User`s guide

FLAMINGOS at the MMT
C. Calibrations
There are two types of calibrations required for long slit and mos spectra: wavelength calibration and flat fields.
These measurements need to be made after the instrument is fully configured, and before you change the
configuration (do not move any wheels until you've taken these data!). If the telescope stays focused and
collimated for several hours, then it's probably good to take flat field images at the start and the end of acquiring
an object's spectrum; wavelength calibrations can be taken at the start or end of the observation, but only need to
be measured once per object.
To take calibrations, guiding must be suspended while the lamps are on.
The observer selects what lamps are on using an interface box on the table next to packrat.
After setting the filename and exposure time, use more.single.images.pl to take 3 to 5 images.
When you have finished with the calibrations and are back to guiding on the sky, take a junk image with
the same exposure time that you want to use on your object. You should do this because the first image
taken in low-flux conditions after being in high-flux conditions has lower counts than normal. For
example, the calibrations might be taken at 30 seconds and the object taken at 300 seconds, so you need to
take a junk image at 300 seconds before taking any real data.
D. Taking spectra
There are two common techniques for taking spectra: walking up the slit, and nodding the telescope back and
forth between two beams A and B in a ABBA pattern.
Walking up the slit:
Use singleimage.pl to take an image at every location.
Use guided.relative.offset.mmt.pl to move the star up and down the slit while continuing to guide.
Nodding between A & B beams:
Use config.mos.dither.mmt.pl to set up the distance in arcseconds between beams and the number of
times to repeat the ABBA pattern. If you want, you can nudge the entire ABBA pattern up and down
the slit by a small amount (in arcseconds; typically the size of one or two pixels). I think this nudging
works, but we'll have to test it.
Use dither.mos.mmt.pl to execute the actual dither pattern.
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