Input file Option

In all XRONOS applications up to 10 INPUT FILE OPTIONS can be specified for each input file. Options are specified in the same string in which each input filename is given and consist of 2 characters followed, in most cases, by a numerical constant containing up to 8 characters. Most of the avaliable options given in the chapter Input File can be used also for FITS input file. New options are available to account the versatility of the FITS format. Those (valid only for FITS input file) allow : energy selection, extension table selection, columns selection. Below are listed : a) the subset of all the pre-existing options which meaning is also valid to the FITS input file structure; b) the new options valid only for a FITS input file; c) the list of those which are not applicable to FITS input file.

Any other options described in the chapter Input File and not listed here are still valid for FITS input file.

Group a)

• frN= start reading input file from record number N (First Record). If the input file is in FITS format, the option frN indicates the first row to start reading.
• lrN= stop reading input file at record number N (Last Record) If the input file is in FITS format, the option lrN indicates the last row to stop reading. (Options fr and lr are useful to speed up the reading of a very large input file, when only part of the input file has to be analysed. They effectively work as fast time windows. The correspondence of record number and time can be worked out based on the input file type. These options apply to Rate Buffers only)
• vxN= use vector number N as x-axis (i.e. time axis) in a QDP input file (a negative value of N means that X-axis will be stepped according to the content of the XRONOS header line in the QDP input file) If the input file is in FITS format, N gives the column number used as x-axis. By default the reader searches for x-axis, a column named TIME.
• vyN= use vector number N as y-axis (i.e. series to be analysed) in a QDP input file. If the input file is in FITS format, N gives the column number used as y-axis. By default the reader searches for y-axis, a column named COUNT or RATE.
• veN= use vector number N as bin exposure in a QDP input file (a negative value of N means that no exposure vector is specified even if the input file contains more than 2 vectors). If the input file is in FITS format, N gives the column number used as fractional exposure. By default the reader searches for a column named FRAC_EXP. The fractional exposure column needs to be in the same extension of the x-axis and y-axis. If the FITS file format is an EVENT list, exposure is by default calculated using the GTI extension. In the case of EVENT list N=0 turns off the usage of the GTI extension for the exposure calculation.

Group b)

• rtN= use extension N of the FITS file to read the data, where N =1 is the first extension in the FITS file (the primary array is irrelevant).
• ysN= use column number N as error for y-axis. By default the reader searches for y-axis error , a column named ERROR.
• feN= select binned counts or events from channel number N (First Energy). By default for an event list the channel selection is made on the column named PHA.
• leN= select binned counts or events up to channel number N (Last Energy). If feN is not specified all the counts or events up to channel leN are used. By default for an event list the channel selection is made on the column named PHA.
• vcN= use column number N as channel selection column. By default the reader searches for a column named PHA

The option bt, dn, dv, and fs, listed in the chapter Input File, are not relevant for FITS file format, but applicable only for rate buffer format input file.