Getting Started Observing

The basic observing procedures with CIRIM are outlined in this section. For comparison, a nominal CIRIM K band flat field, 0.4 second dark and 100 second dark can be found in the directory /usr/wfire/cirimnorm/cirim*.imh on ctioa2. During the first day that CIRIM is on the telescope you should carry out the following procedures:

• Initialize the filter wheel (fwinit) and the Lyot stop (lyotinit).
• Select the dark filter. Take a number of short exposures and combine them to measure the array noise. With one low noise read the noise in all the quadrants should be uniform and less than about 3 ADU. Also take some long, 100 second, darks. The dark current should be less than about 3 ADU per second.
• Select the correct Lyot stop for the telescope and secondary you are using (lyot n).
• Select the ``hlens'' to align the pupil. Turn on the flat-field lights and adjust ``lr'' and ``lt'' using jog commands to align the pupil stop with the central obstruction and the edge of the primary. If you have jogged filter wheel three to view the pupil stop intialize the filter wheels again (fwinit)
• Obtain dome flats is the filters you intend to use. Adjust the lamp intensities so that you obtain about 10,000 ADU in a few seconds. I usually take a few flats with both the lamps on and then a few with the lamps off. I then subtract the lights off images from the lamps on the remove the dark current and any telescope emission components. Since the lamps-off images have a lot less background than the lamps-off image it is best to take a few junk images after turning the dome lights off since there is array memory.
• Write and test any TCL scripts you will want to use during the night.

During twilight carry out the following steps:

• Set the telescope to the approximate focus given on the first page of this manual.
• Select the ``klens'' and image the telescope pupil against the sky. If you see excess thermal emission from any edge of the stop adjust the stops position using jogs in ``lt'' and ``lr''. If you have jogged filter wheel three to view the pupil stop intialize the filter wheels again (fwinit)
• Acquire a bright star and center it in the array using a narrow band filter and center it on the array. Zero point the telescope and an approximate focus for the telescope.
• Move to a faint standard star. Focus the telescope carefully on the array in a filter of interest. Put in the acquisition TV and focus it. Also, focus the guider if your telescope has one.
• Finally, carefully measure the focus offsets of the filters you plan on using.
• Measure the faint standard in any filters of interest. I recommend measuring standard stars at nine positions on the array. Be sure to not exceed 15000 ADU in peak counts on the standard star.