About imo-vmdb
imo-vmdb processes visual meteor observation data from the Visual Meteor Database (VMDB) of the International Meteor Organization (IMO).
What it does
The IMO distributes observation data as CSV files. These raw files contain counts and times, but lack the derived quantities needed for most analyses.
imo-vmdb imports the raw CSV data, validates it, and then normalizes it — enriching each observation with computed astronomical properties:
Solar longitude at the start and end of the observation
Radiant position (altitude and azimuth) with zenith attraction applied
Sun position (altitude and azimuth)
Moon position (altitude, azimuth) and illumination
Field-of-view position (altitude and azimuth)
The statistical analysis itself happens outside imo-vmdb. The REST API provides machine-to-machine access to the prepared data — for example, from the vismeteor R package.
Coordinate systems and time
All observation times are handled in UTC (Coordinated Universal Time).
Computed positions — solar longitude, radiant, Sun, Moon, and field-of-view — are calculated using the J2000.0 epoch (Julian epoch 2000 January 1.5 TT, equivalent to JD 2451545.0). Input right-ascension and declination values (e.g. shower radiant coordinates) must therefore also be referenced to J2000.0.
Internally, imo-vmdb uses Astropy
with the built-in solar-system ephemeris. The ecliptic frame is
GeocentricMeanEcliptic with equinox='J2000' set explicitly;
body positions from get_body() are in the GCRS frame, whose
fundamental epoch is J2000 by definition.
Accessing the data
Normalised data can be accessed in three ways:
REST API — query observations as JSON, filtered by shower, date range, solar longitude, and more; see REST API.
CSV export — download tables directly from the web UI or CLI; see export.
Direct database access — SQLite, PostgreSQL, or MySQL; field reference at Field Reference.
Getting started
The fastest way to get started is the Docker image — no local Python installation required: