User's Guide to ShARCS


Table of Contents


Introduction
Summary Table
Detector Characteristics
Filters, Grisms, Apertures, Polarimeter
Software Overview
Data Taker GUI
Filter & Aperture Wheel GUI
Image Display GUI
Scripts
Sound server
Temperature Monitor
Observing Procedures and Tips
FITS Header Keywords
Trouble-Shooting
Logsheet

Data Archive
Mt. Hamilton Homepage

Observing Procedures

Dome Flats | Arc Lamps | Windowing the Detector


Dome Flats

To take direct imaging 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. 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
  7. The following narrowband filter should use the Blue flat field lamp.
    • CH4-2.4: 6.0 sec
  8. 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)
50x501.65x1.650.06
100x1003.30x3.300.11
150x1504.95x4.950.24
200x2006.60x6.600.42
250x2508.25x8.250.65
300x3009.90x9.900.93
350x35011.55x11.551.26

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.

The windowed region is set from the Window GUI in the sharcs_fe data taking software. The start x, end x, start y, and end y values entered into the GUI fields are Detector Pixel coordinates (which are not displayed by default in the sharcsdisplay image display software). To display the detector pixel axes so the proper region can be specified, select Sky Pixels or Detector Pixels from the Axes menu in the sharcsdisp GUI.

The first full frame (2048x2048) exposure taken after windowing the detector will have undesirable bias levels in the sub-region area, so always take a quick full-frame test exposure to clear the bias defect before taking any science or calibration data.


Last modified: Mon Jan 25 15:17:36 PST 2016