# FITSCUBE
From the [wsclean](https://wsclean.readthedocs.io/) docs:
> WSClean does not output these images in a normal “imaging cube” like CASA does, i.e., a single fits file with several images in it. For now I’ve decided not to implement this (one of the reasons for this is that information about the synthesized beam is not properly stored in a multi-frequency fits file). One has of course the option to combine the output manually, e.g. with a simple Python script.
This is a simple Python script to combine (single-frequency or single-Stokes) FITS images manually.
Current assumptions:
- All files have the same WCS
- All files have the same shape / pixel grid
- Frequency is either a WCS axis or in the REFFREQ header keyword
- All the relevant information is in the first header of the first image
## Installation
Install from PyPI (stable):
```
pip install fitscube
```
Or, onstall from this git repo (latest):
```bash
pip install git+https://github.com/AlecThomson/fitscube.git
```
## Usage
Command line:
```bash
fitscube -h
# usage: fitscube [-h] [-o] [--freq-file FREQ_FILE | --freqs FREQS [FREQS ...] | --ignore-freq] file_list [file_list ...] out_cube
# Fitscube: Combine single-frequency FITS files into a cube. Assumes: - All files have the same WCS - All files have the same shape / pixel grid -
# Frequency is either a WCS axis or in the REFFREQ header keyword - All the relevant information is in the first header of the first image
# positional arguments:
# file_list List of FITS files to combine (in frequency order)
# out_cube Output FITS file
# optional arguments:
# -h, --help show this help message and exit
# -o, --overwrite Overwrite output file if it exists
# --freq-file FREQ_FILE
# File containing frequencies in Hz
# --freqs FREQS [FREQS ...]
# List of frequencies in Hz
# --ignore-freq Ignore frequency information and just stack (probably not what you want)
stokescube -h
# usage: stokescube [-h] [-v STOKES_V_FILE] [--overwrite] stokes_I_file stokes_Q_file stokes_U_file output_file
# Fitscube: Combine single-Stokes FITS files into a Stokes cube. Assumes: - All files have the same WCS - All files have the same shape / pixel
# grid - All the relevant information is in the first header of the first image
# positional arguments:
# stokes_I_file Stokes I file
# stokes_Q_file Stokes Q file
# stokes_U_file Stokes U file
# output_file Output file
# optional arguments:
# -h, --help show this help message and exit
# -v STOKES_V_FILE, --stokes_V_file STOKES_V_FILE
# Stokes V file
# --overwrite Overwrite output file if it exists
```
Python:
```python
from fitscube import combine_fits, combine_stokes
hdu_list, frequencies = combine_fits(
['file1.fits', 'file2.fits', 'file3.fits'],
)
hdus_list = combine_stokes(
'stokes_I.fits',
'stokes_Q.fits',
'stokes_U.fits',
)
```
## Convolving to a common resolution
See [RACS-Tools](https://github.com/AlecThomson/RACS-tools).
## License
MIT
## Contributing
Contributions are welcome. Please open an issue or pull request.
## TODO
- [ ] Add support for non-frequency axes
- [ ] Add tracking of the PSF in header / beamtable
- [ ] Add convolution to a common resolution via RACS-Tools
