This program is part of Netpbm. sirtopnm reads a Solitaire Image Recorder file as input and produces a PNM image as output. The type of the output file depends on the input file - if it's an MGI TYPE 17 file, sirtopnm generates a PGM file. If it's an MGI TYPE 11 file, sirtopnm generates PPM. The program tells you which type it is writing.
There are no command line options defined specifically for sirtopnm, but it recognizes the options common to all programs based on libnetpbm (See Common Options.)