NIRSPEC Home Page
Start of Night Procedure
- 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:
- 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.
- 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.
- 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 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.
- The OA tells the Observer, "I am taking control of SCAM
- The OA then clicks on SET SCAM GUIDING ON
in the NIRSPEC Eavesdrop GUI.
- The OA selects SCAM in XGUIDE.
- The OA points the MAlign star to REF.
- The OA offsets 60 arcseconds in any direction.
- The OA clicks MAKE SKY on the NIRSPEC Eavesdrop GUI
to get a fresh sky frame for improved visibility with SCAM guiding.
- The OA undoes the 60 arcsecond offset and points the MAlign star
to REF again.
- 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].
- The OA selects NIRSPEC or NULL as the camera in XGUIDE.
- 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.
- The script first offsets the telescope to get a sky frame.
Then it sends the star to the upper left quadrant of the SCAM.
- 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.
- 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.
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
- 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.
- Observer: Set Slit or Sky
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:
- 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
- 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.
NIRSPEC Eavesdrop GUI
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NIRSPEC Malign Image (sky subtracted)
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Last modified: 20 December 2000