FITS header extraction of BMAJ, BMIN, BPA

[kswang1029]

reported by a user:

If the header does not contain BMAJ, BMIN, BPA as keys but these strings are stored as part of the HISTORY context, the backend still picks them up. The backend should ignore any keys from HISTORY.

SIMPLE = T /
BITPIX = -32 /
NAXIS = 3 /
NAXIS1 = 585 /
NAXIS2 = 587 /
NAXIS3 = 1 /
EXTEND = T /Tables following main image
BLOCKED = T /Tape may be blocked
OBJECT = ' ' /Source name
TELESCOP= ' ' /
INSTRUME= ' ' /
OBSERVER= ' ' /
DATE-OBS= '1987-05-26' /Obs start date YYYY-MM-DD
DATE-MAP= '2017-08-14' /Last processing date YYYY-MM-DD
BSCALE = 1.00000000000E+00 /REAL = TAPE * BSCALE + BZERO
BZERO = 0.00000000000E+00 /
BUNIT = 'JY/BEAM ' /Units of flux
EQUINOX = 1.950000000E+03 /Epoch of RA DEC
DATAMAX = 7.697948813E-01 /Maximum pixel value
DATAMIN = -5.964934826E-03 /Minimum pixel value
CTYPE1 = 'RA---SIN' /
CRVAL1 = 8.28809244186E+01 /
CDELT1 = -2.777777845E-04 /
CRPIX1 = 2.980000000E+02 /
CROTA1 = 0.000000000E+00 /
CTYPE2 = 'DEC--SIN' /
CRVAL2 = 2.19817385450E+01 /
CDELT2 = 2.777777845E-04 /
CRPIX2 = 2.750000000E+02 /
CROTA2 = 0.000000000E+00 /
CTYPE3 = 'FREQ ' /
CRVAL3 = 1.41000000000E+09 /
CDELT3 = 1.000000000E+00 /
CRPIX3 = 1.000000000E+00 /
CROTA3 = 0.000000000E+00 /
HISTORY --------------------------------------------------------------------
HISTORY /Begin "HISTORY" information found in fits tape header by FITLD
HISTORY EXTEND = T /Tables following main image
HISTORY BLOCKED = T /Tape may be blocked
HISTORY --------------------------------------------------------------------
HISTORY /Begin "HISTORY" information found in fits tape header by FITLD
HISTORY BLOCKED = T /Tape may be blocked
HISTORY --------------------------------------------------------------------
HISTORY /Begin "HISTORY" information found in fits tape header by FITLD
HISTORY BLOCKED = T /Tape may be blocked
HISTORY --------------------------------------------------------------------
HISTORY /Begin "HISTORY" information found in fits tape header by FITLD
HISTORY BLOCKED = T /TAPE MAY BE BLOCKED
HISTORY /--------------------------------------------------------------------
HISTORY /BEGIN "HISTORY" INFORMATION FOUND IN WERONG FILEHEADER BY IMWER
HISTORY /--------------------------------------------------------------------
HISTORY /BEGIN "HISTORY" INFORMATION FOUND IN FITS TAPE HEADER BY UVLOD
HISTORY BLOCKED = T /TAPE MAY BE BLOCKED
HISTORY / WHERE BASELINE = 256ANT1 + ANT2 + (ARRAY#-1)/100
HISTORY /--------------------------------------------------------------------
HISTORY /BEGIN "HISTORY" INFORMATION FOUND IN FITS TAPE HEADER BY UVLOD
HISTORY /--------------------------------------------------------------------
HISTORY /BEGIN "HISTORY" INFORMATION FOUND IN FITS TAPE HEADER BY UVLOD
HISTORY BLOCKED = T /TAPE MAY BE BLOCKED
HISTORY / WHERE BASELINE = 256ANT1 + ANT2 + (ARRAY#-1)/100
HISTORY /--------------------------------------------------------------------
HISTORY /BEGIN "HISTORY" INFORMATION FOUND IN FITS TAPE HEADER BY UVLOD
HISTORY (UVCOPY)
HISTORY UVCOPY Input file = INFIT1
HISTORY UVCOPY Bcount= 1, Ncount= 272538, Weight= 1.000E+00
HISTORY ASCAL (WERONG)
HISTORY ASCAL Visin = INFIT1
HISTORY ASCAL Input image model = INFIT2
HISTORY ASCAL Visout = OUTFIT1
HISTORY ASCAL Clip level = 0.0000E+00
HISTORY ASCAL Solution interval = 5.0000E+00 minutes
HISTORY ASCAL Solution type = phase
HISTORY ASCAL Minimum no. of antennas = 3
HISTORY ASCAL Sigma clip = 5.0000E+01
HISTORY ASCAL Solution type = all
HISTORY ASCAL Uvrange = 7.5000E+02 to 4.0000E+04 wavelengths
HISTORY ASCAL Exterior weight factor = 1.0000E-01
HISTORY ASCAL (WERONG)
HISTORY ASCAL Visin = INFIT1
HISTORY ASCAL Input image model = INFIT2
HISTORY ASCAL Visout = OUTFIT1
HISTORY ASCAL Clip level = 0.0000E+00
HISTORY ASCAL Solution interval = 2.0000E+00 minutes
HISTORY ASCAL Solution type = phase
HISTORY ASCAL Minimum no. of antennas = 3
HISTORY ASCAL Sigma clip = 5.0000E+01
HISTORY ASCAL Solution type = all
HISTORY ASCAL Uvrange = 7.5000E+02 to 5.0000E+04 wavelengths
HISTORY ASCAL Exterior weight factor = 1.0000E-01
HISTORY ASCAL (WERONG)
HISTORY ASCAL Visin = INFIT1
HISTORY ASCAL Input image model = INFIT2
HISTORY ASCAL Visout = OUTFIT1
HISTORY ASCAL Clip level = 0.0000E+00
HISTORY ASCAL Solution interval = 5.0000E+00 minutes
HISTORY ASCAL Solution type = amphase
HISTORY ASCAL Minimum no. of antennas = 4
HISTORY ASCAL Sigma clip = 5.0000E+01
HISTORY ASCAL Solution type = all
HISTORY ASCAL Uvrange = 7.5000E+02 to 5.0000E+04 wavelengths
HISTORY ASCAL Exterior weight factor = 1.0000E-01
HISTORY /END FITS TAPE HEADER "HISTORY" INFORMATION
HISTORY UVLOD RELEASE= '15OCT87 ' /--------------------------------------------
HISTORY UVLOD OUTNAME='L82A-D SC3 ' OUTCLASS='UVDATA'
HISTORY UVLOD OUTSEQ= 1 OUTDISK= 1
HISTORY UVLOD INFILE='DA01:MFB.L87UV3 '
HISTORY /END FITS TAPE HEADER "HISTORY" INFORMATION
HISTORY UVLOD RELEASE= '15APR88 ' /--------------------------------------------
HISTORY UVLOD OUTNAME='L87A-D SC3 ' OUTCLASS='UVSRT '
HISTORY UVLOD OUTSEQ= 1 OUTDISK= 1
HISTORY UVSUB RELEASE ='15APR88 ' /********* START 02-JUN-1988 13:15:21
HISTORY UVSUB INNAME='L87A-D SC3 ' INCLASS='UVSRT '
HISTORY UVSUB INSEQ= 1 INDISK= 1
HISTORY UVSUB IN2NAME='L82A-D SC3 ' IN2CLASS='ICLN '
HISTORY UVSUB IN2SEQ= 3 IN2DISK= 2
HISTORY UVSUB VER = 0 /CC FILE VER. NO.
HISTORY UVSUB NMAPS = 1 / NUMBER OF MODEL IMAGES
HISTORY UVSUB BCOMP( 1) = 1, NCOMP( 1) = 10 /FIRST-LAST COMP. NO.
HISTORY UVSUB OUTNAME='L87A-D SC3- ' OUTCLASS='UVSRT '
HISTORY UVSUB OUTSEQ= 1 OUTDISK= 2
HISTORY UVSUB /STOKES TYPE OF MODEL = I
HISTORY UVSUB CHANNEL = 1,NCHAN= 1 / CHANNEL(S)
HISTORY UVSUB CMETHOD = 'DFT ' / MODEL METHOD
HISTORY UVSUB CMODEL = 'COMP' / MODEL TYPE
HISTORY UVSUB OPCODE = 'SUB ' / OPERATION TYPE
HISTORY UVSUB FACTOR = 1.000 /MODEL FACTOR
HISTORY ASCAL (WERONG)
HISTORY ASCAL Visin = INFIT1
HISTORY ASCAL Input image model = INFIT2
HISTORY ASCAL Visout = OUTFIT1
HISTORY ASCAL Clip level = 1.0000E-04
HISTORY ASCAL Solution interval = 2.0000E+00 minutes
HISTORY ASCAL Solution type = amphase
HISTORY ASCAL Minimum no. of antennas = 4
HISTORY ASCAL Sigma clip = 1.0000E+01
HISTORY ASCAL Solution type = all
HISTORY ASCAL Uvrange = 7.5000E+02 to 6.0000E+04 wavelengths
HISTORY ASCAL Exterior weight factor = 1.0000E-01
HISTORY /END FITS TAPE HEADER "HISTORY" INFORMATION
HISTORY UVLOD RELEASE= '15OCT87 ' /--------------------------------------------
HISTORY UVLOD OUTNAME='L87A-D SC4 ' OUTCLASS='UVDATA'
HISTORY UVLOD OUTSEQ= 1 OUTDISK= 1
HISTORY UVLOD INFILE='DA01:MFB.L87UV4 '
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVFLG / 1 TIME= 0 23 59 58. TO 2 0 0 2. BL= 4- * FLAGS=tt
HISTORY UVFLG / 1 # SAMPLES SELECTED, VIS. FLAGGED= 754 3016
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVFLG / 1 TIME= 0 23 59 58. TO 2 0 0 2. BL= 17- * FLAGS=tt
HISTORY UVFLG / 1 # SAMPLES SELECTED, VIS UNFLAGGED= 0 0
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVFLG / 1 TIME= 0 23 59 58. TO 2 0 0 2. BL= 4- * FLAGS=tt
HISTORY UVFLG / 1 # SAMPLES SELECTED, VIS UNFLAGGED= 754 3016
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVFLG / 1 TIME= 0 23 59 58. TO 2 0 0 2. BL= 7- * FLAGS=tt
HISTORY UVFLG / 1 # SAMPLES SELECTED, VIS UNFLAGGED= 678 0
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVFLG / 1 TIME= 0 23 59 58. TO 2 0 0 2. BL= 7- * FLAGS=tt
HISTORY UVFLG / 1 # SAMPLES SELECTED, VIS. FLAGGED= 678 2712
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVFLG / 1 TIME= 0 23 59 58. TO 2 0 0 2. BL= 19- * FLAGS=tt
HISTORY UVFLG / 1 # SAMPLES SELECTED, VIS. FLAGGED= 738 2804
HISTORY UVFLG 1 BCHAN= 1 ECHAN= 1 BIF= 1 EIF= 1
HISTORY UVMAP (WERONG)
HISTORY UVMAP Visin = INFIT1
HISTORY UVMAP Output image = OUTFIT1
HISTORY UVMAP Output beam = OUTFIT2
HISTORY UVMAP Cellx,y = 5.0000E-01, 5.0000E-01 arcsec
HISTORY UVMAP Imsizx,y = 2048, 2048 pixels
HISTORY UVMAP Supx,y = 1.0240E+03, 1.0240E+03
HISTORY UVMAP Uvrange = 3.3000E+02 to 1.0000E+06 wavelengths
HISTORY UVMAP Taperx,y = 0.0000E+00, 0.0000E+00
HISTORY UVMAP Gridding convolution function is spheroidal
HISTORY UVMAP Gridding parameters: alpha = 1.0000E+00, width = 6
HISTORY VM (WERONG)
HISTORY VM Input image = INFIT1
HISTORY VM Beam image = INFIT2
HISTORY VM Model = INFIT3
HISTORY VM Output image = OUTFIT1
HISTORY VM Alpha = 7.8240E+02, Beta = 0.0000E+00, Tol = 1.0000E-02
HISTORY VM Measure = gull Niter = 17
HISTORY VM Begin rms = 1.8000E-04, Flux = -8.8740E+00
HISTORY VM End rms = 1.7879E-04, Flux = 8.6676E+02
HISTORY VM Q = 2.4001E+01
HISTORY VM Window = 499, 626 -> 1514,1644
HISTORY RESTOR (WERONG)
HISTORY RESTOR Input image = INFIT1
HISTORY RESTOR Input beam = INFIT2
HISTORY RESTOR Input model = INFIT3
HISTORY RESTOR Output image = OUTFIT1
HISTORY RESTOR Beam = 2.000E+00 x 1.800E+00 arcsec, pa = 8.000E+01 degrees
HISTORY RESTOR Restoration type = restore
HISTORY /END WERONG FILE HEADER "HISTORY" INFORMATION
HISTORY /--------------------------------------------------------------------
HISTORY IMWER OUTNAME ='14.87 SC5 ' OUTCLASS ='IVMR '
HISTORY IMWER OUTSEQ = 1 OUTDISK= 1
HISTORY IMWER RELEASE = '15OCT87 '
HISTORY SUBIM RELEASE ='15APR88 ' /********* START 08-DEC-1988 18:14:07
HISTORY SUBIM INNAME='14.87 SC5 ' INCLASS='IVMR '
HISTORY SUBIM INSEQ= 1 INDISK= 1
HISTORY SUBIM INTYPE ='MA' USERID= 1477
HISTORY SUBIM OUTNAME='14.87 SC5 ' OUTCLASS='UVMR '
HISTORY SUBIM OUTSEQ= 3 OUTDISK= 1
HISTORY SUBIM BLC = 431, 476, 1, 1, 1, 1, 1
HISTORY SUBIM TRC = 1600, 1650, 1, 1, 1, 1, 1
HISTORY SUBIM XINC = 1 YINC = 1
HISTORY RENAM INNAME='14.87 SC5 ' INCLASS='UVMR '
HISTORY RENAM INSEQ= 3 INDISK= 1
HISTORY RENAM OUTNAME='14.87 SC5 ' OUTCLASS='IVMR '
HISTORY RENAM OUTSEQ= 2 OUTDISK= 1
HISTORY /END FITS tape header "HISTORY" information
HISTORY --------------------------------------------------------------------
HISTORY FITLD OUTNAME =' ' OUTCLASS =' '
HISTORY FITLD OUTSEQ = 0 INTAPE = 0 OUTDISK= 1
HISTORY FITLD INFILE = 'DA01:CX1.FTS '
HISTORY FITLD RELEASE = '15JAN95'
HISTORY /END FITS tape header "HISTORY" information
HISTORY --------------------------------------------------------------------
HISTORY FITLD OUTNAME =' ' OUTCLASS ='POLF '
HISTORY FITLD OUTSEQ = 1 INTAPE = 0 OUTDISK= 8
HISTORY FITLD RELEASE = '31DEC01'
HISTORY RENAM INNAME='14.87 SC5 ' INCLASS='POLF '
HISTORY RENAM INSEQ= 1 INDISK= 8
HISTORY RENAM OUTNAME='14.87 SC5 ' OUTCLASS='IVMR '
HISTORY RENAM OUTSEQ= 1 OUTDISK= 8
HISTORY PUTHEAD BMAJ = 0.00000E+00 / old
HISTORY PUTHEAD BMAJ = 5.55556E-04 / new
HISTORY PUTHEAD BMIN = 0.00000E+00 / old
HISTORY PUTHEAD BMIN = 5.00000E-04 / new
HISTORY PUTHEAD BPA = 0.00000E+00 / old
HISTORY PUTHEAD BPA = 8.00000E+01 / new
HISTORY AXDEF INNAME='14.87 SC5 ' INCLASS='IVMR '
HISTORY AXDEF INSEQ= 1 INDISK= 8
HISTORY AXDEF CTYPE3 = 'FREQ ' / NEW Axis type
HISTORY AXDEF CRVAL3 = 1.410000000E+09 / NEW Reference pixel value
HISTORY AXDEF CDELT3 = 1.00000E+00 / NEW Axis increment
HISTORY AXDEF CRPIX3 = 1.000 / NEW Reference pixel loc
HISTORY PUTHEAD EPOCH = 0.00000E+00 / old
HISTORY PUTHEAD EPOCH = 1.95000E+03 / new
HISTORY PUTHEAD NITER = 0 / old
HISTORY PUTHEAD NITER = 17 / new
HISTORY /END FITS tape header "HISTORY" information
HISTORY --------------------------------------------------------------------
HISTORY FITLD OUTNAME =' ' OUTCLASS =' '
HISTORY FITLD OUTSEQ = -1 INTAPE = 0 OUTDISK= 8
HISTORY FITLD INFILE = 'INFITS:DISK08C0006 '
HISTORY FITLD RELEASE = '31DEC05'
HISTORY MOVE INNAME='14.87 SC5 ' INCLASS='IVMR '
HISTORY MOVE INSEQ= 1 INDISK= 8
HISTORY MOVE OUTNAME='14.87 SC5 ' OUTCLASS='IVMR '
HISTORY MOVE OUTSEQ= 1 OUTDISK= 7
HISTORY MOVE INNAME='14.87 SC5 ' INCLASS='IVMR '
HISTORY MOVE INSEQ= 1 INDISK= 7
HISTORY MOVE OUTNAME='14.87 SC5 ' OUTCLASS='IVMR '
HISTORY MOVE OUTSEQ= 1 OUTDISK= 7
HISTORY /END FITS tape header "HISTORY" information
HISTORY --------------------------------------------------------------------
HISTORY FITLD OUTNAME =' ' OUTCLASS =' '
HISTORY FITLD OUTSEQ = -1 INTAPE = 0 OUTDISK= 1
HISTORY FITLD INFILE = 'HOME:crab.fits'
HISTORY FITLD RELEASE = '31DEC09'
HISTORY CONVL RELEASE ='31DEC17 ' /********* Start 14-AUG-2017 07:13:16
HISTORY CONVL INNAME='14.87 SC5 ' INCLASS='IVMR '
HISTORY CONVL INSEQ= 1 INDISK= 1
HISTORY CONVL OUTNAME='14.87 SC5 ' OUTCLASS='CONVL '
HISTORY CONVL OUTSEQ= 1 OUTDISK= 1
HISTORY CONVL BLC= 1. 1. 1. 1. 1. 1. 1./BLC
HISTORY CONVL TRC= 1170. 1175. 1. 1. 1. 1. 1./TRC
HISTORY CONVL FACTOR= 6.94439E+00 / Units scaling factor
HISTORY CONVL BMAJ= 5.0000 BMIN= 5.0000 BPA= 0.0/Output beam
HISTORY CONVL / plane 1 conv with 4.66476 x 4.58257 at 170.0
HISTORY CONVL OPCODE=' ' /Operation requested
HISTORY CONVL DOBLANK = 1 / Blanks restored after FFT
HISTORY SUBIM RELEASE ='31DEC17 ' /********* Start 14-AUG-2017 07:29:59
HISTORY SUBIM INNAME='14.87 SC5 ' INCLASS='CONVL '
HISTORY SUBIM INSEQ= 1 INDISK= 1
HISTORY SUBIM INTYPE ='MA' USERID= 1577
HISTORY SUBIM OUTNAME='14.87 SC5 ' OUTCLASS='SUBIM '
HISTORY SUBIM OUTSEQ= 2 OUTDISK= 1
HISTORY SUBIM BLC = 1, 2, 1, 1, 1, 1, 1
HISTORY SUBIM TRC = 1170, 1175, 1, 1, 1, 1, 1
HISTORY SUBIM XINC = 2
HISTORY SUBIM YINC = 2
HISTORY SUBIM ZINC = 1
HISTORY SUBIM OPCODE = 'AVE '
HISTORY RENAM INNAME='14.87 SC5 ' INCLASS='SUBIM '
HISTORY RENAM INSEQ= 2 INDISK= 1
HISTORY RENAM OUTNAME='14.87 SC5 ' OUTCLASS='IVMRCS'
HISTORY RENAM OUTSEQ= 3 OUTDISK= 1
HISTORY FITTP DATAOUT = 'HOME:crab_1.4GHz.fits' / data written to disk file
HISTORY PBCOR RELEASE ='31DEC17 ' /********* Start 14-AUG-2017 07:33:21
HISTORY PBCOR INNAME='14.87 SC5 ' INCLASS='IVMRCS'
HISTORY PBCOR INSEQ= 0 INDISK= 1
HISTORY PBCOR OUTNAME='14.87 SC5 ' OUTCLASS='PBCOR '
HISTORY PBCOR OUTSEQ= 0 OUTDISK= 1
HISTORY PBCOR BLC= 1, 1, 1, 1, 1, 1, 1 TRC= 585, 587, 1, 1, 1, 1, 1
HISTORY PBCOR PRA= 05 31 31.422 PDec= 21 58 54.26
HISTORY PBCOR Beamcut= 0.02300 /Clip outside this beam value
HISTORY PBCOR DOINVERS =-1.0 / > 0 multiply by beam
HISTORY PBCOR / Beam = 1.000000E+00 + / Beam model
HISTORY PBCOR / -1.449000E-03 * X +
HISTORY PBCOR / 8.020000E-07 * XX +
HISTORY PBCOR / -1.740000E-10 * XXX +
HISTORY PBCOR / Where X = [Angle(arcmin) * f(GHz)]**2
HISTORY PBCOR / above from EVLA 2016 model interpolated between 1.360 GHz
HISTORY PBCOR / and 1.424 GHz parameters below
HISTORY PBCOR / Beam = 1.000000E+00 + / Beam model
HISTORY PBCOR / -1.462000E-03 * X +
HISTORY PBCOR / 8.230000E-07 * XX +
HISTORY PBCOR / -1.830000E-10 * XXX +
HISTORY PBCOR / Where X = [Angle(arcmin) * f(GHz)]**2
HISTORY FITTP DATAOUT = 'HOME:crab_1.4GHz_PB.fits' / data written to disk file
ORIGIN = 'AIPSdailyalice YORKASTRO 31DEC18' /
DATE = '2018-01-31' / File written on Greenwich yyyy-mm-dd
HISTORY AIPS IMNAME='14.87 SC5 ' IMCLASS='PBCOR ' IMSEQ= 3 /
HISTORY AIPS USERNO= 1577 /
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
HISTORY AIPS CLEAN BMAJ= 1.3889E-03 BMIN= 1.3889E-03 BPA= 0.00
HISTORY AIPS CLEAN NITER= 17 PRODUCT=1 / NORMAL
END

In the above case, this line HISTORY CONVL BMAJ= 5.0000 BMIN= 5.0000 BPA= 0.0/Output beam is picked up and used to compute the restoring beam size for the file info. So it is 18000" displayed. In this case, the restoring beam should be undefined.

[pford]

This is an intentional "feature" of casacore::FITSImage, which has this comment:

// Try and find the restoring beam in the history cards if
// its not in the header

@kswang1029 do you want to override the casacore behavior?

[pford]

Another comment indicates that setting the beam from HISTORY is a result of AIPS writing the beam there, rather than in the header keywords. CONVL is an AIPS task so this behavior makes sense and should be a valid beam.

[kswang1029]

Another comment indicates that setting the beam from HISTORY is a result of AIPS writing the beam there, rather than in the header keywords. CONVL is an AIPS task so this behavior makes sense and should be a valid beam.

The example obtained from the user is an example of quoting an incorrect beam size from the history header unfortunately. Is it possible to switch off this guessing “feature”? If beam is not defined with BMAJ, BMIN, and BPA explicitly in the header, we should set them undefined. History is only trustworthy after parsing by human brain I think.