ABOUT LAMBDA

FITS Headers

DIRBE_BAND1A_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 = 'B1A_E90 '           / Band 1A map for solar elongation = 90 deg.     
VERSION = 'Pass 3B '           / Version of Data Reduction Software             
WAVE1   = '1.25 microns'       / nominal wavelength of Band 1                   
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 -- 1.25 microns     
COMMENT           Photometric data for Band 1A (1.25 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 1A, 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                                                                             

A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
LAMBDA Director: Dr. Eric R. Switzer
NASA Official: Dr. Eric R. Switzer
Web Curator: Mr. Michael R. Greason