This Manual is intended primarily for those planning to use NIRSPEC for observations. Separate technical documentation is available for maintenance and repair of the instrument, and for software development.

NIRSPEC, a joint project with UC Berkeley, was built at the UCLA Infrared Imaging Detector Laboratory. Funding for the project began in October 1994 and the instrument was delivered in March 1999. FIRST LIGHT was obtained on April 25 1999. Professor Ian McLean of UCLA served as the Principal Investigator and Project Manager and Professor James Graham of UC Berkeley was Project Scientist. Other members of the team at various times included, Professor Eric Becklin (Chair, Science Advisory Team), Maryanne Angliongto (Electronics), Professor Oddvar Bendiksen (Mechanical Engineering consultant), George Brims (Project Engineer/ Systems Design/ and software), Leah Buchholz (Calibration Unit), John Canfield (Mechanical Design), Dr. Don Figer (Optical Design), Jonah Hare (Calibration Unit), Jim Kolonko (Business Manager), Fred Lacayanga (Software), Professor James Larkin (Software and System Integration), Dr. Samuel Larson (Motion Control & Slit-Viewing Camera), Dr. Nancy Levenson (Data Reduction Software), Dr. Tim Liu (Software), Nick Magnone (Senior Mechanician), Mavourneen Roberts (Data Analysis), Gunnar Skulason (Electronics Technician), Michael Spencer (Electronics), Dr. Harry Teplitz (Software), Jason Weiss (Software) and Woon Wong (Electronics).

It is a pleasure to acknowledge all of these people, together with the shop staff of the Physics & Astronomy Department, and the Engineering Department at UCLA.

On behalf of the entire NIRSPEC team, I would also like to take this opportunity to thank all the members of the CARA staff who helped and supported us throughout the development and delivery of this instrument. A special thanks to Tom Bida, the CARA Instrument Specialist for NIRSPEC. We are also indebted to the many industrial partners who constructed the various sub-systems, including DSP Systems Inc., ISP, National Aperture, Optics 1 Inc., Photometrics Ltd., Rockwell International, Richardson Labs, SBRC-Raytheon, Schwartz Industries, SSG, Speedring Systems and Weld Lab.

Thank you all.

Ian S. McLean, Professor,

Principal Investigator

UCLA

August 18, 1999

NIRSPEC is an all-reflective, near-infrared, high-resolution spectrograph for the Keck II Telescope which is designed to operate over the wavelength region 0.95 to 5.4 microns (F m). To cover this wavelength range efficiently at high spectral resolution, the instrument uses a cross-dispersed echelle grating and is therefore an infrared analog to HIRES. Unlike its optical counterpart however, NIRSPEC is a vacuum-cryogenic instrument operating at about 60 K.

In normal use, NIRSPEC will be mounted on the Right f/15 Nasmyth platform of the Keck II 10-meter telescope. It may also be located behind the Adaptive Optics system on the Left Nasmyth platform, but it is not optimized for AO. For its primary spectrographic detector, NIRSPEC employs an indium antimonide (InSb) array with 1024x1024 pixels from Raytheon-SBRC, but there is also an infrared slit-viewing camera (S-CAM) with a field of view of 46x46 arcseconds and a pixel scale of 0.18O /pixel. This camera utilizes a mercury-cadmium-telluride (HgCdTe) infrared array with 256x256 pixels and a cut-off wavelength of 2.5 microns. The SCAM shares the same filters as the spectrograph optics. In addition, NIRSPEC has a CCD camera which can image the annular field around the SCAM field onto a 1024x1024 SITe chip. Either camera can be used for guiding.

In the dispersion direction at high resolution – the Echelle mode – each pixel represents 0.144 arcseconds and the resolving power is R » 25,000 (12 km/s) for an entrance slit of 0.43 arcseconds (3 pixels) width. Since NIRSPEC contains a single echelle grating and a single cross-disperser, about 25 grating settings are required to span the entire wavelength range (with overlaps) in Echelle mode. Only in the NIRSPEC-1 band at 1.07 F m does almost all of the free spectral range of each order fall on the detector. In other bands the echellogram overfills the 1024x1024 array.

There is also a Low Resolution mode covering the same wavelength range at R » 2,200 (for 2 pixels) in only a few (7) settings. One pixel in this low-resolution mode is 0.19 arcseconds. The scale along the slit length (spatial direction) is 0.198 arcseconds per pixel and 0.143 arcseconds per pixel in the high- and low- resolution modes respectively; this difference is the result of the TMA camera which has a different focal length for the two orthogonal directions.

A small selection of slit widths is available (see next section), and slit lengths are either 12" or 24" in the Echelle mode, or 42" in the Low Resolution mode. NIRSPEC includes a cryogenic image rotator for selecting position angles and for removal of field rotation. There is also a built-in Calibration Unit with four arc lamps and a white light source.

The astronomer can control NIRSPEC by means of a Graphical User Interface (GUI) and Echelle Format Simulator (or EFS). The EFS allows the user to visualize the expected layout of cross-dispersed spectral orders (the "echellogram") for any possible setting of the instrument. Each set-up can be stored and the program can also create observing "scripts" which can be executed to drive the instrument and collect data. Status information, e.g. the position of gratings or filter wheels, or the time remaining on the exposure, or the detector temperatures, or information about the calibration/guider unit, are all shown on special screens. Images from either the spectrograph or the SCAM are displayed using an IDL-based Quick Look package.

Access to the right (f/15) Nasmyth focal station of Keck II is shared with DEIMOS. In normal operation, NIRSPEC will remain cold and powered-up even when it is in its parked position on the Nasmyth platform. It is expected that DEIMOS and NIRSPEC will alternate at the focus every two weeks.

Chapter 3 contains a more detailed technical description of the instrument. Briefly, the f/15 focus is re-imaged at f/10 onto the slit plane inside the instrument. Re-imaging involves collimation and therefore provides a location for a Lyot stop and filters. The collimator section is essentially a rotating K-mirror which provides field rotation at the slit plane. A selection of slits with fixed lengths and widths are mounted in a wheel. Each slit is tilted so that the surrounding field can be viewed with an infrared camera. After the slit plane, the diverging f/10 beam is collimated at 120 mm onto the 22 l/mm echelle grating, used in quasi-Littrow mode, which is followed by a 75 l/mm cross-disperser grating. Finally, the beam is re-imaged at f/3 onto the InSb detector with a Three-Mirror Anastigmat camera. A flat mirror can replace the echelle grating to provide a lower resolution mode in which dispersion is due only to the cross disperser grating. Apart from three lenses used with the slit-viewing camera, NIRSPEC’s optical design is fully reflecting and therefore achromatic. Each mirror is diamond-turned on nickel-aluminum with a post-polished finish for low scatter and a high-reflectivity coating of Denton FSS99 silver.

NIRSPEC has three basic modes:

• Near-infrared imaging using the Slit-Viewing Camera (SCAM),
• Faint object spectroscopy with a low resolving power (R~2,200),
• High-resolution echelle spectroscopy (R~25,000).

Table 1.1 provides a summary of these modes, options and features of NIRSPEC.

Rather than providing a cryogenic mechanism to give arbitrary slit widths, NIRSPEC employs a selection of fixed slit widths, in two lengths for the echelle mode, and a single longer length for the low-resolution mode. The orientation of each slit on the sky is different, but these values are coded into the software. A dual filter wheel in the collimated beam provides a selection of order-sorting filters, blocking filters, narrow-band filters and Lyot stops. Table 1.2 gives a summary of NIRSPEC’s properties and design parameters.

NIRSPEC has seven custom-designed blocking filters (named NIRSPEC-1 through 7) which completely cover the 0.95-2.6 F m region (see Appendix for filter profiles). There are standard K, KN , LN and MN filters together with two special "wide" filters called KL (2.16-4.19 F m) and M_wide(4.40-5.60 F m). Note that NIRSPEC-3 and NIRPSEC-5 approximate J and H. Six narrow band filters (about 1% wide) are included namely, HeI (1.083), Paschen Beta (1.282), [FeII] (1.644), H2 (2.121), Brackett Gamma (2.165), CO (2.291). Two thicknesses of PK50 blocking glass are also available as well as a "dark" slide position. Filters can be selected directly from the FILTER button on the instrument display or from the FILTER button in the Echelle Format Simulator. The EFS can also display the profiles.

In high-resolution mode, NIRSPEC’s sensitivity is read-noise limited for practical exposure times at all short wavelengths between the OH emission lines. Read noise is about 25 electrons rms (with 16 multiple reads). Background-limited performance is obtained due to thermal emission for wavelengths longer than 2.4 microns. In the low-resolution mode, the sensitivity is background limited, provided on-chip exposures greater than 600 s are used. Table 1.4 gives a summary of typical limiting magnitudes per resolution element for a signal-to-noise ratio of 10 with a total on-source exposure time of 3600 s (1 hour).

The primary limitations on performance are,

1. variable light-loss at the slit due to seeing and/or poor tracking - estimated at 40% for the standard slit
2. a read noise of 25 electrons rms (with 16 reads) and a dark of 0.2 e/s/pixel current in the InSb array
3. thermal background and scattered light within the dewar (<0.2 e/s/pixel).

Other useful numbers are contained in Table 1.5 below.

Detector saturation limits are 35,000 DN (140,000 electrons) for the SCAM and 20,000 DN (100,000 electrons) for the ALADDIN chip.

Some examples of typical NIRSPEC images and spectra are shown below (see also the NIRSPEC web page).

For normal operation, the visitor will be in the Remote Operations II room at Keck HQ in Waimea. The instrument control computer is called HANAUMA.

Log in to Hanauma as NIRSPEC and obtain the password from the CARA instrument specialist for NIRSPEC. For example,

Click the RIGHT mouse button on the blank blue screen of the main monitor labeled Hanauma:0.0. This action will generate a pull-down menu. Go to NIRSPEC Control Menu. Another drop-down list appears. Go to START NIRSPEC Server and release the button. A window appears and the NIRSPEC server program starts up. (Note that you cannot type in this window.)

Now, do the same again, but this time select

START ALL NIRSPEC Clients. The instrument cartoon

and the exposure set-up screens will appear as shown above.

This action also starts up the Image Rotator GUI,

the Echelle Format Simulator (EFS), and the Quicklook. The EFS GUI is shown here.

Next, click the right mouse button again and go to LOGIN Windows and select xgterm ‘Waimea’ (NIRSPEC) on both Hanauma:0.0 and Hanauma:0.1. Position these windows to taste. For example, place one under the EFS for a place to type in commands such as slitmove.

You should now use the xterm window on Hanauma:0.0 to create data directories as follows:

time waimea:~ > cd /sdata600/nirspec (or 601, 602 etc.)

time waimea:nirspec > mkdir 29jun99 (for example)

time waimea:nirspec > cd 29jun99

time waimea:nirspec > mkdir scripts

time waimea:nirspec > mkdir spec

time waimea:nirspec > mkdir scam

This sets up directories for the SPEC and SCAM data, and also for the EFS scripts.

Now click the blue SETUP button in the lower left hand DataViews GUI and enter the OBS SETUP. Correct any entries and be sure to enter the full data path e.g.

/s/sdata600/nirspec/29jun99/spec

Repeat this procedure for the lower right hand DataViews GUI, but give the path name with scam at the end.

Go to the EFS screen, click on FILE and select Configure Script File. When the prompt screen appears enter the data path as before but with scripts at the end. Also, enter a number in the box for the first script names e.g. 001.

Go to the blue ENGINEER button in the upper left DataViews GUI on :0.0 and select MOTORS, then INIT, and click on all buttons (they will turn yellow). Click on INIT and then DISMISS. Wait and observe the screens. If all moves are successful there will be no UNKNOWN settings.

Go to Hanauma:0.2 (the right-most monitor) and using the right mouse button on the blue screen to get the drop-down menu, select GUIDER EAVESDROPPING and Master-> Current Screen. This action produces a window, a compass rose – tkrose(g), and a camera display. You can CLOSE the window. Using the right mouse button again, drag to K2 TELESCOPE STATUS and then Facsum- K2 Display. A Facilities Summary display will appear.

Finally, go to the upper left DataViews display and click on the yellow IROT button. Click on TRACKING ON to start the Image Rotator server going. Next look at the IDL-based Image Rotator GUI. The telescope drive and control system controls the rotator mode. If FACSUM shows the rotator mode as STATIONARY then the rotator is not moving. The GUI will have a white box surrounding the screen called Physical Mode.

To set a Slit Position Angle (PA) enter the angle in the box in the lower screen and press SET. The Slit Position and Scam Orientation displays will now be surrounded by a white box to show that they are active. The FACSUM display will now say Position Angle mode and a red "direction" arrow will appear on the physical mode display to show the direction of motion of the image rotator. The Sky PA on the FACSUM display is correct and is always the same as the Scam orientation in practice.

The Observing Assistant (OA) will bring up the PXL ccd camera for guiding and an "eavesdrop" screen automatically appears on Hanauma:0.2. The OA can also provide a telescope "hand-paddle" if needed.

When the OA locates an object it can be placed on REFA on the ccd camera or on REF for the Scam camera.

Look at the DataViews cartoon representation of the instrument to see the current set up. Check the cryogenic temperatures. Numbers should be around 54-58 K for the LN2 and Scam, and 30 K for the ALADDIN chip.

Accept the default settings and simply hit the TEST button on each detector set up GUI to cause a read out and display for each chip. You should see the following images:

Figure 2.1 below illustrates typical raw, short-exposure frames with both detectors.

Figure 2.1 A short (1s) exposure in Correlated Double Sampling (CDS) mode for the ALADDIN InSB detector in the spectrograph (left). A short (1s) exposure in CDS mode for the Rockwell HgCdTe PICNIC device in the Slit-Viewing Camera (SCAM) detector (right).

The Echelle Format Simulator (EFS) is a very powerful tool.

It not only displays the expected echellogram

for any instrument set-up, it enables entire observing

sequences to be defined and incorporated into scripts.

Run the EFS and select SETUP.

Click on filters and choose your order sorting filter.

Click on resolution mode and choose echelle or lo-res.

Then choose your slit from the slit menu.

The EFS will display an echellogram overlaid with a box representing the detector. Hold the mouse button down and drag to move the box around until the part of the spectrum of interest to you is enclosed. Release the mouse and read off the echelle and cross-disperser settings.

These values can be typed into the DataViews GUI in the SET box, or you can click on GO in the EFS menu to cause the complete setup to occur (i.e. move filters, slits and gratings).

Other setup options allow the user to include the exposure values and object names of the source and atmospheric standard star. Arc lamps can be included too. Each setup can be saved as a SCRIPT. Standard scripts can be interpreted by the real-time DRP.

Images obtained with the 256x256 pixel array in the SCAM or with the 1024x1024 array in the spectrograph are displayed using a general-purpose IDL-based package called Quick Look.

Further details of this package are given in the software section of this Manual.

IDL Quicklook windows appear for both the SCAM and the Spec detectors. Data display is automatic when a frame comes back.

The Quicklook display windows can be re-sized in the usual way by clicking and dragging on the corners.

Drop-down menus under File, Display, Math and Plot provide a large variety of options for reading back FITS format data frames, stretching the displays, performing image arithmetic and statistics, and drawing line plots.

Buttons at the bottom provide an easy method of zooming and centering the region of interest. Also, the pixel coordinates and pixel values at the current cursor position are displayed.

NIRSPEC contains an optical means of countering field rotation and a method of selecting the relative position angle of the fixed internal slits on the sky. A graphical user interface similar to the HIRES image rotator is used to control the NIRSPEC image rotator.

In general, a SCAM image is used to locate the object and view the slit. In most cases it is best to use the difference of two frames. A button on the SCAM Exposure Control panel called "snapi" will automatically take a pair of images separated by the "nod" parameters and display them. The "white" image represents the current location of the telescope.

A centering algorithm, selected from the Quicklook menu, can move the telescope to place the object on the slit.

Next, the image rotator GUI is used to select the best physical angle to yield the desired Position Angle of the slit relative to the source or to a reference direction (such as the North Celestial Pole). The Image Rotator performs best between –45 and +45 degrees, which corresponds to –90 to +90 degrees on the sky.

Once the choice is made, click on the "set" button to select that PA.

Take another SCAM image pair to check orientation.

The Image Rotator is a plain-bearing mechanism with high friction and it may not also keep up with the sky rotation. Try to re-initialize the mechanism fairly often during the night.

The HgCdTe array in the slit-viewing camera can be used as a direct, integrating camera or as an infrared guider system. A simple GUI is available to allow the camera to be set up for any exposure time, number of coadds, or readout mode.

To see faint objects it is necessary to remove the sky background and flat-field. This can be done automatically using a simple BOX 9 algorithm to take 9 exposures with slight offsets of the telescope and then using an IDL script to reduce the data and display the image.

To use the SCAM as an infrared guider, control must be relinquished to the telescope operator. Pushing the button marked "guiding on" on the instrument cartoon display will disable the normal exposure control panel. Warn the operator to cancel xguide at his/her end before taking back control of SCAM for normal imaging.

To shut down NIRSPEC in a completely controlled manner please follow these instructions:

Click on the Cal Unit button in the panel containing the instrument cartoon. Click on CLOSE COVER and activate this motion. Dismiss this window. This action will close the cover in front of the Cal Unit.

Now, simply click on the button marked QUIT at the top right of the Instrument Status Window.

Go to the Quicklook panel for the Spec, select FILE and click on QUIT ALL.

Type EXIT in the IDL windows.

Type stop_nirspec at the NIRSPEC prompt.

NIRSPEC was first conceived in 1993, in response to a call for proposals for the Keck II telescope. A 12-month Design Study was carried out and a detailed proposal was prepared for Conceptual Design Review by the Keck Science Steering Committee in April 1994. Funding was approved in July 1994 and the project began on October 1 1994 with an estimated delivery date of November 1998 and a budget of $3.5M. The instrument was delivered in March 1999 and First Light was obtained on April 25 1999.

NIRSPEC is completely remote-controlled. The vacuum enclosure stands on a steel support frame attached to a motorized handling cart, which runs on 1.5-m gauge rails on the Nasmyth platform. When driven into position, the instrument is lowered with jacks onto kinematic mounts and the drive is disabled. All electronics are located in two temperature-controlled and insulated cabinets beneath the dewar.

Digital data are sent along fiber optic cable to the host computer in the control room.

From the outset, NIRSPEC was designed to be a high-resolution instrument, but the design allowed for a lower resolution mode and for a slit-viewing camera. As an analog of HIRES, it was clear from the outset that the instrument would be physically large and unlike any previous infrared vacuum-cryogenic systems. The optical design was developed jointly with industry (Optics 1, ISP, SSG and Speedring Systems) and delivery of the optics was a major long-lead item. It was the acquisition of a good-enough 1024 x 1024 InSb array for the spectrograph however, that was always the critical path. These state-of-the-art detectors have high QE (about 80%) across the 1-5 micron region, fairly good dark current of 0.2 e/s/pixel at 30 K, and relatively low noise (15 electrons rms) with multiple non-destructive readout techniques.

Technical reports have been published in SPIE proceedings (e.g. McLean et al. 1998, Vol. 3354, 566-578) and a large suite of documentation in the form of Design Notes and Application Notes have been provided to CARA.

The optical design of NIRSPEC is based on an f/10 cross-dispersed echelle spectrograph with a 120 mm collimated beam used in the quasi-Littrow mode with a gamma-angle (( ) of 5E . To match the spectrograph to the f/15 Nasmyth focus there is a Front End optical section which collimates the beam to produce a pupil image for filters and a Lyot stop, and also yields an f/converter. The camera section is a Three Mirror Anastigmat (TMA).

The first folded section forms a K-mirror which can be rotated mechanically to cancel field rotation. A selection of entrance slits are located in a wheel. Both the echelle and cross-disperser gratings can be moved to scan the echellogram over the detector.

The TMA camera has different focal lengths in the x and y orthogonal directions, i.e. along and perpendicular to the dispersion.

NIRSPEC has two infrared detectors:

1. HgCdTe array for the Slit-Viewing camera
2. An InSb array for the spectrograph section.

The properties of the infrared detectors are summarized below.

Figure 3.2 Linearity curves for both the spectrograph (ALADDIN – InSb) detector and the SCAM (PICNIC – HgCdTe) array.

About 20,000 DN (100,000 electrons) is safe for the InSb array and 30,000 DN (120,000 electrons) is satisfactory for the HgCdTe device to avoid saturation and minimize non-linearity.

NIRSPEC also has a PXL CCD camera from Photometrics Ltd., which views the entire annular field surrounding the SCAM field. The inner diameter of the annulus is about 60 arc seconds and the outer diameter is about 3.5 arc minutes. The plate scale is 0.21 arc seconds per pixel and the CCD can detect about R = 20 in a few seconds.

NIRSPEC is cooled from ambient temperature using LN2 but it is maintained at operating temperature using only a pair of closed cycle refrigerators (CCRs).

Standard temperatures are summarized in the table below.

Inside NIRSPEC is a cryogenic, optical image rotator which enables the user to select arbitrary position angles and to track the field rotation.

The image rotator covers over 360 degrees on the sky with only a 180E mechanical movement between limit switches.

Just outside the entrance window to the NIRSPEC dewar is a large black box which contains the CCD guider system and a Calibration Lamp system. Light from arc lamps is fed into an Integrating Sphere and the uniformly illuminated output aperture is re-imaged onto the slit plane at f/15 to simulate the telescope optics.

Four arc lamps (Neon, Argon, Krypton and Xenon) and one quartz-halogen white-light source are available.

There is also a Fabry-Perot etalon which can produce a series of fringes to help calibrate the echellogram.

A pinhole can also be used instead of the normal (larger) aperture in order to produce a simulated star.

The first of the three screens is the Instrument Control window shown below.

The first thing to notice is that there is a light path shown here and that it is completed. This indicates that this is a valid light path meaning there is a filter in the beam, there is a slit in the beam and light is going all the way through to the detector. If you put a blank filter in the beam it will go dark. Some temperatures are shown here. The slit viewing camera temperature is shown in Kelvin right beside it. The InSb detector camera temperature is shown right beside it. The only other temperature that is automatically displayed is the liquid nitrogen temperature at the top of the screen. The final thing on this instrument control GUI in the status bar. When you actually try to move one of the mechanisms it will display and give information such as initializing, motor move successful, echelle move successful.

1. Setup

This menu gives a few options about the GUI itself, and not about the instrument.





2. Engineering

1. Lockup Menu: locks the user out of the Engineering menu. Getting back into the menu requires a password (spectrometer).
2. Motors: This button provides a link for direct control and initialization of all mechanisms. You can also check the status of the home, limit and position switches, and move motors by steps to non- standard positions.
3. There are five options under Motors

There are five cryogenic motors and three warm mechanisms for the calibration unit. Clicking on any of the descriptive buttons will highlight them, but in order to activate any of the options it is necessary to click the Init button. If you want to stop the motion, click on the Abort button. To take no action or exit the window, click on the Dismiss button.

2. Move Motors

Clicking on this option will bring up another gray menu as shown below.



3. Read Motor Positions



4. Set Motor Positions appears identical to the Move Motor Position menu. This menu allows you to …….
5. Read Switches is the next display shown below:

1. TSP Link: Connects to the transputers. There are three options under this menu:

Clicking on the Write button brings up another window that says Send Transputer CID and Parameter. CID is the transputer identification code for that action. These codes and keywords are located in a table elsewhere. If you want to send a parameter down, enter it in the space provided and click send or right click on the window to exit.

The TSP Trace flag runs through a series of diagnostics.



The Reset button is used if the link between the host and the transputers has gone down. Clicking on the Reset button is supposed to reset the link.



2. Clock:

1. Frame Test

1. Offsets

This button is for the voltage offsets to the pre-amps for each of the two detectors. This is just like sending down a CID code to set that offset except that the code has been pre-arranged and all the user inputs is the parameter value for each quadrant 1,2,3, and 4. These are numbers between 0 and 4096 that ultimately represent a voltage between 0 and 5 volts. For example, if you put in a number, say 2048, then you get 2.5 volts. You can send any offset down because all it does is apply an offset into the op-amp. All that happens is that it will saturate the A/D device at the top end or at the bottom end. You can experiment with these. You can put in different numbers and set them by clicking the set button and see what the quadrant offsets look like. You may want to do this to try and find the best quadrant offsets so the frame looks as uniform as possible. It is different warm versus cold. Normally, the user will not have to change these.

2. Client Info

Obtains IP Addresses.

To continue setting up the instrument, it is necessary to click on the Orange Buttons, but before you can do that you need to initialize the mechanisms by going into the Engineering Menu and clicking on Motor Init. None of the mechanisms will respond until the motors have been initialized.

Lamp: Clicking on the lamp button brings up a menu, which lists the four mechanisms in the calibration unit.

Irot: The Image Rotator button has two modes.

Filter: Clicking on the Orange filter button reveals a drop down menu of all the available filters there in two columns shown below.

IR Guiding: The IR Guiding button is very similar to the image rotator button. It simply has a Scam Guiding On or Scam Guiding Off.

If you click Scam Guiding On it means that the slit viewing camera is no longer available to the user to take pictures, it has become the guider for the instrument. It’s controlled by the guider GUI, which is a separate user interface. Images taken every 1 second at a rate of 1 HZ will go directly to that display and to the telescope operators console and you simply cannot take arbitrary images. So if you want to take deep infrared images of the field then you have to put Scam Guiding Off so you can use the Slit viewing camera as a simple infrared camera.

Slit: Click on the Slit button and you get a drop down menu listing 12 different slits at different widths and different lengths.

For example, the first slit is 0.144 arc-seconds wide by 12 arc-seconds long.

If you click on it before the mechanism has been initialized it won’t allow you to move it.

Echelle: Clicking on the orange echelle button allows you to take a short cut from the high resolution mode to the low resolution mode, which is a fixed angle of that mechanism. So it will simply rotate the mechanism around to bring the flat mirror into the beam instead of the echelle grating. If you know where you specifically want to go with the two gratings then you can type in the grating angles in the white box where it says Echelle. Then press the orange Set button and it will drive the mechanism to that angle just as long as it has been initialized.

The same procedure is used for the white box that says Cross Disperser.

The way you get the angles is from the EFS (Echelle Format Simulator) program. It will display the echellograms as a function of those angles. You can drag and click the detector around, which really means scanning in wavelength and those angles will change the EFS.

The second Menu Start-Up screen is the Observing Setup window. This is the window used for the current observing setup.

Click on the Setup button. The Obs Setup pop-down menu will display

The current Observing Setup is done in the panel with the green lettering. In this panel there is an entry for Object (this is the object name, flat, dark bias etc.). Next is the

Itime (Integration time), Next is the number of Coadds . It is also necessary to enter a

FileName and a SampleMode. Sample-Modes will be discussed shortly.

Setting up for the next observation is done in the panel with the yellow lettering. This is a nice feature because you can setup for your next observation during your current exposure and save time.

The Red ABORT button will abort the exposure, However if you are running a script it will not abort.

In order to choose or change Sampling Modes you need to right mouse click on the blue SampMode button in the observing setup window. There are three options Single, CDS and MCDS as shown below.

Single sampling mode stands for single-read mode, with no correlated double sampling or other effects. The appearance of frames taken in this mode is dominated by the bias structure of the chip, including 8 column readouts with 4 separate quadrants for the ALADDIN chip and column-to-column offsets in the PICNIC. This mode is recommended for checking the saturation levels and for observing in high background situations. The dynamic range of each array in DN in this mode are:

Correlated-double-sampling (CDS) is the standard mode. The chip is first reset pixel-by-pixel, then read out once. After the integration time has elapsed, the chip is read out again, and the resulting frame is the difference between the second and first reads. Ideally, there would therefore be no bias – a frame with zero photons should be uniformly zero. In practice, both chips have a slight bias in this mode (caused by a slight settling of the chip after it has been reset), at the 10s of DN level. A complication is that for high signal levels, the chip may saturate wholly or partially between the second and first reads, and will therefore be near zero; detecting saturation in CDS modes can be quite difficult, especially in short exposures.

This is the recommended readout mode for long exposures times (many seconds or more). The array is reset pixel-by-pixel. Then in this mode, the array is read out several times (set by the "multiple reads" parameter) at both the start and end of the integration;

the results are averaged to reduce noise. Each multiple read takes approximately 0.1 seconds. Thus the minimum integration time is (0.1x # of reads). Also there will be 0.1 seconds of overhead per multiple read. Thus this is the best mode employed for longer integrations, where the overhead is not a significant portion of the duty cycle. Typically,8 multiple reads are used for integrations on the order of 10 seconds. More (16 or 32 ) reads may be used for 3-5 minute integrations.

The third graphical user interface window is the SlitView Camera interface shown below:

The SlitView Camera is a Picnic Array made by Rockwell sensitive from 1-2.5 microns.It is used to look at the light that is reflected off the slit mask that does not go down into the spectrograph. There is a mirror with a very thin slit cut into it. The light that you’re taking a spectrum of goes through the slit and eventually hits the Aladdin array. The light that hits the mirror, which does not hit the slit, is reflected back up through some optics to the slit viewing camera. Its function is to watch what is on the sky around the slit. It is a very sensitive infrared array and will be used for deep imaging directly. The other purpose of the slit viewing camera is to center objects in the slit. You can also guide with the slit viewing camera, but the primary guider will probably be the PXL camera.

Click on the Setup button. The Obs Setup pop-down menu will display

The current Observing Setup is done in the panel with the green lettering. In this panel there is an entry for Object (this is the object name, flat, dark bias etc.). Next is the

Itime (Integration time), Next is the number of Coadds . It is also necessary to enter a

FileName and a SampleMode. Sample-Modes will be discussed shortly.

Setting up for the next observation is done in the panel with the yellow lettering. This is a nice feature because you can setup for your next observation during your current exposure and save time.

The Red ABORT button will Abort the exposure, However if you are running a script it will not Abort.

There are three options after you set up to take an exposure. Tele. Nod, Sky Frame, or Box9 shown below.

Clicking on the Tele. Nod will bring up a grey menu where nod parameters are entered. Entering values into this window will run a separate program. This program sets two parameters in the server.

Sky Frame: The sky frame button runs a script that takes an exposure at all the current settings then it moves the telescope by the amount specified by the nod east and nod north parameters of the server. Then it takes another exposure off locations comes back and re-centers the telescope back on the object. Then it runs an IDL script, which actually subtracts the two frames and makes the Quick Look display them. In other words it’s going to take a difference of the two frames and display them on the Scam.

Box 9: Is the same kind of thing but is used for fainter sources. Box 9 takes nine exposures moving around the object. It starts in the center then moves over a 3x3 pattern and eventually returns the telescope to the central position. Using all 9 of the exposures it writes a script and uses them to generate an artificial sky then subtracts it from all the 9 exposures and combines the images into a relatively deep image. This image is made to appear in the quick look, which then you will use to center your object. Therefore Box 9 is more useful when you need to go pretty faint.

Since the slit viewing camera can be used as a guider it is good to know that there is a different program that sometimes takes control of the guiding program. In that situation you don’t want the Data Views to actually run the instrument. So if you set IR Guiding to On then your not allowed to take exposures in this window. The reason is you’ve given the telescope operator control of the slit viewing camera and they can turn the guiders off or on and take pictures with them so at that point the data views lose control of the slit viewing camera. Therefore if you ever get that warning you need to turn IR Guiding off and then you will have control again.

1. Introduction

 

Purpose of the EFS

The Echelle Format Simulator (EFS) is used primary in two ways. The first is to run the NIRSPEC Instrument. It does this by allowing the user to set up a number of options and settings, such and slit width, filter, and exposure time, and sending a script of commands to the NIRSPEC server, which carries out these commands. The second use is to set up one of these scripts but instead of running, save it for use at another time. By using the EFS, an observer can set up a script from the comfort of his or her office, home, or any other location, save it, and execute it at the instrument, saving valuable observing time.

Interaction with the DRP

The NIRSPEC software package is an interweaving collaborative effort in which the multiple programs all interact with each other, the server, and the instrument. In this way, NIRSPEC becomes increasingly more powerful, while at the same time, easier to use. This is clearly evident in the interaction between the EFS and the Data Reduction Pipeline, or the DRP. When the EFS writes a script, the DRP, which is constantly monitoring the server, takes note and begins to process the script itself. It therefore knows what the instrument is going to do, and begins to prepare for the incoming data. The data, upon arrival, is then processed, using the various information stored in the script by the EFS. After processing, the reduced data is either saved to disk, or sent to another component of the NIRSPEC software package, Quicklook. Therefore, when used in conjunction, you can go from a simple user interface like the EFS to a reduced image with minimal effort.

Scripts and Configurations

Information about the instrument and telescope setup is stored in a script. A script is a text file in which a set of commands are written, and when desired, is executed as a C-Shell program. They typically have the extension of *.csh. A configuration is the set up of every parameter to be set by the EFS. This includes filters, slits, integration times, object name, etc. When a you hit the Save Configuration As… button in the main menu, the configuration is saved to a file in the form of a script. When the GO button is hit, first the configuration is saved to a script, then the script is exectued. If a previously written script is opened, EFS looks through the script to determine the configuration, then sets up the fields and dropdown menus and such in the EFS to reflect this configuration.

2. Using the EFS

To start the EFS, you can either launch it from a script or from the IDL prompt. If you launch it from a script, from the shell prompt, type run_efs to run the normal EFS, connected to a server. To run the EFS with a simulated server, type run_efs -s.

To run the EFS from the IDL prompt, first you have to set the device to handle 24 bit colors. Do this by typing device, true_color=24 at the IDL prompt. If running it connected to the server, first you have to compile the KIDL routines. Do this by typing .r kidl at the prompt. Then type in nirspec_efs, sim="nirspec" to start the EFS. To run the EFS with a simulated server, it is not necessary to compile the KIDL routines. Start the EFS by typing nirspec_efs, sim="nirspecsim".

1. Display window

This window displays the simulated echellogram for the given setup. The box is called a Set-Up Box. It defines approximately the limits of the detector. By using the box, you can tell which parts of the echellogram will fall on the detector, and which parts will be chopped off. By clicking and dragging the mouse in the window, you can move the box around, which automatically changes the Echelle and Cross Disperser angles correspondingly. In this way, mechanisms in NIRSPEC will be moved so that the matching parts of the echellogram fall on the detector.

2. X/Y Pixel

These boxes display the X (horizontal) and Y (vertical) pixel of the detector the cursor is currently on. Pixels begin with (1,1) in the lower left corner of the Set-Up Box.

3. Lambda

This box gives the wavelength in the echellogram that the cursor is currently on.

4. Ech Order

This section describes the routines and functions that can be called by clicking on an option the main menu bar, above the draw window. The menu bar is divided into four main sections, File, Telescope, Overlays, and Help.

1. File

1. Open Configuration (Ctrl+o)

This option opens a script to be edited or executed by the EFS. It uses a dialog box that allows the changing of directories, filters, and filenames directly by typing it into the box, or by clicking on the appropriate filename or directory in the scroll window. This same dialog is used for opening files throughout EFS, including saving files as well.

 

2. Save Configuration As… (Ctrl+s)

Use this option to save the current settings of the EFS to a file. Every settings, such as filter, echelle and cross dispersor angles, and integration time are saved into a script file, that can be opened at a later time for editing or execution.

3. Configure Script File (Ctrl+f)

1. OK

Click this button to accept changes and close the dialog.

2. APPLY

Click this button to save changes, but leave the dialog open.

3. CANCEL

1. Quit (Ctrl+q)

1. Telescope

1. Set Nod Parameters (Ctrl+p)

1. Overlays

1. Clear Overlays (Ctrl+c)

This option removes any lines plotted on the echellogram.

2. User Lines (Ctrl+u)

1. Browse

Hit this button to open a previously written line list.

2. Add Line to List

Enter the wavelength for the new line here.

3. Add

Hit this button to add the line to the list.

4. New Line Comment

Enter a comment for the new line here.

5. Z=

To plot the lines redshifted by a specific Z, enter the Z here.

6. Remove Selection

Hit this button to remove the currently selected line from the list.

7. Clear List

Hit this button to completely clear the list.

8. Select Color

1. Select Color System

Hit this button to switch between the various color systems. RGB is the default.

2. Red / Green / Blue

Slide the sliders to the various positions until the desired color is obtained.

3. OK

1. Save List As

Enter the filename you wish to save the list as.

2. Save

Hit this button to save the list. It brings up a dialog to browse for a file to save to .

3. OK

Hit this button to plot the lines in the list and close the dialog.

4. Apply

Hit this button to plot the lines in the list, but leave the dialog open.

5. Cancel

1. OH Lines (Ctrl+l)

Hitting this option plots the OH lines on the echellogram. Hitting it again removes them.

2. Arc Lines

1. Neon Lines (Ctrl+n)

Hitting this option plots the Neon lines on the echellogram. Hitting it again removes them.

2. Argon Lines (Ctrl+a)

Hitting this option plots the Argon lines on the echellogram. Hitting it again removes them.

3. Krypton Lines (Ctrl+k)

Hitting this option plots the Krypton lines on the echellogram. Hitting it again removes them.

4. Xenon Lines (Ctrl+x)

1. Help

1. Keyboard Hotkey List

This help dialog shows the various Hotkeys used by the EFS. Hit OK to dismiss the dialog.

2. User Manual

1. Calibration

This menu selects the type of calibration mode to use. First option, Setup Only, only moves the mechanisms in the instrument, but does not take an exposure. The second option, Object Only, allows the exposure of an object by the camera. Multiple setups are supported by use of the setup boxes. The Object+Lamps option is the same as the Object Only mode, except that at the end of the script, the use of arc lamps for calibration is included. The fourth option, Object+Star is and option that will take two exposures. The first is of the object. Then, you are prompted to move the telescope to the calibration star, and the star exposure begins. The Full Sequence is a Object+Star+Lamps sequence.

 

 

 

 

2. Nod Pattern

This menu selects the nod pattern to be used. A Stare is no nodding, a Nod two through four splits the slit makes two through fours nods in the slit. A Nod Chop makes a nod in the amount specified by the Set Nod Parameters option in the Telescope section of the main menu.



3. Number of Reps

This menu selects the number of nods to perform.

 

4. Spec. Mode



This menu selects the spectral mode between High Resolution, Low Resolution, and Imaging. Consult the NIRSPEC manual for more about the spectral modes.



5. Slit

Change this dropdown menu to select the size of the slit to be used for the current setup.

6. Filter

Select the filter to be used for the current setup from this list.

7. Blocking



Select the type of blocking to be used from None, Thin, or Thick.

 

8. Plot Filter Profile

Hit this button to see a transmission plot of the currently selected filter.

9. Bad Pixel Mask

Switch this toggle to turn on and off the overplotting of a bad pixel mask over the detector box. This is useful in determining which part of the echellogram may be affected by bad pixels.



10. Echelle

This box displays the current echelle angle. It can be changed either by moving the box, or by entering a value into this field.



11. Cross Disp.

This box displays the current cross dispersor angle. It can be changed either by moving the box, or by entering a value into this field.

12. Setup Boxes

1. New (Insert)

Hit this button to create a new setup box.

2. Previous (PageUp)

Hit this button to go to the previous setup box.

3. Next (PageDown)

Hit this button to go to the next setup box.

4. Delete (Delete)

Hit this button to delete the currently selected setup box.

5. Current

1. Object

1. Itime

Enter the integration time of the object exposure in this box. It is disabled for Setup Only mode.

2. Coadds

1. Star

1. Itime

Enter the integration time of the calibration star exposure in this box. It is enabled for Object+Star and Full Sequence modes.

2. Coadds

1. GO (Ctrl+g)

Hit this button to send the script to the NIRSPEC server to be executed.



2. ABORT (Meta+x)

3. Advanced Features

Setting Up a Configuration

The first thing to decide is what you want to take an exposure of and how you want to calibrate it. There are basically two ways to calibrate: using a star, or using arc lamps. To use a star, either pick the Object+Star mode or the Full Sequence mode. To use arc lamps, pick the Object+Lamps mode or the Full Sequence mode. To disable all calibrations, choose the Object Only mode, and to select setup of the mechanisms only without taking an exposure, pick the Setup Only mode.

Next, you’ll want to determine the nod pattern to use. Nod Stare does not move the telescope before taking an exposure; it simply takes one exposure with the slit in its current position. The numbered nod positions divide the slit into the same number of pieces as the number following Nod and takes exposures in the center of these pieces. Nod 2 moves the telescope from center up to one fourth of the slit length from to the top of the slit, takes an exposure, moves down to one fourth of the slit length from the bottom of the slit and takes another exposure. Nod 3 performs a similar action, except the three positions where exposures are taken are one sixth of the slit length from the top and bottom, and in the center of the slit. Nod 4 is also similar, where the four exposures are taken at one eighth of the slit length from the top and bottom and one eighth the slit length above and below the center. Nod Chop uses the numbers set by the Set Nod Parameters dialog in the Telescope section of the main menu to determine how much to nod. This is slightly different than normal nodding, because often times, the object will be completed moved out of the slit.

Now, determine the number of nod repetitions to make. You can repeat the nod pattern from one to six times.

Next, determine the Spectral Mode you wish to use. In the High Resolution mode, both the echelle grating and the cross disperser are used to produce a complete echellogram. In the Low Resolution mode, the echelle grating is replaced with a flat mirror so that the spectrum is produced only by the cross dispersion grating. In imaging mode, the light is not dispersed at all, and the field is imaged onto the detector.

Now, determine the slit and filter to use for the exposure. The filter determines which wavelengths are detected, and the slit determines how much light is passed in and how wide the spectral features are. An important aspect to note than may not be obvious is that only certain slits are intended to be used for each Spectral Mode. In the High Resolution mode, the slits with slitlengths of 12" and 24" are intended to be used. In the Low Resolution mode, the 42" slits are intended to be used.

Next, position the setup box to set the echelle and cross disperser angles. These angles determine which parts of the echellogram fall on the detector. Move the box by dragging it or by using the arrow keys so that the desired portion of the echellogram falls inside the box.

Lastly, enter information about the Object and Star, if necessary. Often, certain parts of this area may be disabled. This is because some of these fields only apply to certain calibration modes. For instance, in Object Only mode, no information about the calibration star is needed since no calibration star is used. Furthermore, for Setup Only mode, this entire area is disabled, since no exposure at all is taken. If necessary, enter the object and star names, and the integration time and coadds for each. If the mode supports multiple setups, enter the box number that corresponds to the setup you which use for the current exposure.

When all of the above is done, your configuration is done. Now you are ready to turn your configuration into a script.

From a Configuration to a Script

Once you have your configuration set up the way you want it, you can either save it to a file for execution later, or execute it immediately. To save it, hit the Save Configuration As… option from the File section of the main menu. This brings up the Pickfile dialog. Pick a file to write to or enter a filename in the filename box.

Be sure to include the extension *.csh so that loading the file will be easier.

To execute the script, hit the GO button. This saves the script with a default filename consisting of the date and a file number with the *.csh extension, written to the default script directory. These files are the scripts the DRP looks for when a script is running. Next, after the script has been written, the EFS spawns a C-Shell for the execution of the script. Then, it is up to the server to carry out the commands.

While the script is running, the EFS is still fully functional, allowing the you to setup another configuration while waiting for the running script to finish. To stop the execution of the currently running script, hit the red ABORT button.

More About Using Setup Boxes

Setup boxes, when properly utilized, can save valuable time, as well as reduce the work by automating the data collection process. By using setup boxes, you can condense multiple scripts into one, and by simply hitting the Go button, you can sit back and watch the EFS take as many exposures as desired.

It may take a bit of experimenting to become comfortable with the manipulation of setup boxes. This section is intended to help you reach that comfort level by introducing a few techniques in setting up your configuration.

Moving Boxes

To move a box, click somewhere in the box, and move the mouse while holding the mouse button down (i.e. dragging the mouse) until the box is in the desired location. If you click somewhere in the echellogram that is not occupied by a box, the current box snaps to that location, centered about the point clicked. The current box can be moved in small increments by using the arrow keys.

 

 

Creating New Boxes

Setup boxes are only allowed in Object and Object+Lamps calibration modes. A new box can not be created unless you are in one of these modes. To create a new box, hit the New button. The new box is drawn in the center of the echellogram and colored yellow, while the old box’s color changes to green. The box colored yellow is the active or "current" box, while green boxes indicate the inactive boxes. The new box always becomes the current box. You can enter create a new box anywhere in the chain of boxes. Boxes that fall after the new box are shifted in number by one.

Changing the Current Box

There are two ways of switching between boxes: 1) by hitting the Previous or Next buttons until the desired box is current; 2) by simply clicking within the box you want to make active. If you click in an area occupied by more than one box, the current box is decided by the following: 1) if one of the boxes is already the current box, it remains the current box; 2) otherwise, of the remaining boxes containing the point that was clicked, the box with the highest number becomes the current box.

You may have noticed that when in a calibration mode that does not allow multiple setup boxes, the current box ( Box 1, the only box allowed ) follows you when you change filters, Spectral Modes, etc. This also happens for the current box in a multiple box setup. For instance, now you have two boxes, Box 2 is active, and Box 1 is inactive. If you change another filter, Box 2 follows you and is now centered in the echellogram of the new filter. Box 1 is still in the same position is was in the previous filter. To see this, hit the previous button.

Deleting Boxes

To delete the current box, hit the delete button. If the current box is not the last box, all the boxes with numbers higher than the deleted box get shifted down, so that there is continuity. For example, if you have 6 boxes and you delete box 3, boxes 4 through 6 become boxes 3 throught 5 respectively. Their setups are the same; only their numbers change. If the box deleted is the last box, the current box becomes the one previous to the deleted box. Otherwise, the current box number remains the same, but reflects the change in numbering, and therefore represents the box that was one after the deleted box. Using the above example, the current box is still number 3, but has the configuration of what Box 4 had before the deletion.

Using Multiple Boxes

One use of multiple boxes is to take a sampling of images in the various filters. The most importing thing to remember is that once you have a box where you want it, before switching to another filter for your new box, create the new box first. Remember, if you change filter, the current box comes with you. To avoid this, create a box, making it the current box, then change filters. This also applies to switching between Spectral Modes.

Another common utilization of setup boxes is to create a "postage stamp" of the echellogram. This is the use of multiple boxes to cover the entire filter bandpass. For example, lets say you wanted the entire echellogram for the Nirspec-6 filter. When you bring it up in the EFS, you notice that one box is two small to cover the entire echellogram. Therefore, use multiple boxes. Move the box to the so that it covers the lower left corner of the echellogram (e.g. echelle: 62.5, Cross Disp.: 33.34). Then hit New. Move that box to the lower right of the echellogram (e.g. e.: 63.84, c.d.: 33.42). Hit new two more times and move the two new boxes to cover the top half of the echellogram (e.g. e.: 62.25, c.d.: 35.19, e.: 63.95, c.d.: 35.16). If necessary, adjust the four boxes so that the entire echellogram is covered. Now you are ready to expose!

Using User Line Lists

The use of Arc lines are a valuable resource to the astronomer in terms of calibration and setup. However, the User Lines feature of the EFS is another powerful tool, allowing you to customize existing lists, and to create your own lists. The EFS can then plot the lines specified in your list over the simulated echellogram, giving you the ability to adjust your setup so that the desired line(s) fall on the detector.

To enable the User Lines, hit User Lines under the Overlays section of the main menu. This brings up a dialog that lists the user line list. To open an existing line list, hit the Browse button. Then select the desired file, and hit the okay button. The list is displayed in the box. To start a list from scratch, simply start adding lines. If a list is already displayed, and you want to start a new list, hit the Clear List button. This will remove all lines from the list box.

To add a line to the list, simply type the wavelength (in microns) in the Add Line to List: box. If you want to add a comment to the line, perhaps describing which line it represents, enter the text in the New Line Comment: box. When the new line is ready to be added, hit the Add button. The line is added and the list is automatically sorted from the shortest wavelength to the longest. If you want to remove a line from the list, click on the line in the list and hit the Remove Selection button.

Once you have the list the way you want it, you may save it if you like. Do this by typing the filename in the Save List As: box and/or hitting the Save button. The pickfile dialog is brought up and you can select a file to write to or enter the name of a new file in the box.

If you are ready to plot the lines on the echellogram, hit either the OK button or the Apply button. The OK button will close the dialog, while the Apply button will leave the dialog open. If the list has been modified in anyway, hitting OK will prompt you to save the list if desired. Hit Yeas on the prompting dialog to save the list to a file, hit no to plot the lines and close the dialog without saving the list.

Before you plot the lines however, you may want to select the color for plotting. To do this, hit the Select Color button. The current color is shown in the box next to the button. If you hit the button, a new dialog is created. The box on the top shows the currently selected color. To adjust the color, move the sliders for the Red, Green, and Blue to the desired color. To adjust the Color System, click on the Select Color System menu, although, this is usually unnecessary. The RGB system is the default. The following table shows some sample colors in the RGB system.

RGB	Color	EFS Line
255, 200, 50	Yellow-Orange	Neon
220, 220, 220	Light Gray	Argon
255, 100, 0	Red-Orange	Krypton
100, 255, 100	Light Green	Xenon
200, 200, 0	Yellow	OH
255, 0, 255	Magenta	User Lines Default
255, 255, 255	White	None
0, 0, 0	Black	None
0, 255, 255	Cyan	None

 

A special, useful feature of the user lines list is the ability to enter a Z to simulated a redshift of a spectral line, so that the lines in the list are plotted on the echellogram where the would fall if there were shifted by the specified amount. Redshifted wavelengths are determined using the relation:

l_shifted = ( 1+ Z ) l_rest

By using this feature, if the object’s Z is known, it is easy to determine which filter and echelle and cross disperser angles to use to make sure the desired line falls on the detector.

4. Troubleshooting

Solution: Make sure the file is a *.csh file. If necessary, change the filter in the Open File Dialog to match the extension of the file to be opened. For example, if the file you want to open is a *.csh file named filename.sh, change the filter to *.sh or *.*.

Solution: Multiple setup boxes are only enabled for the Object Only and Object+Lamps calibration modes.

Solution: You may need to change the slit. In the High Resolution mode, the slits with slitlengths of 12" and 24" are intended to be used. In the Low Resolution mode, the 42" slits are intended to be used.

Solution: Some of filters transmission curves have not yet been determined due to lack of data. The filters for which the Plot Filter Button is enabled have complete data and therefore transmission curves available.

Solution: The easiest way to redraw the echellogram is to reselect the slit you want to use from the slit dropdown menu. Every time the slit is changed, the echellogram is redrawn. Even if you don’t change the slit, selecting the same slit again will also redraw it, removing any stray marks left over from the bad pixel mask.

The purpose of Quicklook (QL) is to provide the user of NIRSPEC with a real time tool for viewing and manipulating the images taken. QL can, however, be used to analyze any FITS file taken at anytime from any source. Armed with powerful analytical tools such as Gaussian Fitting, Photometry, and Surface Plotting, QL is an ideal package for data reduction, manipulation, and visualization.

NIRSPEC has two detectors, one used as a spectrograph, and one used for guiding purposes, referred to as the slit-viewing camera, or scam. Therefore, when taking an exposure, it is useful to have two QL windows, one for each set of data gathered from the two detectors. For this reason, the default launching of QL produces these two versions of QL, two windows each with its respective title.

The DRP version is automatically launched by the DRP after reduction. The major advantage of the DRP version is its ability to give the corresponding wavelength for a given pixel in the image. This is done both in the draw window and for a horizontal cut of the image. It assumes that the image loaded is an echellogram, and therefore, any pixel, particularly a spectral line, on the echellogram can be identified by its corresponding wavelength.

Quicklook supports only