ANTARES Broker Filter for LSST Alerts to Cross-Match

A Python filter for the ANTARES broker that selects high-quality LSST transient candidates for downstream cross-matching against the Gaia catalog using LSDB, running in SCiMMA infrastructure.

Filter

lsst_transient_quality_filter.py implements LsstTransientQualityFilterScimma, a BaseFilter subclass that runs inside ANTARES infrastructure. For each incoming LSST alert it checks ten quality criteria against the latest alert's lsst_diaSource_* properties. Alerts that pass all criteria are tagged lsst_scimma_quality_transient and routed to the SCiMMA subscription topic for cross-matching.

Selection criteria — the latest alert must satisfy all of:

Criterion	Condition
Signal-to-noise ratio	lsst_diaSource_snr > 10
Not a solar system object	lsst_diaSource_ssObjectId in (0, None, "0")
No PSF flux flag	lsst_diaSource_psfFlux_flag is falsy
No centroid flag	lsst_diaSource_centroid_flag is falsy
No shape flag	lsst_diaSource_shape_flag is falsy
Not a dipole	lsst_diaSource_isDipole is falsy
Not saturated	lsst_diaSource_pixelFlags_saturated is falsy
Not near image edge	lsst_diaSource_pixelFlags_edge is falsy
No cosmic ray flag	lsst_diaSource_pixelFlags_cr is falsy
No streak flag	lsst_diaSource_pixelFlags_streak is falsy

If any required property is absent from the alert, ANTARES skips execution of the filter automatically (via REQUIRED_ALERT_PROPERTIES).

Test

test_lsst_transient_quality_filter.py is a standalone script that fetches a real LSST locus from ANTARES by diaObject ID, runs it through the filter using the ANTARES devkit filter_report() utility, and prints the result.

Setup

Create and activate a Python virtual environment, then install the required packages:

python3 -m venv antares_env
source antares_env/bin/activate
pip install antares-client antares-devkit

Running the Test

With the virtual environment active:

python test_lsst_transient_quality_filter.py

The script fetches locus 170055002004914266 from ANTARES, runs the filter, and prints the filter_report() output along with a PASS or REJECT summary.

References

• ANTARES DevKit — Structure of a Filter
• ANTARES DevKit — Testing Filters