Troubleshooting guide

~4mguest/bin/Example.many.scripted.darks.csh
Note that the blank lines are very important!
Also, be very certain to check later that the script completed successfully; cf. § VIII. Troubleshooting for
possible failure modes, such as bad reads, scrambled images, zero frames, and MCE4 hangs.
H. Dome Flats
Although most observers use sky flats generated from the target observations, one may take dome flats as a
backup. These can be taken at the end of the night or during the afternoon, if one has arranged beforehand with
the telescope operator to have the telescope set up for flats—this can also be done through the Service
maintenance request form. The telescope will be pointed at the White Spot with all of the mirror covers opened.
The observer will only have to turn on the flatfield lamps at the telescope console and set the intensity.
Instead of taking darks for bias and dark current subtraction, we recommend taking a series (10 – 20) of flats
with the lamp at the proper intensity to yield signal levels in the 10000 – 15000 ADU range and a second series
with the lamp turned off. These two sets are then averaged and subtracted to eliminate the bias and dark
current, as well as any ambient background light and thermal emission.
The following table gives empirical settings for the flatfield lamp setting and integration time which have given
acceptable flux levels in the past.
Filter Flat Lamp Setting Time
J Low 53 20 s
H Low 53 8 s
Ks Low 53 3 s
I. Custom Scripts
Various user scripts are located in the directory ~/bin and have the general format <scriptname>.csh. To create
a custom script, cd ~/bin and copy an existing script to a new name:
cp <scriptname>.csh <newscriptname>.csh
After editing the new script, you may execute it from the command window with
~/bin/<newscriptname>.csh
FLAMINGOS@4-m, Ver. 2.39, 2013 April 23 Page 22 of 47