LRIS Red CCD Image Readout Problem Update
(2009-Nov-9)
-
The LRIS Red CCD and electronics were shipped back to the W.M. Keck
Observatory 4 Nov. 2009 and was reinstalled in LRIS in
time for the upcoming LRIS run starting 9
Nov. 2009. Although the charge transfer efficiency problem
is not fixed, the UCSC team has made tremendous strides to
recover a half of the detector that is closest to the
gap. This means that in two-amp readout mode about 2/3 of
the illuminated area of detector 1-12 is usable. As a
reminder, the region on which the longslit spectrum
typically falls is not affected as it falls on detector
1-13 (functioning normally). Imaging or multislit
spectroscopic science programs requiring the entire FOV
are impacted by this problem. For observers who want or
need the full LRIS FOV to achieve their science goals, the
array may be read out in single-amp mode to recover the
entire LRIS Red FOV at the cost of increasing the readout
time, as indicated in the table below..
Although the UCSC team was able to recover half of the CCD, the serial
CTE, gain, effective readnoise, and linearity is degraded
relative to values determined at commissioning. Below are
preliminary performance results which will be confirmed
after the system is re-installed in LRIS. These performance
numbers mostly pertain to the 1-12A half of the CCD. The
performance of the second half (1-12B) has not been
quantified completely but is in general worse. If observers
want to use the full array, we are recommending that
detectors be readout in single-amp mode. In single-amp mode,
the 1-12A specifications will apply to both A and B sides of
detector 1-12.
The gain and readnoise for 1-12A are now 1.224 (e-/DN) and 6.52
(e-/rms), while at commissioning three months prior the
values were 1.022 (e-/DN) and 4.67 (e-/rms). The UCSC team
also measured gain and readnoise for 1-12B: current -
1.171 (e-/DN) and 12.9 (e-/rms) vs before 0.955 (e-/DN)
and 3.79 (e-/rms).
The CTE for 1-12A as measured using deferred charge (ratio of
signal in the last column to that left behind in the
over scan) is not constant, but it depends on signal
level. The main effect of the smearing will spread 13%,
2%, and 6% of the object flux in the spatial direction
for signal levels of < 250, 1000-15000, and >15000 DN,
respectively. This flux will be smeared into the sky
where it will be difficult or impossible to recover.
The bad CTE at high intensity levels will be a problem
for flats as there are many sharp features in the flats
and those will not be recovered well with bright flat
exposures that smear.
Detector 1-12A is linear to 50,000 DN, while 1-12B appears to be
non-linear. Once LRIS is installed in the instrumen,
we will be able to better quantify linearity.
READOUT TIMES:
AMPMODE XBIN YBIN Readout time Total (Erase + Readout)
-------- ---- ---- ------------ -----------------------
DUAL:L+R 1 1 83s 100s
SINGLE:L 1 1 153s 170s
DUAL:L+R 2 1 51s 68s
SINGLE:L 2 1 90s 107s
DUAL:L+R 1 2 45s 62s
SINGLE:L 1 2 81s 98s
DUAL:L+R 2 2 30s 47s
SINGLE:L 2 2 49s 66s
LRIS Red CCD Image Readout Problem Update
(2009-Oct-30)
-
The UCSC team checked the internal connections and they all
appear to be good and replaced a cable. After cooling down and
testing, the problem persists. In the short term, we have
decide that the dewar will be shipped back to Keck Nov 4 so
that the good ccd (1-13) may be used for the upcoming
science run starting Nov 9. While LRIS is on sky, the UCSC
team will have two parallel troubleshooting activities. Test
an engineering grade detector in their test setup to
determine whether broken
connections can reproduce the problem. Second, they will
play with waveforms on CCD 1-12 (poorly performing detector)
while LRIS is installed. If
the waveforms can be adjusted to obtain normal readouts,
then 1-12 can be made available for use during the November
run.
Observers who will be using slitmasks, should be aware
which region is available on the red side. This
slitmask image shows
where slits may be placed to land on the good CCD on the red
side. The image is example Autoslit3 output. You are not
limited to using just the top half of a
slitmask but you should consider the locations of your
highest priority objects.
LRIS Red CCD Image Readout Problem Update
(2009-Oct-26)
- The dewar and associated electronics arrived at UCSC Monday
morning. Upon arrival, the dewar was opened after
backfilling with ultra-dry N2, and internal cabling and
connectors were inspected. UCSC staff also examined the wire
bonds on the CCD, and a series of
photographs that show that all bond wires appear to be
intact. Thus far, nothing obvious was discovered in the
initial internal component investigation.
Late Monday, UCSC staff re-assembled everything, replacing a flex
cable with a spare. The dewar is now on the vacuum pump, and
the plan is to cool the dewar Tuesday morning with testing
to follow in the afternoon.
LRIS Red CCD Image Readout Problem Update
(2009-Oct-24)
- The LRIS Red Dewar and electronics were removed from LRIS
following the last night on sky in October and was shipped
back to UCSC for further investigation by the instrument
team. Upon arrival at UCSC, the dewar will immediately be
opened and internal components investigated. In parallel, the
electronics will be tested with their test dewar to ensure
proper operation. At this time, we fully expect the dewar
to return to Keck for use during the November run with at
least one normally functioning CCD.
LRIS Red CCD Image Readout Problem Update
(2009-Oct-10)
- As most of you are aware, one of the CCDs in the new LRIS Red detector
mosaic is experiencing a charge transfer efficiency
problem. Troubleshooting has determined that the problem is
internal to the dewar. Friday, we decided to send the LRIS Red
dewar to UCSC to attempt a repair of the poorly performing CCD
immediately following the current LRIS run ending the morning
of Oct 24. The dewar and associated electronics will be
removed from LRIS on Oct 24 and then shipped to UCSC on Oct
25. At UCSC, the dewar will be opened and internal components
inspected. Small repairs will be completed if the identified
issues are obvious and easily fixed. Repairs that will require
parts with long lead times or otherwise deemed longer term
will be deferred to a later date. If repairs are deferred, the
dewar will be returned as-is to the observatory so that at
least one working Red CCD is available for upcoming science runs.
At this time, we fully expect the LRIS Red CCD mosaic to be ready in
time for observing during the November and December observing
Runs. We expect the Red side to function with at least the
currently 1 good CCD, and hopefully, a repair of the poorly
performing CCDs will be successful. As with any repair
mission, there is a small risk that the system will not be
available during your observing session due to circumstances
as yet unknown, but we firmly believe the risk of LRIS Red
being unavailable is very low. We will of course notify observers of
any changes critical to LRIS red observing, and please view
the LRIS News pages for regular updates.
LRIS Red CCD Image Readout Problem
(2009-Sep-14)
- One of the two CCDs in the LRIS red mosaic is reading out
incorrectly for undetermined reasons. The problem affects half
of the red mosaic and is characterized by a general smearing of
the image in the vertical direction, as shown in the bottom half
of the accompanying image of a longslit
spectrum. Data from the affected detector are probably
unusable. Fortunately for longslit observers, the region on
which the longslit spectrum typically falls is not affected.
Our investigation so far has eliminated all of the
easily-accessible components of the CCD readout chain as
culprits. Further testing of dewar electronics will take place
after the completion of the September LRIS run.
Updated Versions of multi-HDU Readers Handle Binned Images
(2009-Jun-19)
- The original versions we provided of the IRAF and IDL
routines for reading the new LRIS images were unable to read
data acquired in binned formats. We have now given both tools
the ability to read binned data. Download the latest versions
of the tools in the links shown below.
IDL Routine Reads multi-HDU LRIS Images
(2009-Jun-17)
- As a service to the LRIS community, we provide an IDL
routine which will read mutli-HDU LRIS images and assemble
them into a 2-D array, with optional bias subtraction.
Download the readmhdufits.pro routine here.
Sample LRIS Images Available (2009-Jun-17)
-
As part of the May 2009 upgrade to the LRIS Red Dewar, the
instrument datataking system has been revamped to output data
in a different format. LRIS images now consist of multiple
"header data units" (HDUs), one per CCD output amplifier.
These images require different handling from the old IRAF
images, which were written as simple FITS files combining data
from all amplifiers. As a service to the LRIS user community,
WMKO is providing a set of sample images to allow observers to
work with the new data format. The collection can be
downloaded here
and includes both raw, multi-HDU images as delivered by the
datataking system and simple FITS images generated using an
IRAF task.
KECK.LRIS IRAF Package Updated for Red Upgrade
(2009-Jun-09)
- The keck.lris IRAF package has undergone a
complete revision to support the new image formats now generated
by the LRIS red and blue datataking systems. See this article for full
details. Users may download the entire keck package
here.
LRIS Red Upgrade: Big Red Arrives (2009-May-14)
- The LRIS Red Upgrade project started the installation phase
earlier this month. In the last two weeks, the old LRIS red
camera and associated electronics were removed
from LRIS. The new camera and dewar arrived today and is
headed to the summit on Friday. Thus far, the installation
is on schedule with first light on slated for June 6 & 7, and the first
official science night scheduled for June 14. Observers have
been asking about the improved FOV and spectral coverage. At
this time we have not verified the pixel scale or
increase in coverage. The predictions are that the pixel
scale will be around 0.13 arcsec/pix with the change from 24
to 15 micron size pixels. Given the mosaic detector size,
the new camera should increase the spectral coverage by around 25%.
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.
