National Aeronautics and Space Administration

BBXRT Software

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:

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 Point Spread Function and the Mask
• The Detector Background
• Background Subtraction
• Detector Alignment
• The Off-axis angle; Matrices and Aspect Solutions
• Microphonics
• Timing information
• Discriminator Thresholds
• Deadtime
• Co-adding pixels
• The Detector Response