Commits on Aug 1, 2024

1. feat(ch_ephem): CHIME ephemeris refactored from ch_util. …

   Extracts a lot of `ch_util.ephemeris` into a separate package.
   
   General changes:
   
   * Solar and lunar ephemeris functions have been converted into
     `caput.time.Observer` methods: radiocosmology/caput#271
   * Other functions that take a `Observer` object, now use `None`
     as a default, and load the `chime` observer during execution if
     necessary.
   
   More comments on specific submodules follow.
   
   Catalogs:
   
   This contains all the `ch_util/catalogs` plus a function
   (`ch_ephem.catalogs.load`) to read them and return the parsed JSON.
   
   The standard source catalogues loaded by the `sources` submodule need
   to move to `ch_ephem`.  The other catalogues could stay in `ch_util`,
   but it seems simpler to me to keep them all in the same place and
   provide a uniform interface to them.
   
   Coord:
   
   Co-ordinate transforms etc.  These are essentially unchanged from
   their versions in `ch_util.ephemeris`.
   
   Observers:
   
   Re-creates all the `caput.time.Observers` which used to be created
   by `ch_util.ephemeris`, but for the most part, they have to be
   fetched via name from the `get()` function.  The exception to this
   is the `chime` Observer, which can be directly imported, since it's
   the one usually needed.
   
   Position data for the observers is now in a YAML data file
   `instruments.yaml` which is parsed at import time.  New instrument
   `Observer` objects can be added to `ch_ephem` just by adding information
   for it to the YAML file.
   
   Also note that `Observers` returned by this submodule have an extra
   attribute, `rotation`, inserted into their `__dict__`, which is not
   in `caput`.  This rotation is needed by `ch_ephem.coord.peak_ra`.
   If we don't want to do this to these `Observers`, one other options
   would be to keep `peak_ra` in `ch_util` (moving it to, say,
   `ch_util.tools`), and then there's no need for rotation information
   in this module.
   
   Like `sources`, this submodule reads data from disk at import time,
   so is not automatically imported into the base `ch_ephem` object.
   
   Pointing:
   
   Just Galt telescope pointing routines, unchanged from
   `ch_util.ephemeris`.  These are another candidate we could consider
   putting somewhere else in ch_util, if we don't want them here.
   
   Sources:
   
   Loads the standard source catalogs, and provides the calibrator objects
   `CasA`, `CygA`, `TauA`, `VirA`.  Like `observers`, this submodule
   reads data from disk at import time, so is not automatically imported
   into the base `ch_ephem` object.
   
   Time:
   
   Time utilities, largely unchanged from what was in `ch_util.ephemeris`.

   

   ketiltrout committed Aug 1, 2024
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