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Text in red shows what was adopted for the revised draft presented further below.
Jump to the comments added in addition to the issues.
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I stuck with integral fluxes, for >100 MeV, >300 MeV, >1 GeV, and >3 GeV
energy ranges, with uncertainties included for each flux. This will still be useful for finding unusual spectra.
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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 |
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(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)
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- 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)
Answers to Seth by Isabelle:
- the name precision is guided by the source localization precision rather than by source separation to allow comparison with other catalogues.
- given the IAU guidelines and the brightest LAT sources localization down to a fraction of an arcminute, the only possible naming scheme in R.A and Dec is 1GL JHHMMSS.s-DDMMSS. IAU does not want decimals before the arcsecond and time second levels, nor decimal degrees in R.A. and Dec (1GL JDDD.ddd-DDD.ddd) even though it is much easier for your brain to grasp and memorize.
- Practice from INTEGRAL and HESS sources tells that 1GL JHHMMSS.s-DDMMSS names are extremely difficult to memorize and use efficiently. One gets lost only after a few sources, especially if they are closeby. For instance, try to memorize NGC4151 = J121032.6+392420 for a few days!
- One can use decimal degrees in Galactic coordinates, which would lead to 1GL GLLL.lll-BB.bbb and your brain will round the number up to help your memory. The COS-B catalogue was in Galactic coordinates. Yet, quasars (that will dominate the LAT catalogue) are usually in R.A. and Dec. So, what do we choose ?
- We can use 1GL, 1GLA, or 1LAT acronyms as long as it is longer or equal to 3 letters.
16. Galactic coordinates (25 July 2007)
Isabelle asks if we should include Galactic coordinates in the catalog. Sounds reasonable, right?
To compare source positions and lock different frames in ds9 to compare counterpart positions, we need Galactic coordinates as well as R.A. and Dec !Isabelle asks if we should include Galactic coordinates in the catalog. Sounds reasonable, right?
17. Technical issues in generating the catalog (25 July 2007)
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