FITS Headers
DIRBE_DCAF_P3B_FACE5.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 = '09/04/97' / 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 = 'FACE5 ' / 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= '11/12/89' / date of initial data represented (dd/mm/yy)
DATE-END= '21/09/90' / date of final data represented (dd/mm/yy)
PIXRESOL= 9 / Quad tree pixel resolution [6, 9]
COMMENT
COMMENT DIRBE specific keywords
PRODUCT = 'DCAF_F5 ' / DIRBE Calibrated Annual File, Face 5
VERSION = 'Pass 3B ' / Version of Data Reduction Software
WAVE1 = '1.25 microns' / nominal wavelength of Band 1
WAVE2 = '2.2 microns' / nominal wavelength of Band 2
WAVE3 = '3.5 microns' / nominal wavelength of Band 3
WAVE4 = '4.9 microns' / nominal wavelength of Band 4
WAVE5 = '12. microns' / nominal wavelength of Band 5
WAVE6 = '25. microns' / nominal wavelength of Band 6
WAVE7 = '60. microns' / nominal wavelength of Band 7
WAVE8 = '100. microns' / nominal wavelength of Band 8
WAVE9 = '140. microns' / nominal wavelength of Band 9
WAVE10 = '240. microns' / nominal wavelength of Band 10
SOLELONG= 'ALL ' / all available solar elongations included
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 = 131 / Number of 8 bit bytes in each row
NAXIS2 = 2102039 / Number of rows
PCOUNT = 0 / Number of bytes of data following table
GCOUNT = 1 / Group count (always 1 for bintable extensions)
TFIELDS = 15 / Number of fields (columns) in the table
COMMENT
COMMENT
TIMVERSN= 'OGIP/93-003' / GSFC Office of Guest Investigator Programs
COMMENT / (OGIP) memo in which the convention is
COMMENT / 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 = 282185275.611 / observation start time in TIMESYS system
TSTOP = 306753235.358 / observation stop time in TIMESYS system
COMMENT
COMMENT
COMMENT -------------------------------------------------------------------
COMMENT *******************************************************************
COMMENT ------ DIRBE Calibrated Annual File: Face 5 -----
COMMENT --------------- Cryogenic Mission ---------------
COMMENT
COMMENT The DIRBE Calibrated Annual File (DCAF) combines the
COMMENT information contained in the 41 DIRBE Weekly Sky Maps
COMMENT into a merged all-sky version which is sorted by ascending
COMMENT DIRBE pixel number (resolution 9). Although the
COMMENT information is identical to that given in the complete
COMMENT set of Weekly Sky Maps for the cryogenic mission, the
COMMENT data are organized differently, allowing more convenient
COMMENT access to the full range of temporal variations observed
COMMENT for each pixel. The DCAF table contains multiple row
COMMENT entries for each pixel, one row for each mission week for
COMMENT which photometric data are available. The multiple entries
COMMENT per pixel are stored in consecutive rows which are
COMMENT sorted in order of increasing observation time.
COMMENT A companion Pixel Index is provided to facilitate data
COMMENT selection and extraction.
COMMENT
COMMENT Because of its relatively large size, the DCAF has been
COMMENT divided into six separate data files, each of which has
COMMENT its own Pixel Index. Each of the six data files
COMMENT corresponds to a face on the DIRBE skycube, and each is
COMMENT named according to the face number. The face number
COMMENT is also recorded in the OBJECT and PRODUCT keywords.
COMMENT There is no overlap in sky coverage between the files.
COMMENT Sky coverage is as follows:
COMMENT
COMMENT Range(*) of Range(*) of
COMMENT Face No. DIRBE Pixel No.s Ecl. Longitude Ecl. Latitude
COMMENT -------- ---------------- -------------- -------------
COMMENT 0 0 - 65535 0 - 360 deg +45 to +90 deg
COMMENT 1 65536 - 131071 315 - 45 -45 to +45
COMMENT 2 131072 - 196607 45 - 135 -45 to +45
COMMENT 3 196608 - 262143 135 - 225 -45 to +45
COMMENT 4 262144 - 327679 225 - 315 -45 to +45
COMMENT 5 327680 - 393215 0 - 360 -45 to -90
COMMENT
COMMENT (*) The ecliptic coordinate ranges are only approximate.
COMMENT A more complete description of the sky coverage for each
COMMENT face is provided in the DIRBE Explanatory Supplement,
COMMENT Chapter 5.
COMMENT
COMMENT As with the DIRBE Weekly Sky Maps, the as-observed sky
COMMENT brightness is tabulated; the foreground signal from
COMMENT Zodiacal dust has not been removed.
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 Sub-pixel containing the mean DIRBE LOS (line-of-sight)
COMMENT when pixel is divided into 256
COMMENT sub-pixels (16x16 grid) according to
COMMENT standard quad-sphere rules
TTYPE2 = 'PSubPos ' / pipeline fieldname = Pixel_subpos
TUNIT2 = ' ' /
TFORM2 = '1B ' /
COMMENT --------------------------------------------------------------------
COMMENT Sub-pixel number of the average line-of-sight
COMMENT for individual bands which are expected to
COMMENT have the largest offsets from the nominal position.
COMMENT Subpixels are specified as a 16x16 grid
COMMENT according to standard quad-sphere rules.
COMMENT Byte 1: Sub-pixel for Band 1A
COMMENT Byte 2: Sub-pixel for Band 4
COMMENT Byte 3: Sub-pixel for Band 7
COMMENT Byte 4: Sub-pixel for Band 8
TTYPE3 = 'Displace' / pipeline fieldname = Displacement_Means
TUNIT3 = ' ' /
TFORM3 = '4B ' /
TDIM3 = '(4) ' /
COMMENT --------------------------------------------------------------------
COMMENT Time in International Atomic Time (TAI) seconds
COMMENT elapsed since 01-JAN-1981:00:00:00.000 UTC.
COMMENT This is the average time of all observations of a pixel
COMMENT within the time interval TSTART to TSTOP,
COMMENT regardless of the weight assigned to a particular observation.
TTYPE4 = 'Time ' / pipeline fieldname = Time
TUNIT4 = 's ' /
TFORM4 = '1D ' /
COMMENT --------------------------------------------------------------------
COMMENT Difference between the average time of observation of the pixel
COMMENT for each photometric band, and the
COMMENT average time of all observations of the pixel (as given in the
COMMENT TIME field). Therefore, for each pixel:
COMMENT Average time of observation of Band x = TIME + (DeltaT for Band x).
COMMENT Given in the order: 1A,2A,3A,4,5,6,7,8,9,10.
COMMENT Range = [-7.0,+7.0) days
TTYPE5 = 'DeltaT ' / pipeline fieldname = Delta_times
TUNIT5 = 's ' /
TFORM5 = '10B ' /
TDIM5 = '(10) ' /
TSCAL5 = 4725.0 / bin size (7*24*60*60)/(2**7) seconds
TZERO5 = -602437.5 / offset to bin center in secs for unsigned byte
COMMENT --------------------------------------------------------------------
COMMENT Mean solar elongation of observation, i.e.
COMMENT angle between the vector from the spacecraft to the center
COMMENT of the Sun and the DIRBE line-of-sight,
COMMENT averaged over all observations of the pixel.
COMMENT Nominal range = [64,124] degrees
TTYPE6 = 'SolElong' / pipeline fieldname = Elongation
TUNIT6 = 'deg ' /
TFORM6 = '1I ' /
TSCAL6 = 0.0109867 / bin size 360/(2**15 -1) degrees
TZERO6 = 0.00549333 / offset to bin center in degrees
COMMENT --------------------------------------------------------------------
COMMENT ====================================================================
COMMENT DIRBE Sky Brightness and Polarization Information:
COMMENT ====================================================================
COMMENT --------------------------------------------------------------------
COMMENT Robust average of the week's photometric measurements
COMMENT for the bands in the following order:
COMMENT 1A,2A,3A,4,5,6,7,8,9,10. The photometric measurements
COMMENT are given as 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.
TTYPE7 = 'Photomet' / pipeline fieldname = Photometry
TUNIT7 = 'MJy/sr ' /
TFORM7 = '10E ' /
TDIM7 = '(10) ' /
COMMENT --------------------------------------------------------------------
COMMENT Stokes parameters Q and U for Band 1, Q and U
COMMENT for Band 2, and Q and U for Band 3.
COMMENT Range = (-2.0,2.0)
COMMENT Nominal range = (-1.0,1.0)
COMMENT Three possible cases arise in
COMMENT storing the Stokes parameters for each band.
COMMENT Bits 5 and 6 of the Polarization_quality_flag
COMMENT field (StokQual) indicate which case applies:
COMMENT Case 1:
COMMENT Stokes parameters were calculated for the B and C
COMMENT channels and the averages over both channels are
COMMENT stored.
COMMENT Case 2:
COMMENT Stokes parameters were calculated for the B channel only.
COMMENT Case 3:
COMMENT Stokes parameters were calculated for the C channel only.
COMMENT
COMMENT Indeterminate quantities are set to a flagged value .LE. -16375.
COMMENT
TTYPE8 = 'Stokes ' / pipeline fieldname = Polarization
TUNIT8 = ' ' /
TFORM8 = '6E ' /
TDIM8 = '(6) ' /
COMMENT --------------------------------------------------------------------
COMMENT Number of observations of the pixel for this week
COMMENT that contained at least one valid photometric measurement.
TTYPE9 = 'NumRecs ' / pipeline fieldname = Num_recs
TUNIT9 = ' ' /
TFORM9 = '1I ' /
COMMENT --------------------------------------------------------------------
COMMENT Number of observations which survived robust averaging
COMMENT and quality constraints to form the photometric averages
COMMENT supplied for each band in the 'Photomet' field.
COMMENT Given in the order: 1A,2A,3A,4,5,6,7,8,9,10.
TTYPE10 = 'WtNumObs' / pipeline fieldname = Weighted_num_obs
TUNIT10 = ' ' /
TFORM10 = '10B ' /
TDIM10 = '(10) ' /
TSCAL10 = 0.50 / bin size 0.5
TZERO10 = 0.0 /
COMMENT --------------------------------------------------------------------
COMMENT Standard deviation of the mean, in MJy/sr, for the
COMMENT 10 photometric measures, given in
COMMENT the following order: 1A,2A,3A,4,5,6,7,8,9,10.
COMMENT
COMMENT The contents B of the Standard_Deviation fields
COMMENT are given on a uniform logarithmic scale,
COMMENT spanning 4 decades, having been calculated
COMMENT from the standard deviations S (in MJy/sr) as follows:
COMMENT if S <= 10**-N then B = 0
COMMENT if 10**-N < S < 10**(-N+4) then B = IFIX((N+log10(S))*254./4.)+1
COMMENT if S >= 10**(-N+4) then B = 255
COMMENT where the value of N is band-dependent, and given below.
COMMENT
COMMENT Conversely, the standard deviations
COMMENT can be reconstructed by:
COMMENT S <= 10**-N if B = 0
COMMENT S = 10**(4*(B-0.5)/254. - N) if 1 <= B <= 254
COMMENT S >= 10**(-N+4) if B = 255
COMMENT (The maximum error on the reconstructed value is 1.8 %)
COMMENT
COMMENT
COMMENT The values of N are:
COMMENT Bands 1A, 2A, 3A, 4: N = 4
COMMENT Bands 5, 6: N = 3
COMMENT Bands 7, 8: N = 2
COMMENT Band 9: N = 0
COMMENT Band 10: N = 1
COMMENT
COMMENT Range of S = [10**-N,10**(-N+4)]
TTYPE11 = 'StdDev ' / pipeline fieldname = Standard_Deviation
TUNIT11 = 'MJy/sr ' /
TFORM11 = '10B ' /
TDIM11 = '(10) ' /
COMMENT --------------------------------------------------------------------
COMMENT Standard deviation of the mean, in dimensionless units,
COMMENT for Stokes parameters Q and U for Band 1,
COMMENT Q and U for Band 2, and Q and U for Band 3.
COMMENT
COMMENT The contents B of the Stokes_Standard_Deviation fields
COMMENT are given on a uniform logarithmic scale,
COMMENT spanning 4 decades, having been calculated
COMMENT from the standard deviations S (dimensionless) as follows:
COMMENT if S <= 10**-4 then B = 0
COMMENT if 10**-4 < S < 1 then B = IFIX((4+log10(S))*254./4.)+1
COMMENT if S >= 1 then B = 255
COMMENT
COMMENT Conversely, the standard deviations
COMMENT can be reconstructed by:
COMMENT S <= 10**-4 if B = 0
COMMENT S = 10**(4*(B-0.5)/254. - 4) if 1 <= B <= 254
COMMENT S >= 1 if B = 255
COMMENT (The maximum error on the reconstructed value is 1.8 %)
COMMENT
COMMENT
COMMENT Range of S = [0.0001,1.0]
TTYPE12 = 'StokesSD' / pipeline fieldname = Stokes_Standard_Deviation
TUNIT12 = ' ' /
TFORM12 = '6B ' /
TDIM12 = '(6) ' /
COMMENT --------------------------------------------------------------------
COMMENT Solar System Objects Flag
COMMENT A one-byte flag which is used to signal
COMMENT which solar-system objects' exclusion
COMMENT zones intersect this pixel during
COMMENT part or all of the time period
COMMENT covered by the observations.
COMMENT Data intersected by an exclusion zone
COMMENT are not included in the photometric
COMMENT or polarimetric averages.
COMMENT If set, bits indicate intersection with
COMMENT the exclusion zone of the following objects:
COMMENT (Least significant bit = bit 0)
COMMENT bit 0 --- Moon
COMMENT bit 1 --- Mars
COMMENT bit 2 --- Jupiter
COMMENT bit 3 --- Saturn
COMMENT bit 4 --- Uranus
COMMENT bit 5 --- Neptune
COMMENT bit 6 --- asteroids and comets
COMMENT bit 7 --- spare
TTYPE13 = 'SSOFlag ' / pipeline fieldname = Pixel_Quality_Flag, byte 3
TUNIT13 = ' ' /
TFORM13 = '1B ' /
COMMENT --------------------------------------------------------------------
COMMENT Fraction of Data Used
COMMENT Three-byte flag indicating the fraction
COMMENT of available data used in the generation
COMMENT of the weekly averages.
COMMENT Byte 1 : Average % of all the
COMMENT available data that was used in
COMMENT the construction of the averaged
COMMENT observations for Bands 1A, 2A, 3A,
COMMENT 4, 5, 6, 8, 9, and 10
COMMENT Range = [0,100%]
COMMENT Byte 2 : Percent of the available Band 1B data
COMMENT that was used.
COMMENT Range = [0,100%]
COMMENT Byte 3 : Percent of the available Band 7 data
COMMENT that was used.
COMMENT Range = [0,100%]
TTYPE14 = 'FracUsed' / pipeline fieldname = Pixel_Quality_Flag,byte 4-
TUNIT14 = ' ' /
TFORM14 = '3B ' /
TDIM14 = '(3) ' /
TSCAL14 = 0.392 / bin size 100./(2**8 - 1) %
TZERO14 = 0.0 /
COMMENT --------------------------------------------------------------------
COMMENT Six-byte Flag indicating the quality of
COMMENT data in each set of polarization ratios ( 1B/1A,
COMMENT 1C/1A...,3C/3A), used to find the Stokes parameters.
COMMENT If any of bits 0 through 4 are set, then the
COMMENT values of the Stokes parameters
COMMENT found from these ratios may be subject to error
COMMENT beyond the formal uncertainties.
COMMENT One byte per polarization ratio, given in the order
COMMENT (1B/1A,1C/1A,2B/2A,2C/2A,3B/3A,3C/3A).
COMMENT Each bit, if set, is interpreted as follows:
COMMENT Least Significant Bit = Bit 0
COMMENT Bit 0: Only one ratio available.
COMMENT Bit 1: Only two ratios available.
COMMENT Bit 2: Between 3 and 9 ratios available.
COMMENT Bit 3: Distribution of data such that the
COMMENT Robust fitting used to deduce Stokes
COMMENT parameters failed to converge.
COMMENT Bit 4: Moon is within 25 degrees of boresight
COMMENT for at least one of the polarization
COMMENT ratios.
COMMENT Bit 5: No ratios for 'C' channel: polarization
COMMENT found from channel 'B' alone.
COMMENT Bit 6: No ratios for 'B' channel: polarization
COMMENT found from channel 'C' alone.
COMMENT Bit 7: Processing of ratios failed to produce a value
COMMENT of Q or U, or else set them to flag values.
TTYPE15 = 'StokQual' / pipeline fieldname = Polarization_Quality_Flag
TUNIT15 = ' ' /
TFORM15 = '6B ' /
TDIM15 = '(6) ' /
COMMENT --------------------------------------------------------------------
END