Here we demonstrate how to extract an image over various energy bands. The PC data from the first observation of GRB 091029 are used as an example.
>xselect ** XSELECT V2.2a ** > Enter session name >[xsel] xsel:ASCA >read event > Enter the Event file dir >[./] > Enter Event file list >[ ] sw00374210000xpcw3po_cl.evt Got new mission: SWIFT > Reset the mission ? >[yes] Notes: XSELECT set up for SWIFT Time keyword is TIME in units of s Default timing binsize = 5.0000 Setting... Image keywords = X Y with binning = 1 WMAP keywords = X Y with binning = 1 Energy keywords = PI with binning = 1 Getting Min and Max for Energy Column... Got min and max for PI: 0 1023 Got the minimum time resolution of the read data: 2.5073 MJDREF = 5.1910000742870E+04 with TIMESYS = TT Number of files read in: 1 ******************** Observation Catalogue ******************** Data Directory is: /home/work/kpa/2009/grb091029/00374210000-xrt/ HK Directory is: /home/work/kpa/2009/grb091029/00374210000-xrt/ OBJECT OBS_ID DATE-OBS DATAMODE
1 GRB091029 ( 00374210991 2009-10-29T PHOTON > extract image extractor v5.11 11 May 2009 Getting FITS WCS Keywords Doing file: /home/work/kpa/2009/grb091029/00374210000-xrt/sw00374210000xpcw3po_cl.evt 100% completed Total Good Bad: Time Phase Grade Cut 5858 5858 0 0 0 0 =============================================================================== Grand Total Good Bad: Time Phase Grade Cut 5858 5858 0 0 0 0 in 15790. seconds Image has 5858 counts for 0.3710 counts/sec > plot image
The image above was extracted for the full energy range of the XRT: about 0.2-10 keV. However, the data can be filtered to produce images over any energy band within this range, using the command
filter pha_cutoff, where the range must be given in terms of channels. For the XRT, 1 channel = 10 eV.
> filter pha_cutoff 30 100 > extract image > save image 0.3-1keV.im > clear pha_cutoff > filter pha_cutoff 100 1000 > extract image > save im 1-10keV.im
The commands above extract and save images over soft (0.3-1 keV) and hard (1-10 keV) bands for the full field of view. Filtering on regions and time can also be performed, as explained in the Introduction to XSELECT thread.