# da_fits_warp
Aim: Warp catalogues and images to remove the distorting affect of the ionosphere. This version uses Dask arrays to handle code parallelisation.
Authors: Natasha Hurley-Walker, Paul Hancock, Tim Galvin
## Usage
```
usage: da_fits_warp [-h] [--xm XM] [--infits INFITS] [--suffix SUFFIX] [--ra1 RA1] [--dec1 DEC1] [--ra2 RA2] [--dec2 DEC2] [--plot] [-c CORES] [--overlap-factor OVERLAP_FACTOR]
[--testimage] [--smooth SMOOTH] [--signal SIGCOL] [--noise NOISECOL] [--SNR SNR] [--nsrcs NSRCS] [--enforce-min-srcs ENFORCE_MIN_SRCS] [-v] [--incat INCAT]
[--refcat REFCAT] [--xmcat XM] [--corrected CORRECTED] [--cite]
options:
-h, --help show this help message and exit
Warping input/output files:
--xm XM A .fits binary or VO table. The crossmatch between the reference and source catalogue.
--infits INFITS The fits image(s) to be corrected; enclose in quotes for globbing.
--suffix SUFFIX The suffix to append to rename the output (corrected) fits image(s); e.g., specifying "warp" will result in an image like image_warp.fits (no default; if not
supplied, no correction will be performed).
catalog column names:
--ra1 RA1 The column name for ra (degrees) for source catalogue.
--dec1 DEC1 The column name for dec (degrees) for source catalogue.
--ra2 RA2 The column name for ra (degrees) for reference catalogue.
--dec2 DEC2 The column name for dec (degrees) for reference catalogue.
Other:
--plot Plot the offsets and models (default = False)
-c CORES, --cores CORES
Number of cores to instruct dask to use throughout processing
--overlap-factor OVERLAP_FACTOR
Factor mulptipled against size of fastest moving image axis to determine the number of pixels from neighbouring sub-blocks to include in image interpolation. To
small and artefacts can be introduced.
--testimage Generate pixel-by-pixel delta_x, delta_y, and divergence maps (default = False)
--smooth SMOOTH Smoothness parameter to give to the radial basis function (default = 300 pix)
--signal SIGCOL Column from which to get the signal for a signal-to-noise cut (e.g. peak_flux) (no default; if not supplied, cut will not be performed
--noise NOISECOL Column from which to get the noise for a signal-to-noise cut (e.g. local_rms) (no default; if not supplied, cut will not be performed
--SNR SNR Signal-to-noise ratio for a signal-to-noise cut (default = 10)
--nsrcs NSRCS Maximum number of sources used when constructing the distortion model. Default behaviour will use all available matches.
--enforce-min-srcs ENFORCE_MIN_SRCS
An exception is raised if there are fewer than this many cross-matched sources located in the internal cross-match procedure.
-v, --verbose Provide extra logging throughout the procedure
Crossmatching input/output files:
--incat INCAT Input catalogue to be warped.
--refcat REFCAT Input catalogue to be warped.
--xmcat XM Output cross match catalogue
--corrected CORRECTED
Output corrected version of input catalogue
Information:
--cite Print citation in BibTeX format.
```
## Bugs/Questions
Please use the GitHub issue tracker to submit bug reports, feature requests, or questions.
## Credit
If you use fits_warp in your work please Cite [Hurley-Walker and Hancock 2018](http://adsabs.harvard.edu/abs/2018A%26C....25...94H).
This `da_fits_warp` is an update to the original [`fits_warp`](https://github.com/nhurleywalker/fits_warp) implementation, with the most major change being the use of `dask` to handle parallelism.