å at the outer edge. Plots and data representing one cut across the filter are accessible from the LRIS General Filter List.

Imaging Foci Recalibrated (02 Jan 2000)

During the LRIS engineering nights of 31-Dec-1999 and 1-Jan-2000, the focus values for all common imaging filters were re-measured using night sky illumination. The revised filter values have been posted online and incorporated into the redfocus command to enable automated focusing of the spectrograph from within shell scripts.

LRIS Red Shutter Accuracy Measured (17 June 1999)

The finite length of time it takes LRIS to open and close the shutter yields different effective exposures times at the detector center verses the edges. Engineering test T893: LRIS Shutter Timing Test was recently completed in order to quantify the effect. This systematic effect is less than 1% in 2 seconds with LRIS. This does not necessarily mean that any single exposure of 2 seconds is accurate to 1% in exposure time, because a random component to the shutter opening time may exist, which would increase the uncertainty.

Guider Filters Changed (16 June 1999)

Since the LRIS slit-viewing guider filter wheel remains inoperative pending software changes to take effect in late June, the filter wheels for the slit-viewing and offset (movable) guiders have been exchanged. The offset guider now has available clear, B, R, and I filters, and the slit-viewing guider is set to clear. The guider filter list has been updated accordingly.

LRIS Scripting Macros Available (1 June 1999)

Bob Goodrich has ported to LRIS many of the useful macros which NIRC observers use to write their own observing scripts. These commands allow shell scripts to set up the spectrograph, define exposure parameters, start exposures or exposure sequences, and move the telescope. Please see the document Script Control of LRIS for further discussion.

New Filter Transmission Curves (26 May 1999)

Newly-measured transmission curves are now available on the LRIS Filter List web page. In addition to PostScript plots of the passbands, raw data are available as ASCII text and FITS images. Also listed are filter bandwidths and effective wavelengths.

600/10000 Grating Now Available (21 May 1999)

A new gold-coated 600-line grating blazed at 1µm is now available for general use with LRIS, courtesy of Alan Stockton (U. Hawaii). Although we have not yet completely characterized this 600/10000 grating, it is expected to provide superior throughput to the 600/5000 and 600/7500 gratings in the near infrared.

LRIS Imaging Mirror Realigned (18 Mar 1999)

For several weeks the LRIS imaging mirror has been out of adjustment, causing the center of the imaging field-of-view to lie well of the center of the detector. The mirror has been re-aligned to put the center of the field of view (and the slitmask crossbar) within 20 pixels of the CCD center. A locknut was noted to be missing during this procedure, possibly explaining the drift in angle.

ESO Spectrophotometry Catalog Link Available (16 Mar 1999)

Esther Hu brought to our attention the nice on-line catalog at ESO which gives finding charts and spectral plots for various spectrophotometric standards. The link is now available through the Calibrations Menu.

Autoslit Documents Available in HTML Format (16 Mar 1999)

The documents Introduction to Autoslit and the Autoslit3 Manual are now available on-line in HTML format for your reading enjoyment.

WMKOLRIS IRAF Package "Alpha" Release (16 Mar 1999)

The first release of the wmkolris IRAF package is now available on both the summit and HQ networks. The package contains two tasks: lrisbias subtracts overscan from images taken in either single- or dual-amp readout modes, and lccdproc is a version of the ccdproc task modified to use lrisbias for overscan removal. Observers can access the package for data reduction at Keck by starting IRAF and typing wmkolris. The package is also available for downloading and installation at home institutions.

New Tool Sets LRIS Red Camera Focus Appropriately (15 Mar 1999)

The redfocus command allows scripts to always set the LRIS red camera focus to the appropriate value, even when the focus values change. Given the current filter and observing mode (direct, longslit, or multislit) as command-line arguments, this script will read the current focus values from a lookup table (maintained by the LRIS Instrument Specialist) and set the focus accordingly. The observer can also override certain focus settings by using a ``personal'' version of the focus table.

Scripter Program Eases LRIS Setup-Script Composition (15 Mar 1999)

The Scripter web-based LRIS setup script composition tool has been released for public consumption. This program will generate an LRIS setup script based on the settings filled in by the observer on the input form. All the observer needs to do is fill out the form, download the script, and install it in the ~/setups directory on punaluu, the LRIS control computer. The script can then be executed via the GO button on XLRIS.

LRIS Focus Values Updated (12 Mar 1999)

Focus images taken during the last engineering run in late February showed that the R-band imaging focus for LRIS had changed by about 30 microns, a relatively minor change. In response, the LRIS focus values web page has been updated with all values increased by this amount. More comprehensive data will be taken at the next available opportunity.

All Grating Stations Operational Again (2 Mar 1999)

All grating stations are now functioning normally again thanks to the efforts of the capable summit techs. Grating station 3, which had been flaky, was repaired and returned to service. Observers may return to using 4 gratings per night.

Movable Guider Slippage Fixed (22 Jan 1999)

The LRIS movable guider was repaired --- the problem turned out to be a broken brake and a loose set-screw. This should eliminate the slippage noted since December and return operation of the guider to normal.

LRIS Now Initializes on Startup (10 Dec 1998)

The script to startup the LRIS control software has been changed to include an optional LRIS initialization step. Running this script when you first start the instrument will return all LRIS settings to their default configuration, undoing any changes that the previous observer may have made. You may also wish to execute the script on succeeding observing days to undo any changes made by CARA staff during the day. The script window will appear automatically once you select the "Start Up All LRIS Control" option under the "LRIS Control Menu" pulldown menu, and must be run or dismissed before other LRIS control windows (Xpose, XLRIS, etc.) will appear.

LRIS Rotator Repaired (07 Dec 1998)

The badly degraded LRIS rotator bearing was replaced during the first week of December and initial tests indicate that the friction has been reduced to nominal levels. Correspondingly, the maximum LRIS rotator slew rates have been increased from 0.75 deg/sec to 1.5 deg/sec.

Intermittent Banding Noted in Spectral Flats (30 Oct 1998)

Ratio of two flats

Spectroscopic-mode flatfields taken with the internal halogen lamp have shown intermittent banding across the illuminated portion of the chip. As shown in the accompanying image, the symptom of this behavior is diagonal banding seen in the ratio of two flatfields. The banding is subtle, much lower in intensity than the fringing already present in the chip, and thus may not be visible in a single image. It can appear and disappear within the span of a few minutes. Please report any further instances of banding that you observe.

Get Notified When Readout Is Complete (14 Oct 1998)

LRIS users are familiar with the automated announcement ``exposure complete'' provided by the datataking system. A new widget now allows you also to be notified when the CCD readout is complete and a new exposure can be started. The Readout Complete Audio Notifier Widget starts automatically when you select the Start Up ALL LRIS Control item from the pulldown menu, and allows you to select the sound you'd like to hear when readout has completed.

LRIS Slitmask Holder To Be Re-Designed (7 Oct 1998)

A design effort is underway to replace the existing LRIS slitmask crossbar constraint with a holder that mounts to the side of the slitmask frame, thereby eliminating the crossbar as an obstruction to object slits. An accessory to this holder will be a new pickoff mirror mount that will bolt to the side of the slitmask frame, extending into the beam with an arm the approximate cross section of the existing crossbar. This replacement hardware provides an opportunity to increase the available area for the pickoff mirror field, up to a factor of roughly 2, by extending it in the LRIS field Y-axis into the field visible in the guider on the other side of the existing bar. The new pickoff mirror mount will be fixed and should eliminate the current problems of rotation and vignetting of the beam.

So, this is a poll to find out if users would benefit from an increased pickoff field size, and whether we need be very particular about the size and dimensions of the field; or, are content with the existing size (35 arcsec square) because more area is available for slit placement (indeed object field area increases with this mount even with the same reflecting field, because the existing pickoff mirror mount and crossbar will disappear). Also, if we do keep the existing field size, would it be acceptable to offset it to center in the slitmask frame? In any case note that the slitmask design programs will need to be modified to map the new mirror and mount obstruction, and eliminate the crossbar.

Thanks in advance for your input, and feel free to forward this note to any LRIS multi-object observers that I may have missed in the list.

Tom Bida

LRIS Shutter Problems (15 Sep 1998)

The LRIS shutter control system has been returning error conditions intermittently, causing CCD exposures to fail. Inspection of the shutter mechanism suggests that it is working fine, and that the problem is a faulty limit switch. We have temporarily disabled the circuit which returns the error code to the LRIS control software. Although we expect no problems, observers should be on the lookout for any symptoms of shutter malfunction. Failure to open is indicated by all exposures being ``dark,'' while failure to close would manifest itself as a strong gradient in the background level from the top of the chip to the bottom, as well as pronounced vertical streaking in the resultant image. The shutter limit switches will be checked when LRIS next comes off the telescope in late September. Update: The shutter mechanism failed due to a broken part on 17 Sep, and the broken part was fixed, restoring normal operation.

``copymon'' Script Provides Automated Image Copies (5 Aug 1998)

The new script copymon available on pelekane will automatically copy incoming LRIS images from the datataking system's output directory into another directory for quick reduction. The user can start this script running in the afternoon and allow it to run all night (it terminates automatically after 10 a.m.). This frees the user to worry about reducing the images rather than having to manually check for new incoming images and copy them over. Please see the help page for copymon or consult your Instrument Specialist for further information.

Observer Accounts Enhanced (31 Jul 1998)

In response to observer requests, the following enhancements have been made to the numbered LRIS accounts in Waimea:

• The default login shell was changed from csh to tcsh.
• The default login windows have been changed from shelltool and cmdtool to xgterm type, allowing full support for tcsh command-line editing.
• IRAF and IDL are now accessible from the top-level menu on the window manager. For reasons of setting environment variables properly, use of the pulldown menu to launch IDL and IRAF is preferred over typing cl or idl on the command line.
• IRAF has been upgraded to allow use of the cl or ncl command shells, and the Ximtool, SAOtng, or SAOimage display tools on all HQ Unix machines (SunOS and Solaris).
• Startup of IRAF has been simplified by a script which launches both the command shell of choice and the image display tool of choice.
• The TAPE environment variable is set to the Exabyte drive name if one exists on the machine to which you log in, enabling easier operation of the tape drives.
• The most recent TeX/LaTeX/BibTeX and friends (including xdvi) are now available on Solaris machines so you can write up and submit your results before going to bed in the morning.

LRIS Grating Turret Troubleshooting Guide (23 Jul 1998)

John Cromer has now provided three new macros to help LRIS users diagnose and fix the most common causes of LRIS grating move failures. These are documented in the LRIS Grating Turret Troubleshooting Guide. Please consult your Instrument Specialist before attempting to execute these macros.

Motor Troubleshooting Guide (05 Jul 1998)

John Cromer's LRIS Motor Control Software Troubleshooting Guide is now available on-line. This is really meant for use by the Instrument Specialists and other ``black-belt'' LRIS users --- please don't use this unless you really know what you're doing. Some of the low-level commands lack safeguards and can potentially damage the spectrograph.

Improve Slitmask Alignment Efficiency with Zeroth Order Imaging (09 June 1998)

Observers have reported success performing slitmask aligning using zeroth-order imaging with the gratings. This can save nearly 8 minutes per mask over the traditional method of inserting the mirror to take mask alignment images. See this document for more information.