NIRSPEC Start of Night Procedure

Observing with NIRSPEC can start directly at sunset, beginning by setting pointing "collimations" and focusing the telescope. The following procedures should be completed at the start of each night.

1. OA: Start NIRSPEC Eavesdrop
2. Observer: Enable Night-Time Mode
3. OA: Begin SCAM Guiding And Adjust Pointing
4. OA: Run NIRSPEC Malign-acq
5. Observer: Set Slit or Sky PA

OA: Start NIRSPEC Eavesdrop

The OA needs to first run the NIRSPEC Eavesdrop GUI from DCSGui/Instruments/NIRSPEC. It is an IDL display that allows the OA to take control of the SCAM for setting pointing, take sky background exposures required for SCAM guiding, and provide a status of exposures in progress on NIRSPEC. The active buttons are:
• MAKE SKY, copies the most recent SCAM frame for sky subtraction while SCAM guiding (required to see objects clearly).
• SET SCAM GUIDING, gives the OA on/off control of SCAM for guiding. Note that this button should never be pressed before checking with the NIRSPEC operator, or being asked to start SCAM guiding.

Observer: Enable Night-Time Mode

Before anything else can be done, the Observer must enable "night-time mode" on NIRSPEC. Follow these steps:
1. Put the mouse pointer on the blue background, hold down the right button, go into the NIRSPEC Control Menu and let up on Enable Night-time Mode.
2. Work through the script that pops up, responding to the questions asked. The script will check whether all mechanisms are initialized; if any are not, initialize now. When the script is finished, the Image Rotator GUI will appear.
3. On the top panel of XNIRSPEC, left-click on the button labelled "IROT". On the popup menu that appears, left-click on "IROT Tracking On."
4. On the Image Rotator GUI, type 0.0 in the lower left text-entry box, and left-click the SET button next to that text-entry box. This will set the rotator to stationary mode at physical angle 0 degrees as is required for MAlign.

OA: Begin SCAM Guiding And Adjust Pointing

After opening, the observer should tell the OA what the first object is, and the OA will pick a Magnitude 10.5-11 (nominal) star nearby to both set pointing and focus with.
1. The OA tells the Observer, "I am taking control of SCAM now."
2. The OA then clicks on SET SCAM GUIDING ON in the NIRSPEC Eavesdrop GUI.
3. The OA selects SCAM in XGUIDE.
4. The OA points the MAlign star to REF.
5. The OA offsets 60 arcseconds in any direction.
6. The OA clicks MAKE SKY on the NIRSPEC Eavesdrop GUI to get a fresh sky frame for improved visibility with SCAM guiding.
7. The OA undoes the 60 arcsecond offset and points the MAlign star to REF again.
8. The OA centers the star on REF using the Adjust Pointing button on XGUIDE. The star should be at the nominal value of REF on SCAM, which is at pixel [128,134].
9. The OA selects NIRSPEC or NULL as the camera in XGUIDE.
10. The OA clicks on SET SCAM GUIDING OFF in the NIRSPEC Eavesdrop GUI.

Now everything is ready to run MAlign.

OA: Run NIRSPEC Malign-acq

Malign is run by the OA, from DCSGui/Instruments/NIRSPEC. Begin with the star set at REF.
1. The script first offsets the telescope to get a sky frame. Then it sends the star to the upper left quadrant of the SCAM.
2. The script next prompts the OA to set the ACS to pmfm = +350 nm. The OA must do this by hand, because NIRSPEC cannot communicate directly with the ACS.
3. The script takes the first illuminated image and displays a surface plot of the image to help judge if it has enough counts without being saturated. Three options are then given:

   
    The first image is displayed (with no sky subtraction); 
   
     To avoid saturation: ( sky counts < 200,000 DN )
                          ( segment counts < 250,000 DN )
   
     Enter n to try a fainter or brighter star,
   
      OR, adjust pointing, then enter r to re-image,
   
      OR, enter return to continue:
   
   

   To adjust pointing, the OA can simply send instrument-frame offsets. If n is selected, the OA must reset pmfm to 0, while the script offsets the star back to center. The OA then selects a fainter or brighter or non-double star as required.
4. Once past the first image, the script indicates that the first image is available to read into the OA's Malign analysis tool. The script writes out the same four files to /s/sdata600/nirspec/malign every time Malign is run, over-writing the data from the previous run, so the OA must be sure that the files are current. Each file is pre-sky-subtracted. The first file is called "scam+350a.fits", where +350a is the first (a) image at +350. Then, 3 more images are taken; the files are written and reported so in the script. The set of 4 are:

-rw-r--r--   1 nirspec  870       276480 Aug 22 22:41 scam+350b.fits
-rw-r--r--   1 nirspec  870       276480 Aug 22 22:40 scam+350a.fits
-rw-r--r--   1 nirspec  870       276480 Aug 22 22:39 scam-350b.fits
-rw-r--r--   1 nirspec  870       276480 Aug 22 22:39 scam-350a.fits

5. The OA analyzes the images and sends the required moves. Normally, only PISTON and TILT moves are sent. However, if the contribution of STACK to image blur is greater than the contribution of the other two, then it is OK to send STACK moves as well. If the piston move is greater than 150 microns, a second cycle of Malign should be run.
1. Observer: Set Slit or Sky PA

   Now the Observer needs to select a Slit PA on the sky, or a SCAM PA if that's what is of interest. On the Image Rotator Gui:

   1. Type the desired PA in the text entry box that is correct for the mode you want:
      • Lower-Center panel for a Slit PA
      • Lower-Right panel for a SCAM PA
   2. Click the SET button next to the text entry box where you typed in your angle.

So now, the telescope is focused and the observer has control of SCAM, and scientific observing can begin.

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