Troubleshooting guide

Opening the telescope and dome.
Preliminary pointing check of a bright star on the North Port TV camera. The star should be located
on the grease pencil x-mark on the monitor that corresponds to the FLAMINGOS hot spot.
Focus telescope on North Port TV camera (in direct video mode, not on the guide camera).
Measure seeing. Note that the seeing camera has a focus offset from the best focus on the North Port
TV camera; if the seeing is measured after you have started observing, make certain the focus is
returned to the correct value.
2. Verify FLAMINGOS is set up for imaging. The Decker and MOS wheels should be at their imaging
positions, the Lyot wheel should be at the 4-m stop, and the Grism wheel should be at position open1. The
K
s
filter is quite useful for these startup tasks.
3. Center a bright star to within 10 pixels of (x,y) = [1024,1024] on FLAMINGOS.
Within ds9 you can draw rulers from the approximate center of the star to the center of the array.
Double clicking on the ruler line will pop up a GUI with the length of the ruler line and its
decomposition in detector (x,y) coordinates. The starting and ending (x,y) coordinates of the
ruler are also listed and are modifiable.
Enter new values for the center of the star for one endpoint of the ruler, then enter in (1024,
1024) for the center of the array for the other ruler endpoint. Afterwards click the Apply button at
the bottom.
Next, hold and select the Distance pulldown button and choose the Arcseconds distance scale.
The numbers in the window will change accordingly.
Use relative.offset.kpno.pl δ RA δ Dec to offset the telescope.
Note δ RA and δ Dec 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. At the 4-m the
instrument's default position angle is 90°; under this condition, moving an object from its present
location on the array by (+dx, +dy) in detector space corresponds to (+dDec, -dRA).
Take another image, and iterate with rulers and relative.offset.kpno.pl until the star is
centered.
4. Ask the telescope operator to Zero the telescope pointing.
5. Verify optical alignments. During the first pointing check of the evening, 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.
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 recommend 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
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