Overview

Last Update: 2009 February 12

We have made a lot of progress in improving NIRSPEC over the last couple of years. Many things have changed on NIRSPEC in terms of its day-to-day operation. This page is meant to re-introduce NIRSPEC to Support Astronomers.

Crashes less frequent

The NIRSPEC server crashes much less frequently than before.
The remaining crashes are not caused by the rotator; therefore, position angle mode (PA mode) is no longer crash-prone.
Some crashes are not really crashes--rather XNIRSPEC has locked up access to the keyword server. Kill XNIRSPEC (via kill_em xnirspec) and wait 30s and your server may come back to life.

Recover script (automated crash recovery)

NIRSPEC still experiences crashes at a rate of about 1 per 4-5 days of operation. Crashes exhibit some of these symptoms:

Inability to show keywords.
Exposure fails to readout.
tklogger pops up multiple times complaining of a "LOPS" error.

Solution: Run the recoverscript in one of two ways:

Type recover at a waimea prompt.
Select NIRSPEC Engineering --> Recover from server crash from the pull-down menu.

There is a test version of the recover script that will try to kill XNIRSPEC first. Type recover.dev or select Recover (test version) from the pull-down.

Observing Tips

Target Acquisition

If possible, ask OA to take control of SCAM and position the target on slit center (both vertically and horizontally) with the "SLIT" pointing origin selected.
If long SCAM integrations are necessary for target identification (i.e. SNAPI integrations), once target is at the SLIT center, ask the OA to stop and restart guiding.

Guiding

Guiding and tracking on NIRSPEC is different than most other Keck instruments. There are 3 main variables with 2 choices each:

Target type
- Sidereal -- stars and galaxies
- Non-sidereal -- planets, asteroids, comets
Guide Camera
- SCAM -- Slit-viewing CAMera, HgCdTe IR detector 46 arcsec FOV.
- Annular -- also known as the MAGIQ guider, nirspecm, CCD guider, NIRSPEC guider.
Rotator Mode
- Stationary -- the rotator holds a fixed physical position and the field rotates about the pointing origin.
- Position angle -- the rotator corrects for field rotation

Therefore, there are 8 different combinations of these variable, but luckily, the MAGIQ guiding software handles this (mostly). Trust your OAs to do this right!

Gotchas

Please note that this is a very abbreviated list. Futher help can be found on the troubleshooting webpage.

Incorrect Guider Filter

The MAGIQ guider has 2 filter wheels, one with bandpass filters and one with neutral density filters. If you have any issues seeing stars, please ask the OAs to verify that the filters are "Open" and "RG780".

Rotator not in position

A box is drawn on the Rotator GUI to show in what mode the NIRSPEC image rotator is. When in position, this box is white. When out of position, this box is red. In PA mode, the box occasionally turns red briefly, then back to white. This is normal. If, however, the box stays red, look at the actual physical position of the rotator. This is in the left-hand "Physical" column of the Rotator GUI. If the "Actual" value does not change, the rotator server may have stopped. You may restart it in one of three ways:

Type restart_rotator at a waimea prompt.
Select NIRSPEC Control Menu --> Restart Rotator from the pull-down menu.

Kill the task watch_keywords listed by the command ctx. See ctx output below:

==========================================================================

Current processes:

nirspec  24145 15:02:02  0:00 EFS -Wl EFS 
nirspec  23560 18:37:21  0:00 IMROT -Wl IMROT 
nirspec  24107 15:02:01  0:00 NIRSPEC_log 
nirspec  24143 15:02:02  0:00 SCAM -Wl SCAM 
nirspec  23569 18:37:21  0:00 SLITMOVE -Wl SLITMOVE 
nirspec  24144 15:02:02  0:00 SPEC -Wl SPEC 
nirspec  24314 15:02:11  0:03 caRepeater
nirspec  23809 18:40:05  0:02 irot_wrapper
nirspec  24029 15:01:57  0:02 nirspec_server_bin -noacs
nirspec  24030 15:01:57  0:00 nirspec_server_bin -noacs
nirspec  24031 15:01:57  4:58 nirspec_server_bin -noacs
nirspec   2010   May 13  0:00 pwr_ctrl -l iboot_service -s iboot
nirspec  23748 15:01:30  1:19 tklogger -f /home/waimea/nirspec
nirspec  23817 18:40:11  0:31 watch_keywords -l rotator -l nspecIrot
-s nirspec -s dcs2
nirspec  24279 15:02:08  0:00 xnirspec -noql   ; sleep 180 ; exit
nirspec  24312 15:02:10  1:03 xnirspec -noql

Next, wait about 5 seconds, then reselect IROT and Tracking On on the XNIRSPEC GUI and re-set your desired PA.

SCAM not updating

The SCAM Quicklook display polls the disk for a new image at 1 Hz. If the product of your SCAM itime and coadds is not greater than 1 second, Quicklook may miss your image. For example, if you are taking a 0.3 second image with 1 coadd, up the coadds to 4 to ensure Quicklook will catch the image. More info is available on our troubleshooting webpage.

Array Linearity

The SPEC array is an Aladdin-3 that is linear to 18,000 DN; however, please try to limit the counts in a single co-add to 8,000 DN or less. This is due to a charge persistence problem with the SPEC detector when exposed to close to its linear limit. N. B. that Quicklook sums the counts in images with multiple co-adds such that peak counts of 15,000 DN in 3 co-adds is really 5,000 DN per co-add and well within the safe range.

Charge persistence

If you notice charge persistence or have just looked at a bright source (flat, standard star, etc.), you can issue the flush or flush2 commands from a waimea prompt for the SPEC and SCAM detectors respectively. More information can be found on our troubleshooting webpage.