https://github.com/space-physics/astrometry_geomap
FITS to Azimuth/Elevation using Astrometry.net--calibrate and plate scale images
https://github.com/space-physics/astrometry_geomap
astrometry astropy citizen-science
Last synced: 4 months ago
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FITS to Azimuth/Elevation using Astrometry.net--calibrate and plate scale images
- Host: GitHub
- URL: https://github.com/space-physics/astrometry_geomap
- Owner: space-physics
- License: isc
- Created: 2014-05-02T05:14:44.000Z (almost 11 years ago)
- Default Branch: main
- Last Pushed: 2024-02-06T04:39:39.000Z (about 1 year ago)
- Last Synced: 2024-12-06T21:09:19.273Z (5 months ago)
- Topics: astrometry, astropy, citizen-science
- Language: Python
- Homepage: https://www.scivision.dev/astrometry-tips-techniques
- Size: 646 KB
- Stars: 10
- Watchers: 5
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
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README
# Azimuth/Elevation converter for [Astrometry.net](https://github.com/dstndstn/astrometry.net)
[](https://zenodo.org/badge/latestdoi/19366614)
[](https://github.com/space-physics/astrometry_geomap/actions/workflows/ci.yml)
[](https://pypi.python.org/pypi/astrometry-azel)
[](http://pepy.tech/project/astrometry-azel)
[Tips and techniques article](https://www.scivision.dev/astrometry-tips-techniques), especially for DSLR citizen science data.
Get
[Astrometry.net ≥ 0.67](https://scivision.dev/astrometry-install-usage)
or use the
[astrometry.net cloud service](http://nova.astrometry.net/upload).
```sh
python3 -m pip install -e .
```
The main program used is [PlateScale.py](./PlateScale.py).
Auxiliary scripts are under [scripts/](./scripts/)
## PlateScale.py
The main script most users would use to register a star field image to Azimuth and Elevation is "PlateScale.py".
The "--args" command line option allows passing through a variety of parameters to `solve-field`, which underlies this program.
Type `solve-field -h` or `man solve-field` for a brief description of the nearly 100 options available.
Be sure to enclose the options in quotes.
For example, to specify that the image field is at least 20 degrees in extent:
```sh
python PlateScale.py ~/data/myimg.jpg --args "--scale-low 20"
```
Citizen science images often contain extraneous items in the image field of view.
These can very easily break `solve-field`, which is designed for professional science-grade imagery from telescopes and narrow to medium field of view imagers (at least to 50 degree FOV).
To mitigate these issues, judicious use of arguments passed to `solve-field` via `--args` is probably a good start.
The parameters I find most useful for citizen science images include:
```
--scale-low : lower bound of image scale estimate
--scale-high : upper bound of image scale estimate
--depth : number of field objects to look at, or range
of numbers; 1 is the brightest star, so "-d 10" or "-d 1-10" mean look
at the top ten brightest stars only.
```
For extraneous regions of the image, try making a copy of the original image that has the offending regions cropped out.
If the original image is in a lossy format such as JPEG, consider saving in a lossless format such as PNG after cropping.
### Astrometry.net installed on local computer
```sh
python PlateScale.py myimg.fits 61.2 -149.9 2013-04-02T12:03:23Z
```
gives netCDF .nc with az/el ra/dec and PNG plots of the data.
Both files contain the same data, just for your convenience.
61.2 -149.9 is your WGS84 coordinates, 2013-04-02T12:03:23Z is UTC time of the picture.
### wcs.fits from the Astrometry.net website
Download from nova.astrometry.net solved image the "new-image.fits" and "wcs.fits" files, then:
```sh
python PlateScale.py 61.2 -149.9 2013-04-02T12:03:23Z new-image.fits
```
## Notes
* 2MASS [index](http://broiler.astrometry.net/~dstn/4200/)
* Tycho [index](http://broiler.astrometry.net/~dstn/4100/)
* ways to [use astrometry.net](http://astrometry.net/use.html)
* astrometry.net [source code releases](http://astrometry.net/downloads/)
* astrometry.net [GitHub](https://github.com/dstndstn/astrometry.net)
* [article](https://www.dsi.uni-stuttgart.de/institut/mitarbeiter/schindler/Schindler_et_al._2016.pdf) on good robustness of Astrometry.net to shaky, streaked images.
### Download star index files
```sh
python downloadIndex.py
```
Edit file /etc/astrometry.cfg or similar:
Be sure `add_path` points to /home/username/astrometry-data, where username is your Linux username.
Don't use ~ or $HOME.
Uncomment `inparallel` to process much faster.
Optionally, set `minwidth` smaller than the smallest FOV (in degrees) expected.
For example, if NOT using a telescope, perhaps minwidth 1 or something.
## PlotGeomap.py
Plot an image registered to Latitude and Longitude, assuming the image features all occurred at a single altitude.
This technique is used in aeronomy assuming a certain altitude of auroral or airglow emissions.
This approximation is based on colors representing particle dynamics at a range of altitudes, approximated by a single altitude.
For example, if a short wavelength filter (blue) was applied to the auroral image, one might assume the emissions were at about 100 km altitude.
## Related
For source extraction or photometry, see my AstroPy-based
[examples](https://github.com/scivision/starscale).