...
(Digel) It has gone unspecified until now, but the fluxes and flux history values described above are assumed to apply for the entire time range of the catalog (or of the time interval for a flux history evaluation). The catalog also includes Flux_Peak, Unc_peak_Flux, Signif_Peak, Time_Peak, and Peak_Interval to allow for specification of properties of flaring sources that we see only once for a short period of time. Defining significances for a specific time interval may be problematic, as the time interval has been selected to be when the detection significance is greatest.Anchor
12. Source names (25 July 2007)
Is the 1GL J123456-012345 naming scheme what we want to use? (1GL indicating first version of GLAST LAT catalog)
- Is fewer digits of precision acceptable? Probably, I think. So, a name like 1GL J123456-0123 should be enough precision
- Isabelle has suggested that we might be able to use decimal degrees in the names. These would be RA, Dec, but I'm not sure of the format, maybe something like 1GL J305.3-10.6, Wor perhaps just decimal minutes of time, e.g., 1GL J1234.5-0123.
Draft header (Last update: 30 December 2005)
Here is the FITS version of the first extension header of the FITS version of the catalog, with the changes specified above and in the comments section below incorporated.
Draft header (Last update: 30 December 2005)
Here is the FITS version of the first extension header of the FITS version of the catalog, with the changes specified above and in the comments section below incorporated.
| No Format |
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XTENSION = 'BINTABLE' |
| No Format |
XTENSION = 'BINTABLE' / binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-dimensional binary table
PCOUNT = 0 / size of special data area
GCOUNT = 1 / one data group (required keyword)
TFIELDS = 34 / number of fields in each row
CHECKSUM = / checksum for entire HDU
DATASUM = / checksum for data table
TELESCOP = 'GLAST' / name of telescope generating data
INSTRUME = 'LAT' / name of instrument generating data
EQUINOX = 2000.0 / equinox for ra and dec
RADECSYS = 'FK5' / world coord. system for this file (FK5 or FK4)
EXTNAME = 'LAT_Point_Source_Catalog' / name of this binary table extension
HDUCLASS = 'OGIP' / format conforms to OGIP standard
HDUCLAS1 = 'EVENTS' / extension contains events
HDUCLAS2 = 'ALL' / extension contains all events detected
TSTART = / mission time of the start of the observation
TSTOP = / mission time of the end of the observation
TIMEUNIT = 'd' / units for the time related keywords
TIMEZERO = 0.0 / clock correction
TIMESYS = 'MJD' / type of time system that is used
TIMEREF = 'LOCAL' / reference frame used for times
DATE = / file creation date (YYYY-MM-DDThh:mm:ss UT)
DATE-OBS = / start date and time of the observation (UTC)
DATE-END = / end date and time of the observation (UTC)
NDSKEYS = 0 / number of data subspace keywords in header
HDUCLASS = 'OGIP ' / format conforms to OGIP standard
HDUDOC = '?' / document describing the format
HDUVERS = '1.0.0 ' / version of the format
HDUCLAS1 = 'SRCLIST' / an OGIP standard class
TTYPE1 = 'Source_Name' / e.g., 1GL J123456-012345
TFORM1 = '18A ' / character string
TUNIT1 = 'none' / units of field
TTYPE2 = 'RA' / right ascension of source
TFORM2 = 'E' / floating point
TUNIT2 = 'deg' / units of field
TLMIN2 = 0.0 / minimum value
TLMAX2 = 360.0 / maximum value
TTYPE3 = 'DEC' / declination of source
TFORM3 = 'E' / floating point
TUNIT3 = 'deg' / units of field
TLMIN3 = -90.0 / minimum value
TLMAX3 = 90.0 / maximum value
TTYPE4 = 'Conf_68_SemiMajor' / semimajor axis, 68% containment confidence region
TFORM4 = 'E' / floating point
TUNIT4 = 'deg' / units of field
TLMIN4 = 0.0 / minimum value
TLMAX4 = 360.0 / maximum value
TTYPE5 = 'Conf_68_SemiMinor' / semiminor, axis, 68% containment confidence region
TFORM5 = 'E' / floating point
TUNIT5 = 'deg' / units of field
TLMIN5 = 0.0 / minimum value
TLMAX5 = 360.0 / maximum value
TTYPE6 = 'Conf_68_PosAng' / position angle, 68% containment confidence region, E of N
TFORM6 = 'E' / floating point
TUNIT6 = 'deg' / units of field
TLMIN6 = 0.0 / minimum value
TLMAX6 = 360.0 / maximum value
TTYPE7 = 'Conf_95_SemiMajor' / semimajor axis, 95% containment confidence region
TFORM7 = 'E' / floating point
TUNIT7 = 'deg' / units of field
TLMIN7 = 0.0 / minimum value
TLMAX7 = 360.0 / maximum value
TTYPE8 = 'Conf_95_SemiMinor' / semiminor, axis, 95% containment confidence region
TFORM8 = 'E' / floating point
TUNIT8 = 'deg' / units of field
TLMIN8 = 0.0 / minimum value
TLMAX8 = 360.0 / maximum value
TTYPE9 = 'Conf_95_PosAng' / position angle, 95% containment confidence region, E of N
TFORM9 = 'E' / floating point
TUNIT9 = 'deg' / units of field
TLMIN9 = 0.0 / minimum value
TLMAX9 = 360.0 / maximum value
TTYPE10 = 'Flux100' / average photon flux >100 MeV
TFORM10 = 'E' / floating point
TUNIT10 = 'cm**(-2) s**(-1)' / units of field
TLMIN10 = 0.0 / minimum value
TLMAX10 = 1.0 / maximum value
TTYPE11 = 'Unc_Flux100' / uncertainty (1-sigma) in average flux >100 MeV
TFORM11 = 'E' / floating point
TUNIT11 = 'cm**(-2) s**(-1)' / units of field
TLMIN11 = 0.0 / minimum value
TLMAX11 = 1.0 / maximum value
TTYPE12 = 'Flux30_100' / average photon flux 30-100 MeV
TFORM12 = 'E' / floating point
TUNIT12 = 'cm**(-2) s**(-1)' / units of field
TLMIN12 = 0.0 / minimum value
TLMAX12 = 1.0 / maximum value
TTYPE13 = 'Unc_Flux30_100' / uncertainty (1-sigma) in average flux 30-100 MeV
TFORM13 = 'E' / floating point
TUNIT13 = 'cm**(-2) s**(-1)' / units of field
TLMIN13 = 0.0 / minimum value
TLMAX13 = 1.0 / maximum value
TTYPE14 = 'Flux100_300' / average photon flux 100-300 MeV
TFORM14 = 'E' / floating point
TUNIT14 = 'cm**(-2) s**(-1)' / units of field
TLMIN14 = 0.0 / minimum value
TLMAX14 = 1.0 / maximum value
TTYPE15 = 'Unc_Flux100_300' / uncertainty (1-sigma) in average flux 100-300 MeV
TFORM15 = 'E' / floating point
TUNIT15 = 'cm**(-2) s**(-1)' / units of field
TLMIN15 = 0.0 / minimum value
TLMAX15 = 1.0 / maximum value
TTYPE16 = 'Flux300_1000' / average photon flux 300-1000 MeV
TFORM16 = 'E' / floating point
TUNIT16 = 'cm**(-2) s**(-1)' / units of field
TLMIN16 = 0.0 / minimum value
TLMAX16 = 1.0 / maximum value
TTYPE17 = 'Unc_Flux300_1000' / uncertainty (1-sigma) in average flux 300-1000 MeV
TFORM17 = 'E' / floating point
TUNIT17 = 'cm**(-2) s**(-1)' / units of field
TLMIN17 = 0.0 / minimum value
TLMAX17 = 1.0 / maximum value
TTYPE18 = 'Flux3000' / average photon flux >3000 MeV
TFORM18 = 'E' / floating point
TUNIT18 = 'cm**(-2) s**(-1)' / units of field
TLMIN18 = 0.0 / minimum value
TLMAX18 = 1.0 / maximum value
TTYPE19 = 'Unc_Flux3000' / uncertainty (1-sigma) in average flux >3000 MeV
TFORM19 = 'E' / floating point
TUNIT19 = 'cm**(-2) s**(-1)' / units of field
TLMIN19 = 0.0 / minimum value
TLMAX19 = 1.0 / maximum value
TTYPE20 = 'Spectral_Index' / photon spectral index, >100 MeV
TFORM20 = 'E' / floating point
TUNIT20 = 'none' / dimensionless
TLMIN20 = -10.0 / minimum value
TLMAX20 = 10.0 / maximum value
TTYPE21 = 'Unc_Spectral_Index' / 1-sigma uncertainty, photon spectral index
TFORM21 = 'E' / floating point
TUNIT21 = 'none' / dimensionless
TLMIN21 = 0.0 / minimum value
TLMAX21 = 10.0 / maximum value
TTYPE22 = 'Variability_Index' / flux variability index (TBD)
TFORM22 = 'E' / floating point
TUNIT22 = 'none' / dimensionless
TLMIN22 = ### / minimum value (TBD)
TLMAX22 = ### / maximum value (TBD)
TTYPE23 ='Signif_Avg' / detection significance (whole time interval)
TFORM23 = 'E' / floating point
TUNIT23 = 'none' / dimensionless (sigmas)
TLMIN23 = 0.0 / minimum value
TLMAX23 = 1.0E9 / maximum value
TTYPE24 = 'Signif_Peak' / detection significance (peak)
TFORM24 = 'E' / floating point
TUNIT24 = 'none' / dimensionless (sigmas)
TLMIN24 = 0.0 / minimum value
TLMAX24 = 1.0E9 / maximum value
TTYPE25 = 'Flux_Peak' / peak flux (>100 MeV) for time interval above
TFORM25 = 'E' / floating point
TUNIT25 = 'cm**(-2) s**(-1)'
TLMIN25 = 0.0 / minimum value
TLMAX25 = 1.0 / maximum value
TTYPE26 = 'Unc_Peak_Flux' / uncertainty (1-sigma) in peak flux >100 MeV
TFORM26 = 'E' / floating point
TUNIT26 = 'cm**(-2) s**(-1)' / units of field
TLMIN26 = 0.0 / minimum value
TLMAX26 = 1.0 / maximum value
TTYPE27 = 'Time_Peak' / center of time interval of peak significance
TFORM27 = 'D' / double precision
TUNIT27 = 'd' / units of field
TLMIN27 = 0.0 / minimum value
TLMAX27 = 1.0D5 / maximum value
TTYPE28 = 'Peak_Interval' / duration of time interval of peak significance
TFORM28 = 'D' / double precision
TUNIT28 = 's' / units of field
TLMIN28 = 0.0 / minimum value
TLMAX28 = 3.0D7 / maximum value
TTYPE29 = 'Flux_History' / flux (>100 MeV) history (monthly)
TFORM29 = '12E' / floating point array, 12 months (number TBR)
TUNIT29 = 'cm**(-2) s**(-1)' / units of field
TLMIN29 = 0.0 / minimum value
TLMAX29 = 1.0 / maximum value
TTYPE30 = 'Flux_Unc_History' / flux uncertainty (1-sigma, >100 MeV) history
TFORM30 = '12E' / floating point array, 12 months (number TBR)
TUNIT30 = 'cm**(-2) s**(-1)' / units of field
TLMIN30 = 0.0 / minimum value
TLMAX30 = 1.0 / maximum value
TTYPE31 = 'Hist_Start' / start of time intervals of flux history
TFORM31 = '12E' / floating point array, 12 months (number TBR)
TUNIT31 = 'd' / units of field
TLMIN31 = 0.0 / minimum value
TLMAX31 = 1.0D5 / maximum value
TTYPE32 = 'ID_Counterpart' / source counterpart (if any)
TFORM32 = '20A' / character string
TUNIT32 = 'none' / dimensionless
TTYPE33 = 'Conf_Counterpart' / confidence of association of counterpart with source
TFORM33 = 'I' / index, 1 = Figure of Merit, 2 = Correlated variability
TUNIT33 = 'none' / dimensionless
TLMIN33 = 0 / minimum value
TLMAX33 = 2 / maximum value
TTYPE34 = 'Flags' / flags (TBD) for catalog entry
TFORM34 = 'I' / integer
TUNIT34 = 'none' / dimensionless
END
|
...
(Jurgen) It could be reasonable to change the column names to more generic names (i.e. names that are also used in many other catalogues). For example, instead of RA and DEC we may use RAJ2000 and DECJ2000 (for galactic coordinates it would be GLON and GLAT). Uncertanties are often named "e_XXXX" so instead of "Unc_Flux100" we may use "e_Flux100".
Maybe we should submit our column naming proposal to CDS or HEASARC to get their opinion about our choices. This may help to create more conventional naming conventions ...
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Additional issues (starting 25 July 2007)
15. Source names (25 July 2007)
Is the 1GL J123456-012345 naming scheme what we want to use? (1GL indicating first version of GLAST LAT catalog)
- Is fewer digits of precision acceptable? Probably, I think. So, a name like 1GL J123456-0123 should be enough precision
- Isabelle has suggested that we might be able to use decimal degrees in the names. These would be RA, Dec, but I'm not sure of the format, maybe something like 1GL J305.3-10.6, Wor perhaps just decimal minutes of time, e.g., 1GL J1234.5-0123. This would allow at worst 0.025 deg precision in the naming of a source. We don't expect to have sources closer together than that.
16. Galactic coordinates (25 July 2007)
Isabelle asks if we should include Galactic coordinates in the catalog. Sounds reasonable, right?
17. Technical issues in generating the catalog (25 July 2007)
These are from Isabelle:
- are we able to give ellipses for the 1st release?
- are we able to deliver a 30-100 MeV flux for all sources?
- we cannot fill the flux monthly history for sources that are just significant over one year. So we need to define what TS threshold allows to measure monthly lightcurves above 100 MeV. The vast majority of the sources, being too faint, won't have lightcurves.