spi_add_sim allows to add a simulated source into a real observation analysis. A source position and flux must be given as input parameters. spi_add_sim uses the IRF response to compute the detector counts expected for this source, and adds the counts to the data set. This program is useful to investigate crowding effects, by comparing outputs with inputs for the added source(s) in the presence of other real sources.
This program must be used as part of the ISDC pipeline as it needs an OG group with all the relevant information, such as the pointing pattern, the detector list etc. It also does not create any new data structure, but it add counts to the detector spectra data structure (SPI.-OBS.-DSP), updating this file.
At the moment only one source can be added at one time. However, several sources can be added just by running the program several times.
The program works only if the (image) analysis is carried out in one energy bin only. If there is more than one energy bin, spi_add_sim does not do anything, and the detector spectra will not be changed!