Scripts Package:
Version History

These scripts are designed to reproject and merge observations, with the option of creating exposure-corrected images of the combined data. The merge_obs and reproject_obs scripts replace the merge_all script, depending on whether or not you want the exposure-corrected image(s).

See:

• Using merge_obs to combine observations and create exposure-corrected images
• Merging Data from Multiple Imaging Observations
• Making an exposure-corrected mosaic

The script has seen numerous improvements including: a simplified user interface (you can now supply just the input and output files); the output file names have been renamed; support for spectral weights file; is is now possible to create exposure maps with units of time; the run-time has been reduced when large bin sizes are used; the background subtraction done with HRC-I data can be turned off; and several minor bug fixes for handling gzipped data and grating observations.

See:

• Exposure-corrected image (single ACIS chip)
• Exposure-corrected image (multiple ACIS chips)
• Exposure-corrected image (HRC-I)
• Exposure-corrected image (HRC-S)

A collection of color look-up tables has been added to $ASCDS_CONTRIB/data/ and available via the imagej and ximage parameter files. These files can be used in ds9 or ChIPS (image thread or colormap gallery example).

See:

• The default value of the check_vf_pha parameter has been changed from yes to no, so that the ACIS VFAINT background-filtering step will no longer be applied to relevant data sets by default. This change was made because the VFAINT filtering is known to remove valid events for sources bright enough to be affected by pile up.

• The auxilliary files - such as bad-pixel, mask, aspect solution - are now copied when the file system does not support soft links. In earlier versions the script would exit with an error in this case.

Stack files can now be used for the obsids and filetypes arguments. So, if

unix% cat obsids.lis
1234
1235
4356

then you can download these obsids by saying

unix% download_chandra_obsid @obsids.lis

The module contains the imextent routine for creating linear 2D transforms for an image. These can then be used in add_image calls to display the image.

This script lets you search the publicly-available Chandra observations by position (RA and Dec, J2000) or name (using the CADC name resolver). It is a command-line wrapper for the Chandra Footprint Service.

A list of matching observations, including relevant information is returned, or the data can be directly downloaded from the archive. Examples:

unix% find_chandra_obsid 'ngc 1333'
unix% find_chandra_obsid 12:45:32 -32:30:10
unix% find_chandra_obsid 350.86 58.81 download=ask 

• works around a bug in addresp (no TLMIN4 keyword in the output RMF file) so that combined RMF files can be used in Sherpa and X-Spec;
• minor improvements to the handling of temporary files.

• now supports setting badpixfile=NONE if you wish to create an exposure map with no bad pixels;
• all temporary files are now created in the directory given by the tmpdir parameter, so that the script can now be run from a directory in which you do not have write permission;

• a COMMENT line is added to the headers of the files listing the version of the script that was run (to aid in provenance tracking); for instance:

  unix% dmlist 0.5-7.0_2.3_bin8_flux.img header,clean,raw | grep COMMENT | grep fluximage 
  COMMENT      =  fluximage version 14 February 2012 /                     
  

Two Python modules have been added to support some common coordinate tasks:

• coords.resolver provides simple access to the CADC name resolver;
• coords.format converts between many sexadecimal and decimal degree formats for Right Ascension and Declination values.

• make_image_crate
• add_colvals
• add_keyval

The make_image_crate and write_columns routines now accept dictionaries or structured arrays as input, and will convert arrays of np.int32 values to np.int64 to work around a CRATES bug.