User's Guide to ShARCS

Table of Contents

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

Data Archive
Mt. Hamilton Homepage

FITS Header Keywords

ShARCS records a great deal of information in the FITS header keywords about the state of the detector and exposure parameters, state of the filter and aperture wheels, as well as the state of the ShaneAO adaptive optics system. A summary of the pertinent keywords for each system is listed below (this is not an exhaustive list of the unique keywords, just those that are most relevant for observers analyzing the data).

Detector Keywords

DATE-OBS - Unreliable date of exposure begin, don't use this keyword
TIME-OBS - Unreliable time of exposure begin, don't use this keyword
TIME-END - Unreliable time of exposure end, don't use this keyword
DATE-BEG - Accurate UT date and time of exposure start time
ITIME - Requested integration time in milliseconds of each coadd. Note, actual itegration time of each coadd is in the TRUITIME keyword.
TRUITIME - True integration time in seconds per coadd
COADDS - Number of coadds
GROUPS - Number of sampling groups
NUMREADS - Number of reads
READTIME - Detector readout time in seconds.
RESETS - Number of resets before exposure
SAMPMODE - Sampling mode. Can be MCDS, CDS, UTR, or Single.
BUNIT - Units of pixel value, usually 'ADU per coadd'
STARTX - Sub-array start x pixel
STARTY - Sub-array start y pixel
ENDX - Sub-array end x pixel
ENDY - Sub-array end y pixel
PSCALE - Pixel scale in arcsec/pixel for science camera, should be 0.033
RMPRESET - Number of resets in ramp
RMPREADS - Number of reads in ramp
DMPDROP - Number of drop frames in ramp
RMPGROUP - Number of groups in ramp
RDITIME - Time between sampling groups in seconds
ABORTED - Exposure was stopped before completion, either T or F
COADDONE - Number of coadds actually completed
READDONE - Reads actually completed in this coadd
GRPSDONE - Groups actually completed in this coadd
IGNORDRD - Number of discarded initial reads
SATURATE - Detector saturation level (DN) from config file, usually 33000
SYSGAIN - System gain in e-/ADU, usually 2.15

Filter and Aperture Wheel Keywords

APERNAM - Dewar aperture wheel, named position
FILT1NAM - Dewar filter wheel 1, named position
FILT2NAM - Dewar filter wheel 2, named position
SCIFILT - External (warm) science filter wheel position

ShaneAO State Keywords

LENSLETN - Lenslet, named position. Can be 8x, 16x, or 30x.
TTDICHRN - Tip/Tilt dichroic position. Can be Splitter or Mirror.
LOOPSTAT - AO loop state. Can be Open or Closed.
LOOPSUB - AO Loop subaperture mode. Can be 8xLGS, 16xLGS, or 30xLGS.
TWTRGAIN - AO tweeter DM integrator gain
WOOFGAIN - AO woofer DM integrator gain
WFSRATE - WFS camera frame rate in Hz
TTRATE - Tip/tilt camera frame rate in Hz

Dithering Script Keywords

SCRPTSTA - Scripting message
SCRPTMSG - Scripting status
AUTOCLOS - Auto-close AO loops after a dither. Can be True or False.
AUTOOPEN - Auto-open AO loops before a dither. Can be True or False.
FPDISPXR - Requested X field steering in arcsec.
FPDISPYR - Requested Y field steering in arcsec.
FPDISPXI - Initial WFS guide star offset, X, in arcsec.
FPDISPYI - Initial WFS guide star offset, Y, in arcsec.
NOD_TELE - Nod telescope in dither script. Can be True or False.
NOD_WFS - Nod WFS field steering mirrors in dither script. Can be True or False.
NEXPOSE - Number of completed exposure in series.

Seeing Keywords

AOS_TIME - Time of seeing data collection.
AOS_AGE - Age of seeing data collection in seconds.
AOSSFILE - IR seeing image file. Not yet implemented.
AOSSBAND - IR filter band of seeing image. Not yet implemented.
AOSSFWHM - FWHM of star on IR image. Not yet implemented.
AOSSR0 - R0 from IR image. Not yet implemented.
AOSTFILE - First TT seeing datafile.
AOSTFWHM - Seeing measurement of FWHM of star on TT sensor in arcseconds.
AOSTR0 - R0 from TT sensor, in cm.
TELMTIME - Time of WFS telemetry data.
TELMAGE - Age of telemetry data in seconds.
TELMFILE - Name of the telemetry data file.
AO_R0 - R0 from telemetry data, in cm.
AO_V - Wind speed from telemetry, in m/s.
AO_F0 - Telemetry low frequency breat, in Hz.
AO_SN - Telemetry noise floor, nm^2/Hz.
AO_P - Mid frequency power law fit, f^-p.
AO_Q - Low frequency power law fit, f^-q.
GIDESTAR - Telemetry star name.
WFS_TRAN - Estimated throughput to WFS, percent.

Last modified: Tue Jan 18 09:49:31 PST 2022