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ORFEUS II FITS Data FormatContents4. Format of dataThe Echelle images as well as the extracted spectra are available in FITS format. The FITS headers, keywords and formats used are described in the following chapters.A) ImagesEchelle images are stored as 1024 x 512 x 16 bit data. This is a sample header of an Echelle image data file: SIMPLE = T / BITPIX = 16 / NAXIS = 2 / NAXIS1 = 1024 / NAXIS2 = 512 / BUNIT = 'counts/pixel' / unit of pixel values TELESCOP= 'ORFEUS-SPAS II' / mission/satellite name INSTRUME= 'Tuebingen UV Echelle Spectrometer (TUES)' / instrument name DATE = '2000-10-25T11:55:05' / file creation date (YYYY-MM-DDThh:mm:ss UTC) ORIGIN = 'IAAT - Institute for Astronomy and Astrophysics Tuebingen' OBS_CODE= 'TUES2276_2' / observation reference number ORFEUSID= '2276 ' / specific ORFEUS target ID number OBS_NO = '2 ' / Echelle observation number OBJECT = 'HD 93521' / target name RA_OBJ = 162.09750 /[deg] right ascension of object DEC_OBJ = 37.57028 /[deg] declination of object EQUINOX = 2000.0 / equinox of coordinate system DATE-OBS= '1996-11-28T04:56:05' / obs start time (YYY-MM-DDThh:mm:ss UTC) DATE-END= '1996-11-28T05:14:05' / obs stop time (YYY-MM-DDThh:mm:ss UTC) CLOCKCOR= 'NO ' / UTC not guaranteed TIMEREF = 'LOCAL ' / Time frame of satellite TASSIGN = 'SATELLITE' / Times assigned on satellite TIMESYS = 'MJD ' / Modified Julian Date MJDREF = 40000 / [days] MJD of reference date TSTART = 899873765 / [s] from MJDREF TSTOP = 899874845 / [s] from MJDREF TIERRABS= 1 / [s] precision of quoted times EXPTIME = 1080 / [s] exposure time FILENAME= 'tues2276_2.fits' / name of this file COMMENT COMMENT --- Original ORFEUS Header --- COMMENT Description of keywords (not all of them used): COMMENT TARGET: ORFEUS ID / object name COMMENT RA/DEC: epoch 2000 coordinates COMMENT BEOBNR: number of observation COMMENT INTANF: obs.start: day of 1996 / hh:mm:ss COMMENT INTEND: obs. end : day of 1996 / hh:mm:ss COMMENT INTTIM: integration time in seconds COMMENT XTRACT: extraction parameters COMMENT ORBITV: orbital velocity towards object [km/s] COMMENT VHELIO: heliocentric velocity towards object [km/s] COMMENT BLAZEO: blaze correction parameters: offset [mm] COMMENT BLAZEW: blaze correction parameters: width COMMENT CNTRAT: count rates (maximum, actual, image) COMMENT V_KORR: additional radial velocity correction [km/s] COMMENT CORRCT: image processing flags COMMENT FACTOR: scaling factor of image COMMENT UPDATE: last update of ORFEUS Echelle image header COMMENT --- start of ORFEUS header --- HISTORY TARGET: 2276 / HD 93521 HISTORY RA/DEC: 10 48 23.40 / +37 34 13.00 HISTORY BEOBNR: 2 HISTORY INTANF: GMT 333:04:56:05 HISTORY INTEND: GMT 333/05:14:05 HISTORY INTTIM: 1080.00 HISTORY COMMNT: HISTORY XTRACT: 40, 61, 1, 0 HISTORY ORBITV: 0.88, 1.77, 2.63, 3.46, 4.23, 4.93, 5.56, 6.11, 6.56, 6.91, 7.1 HISTORY VHELIO: -26.46 HISTORY BLAZEO: 5.00, 5.10, 5.20, 5.30, 5.40, 5.50, 5.60, 5.70 HISTORY BLAZEW: 0.73, 0.73, 0.73, 0.73, 0.73, 0.73, 0.75, 0.75 HISTORY CNTRAT: 9500.0, 6227.4, 5169.1 HISTORY HISTORY HISTORY HISTORY HISTORY HISTORY HISTORY UPDATE: Thu Mar 5 10:14:25 1998 COMMENT --- end of ORFEUS header --- HISTORY Version of ORFEUS-ECHELLE-FITS routines: HISTORY 1.3, 2000-10-25, Juergen Barnstedt HISTORY For description of ORFEUS II Echelle spectrometer performance see: HISTORY J.Barnstedt, N.Kappelmann, I.Appenzeller, et al., HISTORY Astron. Astrophys. Suppl. Ser. 134, 561-567 (1999) HISTORY (astro-ph/0006295) END Description of Echelle image keywords:
The "COMMENT" lines following these keywords describe the original ORFEUS keywords used with the data supplied to the guest observers. The original ORFEUS header follows as "HISTORY" entries. The original ORFEUS keywords are described here in detail:
B) Extracted data of individual echelle ordersThe Echelle spectra are extracted order by order, there are overlap regions between adjacent orders. The extracted orders are stored in FITS format as binary table extensions. The spectra are available as each order in one file or as all orders contained in one file. The primary header contains all information concerning this certain observation or this file, the binary table extension header contains all information concerning the extracted data of the respective order. Sample spectrum primary header: SIMPLE = T / Written by IDL: Wed Oct 25 10:21:15 2000 BITPIX = 8 NAXIS = 0 EXTEND = T FILENAME= 'tues2276_2_ord61.fits'/ name of this file ORD_FRST= 61 / first echelle order in this file ORD_LAST= 61 / last echelle order in this file WVL_FRST= 904.673 / [A] first wavelength in this file WVL_LAST= 926.478 / [A] last wavelength in this file TELESCOP= 'ORFEUS-SPAS II' / mission/satellite name INSTRUME= 'Tuebingen UV Echelle Spectrometer (TUES)' / instrument name DATE = '2000-10-25T09:21:14' / file creation date (YYYY-MM-DDThh:mm:ss UTC) ORIGIN = 'IAAT - Institute for Astronomy and Astrophysics Tuebingen' OBS_CODE= 'TUES2276_2' / observation reference number ORFEUSID= '2276 ' / specific ORFEUS target ID number OBS_NO = '2 ' / Echelle observation number OBJECT = 'HD 93521' / target name RA_OBJ = 162.09750 /[deg] right ascension of object DEC_OBJ = 37.57028 /[deg] declination of object EQUINOX = 2000.0 / equinox of coordinate system DATE-OBS= '1996-11-28T04:56:05' / obs start time (YYY-MM-DDThh:mm:ss UTC) DATE-END= '1996-11-28T05:14:05' / obs stop time (YYY-MM-DDThh:mm:ss UTC) CLOCKCOR= 'NO ' / UTC not guaranteed TIMEREF = 'LOCAL ' / Time frame of satellite TASSIGN = 'SATELLITE' / Times assigned on satellite TIMESYS = 'MJD ' / Modified Julian Date MJDREF = 40000 / [days] MJD of reference date TSTART = 899873765 / [s] from MJDREF TSTOP = 899874845 / [s] from MJDREF TIERRABS= 1 / [s] precision of quoted times EXPTIME = 1080 / [s] exposure time COMMENT ********************* COMMENT The following data are displayed in the COMMENT original ORFEUS header format. COMMENT --- ORFEUS header --- COMMENT COMMENT RA / DEC (2000) [hh mm ss.ss / +dd mm ss.ss] : RA_DEC = '10 48 23.40 / +37 34 13.00' COMMENT integration start time [UT, day of 1996 /hh:mm:ss] : INTSTART= 'GMT 333:04:56:05' COMMENT integration stop time [UT, day of 1996 /hh:mm:ss] : INTSTOP = 'GMT 333/05:14:05' COMMENT original image file : IMGFILE = '/users_12/ORFII/BILDER/E2276/2276_2.bil' TILTEDEX= 'no' / tilted extraction (yes/no) COMMENT ORFEUS comment : ORFCOMM = '' CORBLAZE= 'yes' / blaze correction (yes/no) COMMENT blaze offset values [mm]: OFSBLAZE= ' 5.00, 5.10, 5.20, 5.30, 5.40, 5.50, 5.60, 5.70' COMMENT blaze width values : WIDBLAZE= ' 0.73, 0.73, 0.73, 0.73, 0.73, 0.73, 0.75, 0.75' COREFFAR= 'yes' / effective area correction (yes/no) COMMENT count rates (maximum, actual, image) [counts/sec]: CNTRATES= '9500.0, 6227.4, 5169.1' CORBACKG= 'yes' / background subtraction (yes/no) AVERG512= 'yes' / averaging of pixels 511/512 (yes/no) EDGECORR= 'yes' / edge correction (yes/no) OBSBLKCO= 'yes' / observation block correction (yes/no) BLKCORR = 1.0000321 / observation block wavelength correction factor ORBRVCOR= 'yes' / orbital relative velocity correction (yes/no) ORBITRV = 4.6 / [km/s] average orbital relative velocity VHELCORR= 'yes' / heliocentric correction (yes/no) VHELIOCE= -26.5 / [km/s] heliocentric velocity AVELCORR= 'yes' / additional radial velocity correction (yes/no) ADDRADV = 0.0 / [km/s] additional radial velocity COMMENT wavelength calibration parameters : WLCALPAR= '41.5990, 475.945, 3.52602, -0.480310, -0.335360, -0.0108750, 1.06074' COMMENT --- end of ORFEUS header --- COMMENT ********************* HISTORY Version of ORFEUS-ECHELLE-FITS routines: HISTORY 1.2, 2000-10-13, Juergen Barnstedt HISTORY For description of ORFEUS II Echelle spectrometer performance see: HISTORY J.Barnstedt, N.Kappelmann, I.Appenzeller, et al., HISTORY Astron. Astrophys. Suppl. Ser. 134, 561-567 (1999) END Description of spectrum primary header keywords:
The following keywords show the original ORFEUS header data used with the files supplied to the guest observers. The keywords are described here in detail:
Sample spectrum binary table extension header: XTENSION= 'BINTABLE' /Binary table written by MWRFITS BITPIX = 8 /Required value NAXIS = 2 /Required value NAXIS1 = 42 /Number of bytes per row NAXIS2 = 837 /Number of rows PCOUNT = 0 /Normally 0 (no varying arrays) GCOUNT = 1 /Required value TFIELDS = 11 /Number of columns in table INHERIT = T / primary header applies to this extension EXTNAME = 'ORDER_61' / name of this binary table extension ECHORDER= 61 / echelle order (range 40 - 61) WVLSTART= 904.673 / [A] start wavelength in this extension WVLEND = 926.478 / [A] end wavelength in this extension CUTWIDTH= 9 / [pixel] extraction cut width Y_SHIFT = -3 / [pixel] extraction y-position shift TFORM1 = 'E ' / TFORM2 = 'I ' / TFORM3 = 'E ' / TFORM4 = 'E ' / TFORM5 = 'E ' / TFORM6 = 'E ' / TFORM7 = 'E ' / TFORM8 = 'E ' / TFORM9 = 'E ' / TFORM10 = 'E ' / TFORM11 = 'E ' / COMMENT / TTYPE1 = 'WAVELENGTH' / TUNIT1 = 'ANGSTROM' / TDISP1 = 'F9.3 ' / COMMENT / TTYPE2 = 'PIXEL ' / TUNIT2 = 'PIXEL NO.' / TDISP2 = 'I6 ' / COMMENT / TTYPE3 = 'COUNTS_RAW' / TUNIT3 = 'COUNTS/PIXEL' / TDISP3 = 'F10.1 ' / COMMENT / TTYPE4 = 'COUNTS_BLAZE_CORRECTED' / TUNIT4 = 'COUNTS/PIXEL' / TDISP4 = 'F10.1 ' / COMMENT / TTYPE5 = 'BACKGROUND_RAW' / TUNIT5 = 'COUNTS/PIXEL' / TDISP5 = 'F10.1 ' / COMMENT / TTYPE6 = 'BACKGROUND_SMOOTHED' / TUNIT6 = 'COUNTS/PIXEL' / TDISP6 = 'F10.1 ' / COMMENT / TTYPE7 = 'PHOTON_FLUX' / TUNIT7 = 'PHOTONS/CM^2/SEC/ANGSTROM' / TDISP7 = 'G15.5E3 ' / COMMENT / TTYPE8 = 'ENERGY_FLUX' / TUNIT8 = 'ERG/CM^2/SEC/ANGSTROM' / TDISP8 = 'G15.5 ' / COMMENT / TTYPE9 = 'RELATIVE_ERROR' / TUNIT9 = ' ' / TDISP9 = 'F8.3 ' / COMMENT / TTYPE10 = 'EDGE_CORR' / TUNIT10 = 'SCALING FACTOR' / TDISP10 = 'F8.3 ' / COMMENT / TTYPE11 = 'BLAZE_CORR' / TUNIT11 = 'SCALING FACTOR' / TDISP11 = 'F8.4 ' / COMMENT / END Description of spectrum binary table extension header keywords:
Description of the 11 data columns within one binary table extension:
Formula of calculation: COUNTS_BLAZE_CORRECTED =(COUNTS_RAW - BACKGROUND_SMOOTHED) / BLAZE_CORR / EDGE_CORR RELATIVE_ERROR = SQRT(COUNTS_RAW + BACKGROUND_SMOOTHED*width_factor) / (COUNTS_RAW - BACKGROUND_SMOOTHED)
The above page was written by Jürgen Barnstedt from the
ORFEUS Group at Tübingen and is reproduced here for the
MAST archive with his permission.
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