Sdss-cherno

🏷️ Changed

* By default, apply one last correction after RMS reached.

🔧 Fixed

* Add back sigma-clipping to the median scale calculation.

🚀 New

* [10](https://github.com/sdss/cherno/issues/10) (COS-84) Added a `guide` command that replaces the current `acquire`. `acquire` is still there and does basically the same (they share the same code) but by default applies full corrections and is not continuous. `acquire` also accepts a `--target-rms` flag that will stop the acquisition process if that RMS is reached. In the future we may introduce more differences, with `acquire` aiming to quick acquisition, so some features may be disabled.
* [11](https://github.com/sdss/cherno/issues/11) The marginal distribution extraction now uses the code from `coordio.extraction.extract_marginal()`.
* While the guide/acquire loop is running, the guider status does not change to `IDLE`. If there is a delay between the loop iterations, the guider status will change to `WAITING`.

✨ Improved

* Try to reconnect to the database if necessary when cross-matching with Gaia.
* Add `--fit-all-detections` flag for `cherno acquire` (default to `acquisition.fit_all_detections`) to adjust whether all detections or only the centre of each camera are used.
* `cherno get-scale` now calculates the weighted average, giving higher weigth to recent scale measurements.

🏷️ Changed

* Use astrometry.net 5200 indices for LCO.
* Use Gaia limit of `G<19` for APO

🔧 Fixed

* The cached Gaia query was not being used due to an issue retrieving the field ID.
* Fix typo in `--fit-all-detections`.

🚀 New

* Added a `cherno config` command group that allows to change configuration parameters during runtime.

✨ Improved

* Improved how observatory configuration is managed. There is now a `set_observatory()` function that can be imported directory from `cherno` that allows to set the current observatory. On initial import, that function is called with the value of the `$OBSERVATORY` environment variable.

🚀 New

* Added a new acquisition mode that uses cross-match with Gaia sources to generate a WCS solution for a field (see `coordio.guide.cross_match()`). This method first cross-correlates the detected regions with Gaia sources below a certain magnitude range (`acquisition.gaia_phot_g_mean_mag_max`) to determine the initial translation shift. It then uses a KD-tree nearest neighbout to determine the best matches and creates a WCS using Gaia astrometry. There are three different acquisition modes: `hybrid` (the default) that uses astrometry.net first and Gaia for the cameras that failed to solve; `astrometrynet` that uses only astrometry.net (the past behaviour); and `gaia` that uses Gaia cross-matching for all cameras.

🔧 Fixed

* The TCC module at APO was not applying negative rotator corrections!

🚀 New

* `cherno acquire` now accepts a flag `--only-radec`. When passed, the RA and Dec offsets in the guide loop will calculated as a simple average translation between the GFA positions and the astrometric solutions. Rotation and scale are still measured and output as usual but they are not corrected. This approach is also used then the number of cameras solving is equal or below `config.acquisition.auto_radec_min` (set to 2 by default); this can be changed by setting the `--auto-radec-min` flag.

✨ Improved

* Allow to use all extracted regions (`config.acquisition.astrometry_net_use_all_regions`).

🔧 Fixed

* Calculate FWHM from all cameras with `fwhm_median > 0` instead of using cameras solved.