Characteristics of the L7- 240 model:

Excess variance: < 0.1 ct/sec (2 -10 keV)
Excess variance: < 0.1 ct/sec (10-20 keV)

Reliable spectral subtraction for energies where net signal is > 0.01 ct/sec/keV

Applicability:
Examples:
MCG 2-58-22 is an ~ 1 mCrab source (2-10 keV count rate = 10 ct/sec/3 PCU).
Data and background model for MCG 2-58-22
Data minus background model for MCG 2-58-22


Blank sky: ~ 2 days from a recent nearly continuous observation
Rates showing Raw rate, background model, and net rate
Power Spectrum using the Lomb algorithm from Press et al.; note that there is some residual power at daily (frequency ~ 10e-5) and orbital (frequency ~ 1.7e-4) time scales.



USAGE NOTES: (added 8-28-98)

Use the L7/240 background models for data with Source counting rate < 40 ct/s/PCU, and make .gti files by using MAKETIME on your XTE filter file with the following selection expressions:

These filter files may be entered in your SAEXTRCT runs by writing their names to an ASCII file (e.g. 'gti.files') and entering "@gtifilenames" at the GTIANDFILE prompt. See the GOF recipes or contact xtehelp@athena if the meaning of these selections is not clear.