Dome Flats

1. Open 3-m Shane Telescope mirror cover.
2. Put diagonal mirror in position 3.
3. Turn off lights in dome.
4. Turn on the Red flat field lamp for broadband filters.
5. Sample exposure times for each filter (note, exposure times may change as the brightness of the lamp may change):
   • J: 45 sec
   • H: 15 sec
   • Ks: 9 sec
6. For narrowband filters, one should use the SuperBlue flat field lamp set at 100.
   • BrG-2.16: 1.5 sec
   • FeII: 1.5 sec
   • J + CH4-1.2: 1.5 sec
   • H2-2.122: 1.5 sec
   • Hcont: 1.5 sec
   • Kcont: 1.5 sec
7. For very bright targets, the external ND filter may be required to prevent saturation of the detector using the minimum exposure time. For flat fields for the commonly used filters + ND, one should use the SuperBlue flat field lamp set at 100.
   • BrG-2.16 + ND2: 40 sec
   • J + ND2: 6 sec
   • H + ND2: 3 sec
   • Ks + ND2: 3 sec
8. The following narrowband filter should use the Blue flat field lamp.
   • CH4-2.4: 6.0 sec
   • 2.2/0.04: 25 sec
9. When done with dome flats, please remember to turn off the flat field lamp and close the mirror cover.

To take spectral dome flats, do the following:

1. Open 3-m Shane Telescope mirror cover.
2. Put diagonal mirror in position 3.
3. Turn off lights in dome.
4. Set aperture wheel to Slit-100um-H.
5. Turn on SuperBlue flat field lamp and set to a brightness of 100.
6. Sample exposure times (note: times may vary as lamp brightness changes with time):
   • Kgrism + K: 15 sec
   • H + Hgrism: 12 sec
7. When done with dome flats, please remember to turn off the flat field lamp and close the mirror cover.

Arc Lamp Calibration for Spectroscopy

There is only an Argon lamp available for doing arc calibrations for spectroscopy with ShARCS. To get arc calibrations, do the following:

1. Put the Calibration source at the Red Light position (eventually this will be updated to say Argon).
2. Turn on the Argon lamp (C4 in saopower_ui).
3. Set aperture wheel to Slit-100um-H.
4. Sample exposure times (note that times may change if the lamp brightness changes with time).
   • Kgrism + K: 6 sec
   • H + Hgrism: 3 sec
5. Please turn off Argon lamp when done doing arc calibrations.

Windowing the Detector

Reading out a small region of the detector is sometimes necessary to reduce the minimum exposure time or reduce the overhead of writing files to disk. This reduced overhead also leads to a much reduced FITS header, as there is not time to write all the FITS keywords from the motor controller and adaptive optics systems, hence good logs should be maintained if using a sub-region of the detector.

Sub-Region Size (pixels)	Sub-Region Size (arcsec)	Minimum Exposure Time (seconds)
50x50	1.65x1.65	0.06
100x100	3.30x3.30	0.11
150x150	4.95x4.95	0.24
200x200	6.60x6.60	0.42
250x250	8.25x8.25	0.65
300x300	9.90x9.90	0.93
350x350	11.55x11.55	1.26

Regions larger than 350x350 pixels have a similar minimum exposure time as reading out the full detector (1.46 seconds), so the only gain would be in the reduced overhead of writing the files and for regions larger than about 375x375 pixels, the minimum exposure time becomes greater than the 1.46 second minimum exposure time when reading out the entire detector.