BBXRT Software

artist concept of BBXRT in the Shuttle bay in flight
The analysis of the data products and the raw data in FITS format can be performed using the XANADU and FTOOLS suite of programs.
Public domain software can be used to view the GIF files (e.g. xv on UNIX or directly the Netscape browser on any system PC and MAC).

* General Fits file manipulation : The FTOOLS package, futils , provides a suite of programs that can be used to view and manipulate any of the BBXRT archive files. To view the data particularly useful are the tasks fplot (to plot the data), fdump (to dump the data file content), fstruct and flcol (to get the structure and column name of the FITS files). Basic selection and column manipulation can be done using fselect (to select rows based on the result of a boolean expression), fcalc (to calculate values for new column based on arithmetic expression) and fstatistic (to compute standard statistical value on a column). Alternatively most of the operations (and more) mention above can be done using fv , the interactive FITS file viewer and editor.

* Spectra and Lightcurves : Spectra and lightcurves can be analyzed using Xspec and Xronos respectively. Xspec is a general spectral fitting programs, providing a number of already made standard models. To use XSPEC with the BBXRT archive files, it is necessary to extract from the archive a source and background spectrum and a response matrix.
The BBXRT lightcurves can be used in any of the Xronos programs, each dedicated to a specific timing task.

* Raw files : The average spectra and lightcurves are adequate products for many type of studies. However for specific study (for example spectral variation with source intensity) spectra (and/or lightcurves) need to be re-extracted from the raw data file, the events file. The basic program to use is Xselect . This extracts spectra and lightcurves setting basic filtering on time, phase intensity, energy and region.
Before entering Xselect data cleaning and detector (pixels) selection can be done using fselect . Basic cleaning is obtained using the following expression
VLE==0 && GUARD==0 && LED==0 && PTP==0 && PPU==0
where VLE, GUARD, LED, PTP, PPU are columns in the BBXRT event file. Pixel or detector selection is done instead using the column DETECTOR, where the A detector is identified by the value 1-5 (1=A0,2=A1,..,5=A4) and the B by 6-10 (6=B0,.., 10=B). Example: create a clean event file for the pixel A0:

Name of FITS file and [ext#][] cygx1i.evt
Name of output FITS file[] clean.evt
Selection Expression[] LED == 0 && GUARD == 0 && VLE == 0 && PTP == 0 && PPU == 0 && detector == 1

The output file, containing only good data, can be input in Xselect

* BBXRT Analysis issues : The Legacy article on BBXRT describes a number of calibration and analysis issues related with the BBXRT data. In particular the following topics are discussed:

The instrument calibration is discussed in the Weaver, K.A. et al , ApJS, 1995, 96 30.

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Page authors: Lorella Angelini Jesse Allen
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Last modified: Monday, 20-Apr-2020 15:46:18 EDT