This is the output file from the first stepping observation defined in the input file example, a Multi-wavelength scans of a calibrator.
In this case the object observed is a flux calibrator, so these data can be used to determine a new value of the point source sensitivity. Pointing offsets can also be determined.
A true FITS format is used for this example, so that the primary header contains the keywords SIMPLE, BITPIX, NAXIS, NAXISn, n = 1, ..., NAXIS, other keywords, END, in that order.
Data regarded as character strings are written within quotes. Numeric parameters should all technically be right justified ending at column 30, although only a few have been written that way here. Logical values are T = True of F = False, again right-justified.
Blank lines are permitted in the housekeeping.
It is proposed for stepping observations that the "raw" data be recorded, not the mean or median value at each step as on the HP, so that every datum is available for post-observation analysis and data-quality verification. "Raw" may be literally the stream of raw counts at 10mS intervals from the counters during each track, or they may have been binned or summed to 100mS intervals to match the angle measurement interval in STEER, depending on how the observing algorithm is implemented.
Because each field (column) in the binary table used to store the data must have the same length, each step must generate the same number of data points. Inefficiently, they could be padded with NULL values to the length of the longest column.
The data recorded during the track at each step are here assumed to be of equal length (here 100 points). Any step with calibration diode firing is recorded as two equal length steps. The raw data in each polarization are recorded in separate fields.
It is possible to record further data in extra fields of the binary table. For example, at each step one could include the hour angle and declination and / or the tracking errors in hour angle and in declination. Then in post-processing, only those data meeting offset error criteria would be included in the data analysis, or variations in system temperature with hour angle could be corrected. Here the data are assumed to be the counts from the radiometer outputs only, with no extra information.
FITSIO recognises units in a comment if they are of the form "/ [unit] rest of comment". This is not part of the FITS standard, but can be helpful.
SIMPLE = T / file does conform to FITS standard
BITPIX = 8 / not used as NAXIS is 0
NAXIS = 0 / number of data axes - no primary data array
EXTEND = T / FITS dataset contains extensions
DATE = '1999-08-17T12:25:10'/ date of creation of this HDU, UT
COMMENT information about the object
OBJECT = '0915-11' / flux calibrator
EQUINOX = 1950.0 / coordinate equinox
RADECSYS= 'FK4 ' / Besselian equinox, type FK4
RA = 138.921 / [deg] object RA
DEC = -11.885 / object DEC, in required decimal degrees
OBJFLUX = 36.45 / flux density from catalogue at restfreq, Jy
REFERENC= 'Ott et al. (1994) AA 284, 331.'
COMMENT information about the scan
PROJECT = flux calibration
PROPOSAL= 1999.001
OBSERVER= 'G.D. NICOLSON' / Principal Investigator
DATE-OBS= '1999-08-17T12:13:14'/ UT at start of scan, Y2K-compliant
MJD-OBS = 51187.216818750 / Modified Julian date of start of scan
SCAN = '19990817121314' / scan number (identifier)
SCANTYPE= 'STEP' / set of tracks stepped around object
STEPSEQ = 'FNNCAL, HPN, ON, HPS, FNS, FNE, HPE, ON, HPW, FNW'
RESTFREQ= 1666E6 / rest frequency set by LO chain, in Hz
HA = 0.101 / HA at middle of scan, degrees
ALT = 80.305 / altitude (elevation) at middle of scan, deg
COMMENT TCALCNT not known yet as calibration data have not been processed yet
COMMENT information on the telescope and receiver configuration
TELESCOP= 'HartRAO 26M' / telescope
SURFACE = 'PANEL 1 MISSING' / telescope surface description
GAINFAC = 0.997 / relative to intact surface at upgrade start
SUBTILT = 9.70 / subreflector tilt, arbitrary units
SUBFOCUS= 5.00 / subreflector focus, arbitrary units
DICHROIC= 'OFF' / dichroic was off
FEEDTYPE= 'CIRCULAR' / circular, dual-mode feed
BMOFFHA = 0.096 / beam offset in hour angle, deg
BMOFFDC = -0.904 / beam offset in declination, deg
HPBW = 0.494 / halfpower beamwidth, deg
FNBW = 1.190 / first null beamwidth, deg
RFBANDHI= 1671E6 / 10MHz filter centred on 1666 MHz, in Hz
RFBANDLO= 1661E6 / 10MHz filter centred on 1666 MHz, in Hz
NOMTSYS = 35 / nominal zenith system temperature in Kelvins
INSTRUME= 'NARAD-NA' / used noise-adding radiometers
POL1 = 'LCP' / polarization of data for channel 1
POL2 = 'RCP' / polarization of data for channel 2
COMMENT information for calibrating the data
TCAL1 = 6.2 / Cal noise diode value for channel 1
TCAL2 = 5.3 / Cal noise diode value for channel 2
TCALERR1= 0.0 / uncertainty in Tcal1 is unknown
TCALERR2= 0.0 / uncertainty in Tcal2 is unknown
TCALFREQ= 1668E6 / frequency the calibration applies to, in Hz
TCALDATE= '1900-01-01' / unknown calibration date
TCALUNIT= 'K' / units for cal noise diode values
CALPSS1 = 5.13 / Point source sens for channel1, Jy/K
CALPSS2 = 5.13 / Point source sens for channel2, Jy/K
CALPSSER= 0.07 / uncertainty in CALPSS
CALSRC = 'B0915-11' / object used for calibration
CALFLUX = 36.45 / total flux density assumed at CALFREQ, Jy
CALFREQ = 1668E6 / frequency the calibration applies to, in Hz
CALDATE = '1995-07-26' / calibration date
REFERENC= 'Ott et al. (1994) AA 284, 331.'
COMMENT information about the processing of the data
ATMCOR = 1 / uncorrected raw data
PNTCOR = 1 / uncorrected raw data
GAINCOR = 1 / uncorrected raw data
END / end of HDU
...at the start of a new FITS record is the binary table header...
XTENSION / start of binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-D table
NAXIS1 = 88 / bytes per row = 88 * 4
NAXIS2 = 100 / number of rows
PCOUNT = 0 / number of bytes in extension data
GCOUNT = 1 / single table
TFIELDS = 22 / number of fields (columns per row)
COMMENT above keywords are mandatory for a binary table, in this sequence
COMMENT information about the data in the binary table follows
TFORM1 = 'J' / field = single 32-bit integer
TTYPE1 = 'FNNCAL LCP' / brightness type - step name + polarization
TUNIT1 = 'COUNTS' / brightness units - these are raw data
TDISP1 = 'I12' / recommended display format
TFORM2 = 'J' / field = single 32-bit integer
TTYPE2 = 'FNN LCP' / brightness type - step name + polarization
TUNIT2 = 'COUNTS' / brightness units - these are raw data
TDISP2 = 'I12' / recommended display format
TFORM3 = 'J' / field = single 32-bit integer
TTYPE3 = 'HPN LCP' / brightness type - step name + polarization
TUNIT3 = 'COUNTS' / brightness units - these are raw data
TDISP3 = 'I12' / recommended display format
TFORM4 = 'J' / field = single 32-bit integer
TTYPE4 = 'ON LCP' / brightness type - step name + polarization
TUNIT4 = 'COUNTS' / brightness units - these are raw data
TDISP4 = 'I12' / recommended display format
TFORM5 = 'J' / field = single 32-bit integer
TTYPE5 = 'HPS LCP' / brightness type - step name + polarization
TUNIT5 = 'COUNTS' / brightness units - these are raw data
TDISP5 = 'I12' / recommended display format
TFORM6 = 'J' / field = single 32-bit integer
TTYPE6 = 'FNS LCP' / brightness type - step name + polarization
TUNIT6 = 'COUNTS' / brightness units - these are raw data
TDISP6 = 'I12' / recommended display format
TFORM7 = 'J' / field = single 32-bit integer
TTYPE7 = 'FNE LCP' / brightness type - step name + polarization
TUNIT7 = 'COUNTS' / brightness units - these are raw data
TDISP7 = 'I12' / recommended display format
TFORM8 = 'J' / field = single 32-bit integer
TTYPE8 = 'HPE LCP' / brightness type - step name + polarization
TUNIT8 = 'COUNTS' / brightness units - these are raw data
TDISP8 = 'I12' / recommended display format
TFORM9 = 'J' / field = single 32-bit integer
TTYPE9 = 'ON LCP' / brightness type - step name + polarization
TUNIT9 = 'COUNTS' / brightness units - these are raw data
TDISP9 = 'I12' / recommended display format
TFORM10 = 'J' / field = single 32-bit integer
TTYPE10 = 'HPW LCP' / brightness type - step name + polarization
TUNIT10 = 'COUNTS' / brightness units - these are raw data
TDISP10 = 'I12' / recommended display format
TFORM11 = 'J' / field = single 32-bit integer
TTYPE11 = 'FNW LCP' / brightness type - step name + polarization
TUNIT11 = 'COUNTS' / brightness units - these are raw data
TDISP11 = 'I12' / recommended display format
TFORM12 = 'J' / field = single 32-bit integer
TTYPE12 = 'FNNCAL RCP' / brightness type - step name + polarization
TUNIT12 = 'COUNTS' / brightness units - these are raw data
TDISP12 = 'I12' / recommended display format
TFORM13 = 'J' / field = single 32-bit integer
TTYPE13 = 'FNN RCP' / brightness type - step name + polarization
TUNIT13 = 'COUNTS' / brightness units - these are raw data
TDISP13 = 'I12' / recommended display format
TFORM14 = 'J' / field = single 32-bit integer
TTYPE14 = 'HPN RCP' / brightness type - step name + polarization
TUNIT14 = 'COUNTS' / brightness units - these are raw data
TDISP14 = 'I12' / recommended display format
TFORM15 = 'J' / field = single 32-bit integer
TTYPE15 = 'ON RCP' / brightness type - step name + polarization
TUNIT15 = 'COUNTS' / brightness units - these are raw data
TDISP15 = 'I12' / recommended display format
TFORM16 = 'J' / field = single 32-bit integer
TTYPE16 = 'HPS RCP' / brightness type - step name + polarization
TUNIT16 = 'COUNTS' / brightness units - these are raw data
TDISP16 = 'I12' / recommended display format
TFORM17 = 'J' / field = single 32-bit integer
TTYPE17 = 'FNS RCP' / brightness type - step name + polarization
TUNIT17 = 'COUNTS' / brightness units - these are raw data
TDISP17 = 'I12' / recommended display format
TFORM18 = 'J' / field = single 32-bit integer
TTYPE18 = 'FNE RCP' / brightness type - step name + polarization
TUNIT18 = 'COUNTS' / brightness units - these are raw data
TDISP18 = 'I12' / recommended display format
TFORM19 = 'J' / field = single 32-bit integer
TTYPE19 = 'HPE RCP' / brightness type - step name + polarization
TUNIT19 = 'COUNTS' / brightness units - these are raw data
TDISP19 = 'I12' / recommended display format
TFORM20 = 'J' / field = single 32-bit integer
TTYPE20 = 'ON RCP' / brightness type - step name + polarization
TUNIT20 = 'COUNTS' / brightness units - these are raw data
TDISP20 = 'I12' / recommended display format
TFORM21 = 'J' / field = single 32-bit integer
TTYPE21 = 'HPW RCP' / brightness type - step name + polarization
TUNIT21 = 'COUNTS' / brightness units - these are raw data
TDISP21 = 'I12' / recommended display format
TFORM22 = 'J' / field = single 32-bit integer
TTYPE22 = 'FNW RCP' / brightness type - step name + polarization
TUNIT22 = 'COUNTS' / brightness units - these are raw data
TDISP22 = 'I12' / recommended display format
END
The binary table containing the data follows at the start of the next FITS
record.
This example is the output file from the observation defined in the second input file example, a Routine monitoring of Cir X-1.
In this case I assume that the data will be binned to provide 12 samples per half-power beamwidth. At 3.5cm the HPBW = 0.092 degrees. Each sample is therefore a binning of 0.0077 degrees of RA. At the drift scan rate of 0.004 degrees / second this implies that each sample is an integration of 2 seconds of data. The 1.085 degree drift scan implies that there will be 1.085 / 0.0077 = 141 samples. I also assume that the existing 3.5cm receiver is in place, giving only RCP output. In this example, the raw counts from the radiometer have been scaled to Kelvins using the calibration with the noise diode.
Standard FITS format is assumed. The data are recorded in a binary table.
SIMPLE = T / file does conform to FITS standard
BITPIX = 8 / not used as NAXIS is 0
NAXIS = 0 / number of data axes - no primary data array
EXTEND = T / FITS dataset contains extensions
DATE = '1999-08-17T12:25:10'/ date of creation of this HDU, UT
COMMENT information about the object
OBJECT = 'CIR X-1'
EQUINOX = 1950.0 / B1950 coordinate equinox
RADECSYS= 'FK4 ' / Besselian equinox, type FK4
RA = 229.201 / RA in decimal degrees
DEC = 303.013 / Dec in decimal degrees
COMMENT information about the scan
OBSERVER= 'G.D. NICOLSON'
PROJECT = monitor flux of flaring binary star Circinus X-1
PROPOSAL= 1999.002
SCANTYPE= 'DRIFT' / drift scan
SCANDIST= 1.082 / scan length, deg
RESTFREQ= 8500E6 / use 3.5cm receiver
HA = -44.987 / HA at start of scan, degrees
ALT = 45.305 / altitude (elevation) at middle of scan, deg
TCALCNT1= 433.5 / measured counts per Kelvin from ND cal.
DCALCNT1= 3.7 / uncertainty in measured counts per Kelvin
COMMENT information on the telescope and receiver configuration
TELESCOP= 'HartRAO 26M' / telescope
SURFACE = 'PANEL 13 MISSING' / telescope surface description
GAINFAC = 0.994 / relative to intact surface at upgrade start
SUBTILT = -0.77 / subreflector tilt, arbitrary units
SUBFOCUS= 8.00 / subreflector focus, arbitrary units
DICHROIC= 'OFF' / dichroic was off
FEEDTYPE= 'CIRCULAR' / circular, dual-mode feed
BMOFFHA = 0.015 / beam offset in hour angle, deg
BMOFFDC = 0.588 / beam offset in declination, deg
HABMSEP = 0.254 / beam separation, deg
HPBW = 0.092 / halfpower beamwidth, deg
FNBW = 0.230 / first null beamwidth, deg
RFBANDHI= 8980E6 / 10MHz filter centred on 1666 MHz, in Hz
RFBANDLO= 8180E6 / 10MHz filter centred on 1666 MHz, in Hz
NOMTSYS = 65 / nominal zenith system temperature in Kelvins
INSTRUME= 'DICKERAD' / instrument - dicke radiometer, beam-switching
POL1 = 'RCP' / polarization of data for channel 1
COMMENT information for calibrating the data
TCAL1 = 10.0 / Cal noise diode value for channel 1
TCALERR1= 0.0 / uncertainty in Tcal1 is unknown
TCALFREQ= 8580E6 / frequency the calibration applies to, in Hz
TCALDATE= '1900-01-01' / unknown calibration date
TCALUNIT= 'K' / units for cal noise diode values
CALPSS1 = 8.55 / Point source sens for channel1, Jy/K
CALPSSER= 0.12 / uncertainty in CALPSS
COMMENT if the object is known to be unpolarised
COMMENT double CALPSS1 and CALPSSER to get the total flux density and unc.
CALSRC = 'B0915-11' / object used for calibration
CALFLUX = 7.91 / total flux density assumed at CALFREQ
CALFREQ = 8580E6 / frequency the calibration applies to, in Hz
CALDATE = '1995-07-26' / calibration date
REFERENC= 'Ott et al. (1994) AA 284, 331.'
COMMENT information about the processing of the data
ATMCOR = 1 / uncorrected raw data
PNTCOR = 1 / uncorrected raw data
GAINCOR = 1 / uncorrected raw data
END / end of HDU
...at the start of a new FITS record is the binary table header...
XTENSION / start of binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-D table
NAXIS1 = 8 / bytes per row
NAXIS2 = 141 / number of rows
PCOUNT = 0 / number of bytes in extension data
GCOUNT = 1 / single table
TFIELDS = 2 / number of fields (columns)
COMMENT information about the data in the binary table
TFORM1 = 'E' / field = single precision floating point
TTYPE1 = 'RA' / type
TUNIT1 = 'deg' / units
TDISP1 = 'F8.3' / recommended display format
TFORM2 = 'E' / field = single precision floating point
TTYPE2 = 'ANT_TEMP RCP' / type
TUNIT2 = 'K' / units
TDISP2 = 'E15.9' / recommended display format
END
The HDU is followed by the binary table comprising the 141 RA and antenna
temperature values written as binary real*4 numbers, packed in 2880-byte
blocks.
This example is the output file from the first scan defined in the input file example, Scans for a large map.
JJ: I have used my input file for this example. Scans are 10 degrees long, scan rate is 0.1 deg/sec, scan spacing is 0.1 deg. Each scan has its own data file. Sampling at 10 Hz, the number of data samples should be 1001 (or 1000 ???). Command coordinates not explicitly stored - they can be determined from header information.
MG: I also assumed that the existing 13cm receiver is in place, giving only RCP output. JJ in the binary table also has LCPcounts being recorded, although the preceding keywords show that only RCP is present. Dual polarization and a polarimeter would give Stokes I, Q, U and V parameters.
Standard FITS format is used, with the data stored in a binary table.
SIMPLE = T / file does conform to FITS standard
BITPIX = 8 / not used as NAXIS is 0
NAXIS = 0 / number of data axes - no primary data array
EXTEND = T / FITS dataset contains extensions
DATE = '1999-08-17T12:25:10'/ date of creation of this HDU, UT
COMMENT information about the object
OBJECT = 'UPSCAN1'
OBJECT = 'SCAN001X' / directly from input file
COORDTYP= 'GALACTIC'
COMMENT information about the scan
OBSERVER= J.L. JONAS
OBSLOCAL= G.D. NICOLSON
PROJECT = galactic plane map at 3.5cm
PROPOSAL= 1999.003
DATE-OBS= '1999-08-17T12:13:14'/ UT at start of scan, Y2K-compliant
MJD-OBS = 51187.216818750 / Modified Julian date of start of scan
SCAN = '19990817121314' / scan number (identifier)
SCANTYPE= 'SCAN'
GLON-TAN= 270.0 / Celestial coordinates of map centre and
GLAT-TAN= +20.0 / type of projection used.
LONGPOLE= 0.0 / No field rotation
STARTX = -5.0 / Scan start and stop offsets in
STOPX = -5.0 / projected coordinate frame.
STARTY = -5.0 /
STOPY = +5.0 /
SCANTIME= 100.0 / scan duration in seconds
RESTFREQ= 2300E6 / 13cm receiver
TCALCNT1= 433.5 / measured counts per Kelvin from ND cal.
DCALCNT1= 3.7 / uncertainty in measured counts per Kelvin
COMMENT information on the telescope and receiver configuration
TELESCOP= 'HartRAO 26M' / telescope
SURFACE = 'PANEL 113 MISSING' / telescope surface description
GAINFAC = 0.992 / relative to intact surface at upgrade start
SUBTILT = -0.77 / subreflector tilt, arbitrary units
SUBFOCUS= 8.00 / subreflector focus, arbitrary units
DICHROIC= 'OFF' / dichroic was off
FEEDTYPE= 'CIRCULAR' / circular, dual-mode feed
BMOFFHA = 0.059 / beam offset in hour angle, deg
BMOFFDC = -0.427 / beam offset in declination, deg
HPBW = 0.332 / halfpower beamwidth, deg
FNBW = 0.800 / first null beamwidth, deg
RFBANDHI= 2360E6 / 10MHz filter centred on 1666 MHz, in Hz
RFBANDLO= 2210E6 / 10MHz filter centred on 1666 MHz, in Hz
NOMTSYS = 40 / nominal zenith system temperature in Kelvins
INSTRUME= 'NARAD-NAD' / instrument
POL1 = 'RCP' / polarization of data for channel 1
COMMENT information for calibrating the data
TCAL1 = 3.96 / Cal noise diode value for channel 1
TCALERR1= 0.0 / uncertainty in Tcal1 is unknown
TCALFREQ= 2272.8E6 / frequency the calibration applies to, in Hz
TCALDATE= '1900-01-01' / unknown calibration date
TCALUNIT= 'K' / units for cal noise diode values
CALPSS1 = 4.86 / Point source sens for channel1, Jy/K
CALPSSER= 0.015 / uncertainty in CALPSS
COMMENT if the object is known to be unpolarised
COMMENT double CALPSS1 and CALPSSER to get the total flux density and unc.
CALSRC = 'B0915-11' / object used for calibration
CALFLUX = 27.22 / total flux density assumed at CALFREQ
CALFREQ = 2272.8E6 / frequency the calibration applies to, in Hz
CALDATE = '1995-07-26' / calibration date
REFERENC= 'Ott et al. (1994) AA 284, 331.'
COMMENT information about the processing of the data
ATMCOR = 1 / uncorrected raw data
PNTCOR = 1 / uncorrected raw data
GAINCOR = 1 / uncorrected raw data
END / end of HDU
...at the start of a new FITS record is the binary table header...
XTENSION / start of binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-D table
NAXIS1 = 32 / bytes per row (8 cols x 4 bytes)
NAXIS2 = 1001 / number of rows (perhaps 1000)
PCOUNT = 0 / number of bytes in extension data
GCOUNT = 1 / single table
TFIELDS = 1 / number of fields (columns)
COMMENT information about the data in the binary table
TFORM1 = '1E' / field = single precision floating point
TTYPE1 = 'X' / X offset from field centre
TUNIT1 = 'DEG' / units
TDISP1 = 'F8.3' / recommended display format
TFORM2 = '1E' / field = single precision floating point
TTYPE2 = 'Y' / Y offset from field centre
TUNIT2 = 'DEG' / units
TDISP2 = 'F8.3' / recommended display format
TFORM3 = '1E' / field = single precision floating point
TTYPE3 = 'GLON' / celestial longitide coordinate
TUNIT3 = 'DEG' / units
TDISP3 = 'F8.3' / recommended display format
TFORM4 = '1E' / field = single precision floating point
TTYPE4 = 'GLAT' / celestial latitude coordinate
TUNIT4 = 'DEG' / units
TDISP4 = 'F8.3' / recommended display format
TFORM5 = '1E' / field = single precision floating point
TTYPE5 = 'AZ' / telescope azimuth coordinate
TUNIT5 = 'DEG' / units
TDISP5 = 'F8.3' / recommended display format
TFORM6 = '1E' / field = single precision floating point
TTYPE6 = 'EL' / telescope elevation/altitude coordinate
TUNIT6 = 'DEG' / units
TDISP6 = 'F8.3' / recommended display format
TFORM7 = '1J' / field = 32-bit integer
TTYPE7 = 'LCPcount' / type
TUNIT7 = 'COUNTS' / units
TDISP7 = 'I12' / recommended display format
TFORM8 = '1J' / field = 32-bit integer
TTYPE8 = 'RCPcount' / type
TUNIT8 = 'COUNTS' / units
TDISP8 = 'I12' / recommended display format
END / end of binary table header
The header and extension are followed by the binary data table, packed in
2880-byte blocks.
This example is the output file from the first scan defined in the input file example for spectroscopy, monitoring a methanol maser.
This scan comprises a set three observations, offset NS, offset EW, and ON source, respectively, for determining the pointing error for the subsequent on-source observations. The three observations are recorded as three separate data sets. The first, for the NS pointing spectrum, is shown below.
The last two characters (NS) added to the object name indicate that this is a NS pointing observation. RAUP, DECUP, RADOWN, DECDOWN specify the actual coordinates observed. The HPBW used to offset the object coordinates for the spectra at the half-power points of the beam is listed in the telescope and receiver information.
The format again follows the FITS style.
SIMPLE = T / file does conform to FITS standard
BITPIX = 8 / not used
NAXIS = 0 / number of axes in data array
EXTEND = T / FITS dataset may contain extensions
DATE = '1999-08-17T12:25:10'/ date of creation of this HDU, UT
COMMENT information about the object
OBJECT = 'G213.71-12.60 PNTNS'/ NS pointing spectrum
GLON = 213.710 / object coordinates from input file
GLAT = -12.600 / object coordinates from input file
COMMENT information about the scan
OBSERVER= 'S. GOEDHART' / observer's name
PROJECT = 6.7-GHz methanol maser monitoring
PROPOSAL= 1999.006
DATE-OBS= '1999-08-17T12:13:14'/ UT at start of scan, Y2K-compliant
MJD-OBS = 51187.216818750 / Modified Julian date of start of scan
SCAN = '19990817121314' / scan number (identifier)
SCANTYPE= 'SPECTRUM' / type of observation
RESTFREQ= 6.668518E+09 / line rest frequency in Hz
SPVLSR = 11.0 / spectrum centre VLSR, in km/s
BW = 640000. / original bandwidth of spectrum in Hz
FROFFSET= 320000. / frequency offset for fr sw sp in Hz
EQUINOX = 1999.689 / equinox in years for coords
RAUP = 91.949 / RA of EQUINOX of object
DECUP = -6.322 / DEC of EQUINOX + HPBW/2 (north pnt offset)
RADOWN = 91.949 / RA of EQUINOX of object
DECDOWN = -6.438 / DEC of EQUINOX - HPBW/2 (south pnt offset)
COMMENT the following are parameters measured during the scan
HA = -44.987 / HA at middle of scan, degrees
ALT = 45.305 / altitude (elevation) at middle of scan, deg
TSYS = 59.0315 / measured system temp of SCAN in TCALUNITS
DTSYS = 2.32639612 / measured uncertainty in TSYS in TCALUNITS
DUR = 210. / total integration time of SCAN in S
RMS = 0.142293849 / expected rms noise in data in BUNITs
COMMENT information on the telescope and receiver configuration
TELESCOP= 'HartRAO 26M' / telescope
SURFACE = 'PANEL 103 MISSING' / telescope surface description
GAINFAC = 0.993 / relative to intact surface at upgrade start
SUBTILT = -0.77 / subreflector tilt, arbitrary units
SUBFOCUS= 8.00 / subreflector focus, arbitrary units
DICHROIC= 'OFF' / dichroic was off
FEEDTYPE= 'DIAGONAL' / circular, dual-mode feed
BMOFFHA = -0.472 / beam offset in hour angle, deg
BMOFFDC = 0.010 / beam offset in declination, deg
HPBW = 0.116 / halfpower beamwidth, deg
FNBW = 0.000 / first null beamwidth, deg (0 = unknown)
RFBANDHI= 6668.815710E6 / sky freq at video filt upper band edge, in Hz
RFBANDLO= 6668.175710E6 / sky freq at video filt lower band edge, in Hz
NOMTSYS = 45 / nominal zenith system temperature in Kelvins
INSTRUME= 'SPECTROMETER' / correlator
POL1 = 'LCP' / polarization of data for channel 1
POL2 = 'RCP' / polarization of data for channel 2
COMMENT information for calibrating the data
TCAL1 = 14.2 / Cal noise diode value for channel 1
TCAL2 = 14.2 / Cal noise diode value for channel 2
TCALERR1= 0.0 / uncertainty in Tcal1 is unknown
TCALERR2= 0.0 / uncertainty in Tcal2 is unknown
TCALFREQ= 6670E6 / frequency the calibration applies to, in Hz
TCALDATE= '1900-01-01' / calibration date, unknown
TCALUNIT= 'K' / units for cal noise diode values
CALPSS1 = 7.85 / Point source sens for channel 1, Jy/K
CALPSS2 = 7.85 / Point source sens for channel 2, Jy/K
CALPSSER= 0.125 / uncertainty in CALPSS
CALSRC = 'B0915-11' / object used for calibration
CALFLUX = 9.99 / total flux density assumed at CALFREQ, Jy
CALFREQ = 6670E6 / frequency the calibration applies to, in Hz
CALDATE = '1995-07-26' / calibration date
REFERENC= 'Ott et al. (1994) AA 284, 331.'
COMMENT information about the processing of the data
COMMENT need suffix 1 or 2 to differentiate between channels
ADDED = 1.0 / number of data sets averaged
FIRSTCH = 1 / first valid pixel in data
LASTCH = 256 / last valid pixel in data
POLYFIT = 1 / order of polynomial fit to baseline
FOLDED = 0 / =0 unfolded, =1 folded freq. sw.sp.
SMOOTHD = 0 / =0 unsmoothed =1 smoothed
TRANSFM = 0 / =0 spectrum =1 transform
ATMCOR = 1.0 / atmospheric atten. corr. applied
PNTCOR = 1.0 / pointing correction applied
GAINCOR = 0.0 / antenna gain correction applied
PSS = 0.0 / point source sensitivity applied in Jy/K
END / end of HDU
...at the start of a new FITS record is the binary table header...
XTENSION / start of binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-D table
NAXIS1 = 12 / bytes per row
NAXIS2 = 256 / number of rows
PCOUNT = 0 / number of bytes in extension data
GCOUNT = 1 / single table
TFIELDS = 1 / number of fields (columns)
COMMENT information about the data in the binary table
TFORM1 = 'E' / field = single precision floating point
TTYPE1 = 'VELO-LSR' / type
TUNIT1 = 'KM/S' / units
TDISP1 = 'E15.9' / recommended display format
TFORM2 = 'E' / field = single precision floating point
TTYPE2 = 'ANTENNA TEMP LCP' / type
TUNIT2 = 'K' / units
TDISP2 = 'E15.9' / recommended display format
TFORM3 = 'E' / field = single precision floating point
TTYPE3 = 'ANTENNA TEMP RCP' / type
TUNIT3 = 'K' / units
TDISP3 = 'E15.9' / recommended display format
END / end of binary table header
The header and extension are followed by the binary data table, all packed
in 2880-byte blocks.
This example is the output file from the first scan defined in the input file example for pulsar timing, monitoring the Vela pulsar.
This scan comprises a single observation, done with calibration.
The format again follows the FITS style.
SIMPLE = T / file does conform to FITS standard
BITPIX = 8 / not used - data not in primary data array
NAXIS = 0 / number of axes in data array
EXTEND = T / FITS dataset contains extensions
DATE = '1999-08-17T12:25:10'/ date of creation of this HDU, UT
COMMENT information about the object, from input file + catalogue
OBJECT = 'PSR0833-45' / Vela pulsar
EQUINOX = 1984.0 / FK4? FK5?
RA = 128.4138
DEC = -45.00286
PLPERIOD= 0.089323102747 / seconds
PLPDRV1 = 124.4496E-15 / seconds per second
PLPDRV2 = -230.OE-25 / seconds per second**2
PLDM = 67.321 / dispersion measure pccm-3
PLDMDRV = -0.05 / dispersion measure derivative pccm-3s-1
PLEPOCH = 2451041.21556 / pulsar ephemeris epoch in Julian days
PLPHASE = 1000 / set to deglitch, not latest value
PLTCONST= 150 / post-det time constant, microseconds
PLPINT = 500 / integrate 500 periods at 18cm/1650MHz
COMMENT information about the scan
OBSERVER= 'C. FLANAGAN' / observer's name
OBSLOCAL= 'A. CHUKWUDE' / local observer
PROJECT = daily monitoring of the Vela pulsar
PROPOSAL= 1999.007
DATE-OBS= '1999-08-17T12:13:14'/ UT at start of scan, Y2K-compliant
MJD-OBS = 51187.216818750 / Modified Julian date of start of scan
SCAN = '19990817121314' / scan number (identifier)
SCANTYPE= 'PULSAR' / type of observation
RESTFREQ= 1650E+06 / rest frequency in Hz
PLPBARY = 0.893303419401E-01 / current period, at barycentre, in seconds
PLPAPP = 0.893304195020E-01 / apparent period at epoch of obs, in seconds
PLFREQ = 0.878760067448E+04 / sampling freq = nsamples/Papp (NAXIS1/PLPAPP)
COMMENT the following are parameters measured during the scan
HA = -87.987 / HA at middle of scan, degrees
ALT = 15.305 / altitude (elevation) at middle of scan, deg
TCALCNT1= 13.374 / calibration, counts per Kelvin
DCALCNT1= 0.032 / uncertainty in calibration, counts per K
COMMENT information on the telescope and receiver configuration
TELESCOP= 'HartRAO 26M' / telescope
SURFACE = 'PANEL 1 MISSING' / telescope surface description
GAINFAC = 0.997 / relative to intact surface at upgrade start
SUBTILT = 9.70 / subreflector tilt, arbitrary units
SUBFOCUS= 5.00 / subreflector focus, arbitrary units
DICHROIC= 'OFF' / dichroic was off
FEEDTYPE= 'CIRCULAR' / circular, dual-mode feed
BMOFFHA = 0.096 / beam offset in hour angle, deg
BMOFFDC = -0.904 / beam offset in declination, deg
HPBW = 0.494 / halfpower beamwidth, deg
FNBW = 1.190 / first null beamwidth, deg
RFBANDHI= 1671E6 / 10MHz filter centred on 1666 MHz, in Hz
RFBANDLO= 1661E6 / 10MHz filter centred on 1666 MHz, in Hz
NOMTSYS = 35 / nominal zenith system temperature in Kelvins
INSTRUME= 'PULSARTIMER' / instrument
POL1 = 'LCP' / polarization of data for channel 1
COMMENT information for calibrating the data
TCAL1 = 6.2 / Cal noise diode value for channel 1
TCALERR1= 0.0 / uncertainty in Tcal1 is unknown
TCALFREQ= 1668E6 / frequency the calibration applies to, in Hz
TCALDATE= '1900-01-01' / unknown calibration date
TCALUNIT= 'K' / units for cal noise diode values
CALPSS1 = 5.13 / Point source sens for channel1, Jy/K
CALPSSER= 0.07 / uncertainty in CALPSS
CALSRC = 'B0915-11' / object used for calibration
CALFLUX = 36.45 / total flux density assumed at CALFREQ, Jy
CALFREQ = 1668E6 / frequency the calibration applies to, in Hz
CALDATE = '1995-07-26' / calibration date
REFERENC= 'Ott et al. (1994) AA 284, 331.'
COMMENT information about the processing of the data
ATMCOR = 1.0 / atmospheric atten. corr. applied
PNTCOR = 1.0 / pointing correction applied
GAINCOR = 1.0 / antenna gain correction applied
PSS = 0.0 / point source sensitivity applied in Jy/K
END / end of HDU
...at the start of a new FITS record is the binary table header...
XTENSION / start of binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-D table
NAXIS1 = 8 / bytes per row
NAXIS2 = 785 / number of rows
PCOUNT = 0 / number of bytes in extension data
GCOUNT = 1 / single table
TFIELDS = 1 / number of fields (columns)
COMMENT information about the data in the binary table
TFORM1 = 'E' / field = single precision floating point
TTYPE1 = 'PULSE PHASE' / type
TUNIT1 = 'PERIOD' / units
TDISP1 = 'E15.9' / recommended display format
TFORM2 = 'E' / field = single precision floating point
TTYPE2 = 'PULSE AMPLITUDE LCP' / type
TUNIT2 = 'COUNTS' / units
TDISP2 = 'E15.9' / recommended display format
END / end of housekeeping for data set
The header and extension are followed by the binary data table, all packed
in 2880-byte blocks.