Troubleshooting guide

4. Ask the telescope operator to 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 North Port TV camera should have been set up to be
confocal with FLAMINGOS during the first checkout night. You should be able to tune the telescope focus
on the TV camera and be close to best focus on FLAMINGOS. 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 Mayall (the Kitt Peak 4-m):
fl> epar fwscan
PACKAGE = flmntools
TASK = fwscan
root = ugc3371.j Root infile name?
First = 21 First image in set?
Last = 25 Last image in set?
(telesco= Mayall) Telescope(MMT, Mayall, KPNO2.1-m)?
(mode = q)
• fwscan takes a range of images as inputs, in the form
fwscan <image root name> <First image number> <Last image number>
FLAMINGOS@4-m, Ver. 2.39, 2013 April 23 Page 15 of 47