DIA forced source

Forced measurements in visit and difference images, at the coordinates of all DIA objects.

Schema: ForcedSourceOnDiaObject table

Access

The DIA forced source table is accessible via the TAP and Butler services.

Recommended access service: TAP

TAP

• Citation: NSF-DOE Vera C. Rubin Observatory (2025); Legacy Survey of Space and Time Data Preview 2: ForcedSourceOnDiaObject searchable catalog <doi-tbd>

• Table name: ForcedSourceOnDiaObject

• Columns: <tbd>

• Rows: <tbd>

Butler

• Citation: NSF-DOE Vera C. Rubin Observatory (2025); Legacy Survey of Space and Time Data Preview 2: dia_object_forced_source dataset type <doi-tbd>

• Dataset type: (‘dia_object_forced_source’, {skymap, tract, patch}, ArrowAstropy)

• Format: Parquet

• Number of Butler datasets: <tbd>

Forced sources are sharded by patch, not just tract, because in regions with many epochs the size of a full tract table becomes unwieldy.

Description

“Forced” photometry means a measurement made at a fixed coordinate in an image, regardless of whether an above-threshold region was detected there in that particular image.

The DIA forced source table contains forced PSF flux photometry on both the visit (i.e., “direct” or “science”) and difference images at the coordinates of every object in the DIA object table.

Processing

The DIA forced source table is the result of Difference image analysis (DIA).

Tutorials

See the 200-level catalog Tutorials for a notebook on the DIA forced source table.