IRAS Explanatory Supplement
X. The Formats of the IRAS Catalogs and Atlases
Appendix X.3 Sample FITS Headers


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Header for Sky Plate Intensity

SIMPLE = T / STANDARD FITS FORMAT

BITPIX = 32 / 4 BYTE TWOS COMPL INTEGER

NAXIS = 3 / NUMBER OF AXES

NAXIS1 = nn / # SAMPLES PER LINE (FASTEST VARY INDEX)

NAXIS2 = mm / # LINES OF DATA IN IMAGE FILE

NAXIS3 = 1 / # WAVELENGTHS

BSCALE = S.ssssssE-ee / TRUE=TAPE*SCALE+BZERO

BZERO = 0.0 /

BUNIT = 'JY/SR' / INTENSITY

BLANK = -2000000000 / TAPE VALUE FOR EMPTY PIXEL

CRVAL1 = DD.dd / RA AT ORIGIN (DEGREES)

CRPIX1 = xxx. / SAMPLE AXIS ORIGIN (PIXEL)

CTYPE1 = 'RA--TAN' / DECREASES IN VALUE AS SAMPLE INDEX

COMMENT INCREASES (GNOMONIC PROJECTION

CDELT1 = -3.333333E-02 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON SAMPLE AXIS

CRVAL2 = DD.dd / DEC AT ORIGIN (DEGREES)

CRPIX = yyy. / LINE AXIS ORIGIN (PIXEL)

CTYPE2 = 'DEC--TAN' / DECREASES IN VALUE AS LINE INDEX

COMMENT INCREASES (GNOMONIC PRJECTION)

CDELTA2 = -3.333333E-02 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON LINE AXIS

CRVAL3 = zzzE-6 / WAVELENGTH IN METERS

CRPIX3 = 1.

CTYPE3 = 'LAMBDA '

CDELT3 = 0.

DATAMIX = D.ddddddE ee / JY/SR (TRUE VALUE)

DATAMIN = D.ddddddE ee / JY/SR (TRUE VALUE)

EPOCH = 1950. / EME.50

DATE-MAP = '01/11/84' / MAP RELEASE DATE

DATE = 'DD/MM/YY' / DATE THIS TAPE WRITTEN

ORIGIN = 'JPL-IRAS' / INSTITUTION

TELESCOP = 'IRAS'

INSTRUME = 'SKYPLATE' / IRAS SKY PLATE

OBJECT = 'PLnnn Hn' / PLATE NUMBER/ HCON

PROJTYE = 'GNOMONIC' / PROJECTION TYPE

COMMENT MINSOP = MMM; MAXSOP = NNN

COMMENT LOGTAG = VSFLOG(7.6)

COMMENT GEOMTAG = GEOM(7.5)

COMMENT

COMMENT PROJECTION FORMULAE:

COMMENT FORWARD FORMULA; RA0 AND DEC0 ARE THE PLATE CENTER

COMMENT R2D = 45./ ATAN(1.)

COMMENT PIX = 30.

COMMENT A = COS(DEC) * COS(RA0 - RA)

COMMENT F = PIX * R2D/(SIN(DEC0) * SIN(DEC) + A * COS(DEC0))

COMMENT SAMPLE = -F * COS(DEC) * SIN(RA-RA0)

COMMENT XLINE = -F * (COS(DEC0) * SIN(DEC) - A * SIN(DEC0))

COMMENT

COMMENT INVERSE FORMULA; REQUIRES ARCSINE

X-5l

COMMENT X = SAMPLE/ (PIX * R2D)

COMMENT Y = LINE/ (PIX * R2D)

COMMENT DELTA = ATAN(SQRT(X*X + Y*Y))

COMMENT BETA = ATAN2(-X,Y)

COMMENT DEC = ASIN(SIN(DEC0)*COS(DELTA)-COS(DEC0)*SIN(DELTA)*COS(BETA))

COMMENT XX = SIN(DEC0)*SIN(DELTA)*COS(BETA)+COS(DEC0)*COS(DELTA)

COMMENT YY = SIN(DELTA)*SIN(BETA)

COMMENT RA = RA0 + ATAN2(YY,XX)

COMMENT REFERENCES:

COMMENT IRAS SDAS SOFTWARE INTERFACE SPECIFICATION(SIS) #623-94/NO.SF05

COMMENT ASTRON. ASTROPHYS. SUPPL. SER. 44,(1981) 363-370 (RE:FITS)

COMMENT RECONCILIATION OF FITS PARMS W/SIS SF05 PARMS:

COMMENT NAXIS1 = (ES - SS + 1); NAXIS2 = (EL - SL + 1);

COMMENT CRPIX1 = (1 - SS); CRPIX2 = (1 - SL)

END

Header for 16.5 deg Image Weight

SIMPLE = T / STANDARD FITS FORMAT

BITPIX = 16 / 2 BYTE TWOS COMPL INTEGER

NAXIS = 3 / NUMBER Of AXES

NAXIS1 = nn / # SAMPLES PER LINE (FASTEST VARY INDEX

NAXIS2 = mm / # LINES OF DATA IN IMAGE FILE

NAXIS3 = 1 / # WAVELENGTHS

BSCALE = 1. / TRUE=TAPE*SCALE+BZERO

BZERO = 0.0 /

BUNIT = ' ' / STATISTICAL WEIGHT

BLANK = 0 / TAPE VALUE FOR EMPTY PIXEL

CRVAL1 = DD.dd / RA AT ORIGIN (DEGREES)

CRPIX1 = xxx. / SAMPLE AXIS ORIGIN (PIXEL)

CTYPE1 = 'RA--TAN' / DECREASES IN VALUE AS SAMPLE INDEX

COMMENT INCREASES (GNOMONIC PROJECTION)

CDELT1 0= -3.333333E-02 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON SAMPLE AXIS

CRVAL2 = DD.dd / DEC AT ORIGIN (DEGREES)

CRPIX2 = ny. / LINE AXIS ORIGIN (PIXEL)

CTYPE2 = 'DEC--TAN' / DECREASES IN VALUE AS LINE INDEX

COMMENT INCREASES (GNOMONIC PROJECTION)

CDELTA2 = -3.333333E-02 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON LINE AXIS

CRVAL3 = z.zzE-6 / WAVELENGTH IN METERS

CRPIX3 = 1.

CTYPE3 = 'LAMBDA '

CDELT3 = 0.

DATAMAX = D.ddddddE ee / DIMENSIONLESS

DATAMIN = D.ddddddE ee / DIMENSIONLESS

EPOCH = 1950. / EME50O

DATE-MAP = '01/11/84' / MAP RELEASE DATE

DATE = 'DD/MM/YY' / DATE THIS TAPE WRITTEN

ORIGIN = 'JPL-IRAS' / INSTITUTION

TELESCOPE = 'IRAS '

INSTRUME = 'SKYPLATE' / IRAS SKY PLATE

OBJECT = 'PLnnn Hn' / PLATE NUMBER/ HCON

PROJTYPE = 'GNOMONIC' / PROJECTION TYPE

COMMENT MINSOP = MMM; MAXSOP = NN

COMMENT LOGTAG = VSFLOG(7.8)

COMMENT GEOMTAG = GEOM (7.5)

COMMENT

COMMENT PROJECTION FORMULAE:

COMMENT FORWARD FORMULA; RAO AND DEC0 ARE THE PLATE CENTER

COMMENT R2D = 45. / ATAN(l.)

COMMENT PIX = 30.

COMMENT A = COS(DEC) * COS(RA0 - RA)

COMMENT F = PIX * R2D/ (SM(DEC0) * SIN(DEC) + A * COS(DEC0))

COMMENT SAMPLE = -F * COS(DEC) * SIN(RA-RA0)

COMMENT XLINE = -F * (COS(DEC0) - SIN(DEC), A * SIN(DEC0))

COMMENT

COMMENT INVERSE FORMULA; REQUIRES ARCSINE

COMMENT X = SAMPLE/ (PIX * R2D)

COMMENT Y = LINE/ (PIX * R2D)

COMMENT DELTA = ATAN(SQRT(X*X + Y*Y))

X-53

COMMENT BETA = ATAN2(-X,Y)

COMMENT DEC = ASIN(SIN(DEC0)*COS(DELTA)-COS(DEC0)*SIN(DELTA)*COS(BETA))

COMMENT XX = SIN(DEC0)*SIN(DELTA)*COS(BETA)+COS(DEC0)*COS(DELTA)

COMMENT YY = SIN(DELTA)*SIN(BETA)

COMMENT RA = RA0 + ATAN2(YY,XX)

COMMENT REFERENCES:

COMMENT IRAS SDAS SOFTWARE INTERFACE SPECIFICATION(SIS) #623-94/NO. SF05

COMMENT ASTRON. ASTROPHYS. SUPPL. SER. 44,(1981) 363-370 (RE:FITS)

COMMENT RECONCILIATION OF FITS PARMS W/SIS SFO5 PARMS:

COMMENT NAXIS1 = (ES - SS + 1); NAXIS2 = (EL - SL + 1);

COMMENT CRPIX1 = (1 - SS); CRPIX2 = (1 - SL)

END

X-54

Header for Galactic Plane Fields

SIMPLE = T / STAMDARD FITS FORMAT

BITPIX = 32 / 4 BYTE TWOS COMPL INTEGER

NAXIS = 3 / NUMBER OF AXES

NAXIS1 = nn / # SAMPLES PER LINE (FASTEST VARY INDEX)

NAXIS2 = mm / # LINES OF DATA IN IMAGE FILE

NAXIS3 = 1 / # WAVELENGTHS

BSCALE = S.SSSSSSEee / TRUE=TAPE*SCALE+BZERO

BZERO = 0.0 /

BUNIT = 'JY/SR' / INTENSITY

BLANK = - 2000000000 / TAPE VALUE FOR EMPTY PIXEL

CRVAL1 = DD.dd / GALACTIC LONGITUDE AT ORIGIN (DEGREES)

CRPIX1 = xxx. / SAMPLE AXIS ORIGIN (PIXEL)

CTYPE1 = 'GLON ' / DECREASES IN VALUE AS SAMPLE INDEX

COMMENT INCREASES (LAMBERT EQUIVALENT)

COMMENT CYLINDRICAL PROJECTION)

CDELT1 = -3.333333E-02 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON SAMPLE AXIS

CRVAL2 = 0.0 / GALACTIC LATITUDE AT ORIGIN (DEGREES)

CRPIX2 = yyy. / LINE AXIS ORIGIN (PIXEL)

CTYPE2 = 'GLAT-SIN' / DECREASES IN VALUE AS LINE INDEX

COMMENT INCREASES (LAMBERT EQUIVALENT

COMMENT CYLINDRICAL PROJECTION

CDELTA2 = -3.333333E-02 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON LINE AXIS

CRVAL3 = zzzE-6 / WAVELENGTH IN METERS

CRPIX3 = 1.

CTYPE3 = 'LAMBDA '

CDELT3 = 0.

DATAMAX = D.ddddddE ee / JY/SR (TRUE VALUE)

DATAMIN = D.ddddddE ee / JY/SR (TRUE VALUE)

EPOCH = 1950. / EME5O

DATE-MAP = '01/11/84' / MAP RELEASE DATE

DATE = 'DD/MM/YY' / DATE THIS TAPE WRITTEN

ORIGIN = 'JPL-IRAS' / INSTITUTION

TELESCOP = 'IRAS '

INSTRUME = 'GALPLANE' / IRAS GALACTIC PLANE

OBJECT = 'GPLnn Hn' / GALACTIC PLANE PLATE NUMBER/ HCON

PROJTYPE = 'LAMBECYL' / PROJECTION TYPE

COMMENT

COMMENT PROJECTION FORMULAE:

COMMENT FORWARD FORMULA; XLONG IS THE LONGITUDE OF PLATE CENTER

COMMENT R2D = 45./ ATAN(1.)

COMMENT PIX = 30.

COMMENT XLINE = -SIN(XLAT) * PIX * R2D

COMMENT SAMPLE = (XLON - XLON0) * PIX

COMMENT

COMMENT INVERSE FORMULA; ARCSINE IS REQUIRED

COMMENT XLON = XLON0 - SAMPLE / PIX

COMMENT XLAT = -ASIN(XLINE / (PIX * R2D))

COMMENT REFERENCES:

COMMENT IRAS SDAS SOFTWARE INTERFACE SPECIFICATION(SIS) #623-94/N0. SFO5

COMMENT ASTRON. ASTROPHYS. SUPPL. SER. 44,(1981) 363-370 (RE:FITS)

X-55

COMMENT RECONCILIATION OF FITS PARMS W/ SIS SFO5 PARMS:

COMMENT NAXIS1 = (ES - SS + 1); NAXIS2 = (EL - SL + 1);

COMMENT CRPIX1 = (1 - SS) CRPIX2 = ( 1 - SL)

X-56

Header fOr Low-Resolution All-Sky Image (Galactic Center)

SIMPLE = T / STANDARD FITS FORMAT

BITPIX = 32 / 4 BYTE TWOS COMPL INTEGERS

NAXIS = 3 / NUMBER OF AXES

NAXIS1 = nn / # SAMPLES PER LINE (FASTEST VARY NDEX)

NAXIS2 = mm / # LINES OE DATA IN IMAGE FILE

NAXIS3 = 1 / # WAVELENGTHS

BSCALE = S.ssssssE-ee / TRUE=TAPE*SCALE+BZERO

BZERO = 0.0 /

BUNIT = 'JY/SR' / INTENSITY

BLANK = -2000000000 / TAPE VALUE FOR EMPTY PIXEL

CRVAL1l = DD.dd / GALACTIC LONGITUDE AT ORIGIN (DEGREES)

CRPIX1 = xxx. / SAMPLE AXIS ORIGIN (PIXEL)

CTYPE1 = 'LON-AFT' / DECREASES IN VALUE AS SAMPLE INDEX

COMMENT INCREASES (AITOFF PROJECTION)

CDELTA1 = 'LON-AFT ' 0.5 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON SAMPLE AXIS

CRVAL2 = 0.0 / GALACTIC LATITUDE AT ORIGIN (DEGREES)

CRPIX2 = yyy. / LINE AXIS ORIGIN (PIXEL)

CTYPE2 = 'LAT-ATF' / DECREASES IN VALUE AS LINE INDEX

COMMENT INCREASES (AITOFF PROJECTION)

CDELT2 = 'LAT-AFT' -0.5 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON LINE AXIS

CRVAL3 = z.zzE-6 / WAVELENGTH IN METERS

CRPIX3 = 1.

CTYPE3 = 'LAMBDA '

CDELT3 = 0.

DATAMAX = D.ddddddE ee / JY/SR (TRUE VALUE)

DATAMIN = D.ddddddE ee / JY/SR (TRUE VALUE)

EPOCH = 1950. / EME5O

DATE-MAP = 'O1/11/84' / MAP RELEASE DATE

DATE = 'DD/MM/YY' / DATE THIS TAPE WRITTEN

ORIGIN = 'JPL-IRAS' / INSTITUTION

INSTRUME = 'ALL SKY' / IRAS LOW RES ALL-SKY

OBJECT = 'CENTER n' / ALLLSKY GALACTIC CENTER/ HCON

PROJTYPE = 'AITOFF ' / PROJECTION TYPE

COMMENT MINSOP = MMM; MAXSOP = NNN

COMMENT

COMMENT PROJECTION FORMULAE:

COMMENT FORWARD FORMULA; XLONO IS THE CENTER LONGITUDE OF THE

COMMENT MAP. ARC-SINE AND ARC-COSINE FUNCTIONS ARE REQUIRED.

COMMENT R2D = 45. / ATAN(1.)

COMMENT PIX = 2.

COMMENT RHO = ACOS( COS(XLAT) * COS((XLON-XLON0)2.))

COMMENT THEATA = ASIN( COS(XLAT) * SIN((XLON-XLON0)/2.)/ SIN(RHO))

COMMENT F = 2. * PIX * R2D * SIN(RHO/2.)

COMMENT SAMPLE = -2. * F * SIN(THETA)

COMMENT XLINE = -F * COS(THETA)

COMMENT IF(XLAT.LT. 0.) XLINE = -XLINE

COMMENT

COMMENT REVERSE FORMULA; XLON0 IS THE CENTER LONGITUDE OF THE MAP.

COMMENT ARC-SINE AND ARC-COSINE FUNCTIONS NEEDED.

COMMENT R2D = 45./ ATAN(1.)

X-57

COMMENT PIX = 2.

COMMENT Y = -XLINE/ (PIX * 2. * R2D)

COMMENT X = -SAMPLE/ (PIX * 2. * R2D)

COMMENT A = SQRT(4.-X*X-4.*Y*Y)

COMMENT XLAT = R2D * ASIN(A*Y)

COMMENT XLON = XLON0 + 2. * R2D * ASIN(A*X/(2.*COS(XLAT)))

COMMENT

COMMENT REFERENCES:

COMMENT IRAS SDAS SOFTWARE INTERFACE SPECIFICATION(SIS) #623-94N0. SF05

COMMENT ASTRON. ASTROPHYS. SUPPL. SER. 44,(1981) 363-370 (RE:FITS)

COMMENT RECONCILIATION OF FITS PARMS W/ SIS Ff05 PARMS:

COMMENT NAXIS1 = (ES - SS + 1); NAXIS2 = (EJ - SL + 1);

COMMENT CRPIX1 = (1 - SS); CRPIX2 = (1 - SL)

END

X-58

Header for Low-Resolution All-Sky Intensity Galactic Antit-Center

SIMPLE = T / STANDARD FITS FORMAT

BITPIX = 32 / 4 BYTE TWOS COMPL INTEGER

NAXIS = 3 / NUMBER OF AXES

NAXIS1 = nn / # SAMPLES PER LINE (FASTEST VARY NDEX

NAXIS2 = mm / # LINES Of DATA IN IMAGE FILE

NAXIS3 = 1 / # WAVELENGTHS

BSCALE = S.ssssssE-ee / TRUE=TAPE*SCALE+BZERO

BZERO = 0.0 /

BUNIT = 'JY/SR' / INTENSITY

BLANK = -2000000000 / TAPE VALUE FOR EMPTY PIXEL

CRVAL1 = 150.0 / GALACTIC LONGITUDE AT ORIGIN (DEGREES)

CRPIX1 = xxx. / SAMPLE AXIS ORIGIN (PIXEL)

CTYPE1 = 'LON-ATF' / DECREASES IN VALUE AS SAMPLE INDEX

COMMENT INCREASES (AITOF PROJECTION)

CDELT1 = -0.5 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON SAMPLE AXIS

CRVAL2 = 0.0 / GALACTIC LATITUDE AT ORIGIN (DEGREES)

CRPIX2 = yyy. / LINE AXIS ORIGIN (PIXEL)

CTYPE2 = 'LAT-ATF' / DECREASES IN VALUE AS LINE INDEX

COMMENT INCREASES (AITOFF PROJECTION)

CDELLT2 = -0.5 / COORD VALUE INCREMENT DEG/PIXEL

COMMENT AT ORIGIN ON LINE AXIS

CRVAL3 = z.zzE-6 / WAVELENGTH IN METERS

CRPIX3 = 1.

CTYPE3 = 'LAMBDA '

CDELT3 = 0.

DATAMAX = D.ddddddE ee / JY/SR (TRUE VALUE)

DATAMIN = D.ddddddE ee / JY/SR (TRUE VALUE)

EPOCH = 1950. / EME50

DATE-MAP = '01/11/84' / MAP RELEASE DATE

DATE = 'DD/MM/YY' / DATE THISS TAPE WRITTEN

ORIGIN = 'JPL-IRAS' / INSTITUTION

TELESCOP = 'IRAS '

INSTRUME = 'ALL SKY' / IRAS LOW RES ALL-SKY

OBJECT = 'ACENTERN' / ALL-SKY GALACTIC ANTI-CENTER/ HCON

PROJTYPE = 'AITOFF' / PROJECTION TYPE

COMMENT MINSOP = MMM; MAXSOP = NNN

COMMENT

COMMENT PROJECTION FORMULAE:

COMMENT FORWARD FORMULA; XLON0 IS THE CENTER LONGITUDE OF THE

COMMENT MAP. ARC-SINE AND ARC-COSINE FUNCTIONS ARE REQUIRED.

COMMENT R2D = 45./ ATAN(1.)

COMMENT PIX = 2.

COMMENT RHO = ACOS COS(XLAT) * COS((XLON-XLON0)/2.))

COMMENT THETA = ASIN( COS(XLAT) * SIN((XLON-XLON0)/2.)/ SIN(RHO))

COMMENT F = 2. * PIX * R2D * SIN(RHO/2.)

COMMENT SAMPLE = -2. * F * SIN(THETA)

COMMENT XLINE; = -F * COS(THETA)

COMMENT IF(XLAT .LT. 0.) XLINE = -XLINE

COMMENT

COMMENT REVERSE FORMULAA; XLON0 IS THE CENTER LONGITUDE OF THE MAP.

COMMENT ARC-SINE AND ARC-COSINE FUCTIONS NEEDED.

X-59

COMMENT R2D = 45./ ATAN(1.)

COMMENT PIX = 2.

COMMENT Y = -XLINE/ (PIX * 2. * R2D)

COMMENT X = -SAMPLE/ (P(X * 2. * R2D)

COMMENT A = SQRT(4.-X*X-4.*YY)

COMMENT XLAT = R2D * ASIN(A*Y)

COMMENT XLON = XLON0 + 2. * R2D * ASIN(A*X/(2.*COS(XLAT)))

COMMENT

COMMENT REFERENCES:

COMMENT IRAS SDAS SOFTWARE: INTERFACE SPECIFICATION(SIS) #623-94/NO. SF05

COMMENT ASTRON. ASTROPHYS. SUPPL. SER. 44,(1981) 363-370 (RE:FITS)

COMMENT RECONCILIATION OF FITS PARMS W/ SIS SFO5 PARMS:

COMMENT NAXIS1 = (ES - SS + 1); NAXIS2 = (EL - SL + 1);

COMMENT CRPIXl = (1 - SS); CRPIX2 = (1 - SL)

END


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