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Raw FITS Header Keyword Definitions

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[TRES Data Processing] [Data Directories] [Reduced Data Keywords]

The following keywords are in the primary header of a raw TRES file:

Keyword Sample Value Comment Description
SIMPLE T Primary FITS image array
BITPIX 16 Bits per pixel IEEE single precision floating point
NAXIS 0 Number of axes Primary FITS extension contains no data
EXTEND T File contains extensions
OBJECT 'Vega' OBJECT NAME
RA '18:36:56.3' MEAN RA
DEC '+38:47:01.' MEAN DEC
EPOCH 2000 MEAN EQUINOX
AIR 1.07 AIR MASS BY TELESCOPE
RRA '18:36:56.3' REQUESTED RA
RDEC '+38:47:01.' REQUESTED DEC
REPOCH 2000 REQUESTED EQUINOX
TRA ' 18:36:54.943' RA BY TELESCOPE
TDEC ' 38:48:45.23' DEC BY TELESCOPE
TEPOCH 2000.000 EPOCH BY TELESCOPE
ST '20:15:17.50' Telescope Sidereal Time at start of exposure
HA ' 01:37:58.03' Hour Angle hh:mm:ss at start of exposure
GFWHM ' ' GUIDE FWHM ARC SEC
SFOCUS 2.0700 TRES FOCUS FLOAT
PERI 'OUT ' Periscope position (IN or OUT)
COMPTIME '0.0 ' FLASH TIME (seconds)
FIBSIZE '2.3 ' TRES FIBER SIZE (arcseconds)
IODINE 'OUT ' IODINE POSITION
CTEMPS ' -110.1C - 100% ' Chip temperatures
BTEMPS '23.491 23.610 -265.320 19.789' Bench temperatures- BOT OPT HTR AC
PRES_HUM '779.60 31.81 ' Air Pressure and Rel Humidity
DATE-OBS '2023-07-19T07:51:20' UT date/time at start
UTOPEN '07:51:20 ' UT time at start
UTEND '07:51:24 ' UT time at end
MJD 60144.327315 MODIFIED JULIAN DATE
OBSERVER 'P Berlind ' Observer
P.I. 'Latham ' Principal Investigator
PROGRAM '149 dwlmisc.mct ' TRES Observing Program
OSSWITCH ' NO ' OBJECT/SKY SWAP (YES or NO)
SITENAME 'flwo1' Observatory name = FLWO 1.5 m
SITELONG '+110:52:39.0' Observatory longitude in degrees west of 0 ddd:mm:ss
SITELAT '+31:40:51.4' Observatory latitude in degrees dd:mm:ss
SITEELEV 2320.0 Observatory elevation in meters
DETECTOR tres DETECTOR ID
EXPTIME 15.0000000000 INTEGRATION TIME, SECONDS
DARKTIME 5.000 ELAPSED TIME, SECONDS
ADC 'PA -103.6 A=336.4 B=176.4 HA= 01:33:9.524 defl=10.0 AD=226.1 BD=206.1' ADC correction
CALPOS 'Thar ' LAMP SELECTED
PROJPOS 'N/A ' ARM POSITION
STAGEPOS 'out ' Calibration stage position (in or out)
IMAGETYP 'OBJECT ' IRAF TYPE KEY OBJECT FLAT COMP ZERO DARK
FIBKEY 'OS ' Fiber Decoding Object, Sky, Flat, Comp, Bias, Dark
RFN '20230717.0044' Reduced file number, [yyyymmdd.nnnn]
END Last line of Primary Data Header

The following keywords are in each of the headers of the two image extensions of a raw TRES file:

Keyword Sample Value Comment Description
SIMPLE T FITS data extension image array
BITPIX 16 Bits per pixel IEEE single precision floating point
NAXIS 2 Number of axes
NAXIS1 545 Number of pixels in cross-dispersion axis
NAXIS2 2313 Number of pixels in dispersion axis
INHERIT T If T, inherit parameters from the primary FITS header
BZERO 32768.0000000 True value = BSCALE * (BZERO + value)
BSCALE 1.0000000 True value = BSCALE * (BZERO + value)
EXTNAME 'IM1 or IM2 ' Name of this extension
EXTVER 1 Extension version
DETSIZE '[1:2400,1:4800] ' Unbinned detector amplifier size
CCDSUM '2 2 ' Binning in X and Y during readout
CD1_1 -0.0001667 Rotation Matrix
CD1_2 0.0000000 Rotation Matrix
CD2_1 0.0000000 Rotation Matrix
CD2_2 0.0001667 Rotation Matrix
GAIN 1.0800000 Gain multiplier
RDNOISE 5.1100000 Readout noise in counts
NAMPS 2 Number of amplifiers (file extensions)
DETSEC '[334:1357,97:4704]' Unbinned amp
CCDSEC '[1:1024,1:4608] ' Unbinned amp size
DATASEC '[26:537,2:2305] ' Binned amp data section
BIASSEC '[539:545,2:2313] ' Binned amp bias section
TRIMSEC '[26:537,2:2305] ' Raw image data section
ORIGSEC '[1:512,1:2304] ' Binned amp after trimming
LTM1_1 0.5000000 First coordinate of first data pixel
LTM2_2 0.5000000 Second coordinate of first data pixel
LTV1 25.2500000 Raw first coordinate of first data pixel
LTV2 1.2500000 Raw second coordinate of first idata pixel
RADECSYS 'FK5 ' Coordinate system
DETECTOR 'tres ' Detector ID
EXPTIME 4.000 Integration time in seconds
END Last line of each amplifier data header