X-BACH (Extended Basic Accelerated C++ HOTPANTS) is an astronomical image subtraction software created by Gustav Arneving and Hugo Wilhelmsson, as part of a master's thesis conducted at MindRoad Öst AB. It is based on BACH, an earlier master's thesis by Annie Wång and Victor Lells.
X-BACH is a parallelization of the popular image subtraction tool HOTPANTS, rewritten in C++, and using OpenCL for task acceleration. It operates on two FITS images, one called science and one called template, generates a difference image by subtraction. The purpose of X-BACH was to explore the parallelization potential of non-trivial parallelizable tasks in the HOTPANTS algorithm and check how it would perform.
See here.
The usage of X-BACH is highlighted below:
BACH -t <template image name> -s <science image name>
X-BACH also supports some optional arguments. These arguments are presented below:
-o <convolved output name>
: name of the convolved output FITS image. Defaults todiff.fits
.-op <output path>
: name of the output folder, where the output images will be stored. Defaults toout/
.-ip <input path>
: name of the input folder, where the input images are located. Defaults tores/
.-v
: turns on verbose mode.-vt
: prints execution time.
For instance, if the input files are stored in C:\in
, called science.fits
and template.fits
, and the output files would be written to C:\out
, the following command would be used:
BACH -t template.fits -s science.fits -ip "C:\in\" -op "C:\out\"
This would generate two files, diff.fits
(convolved image) and sub.fits
(subtracted image) in C:\out
.
- Input and output path arguments are glitchy. Always put '/' (or '\') at the end of the path.
- Non-deterministic behaviour is observed between computers in some rare test cases.