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Note that this page, originally written in early 2005, is out of date and is not being maintained. For current, complete specifications of the sources that are available to gtobssim see the Science Tools section of the User Workbook, under the 'Observation Simulation' link. |
Notes on Sources
Here are some notes about using the gamma-ray sources that are available for use with obsSim.
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- source flux (photons m -2 s -1 above 100 MeV integrated over [ Emin,Emax ])
- photon spectral index for a power-law spectrum
- start time (in s)
- stop time (in s) for the flare (both measured with respect to whatever the 0 of time is
- name of the file that has the flare profile
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- Emin (MeV) for the energy range of the gamma rays
- Emax (MeV)
NOTE: The last two arguments are optional; the values for the limits default to 30 MeV and 1e5 MeV if not and Emax (MeV). The gamma rays will be generated within the energy range \[Emin, Emax\]. The values for the limits default to 30 MeV and 1e5 MeV if not specified.
The file (item 5 above) contains two columns, time and flux. They are BOTH RESCALED; the time column is scaled to match the start and stop times specified in the XML file and the flux entries are scaled so that the MEAN flux is the same as specified in the XML file. transient_profile.dat is available here. The profile rises linearly from 0 for the first 1/3rd of the time, plateaus for the next 1/3rd, and then falls linearly to 0 again in the final 1/3rd of the time interval.
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| Code Block |
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<source name="spectral_transient">
<spectrum escale="MeV">
<!--
mean flux = 0.1 (1e4/m^2/s) integrated over [emin,emax]
start time = 0 (MET s)
stop time = 1e4 (MET s)
template file name = $(GENERICSOURCESROOT)/data/testTemplate.dat
emin = 20 (MeV, this is the default)
emax = 2e5 (MeV, default)
lc # (in FITS file) = 0 (default)
z (redshift) = 0 (default)
--!>
<SpectrumClass name="SpectralTransient"
params="1e-1, 0., 1e4, $(GENERICSOURCESROOT)/data/testTemplate.dat, 20, 2e5, 0, 0"/>
<celestial_dir ra="193.4" dec="-5.82"/>
</spectrum>
</source>
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The units of the FITS cube are differential intensity (e.g., photons cm^-2 s^-1 MeV^1 sr^-1), although the integral value is renormalized by whatever total photon flux is specified in the specification of the source.
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