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Hectospec
Data Header Keyword Definitions

Hectospec Image
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KeywordSample ValueCommentDescription
SIMPLE TFits standard
BITPIX -32Bits per pixel -32 = 4-byte floating point
NAXIS 2Number of axes
NAXIS1 4505Axis length dispersion axis
NAXIS2 3Axis length 1=spectrum, 2=sky+spectrum,3=sky
EXTEND FFile has no extensions
ORIGIN 'NOAO-IRAF FITS Image Kernel December 2001'FITS file originator
IRAF-TLM '16:16:11 (31/08/2004)'Time of last IRAF modification
DATE '2004-08-30T21:06:17'Time file was created
OBJECT 'F2.20.bg 1 306' Name of the object observed
SERIALID '8351-7-5'
FILENAME 'SPEC/2004.0413/F2.20.bg_1.0420'Name of one of original FITS files Multiple exposures were combined to make the image from which this spectrum was extracted. See IMCMBnnn below.
DETSIZE '[1:4098,1:4800]'Limiting dimensions of detectors in pixels
NAMPS 4Number of amplifiers reading from detectors
CCDSEC '[1:1024,1:4608]'First amplifier limits in pixels
ORIGSEC '[1:1024,1:4608]'First amplifier limits in pixels
AMPNAME 'ampid 1-1' Name of first amplifier
IMAGEID '1' Amplifier ID
GAIN 2.0000000 Gain, electrons per ADU
RDNOISE 5.0000000 Noise, electrons
DETSEC '[1:1024,97:4704]' Detector data section Mapping of the CCD section to detector coordinates
DTV1 0.0000000 Detector transformation vector The final coordinate system is the detector coordinate system (Dx,Dy). This is important when multiple amplifiers and/or multiple CCDs are used. The detector coordinate system describes a single pixel raster of "unbinned" CCD pixels into which the multiple CCD/amplifier pixels are mapped to make a single, simple picture. It is used for displaying (and possibly processing) multiple amplifier/multiple CCD data in a consistent fashion with offsets, flips and transposes between the image pixels accounted for.
Dx = DTM1_1 * Cx + DTM1_2 * Cy + DTV1
Dy = DTM2_1 * Cx + DTM2_2 * Cy + DTV2
Cx = ( DTM2_2 * (Dx - DTV1) - DTM1_2 * (Dy - DTV2)) / (DTM1_1 * DTM2_2 - DTM1_2 * DTM2_1)
Cy = (-DTM2_1 * (Dx - DTV1) + DTM1_1 * (Dy - DTV2)) / (DTM1_1 * DTM2_2 - DTM1_2 * DTM2_1)
See the NOAO website for more details.
DTV2 96.0000000 Detector transformation vector
DTM1_1 1.0000000Detector transform matrix
DTM2_2 1.0000000Detector transform matrix
SECPIX1 0.0800000 arc-seconds per pixel At center of image along first (dispersion) axis
LTM1_1 1.0000000Image transform matrix The image coordinate system (Ic,Il) refers to the recorded image pixel array. The image array may include other information such as overscan and prescan. Thus the actual data pixels from the CCD may occupy only a region of the image. However the image coordinate system begins with (1,1) for the first pixel in the image. The first data pixel will begin with some coordinate (Ic1,Il1). The data pixels then increment by one for each "binned" pixel. As with the amplifier coordinate system the general linear coordinate transformation between the CCD and image coordinates is given by
Ic = LTM1_1 * Cx + LTM1_2 * Cy + LTV1
Il = LTM2_1 * Cx + LTM2_2 * Cy + LTV2
Cx = ( LTM2_2 * (Ic - LTV1) - LTM1_2 * (Il - LTV2)) / (LTM1_1 * LTM2_2 - LTM1_2 * LTM2_1)
Cy = (-LTM2_1 * (Ic - LTV1) + LTM1_1 * (Il - LTV2)) / (LTM1_1 * LTM2_2 - LTM1_2 * LTM2_1)
LTM2_2 1.0000000Image transform matrix
ATM1_1 1.0000000 Amplifier transform matrix The amplifier coordinate system (As,Ap) is based on the order in which pixels are read. The the serial coordinate is As and the parallel coordinate is Ap. The coordinates begin with one for the first CCD pixel (actual charge well) that the controller records or uses in binning and increments by one for each "unbinned" pixel. If the controller always skips some initial columns or lines which are never used (such as for transient settling) then these are not counted. Prescan pixels which are recorded with the image data will have amplifier coordinates less than one. The general linear transformation between the amplifier and CCD coordinates is given by
As = ATM1_1 * Cx + ATM1_2 * Cy + ATV1
Ap = ATM2_1 * Cx + ATM2_2 * Cy + ATV2
Cx = ( ATM2_2 * (As - ATV1) - ATM1_2 * (Ap - ATV2)) / (ATM1_1 * ATM2_2 - ATM1_2 * ATM2_1)
Cy = (-ATM2_1 * (As - ATV1) + ATM1_1 * (Ap - ATV2)) / (ATM1_1 * ATM2_2 - ATM1_2 * ATM2_1)
See the NOAO website for more details.
ATM2_2 1.0000000 Amplifier transform matrix
ATV1 0.0000000 Amplifier transform vector
ATV2 0.0000000 Amplifier transform vector
VRGlo -8.8860000 HK value for CCD controller
VRGhi 2.9930000 HK value for CCD controller
VSlo -7.8950000 HK value for CCD controller
VShi 1.9850000 HK value for CCD controller
VPlo -8.8870000 HK value for CCD controller
VPhi 0.9920000 HK value for CCD controller
VOG1 -5.9130000 HK value for CCD controller
VOG2 -4.9260000 HK value for CCD controller
VRD 7.9710000 HK value for CCD controller
VDD 14.9080000 HK value for CCD controller
VODL 19.8660000 HK value for CCD controller
VTemp -119.8200000 HK value for CCD controller
DEWTEMP -900.0000000
CCDSIGNM '/sbin/hecsc.bin' ccdsignal file
CCDGAIN 'UNDEFINED' CCD gain state
CAMGAIN 'UNDEFINED' camera gain state
CCDTEMP -119.8200000CCD temperature in degrees Celsius
CCDOVERR 0 CCD controller buffer overruns
CCDLOSTB 0 CCD controller lost buffers
CCDTMOUT 1 CCD controller timeouts
OBSERVAT 'mmto ' observatory IRAF abbreviation
OBSERVER 'dgf, nc, mk, mc ' observers
PROPID 'Engineering ' observing proposal ID
PI 'dgf ' Principal Investigator
EXPTIME 1200. actual integration time, seconds
DARKTIME 1200. total elapsed time, seconds
IMAGETYP 'OBJECT ' object, flat, bias, etc.
DATE-OBS '2004-04-13T04:16:47' UT date/time of start of exposure
UT '04:16:47 ' universal time of start of exposure
ST '10:20:01.041 ' sidereal time of start of exposure
MJD 53108.17833 modified Julian Date of start of exposure
RA '9:21:03.218' right ascension (hh:mm:ss)
DEC '30:42:19.764' declination (dd:mm:ss)
EQUINOX 2000.0 equinox of RA and Dec
EPOCH 2000.0 same as EQUINOX (for back compat.)
AIRMASS 1.026 airmass
ROTANGLE '10.27660791 ' rotation angle, degrees
TELFOCUS '15057.350 ' telescope focus
TELESCOP 'mmt_f5_adc ' telescope name
DETECTOR 'specs ' detector name
ALTTIMIN 0 alttiming, milli-seconds
DWELL 15 sample integration time, microseconds
NSCANROW 1 number of CCD rows scanned
CCDSUM '1 1 ' on chip summation
INSTRUME 'spec ' instrument name
DISPERSE '270_gpm ' disperser
TILTPOS '-1.92600 ' tilt position
INSFOCUS '0.86995 ' instrument focus
COMMENT Data taken with the Hectospec multifiber spectrograph
COMMENT Built at SAO and operated at the MMT f/5 Focus
COMMENT STU Preform Polymicro Fibers are 250u or 1.5arcs at focal plane
CIFOCUS '0.8700 ' commanded focus position
CTILTPOS '-1.9260 ' commanded tiltpos
POSANGLE 70.486 telescope position angle
HA '+00:59:34.248 ' hour angle
INSTAZ '0.00000000 ' instrument azimuth offset(arcsec)
INSTEL '0.00000000 ' instrument elevation offset(arcsec)
PARANGLE '80.7628085 ' telescope parallactic angle(degrees)
CAT-ID '4_12_20_37_50 ' telescope catalog obj name
CAT-RA '9:20:11.359 ' telescope catalog ra (hours)
CAT-DEC '30:31:02.739 ' telescope catalog dec (degrees)
CORRCTOR 'Wide-Field Correct' telescope corrector
ADC 'SAO ADC ' ADC identifier

The following keywords are added by image data reduction tasks:

,td>
HPROC2004-Jul-16 12:34 fixpix, overscan, and trimHPROC output
PREAMPFX2004-Jul-16 12:34 preamplifier correction madeHPROC output
TRIM Jul 16 12:34 Trim is [51:1074,3:4610]
FIXPIX Jul 16 12:34 Fix mscdb$sao/mmto/mmt/spec/badpix1.pl + sat + bleed
OVERSCANJul 16 12:34 Overscan is [1080:1120,3:4610], mean 2490.28
CCDPROC Jul 16 12:34 CCD processing done
GAINCORR 1.Gain correction in CCDPROC
IMCMB001 'F2.20.bg_1.0420.fits[1]' HCOMBINE first image
IMCMB002 'F2.20.bg_1.0422.fits[1]' HCOMBINE second image
IMCMB003 'F2.20.bg_1.0424.fits[1]' HCOMBINE third image
NCOMBINE 3 Number of images combined
HMERGE 2004-Jul-16 13:31 4 amplifiers merged into one imageWritten by hectospec.hmerge task
HNORM 2004-Jul-16 16:30 pixels normalized by flat.fitsWritten by hectospec.hnorm task
JD 2453108.685266Julian date of observation midtime
LJD 2453108.Integer Julian Date
CTYPE1 'LINEAR ' X-axis WCS is linear
CTYPE2 'LINEAR ' Y-axis WCS is linear
CD1_1 1.21003552397869 X-axis WCS units (Angstroms) per pixel
CD2_2 1 Y-axis WCS units (spectra) per pixel
CDELT1 1.21003552397869 X-axis WCS units (anstroms) per pixel
CDELT2 1. X-axis WCS units (anstroms) per pixel
HEXTRACT '2004-Jul-16 16:31 extracted from F2.20.bg_1.fits'Written by hectospec.hextract
HEXAPREF 'dome ' Aperature reference file used by HEXTRACT
HEXAPMAP 'F2.20.bg_1_map'Aperture map file used by HEXTRACT
DCLOG1 'REFSPEC1 = comp.ms' Reference wavelength calibration spectrum
DC-FLAG 0 Wavelength axis is linear, not log wavelength
CRPIX1 1. X-axis WCS (wavelength) reference pixel
CRVAL1 3700. WCS (wavelength) value at X-axis reference pixel
NP1 1 First X pixel to which WCS applies
INTERP 'wavelength interpolated '
HISTORYrvsao.sumspec 2.3.5 run 16-Jul-2004 16:32
FIBRGEOM2004-Jul-16 16:35 geometric correction madeWritten by hectospec.htran
FIBRTRAN2004-Jul-16 16:35 fiber throughput corrected: 10 order spline3Written by hectospec.htran
FIBRFILE 'tpc_dome.ms' File used for throughput correction
WCSDIM 2 Number of WCS dimensions
FIELD 'F2.20.bg_1' Name of field which includes this object
TYPE ' '
TRA '+09:20:11.36'Right ascension of optical axis
TDEC '+30:31:02.74'Declination of optical axis
TEPOCH 2000Equinox of optical axis (J assumed)
FIBER 248Fiber number
APRANGE '0:0 ' meaningless
FIBER_X 49.148Fiber X coordinate on focal plane
FIBER_Y -151.72Fiber Y coordinate on focal plane
CATNAME 'name ' Name of catalog with fiber sky position
CATNUM 306Number of entry in catalog
APERTURE 125Aperture number (sequential on detector)
CATOBJ 'target ' Name of object from catalog
SPECNUM 125Number of spectrum in extracted 2-D file
APNUM1 1 0 1.00 1.00 1.00 1.00 Needed for multispec work
APNUM2 2 0 1.00 1.00 2.00 2.00 Needed for multispec work
APNUM3 3 0 1.00 1.00 3.00 3.00 Needed for multispec work
HABSKY '2004-Aug-30 16:06 hectospec$lib/skyabs.fits divided out'Added by hectospec.habsky
DISPAXIS 1 Dispersion axis (1=X)
WAT0_001'system=equispec' IRAF WCS
WAT1_001'wtype=linear label=Wavelength units=angstroms'IRAF WCS
WAT2_001 'wtype=linear' IRAF WCS
NSKYFIB 5 Number of sky fibers used by hectospec.skyproc
SKYFIB '244_267_279_264_222_'Sky fibers used for background removal
SKYAPER '27+28+104+114+143'Sky apertures used for background removal
SKYCERT 4 Maximim R-value for skies correlated against template for hectospec.skyproc
NSKYMAX 5 Maximum number of sky fibers usable by hectospec.skyproc
SKYDIST 0 If nonzero, only use fibers closer than this in focal plane
SKYMETHD 'SKYSUB ' Sky subtraction method is hectospec.skyproc
SKYRATIO 0.970260 Scale factor from object sky lines to mean sky lines in hectospec.skyproc
SKYSTDLM 0.2 Reject sky spectra with RMS > 0.2 from mean sky RMS in hectospec.skyproc
VELOCITY 47328.1914967525 Best redshift velocity in km/sec
CZERR 16.4119728769627 Redshift velocity error in km/sec
BCV -27.0360641479492 Barycentric velocity correction in km/sec from rvsao.xcsao
CZXC 47328.0782493144 Best cross-correlation redshift velocity in km/sec from rvsao.xcsao
CZXCERR 7.30550220240955 Best cross-correlation redshift velocity error in km/sec from rvsao.xcsao
CZXCR 16.6141650060873 Best cross-correlation redshift R-value from rvsao.xcsao
BESTTEMP 'hemtemp0' Name of best cross-correlation template file from rvsao.xcsao
CZPARAMS '4 4096 1 5 10 100 200 0.05'rvsao.xcsao parameters: number of templates, number of log-wavelength pixels, zpad flag, 4 filter limits, apodization
COMMENTTemplate information from rvsao.xcsao:
COMMENTfile name, cross-correlation velocity, error, R-value
COMMENTcorrelation peak height (0-1) and width (km/sec)
COMMENTvelocity relative to template, template BCV
COMMENTtemplate em. chopped, template filtered
XCTEMP1 'hemtemp0 47328.078 7.306 16.6142 0.661 172.065 47358.835 0.000 0 3'
XCTEMP2 'habtemp90 47390.822 95.386 2.73766 0.193 481.738 57253.165 0.000 0 3'
XCTEMP3 'femtemp97 47329.947 8.079 16.0382 0.666 184.104 47361.315 0.000 0 3'
XCTEMP4 'fabtemp97 47504.457 114.344 2.17596 0.177 475.139 47534.421 0.000 0 '
XCSAO 'rvsao.xcsao 2.3.7 30-Aug-2004 16:41 CZXC = 47328.08 R = 16.61'
VELQUAL '_ ' Velocity quality (_=not set, Q=good, X=bad, ?=uncertain) from rvsao.qplot
QPLOT 'rvsao.xcsao 2.3.5 16-Jul-2004 17:45 VELOCITY = 47430.28 Q = Q'
CZEM 47328.7485072547 Emission line velocity in km/sec from rvsao.emsao
CZEMERR 16.2019607110046 Emission line velocity error in km/sec from rvsao.emsao
CZEMNL 10 Number of emission lines found by rvsao.emsao
CZEMNLF 8 Number of emission lines fit by rvsao.emsao
COMMENTEmission line information from rvsao.emsao:
COMMENTline name, rest wavelength, observed wavelength
COMMENTline height, line width, redshift (km/sec), redshift error (km/sec)
COMMENTequivalent width, weighting factor
EMLINE1 'OII 3727.30 4316.45 152.06 2.8951 47386.15 14.56 1103.48 0.033'
EMLINE2 'Hg 4340.50 5025.82 44.999 2.1767 47334.41 35.10 245.52 0.006'
EMLINE3 'Hb 4861.33 5629.04 204.08 2.5295 47343.62 4.89 1293.98 0.288'
EMLINE4 'OIII 5006.84 5797.94 63.244 4.1075 47368.22 22.82 651.16 0.013'
EMLINE5 'OI 6300.23 7297.30 0.0000 0.0000 0.00 0.00 0.00 0.000'
EMLINE6 'N1 6548.06 3700.00 0.0000 0.0000 -130393.89 0.81 0.00 0.000'
EMLINE7 'Ha 6562.82 7599.53 637.70 2.8218 47357.47 6.96 4510.63 0.142'
EMLINE8 'N2 6583.57 7623.62 218.02 3.7515 47360.24 3.72 2050.23 0.497'
EMLINE9 'S1 6716.44 7777.02 92.506 2.7575 47339.64 28.91 639.41 0.008'
EMLINE10 'S2 6730.81 7794.29 84.108 2.4362 47367.40 22.78 513.61 0.013'
EMSAO 'rvsao.emsao 2.3.7 31-Aug-2004 16:16 CZEM = 47328.75 LINES = 8'
END