SOCAT

The Source CATalog.

Contains information about sources that are being monitored by an obseratory, or that are being used to crossmatch detected sources with.

BUILDING YOUR VERY OWN SOCAT

Once installed, you can read in catalogs with custom ingestion scripts found in socat/ingest/

Set your environment variables to point to the location/name of the database you want to construct:

export socat_client_client_type=db
export socat_model_database_name=socat.db

then run socat-migrate to create the socat.db in your working dir.

Once created, you can add sources via the following example ingest scripts:

socat-act-fits was written to read in an ACT point source catalog which is simply stored as a fits file with certain columns.

socat-jpl-parquet was written to read in a parquet file containing JPL Horizons ephemerides for solar system objects.

These scripts store either FixedRegisteredSources, or SolarSystemObjects.

USING SOCAT

Once sources are ingested into your db, you can use the socat to query sources within a box on the sky within some time range.

Make sure you environment variables point to the correct db, as above.

from socat.client.settings import SOCatClientSettings
from astropy.coordinates import SkyCoord
from astropy.time import Time
from astropy import units as u

settings = SOCatClientSettings()
catalog = settings.client

sso_client = catalog.sso
ephem_client = catalog.ephem

sky_box = [
    SkyCoord(ra=0*u.deg,dec=-20*u.deg),
    SkyCoord(ra=120*u.deg,dec=20*u.deg)
]

results = sso_client.get_box(
    lower_left=sky_box[0],
    upper_right=sky_box[1],
    t_min=Time("2019-06-08T00:00:00Z"),
    t_max=Time("2019-06-11T12:00:00Z"),
    source_cat=catalog,
    ephem_cat=ephem_client,
)

This returns a list of SourceGenerator objects, which you can query for positions and fluxes at time t by initializing the interpolator (whose valid range is the t_min, t_max you input above)

t = Time("2019-01-01T00:00:00Z")

for r in results:
    r.init_interp(ephem_cat=ephem_client)

sources = [r.at_time(t=t) for r in results]

So that each element of sources is a tuple of (position, flux) with position given as a SkyCoord object. In this way, you can query fixed astrophysical sources and moving objects in the same unified calls.

The sotrplib library (github.com/simonsobs/sotrplib) has functional examples of loading in sources within map boundaries, and can be found in sotrplib/source_catalog/socat.py.

Project Leads:

• Jack OS
• Josh B

Project Helpers:

• AF

Status

Pre-alpha