FITS Headers
DIRBE_BAND08_E90_P3B.FITS
Primary Header
SIMPLE = T / file does conform to FITS standard BITPIX = 32 / number of bits per data pixel NAXIS = 0 / number of data axes EXTEND = T / FITS dataset may contain extensions COMMENT FITS (Flexible Image Transport System) format defined in Astronomy and COMMENT Astrophysics Supplement Series v44/p363, v44/p371, v73/p359, v73/p365. COMMENT Contact the NASA Science Office of Standards and Technology for the COMMENT FITS Definition document #100 and other FITS information. DATE = '11/02/97' / FITS file creation date (dd/mm/yy) DATE-MAP= '04/04/96' / Date of original file creation (dd/mm/yy) ORIGIN = 'CDAC ' / Cosmology Data Analysis Center TELESCOP= 'COBE ' / Cosmic Background Explorer satellite INSTRUME= 'DIRBE ' / COBE instrument [DIRBE, DMR, FIRAS] OBJECT = 'ALL-SKY ' / part of sky given [e.g., ALL-SKY, WEEKLY-SKY, COMMENT / DAILY-SKY, GAL-SLICE, FACE ...] EQUINOX = 2000.0 / equinox of coords in following tables REFERENC= 'COBE/DIRBE Explanatory Supplement,' / REFERENC= 'ed. M.G. Hauser, T. Kelsall, D. Leisawitz, and J. Weiland,' / REFERENC= 'COBE Ref. Pub. No. 97-A (Greenbelt,MD: NASA/GSFC),' / REFERENC= 'available in electronic form from the NSSDC.' / COMMENT COMMENT COBE specific keywords DATE-BEG= '08/12/89' / date of initial data represented (dd/mm/yy) DATE-END= '25/09/90' / date of final data represented (dd/mm/yy) PIXRESOL= 9 / Quad tree pixel resolution [6, 9] COMMENT COMMENT DIRBE specific keywords PRODUCT = 'B08_E90 ' / Band 8 map for solar elongation = 90 deg. VERSION = 'Pass 3B ' / Version of Data Reduction Software WAVE8 = '100. microns' / nominal wavelength of Band 8 SOLELONG= '90 degrees' / only solar elongations of 90 deg. represented APPVEC = 'COMBINED' / data having different approach vectors COMMENT / are combined during processing ZLREMOV = F / zodiacal foreground removal indicator COMMENT / if 'T(rue)', zodi foreground has been removed COMMENT / if 'F(alse)', observed sky brightness is given COMMENT COMMENT END
Extension Header 2
XTENSION= 'BINTABLE' / Extension type is Binary Table BITPIX = 8 / Binary data NAXIS = 2 / Data are in a table NAXIS1 = 21 / Number of 8 bit bytes in each row NAXIS2 = 616474 / Number of rows PCOUNT = 0 / Number of bytes of data following table GCOUNT = 1 / Group count (always 1 for bintable extensions) TFIELDS = 7 / Number of fields (columns) in the table COMMENT COMMENT TIMVERSN= 'OGIP/93-003' / GSFC Ofice of Guest Investigator Programs (OGIP COMMENT / memo in which the convention is described COMMENT The times reported in this file are International COMMENT Atomic Time (TAI) seconds elapsed since COMMENT 00:00:00 UTC, 1 January 1981. Time information is COMMENT recorded in a manner consistent with the convention specified COMMENT in OGIP/93-003 with the understanding that time is counted COMMENT in atomic seconds and the origin of time (MJDREF) is quoted COMMENT in ephemeris MJD. TIMESYS = '1981.00 ' / time system (same as IRAS) MJDREFI = 44605 / Integer portion of ephemeris MJD COMMENT / corresponding to 0h UTC 1 Jan 1981 MJDREFF = 0.00059240741 / Fractional portion of ephemeris MJD COMMENT / corresponding to 0h UTC 1 Jan 1981 TIMEUNIT= 's ' / unit for TSTART, TSTOP, TIMEZERO = seconds TSTART = 282007138.349 / observation start time in TIMESYS system TSTOP = 307119590.188 / observation stop time in TIMESYS system COMMENT COMMENT COMMENT ------------------------------------------------------------------- COMMENT ******************************************************************* COMMENT Sky Map Interpolated to Solar Elongation=90 deg -- 100. microns COMMENT Photometric data for Band 8 (100. microns) interpolated COMMENT to a fixed solar elongation of 90 degrees using COMMENT Weekly-Averaged Sky Maps as the basis for the COMMENT interpolation. COMMENT This map represents the sky as it would be COMMENT observed at an elongation of 90 deg.; i.e., signal from COMMENT the interplanetary dust cloud has not been removed. COMMENT Since the data represented here cover a time range COMMENT of 10 months, it is possible for a pixel to have COMMENT more than one entry. COMMENT COMMENT COMMENT ******************************************************************* COMMENT ------------------------------------------------------------------- COMMENT =================================================================== COMMENT Coordinate Information (Spatial and Temporal): COMMENT =================================================================== COMMENT ------------------------------------------------------------------- COMMENT DIRBE Pixel number (resolution 9) TTYPE1 = 'Pixel_no' / pipeline fieldname = Pixel_no TUNIT1 = ' ' / TFORM1 = '1J ' / COMMENT ------------------------------------------------------------------- COMMENT Time in International Atomic Time (TAI) seconds elapsed COMMENT since 01-JAN-1981:00:00:00.000 UTC. COMMENT Computed time corresponding to observation of pixel COMMENT at solar elongation = 90 deg. COMMENT Note that some of the quoted times fall outside of the COMMENT boundaries during which actual observations were made. This COMMENT is because extrapolations have been permitted under a limited COMMENT set of circumstances, as indicated by the Fit Quality COMMENT Flag (FitQual). TTYPE2 = 'Time ' / pipeline fieldname = Time TUNIT2 = 's ' / TFORM2 = '1D ' / COMMENT ------------------------------------------------------------------- COMMENT =================================================================== COMMENT DIRBE Sky Brightness Information: COMMENT =================================================================== COMMENT ------------------------------------------------------------------- COMMENT Photometry for Band 8, interpolated to solar elongation 90 deg. COMMENT The photometric measurements are given as COMMENT spectral intensities, I(nu) in MJy/sr, and COMMENT are quoted at the nominal wavelength COMMENT for a source with nu*I(nu) = constant -- i.e., COMMENT a color correction is required if the source COMMENT spectrum differs from nu*I(nu) = constant. COMMENT Data which have been replaced by flagged values COMMENT in processing have values .LE. -16375. TTYPE3 = 'Photomet' / pipeline fieldname = Photometry TUNIT3 = 'MJy/sr ' / MegaJanskys/steradian TFORM3 = '1E ' / COMMENT ------------------------------------------------------------------- COMMENT Effective number of observations of the COMMENT pixel over the mission. This is an approximate COMMENT number, calculated from the average of the weekly COMMENT weighted numbers of observations for all detectors. TTYPE4 = 'EfNumObs' / pipeline fieldname = Effective_num_obs TUNIT4 = ' ' / TFORM4 = '1I ' / COMMENT ------------------------------------------------------------------- COMMENT Standard Deviation COMMENT Relative or absolute standard deviation COMMENT of the interpolated/extrapolated COMMENT photometry, given in logarithmic bins. COMMENT Units = none (Bands 1 - 8) COMMENT = MJy/sr (Bands 9 and 10) COMMENT Range = [0,255] COMMENT The contents B of the Standard_Deviation COMMENT byte have been found from the relative COMMENT standard deviations R = sigma(I)/ABS(I) (Bands COMMENT 1 through 8) or absolute standard deviations R COMMENT (Bands 9 and 10) as follows: COMMENT N = 3: Bands 1 - 4, 7 and 8 COMMENT N = 4: Bands 5 and 6 COMMENT N = 1: Bands 9 and 10 COMMENT COMMENT if R <= 10**-N then B = 0 COMMENT if 10**-N < R < 10**(-N+4) then B = IFIX((N+log10(R))*254./4.)+1 COMMENT if R >= 10**(-N+4) then B = 255 COMMENT COMMENT Conversely, the standard deviations can be reconstructed by: COMMENT R <= 10**-N if B = 0 COMMENT R = 10**(4*(B-0.5)/254. - N) if 1 <= B <= 254 COMMENT R >= 10**(-N+4) if B = 255 COMMENT COMMENT StdDev = R * ABS(I) (Bands 1 - 8) COMMENT StdDev = R (Bands 9, 10) COMMENT (The maximum error on the reconstructed value is 1.8 %) COMMENT TTYPE5 = 'StdDev ' / pipeline fieldname = Standard_Deviation TUNIT5 = ' ' / TFORM5 = '1B ' / COMMENT ------------------------------------------------------------------- COMMENT Fit Quality Flag COMMENT quality of interpolation to elongation = 90 deg. COMMENT Bit 0 = least significant bit COMMENT COMMENT Bits 0-3: Indicator for solar system COMMENT object effects and interpolation COMMENT quality COMMENT 0000: No special problems COMMENT 0001: One or more weekly average(s) COMMENT had data removed due to solar COMMENT system object contamination. COMMENT 0010: Only two points (weekly averages) COMMENT available for the interpolation. Expect COMMENT systematic error. COMMENT 0100: Average value used rather than interpolated COMMENT value, for quality reasons. COMMENT 1111: Interpolation impossible. Intensity set to COMMENT a flagged value (.LE. -16375.) COMMENT COMMENT Bits 4-7: Interpolation type indicator: COMMENT 0000: Interpolation COMMENT 0001: Extrapolation from observations COMMENT which have elongations > 90 deg. COMMENT 0010: Extrapolation from observations COMMENT which have elongations < 90 deg. COMMENT 0100: One weekly average was flagged COMMENT as an outlier and not used in COMMENT the interpolation process. COMMENT TTYPE6 = 'FitQual ' / pipeline fieldname = Interpolation_flag, Byte 1 TUNIT6 = ' ' / TFORM6 = '1B ' / COMMENT ------------------------------------------------------------------- COMMENT Fit Chi-squared per degree of freedom COMMENT Chi-squared per degree of freedom COMMENT for the fit used in the interpolation. TTYPE7 = 'FitChiSq' / pipeline fieldname = Interpolation_flag, Byte 2 TUNIT7 = ' ' / TFORM7 = '1B ' / TSCAL7 = 0.10 / bin size 0.1 TZERO7 = 0.0 / COMMENT ------------------------------------------------------------------- END
