cplinear: a non-physical piecewise-linear model for low count background spectra.

This is a simple non-physical model for low-count background spectra, used by fitting scripts in the ACIS Extract (AE) package. Using this model outside the context of the AE package should be done with extreme caution since it requires a choice on vertex energies and number of segments. AE places the first and last vertices at the lowest and highest energy of the background counts. Intermediate vertices are placed at energies where a background count exists such that each segment covers a similar number of background counts. Any results using this model should cite Broos et al. (2010).

Note that if all the rate parameters in use are thawed then the norm parameter is degenerate and must be frozen. Freezing one of the rate parameters will not work because if that vertex is driven to zero in the fit then the norm will be zero and the other rate parameters infinite.

par1	energy00 (keV)
par2	energy01 (keV)
par3	energy02 (keV)
par4	energy03 (keV)
par5	energy04 (keV)
par6	energy05 (keV)
par7	energy06 (keV)
par8	energy07 (keV)
par9	energy08 (keV)
par10	energy09 (keV)
par11	log_rate00
par12	log_rate01
par13	log_rate02
par14	log_rate03
par15	log_rate04
par16	log_rate05
par17	log_rate06
par18	log_rate07
par19	log_rate08
par10	log_rate09
norm

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Last modified: Friday, 23-Aug-2024 13:20:40 EDT