Troubleshooting guide

• Note: δRA and δDec must be in arcseconds (see the previous step).
• Look at the compass arrows in ds9 to determine which of (x, y) corresponds to (RA, Dec); you may
have to darken the display to create enough contrast to see the arrows clearly. With FLAMINGOS
mounted onto the 2.1-m in the usual way, moving an object from its present location by (+dx, +dy)
in detector space corresponds to (-δRA, +δDec).
• Take another image, and iterate with rulers and relative.offset.kpno.pl until the star is centered.
4. Zero the telescope pointing.
5. Verify optical alignment. During the first pointing check of the observing run, it is advisable to take an
image of a very bright star way out of focus, to verify that the pupil stop has not been moved, and that the
mirror covers and dome are open and positioned properly. You should see a bright donut, with shadows for
the secondary and the spider vanes. If the donut is not circular (e.g., has a sliver missing at the outer edge)
there may be something vignetting or the Lyot wheel may need adjustment.
6. Optimize focus on sky near first target field. The guide camera should have been set up to be confocal with
FLAMINGOS during the first night of the observing block. You should be able to get close to a good
starting focus for FLAMINGOS by checking the focus on the guide camera's acquisition video display. Then
you should do a short focus run about that point (with steps of 50 units) on FLAMINGOS.
• Use an exposure time ≥ 10 seconds to average over seeing fluctuations.
We suggest using the tasks in the new flmntools IRAF package written by Anthony Gonzalez (UF) for
assessing image quality. However you can also use the IRAF task imexam, in the standard manner. We
detail the use of both here. One may use the IRAF_FLAMINGOS window which is linked to the ds9.
• The flmntools tasks fwcheck and fwscan take differences of images, and then run SExtractor on the central
1250×1250 pixel region to determine the average FWHM; sources brighter than 10,000 ADU in the
difference image are ignored and objects with FWHM < 1.3 pixels are rejected as cosmic ray hits. To use
these, first enter the flmntools package to get the following prompt:
cl> flmn
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Welcome to FLMNTOOLS - The FLAMINGOS Observing Tools
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tasks included are:
fwcheck - Quickly check the fwhm and display the difference image
fwscan - Compute the fwhm for each frame in a set of observations
fwcheck fwscan
fl>
This package is used at more than one telescope, so on the off-chance that the parameters have been
unlearned, verify the telescope field is set to KPNO2.1m:
fl> epar fwscan
PACKAGE = flmntools
TASK = fwscan
FLAMINGOS@2.1-m, Ver. 2.39, 2011 May 13 Page 16 of 46