How is bboxSize determined for alerts?

Support Data Products
#1

I’m trying to understand how the detection footprint of a DiaSource gets determined, and how that gets translated to the bboxSize for the alert. I can’t seem to find the code.

For context, I am working with comet data in the alerts and am trying to reproduce the bboxSize for testing purposes. This alert with a bboxSize of 90 is one example. Can you walk me through how this was determined?

Thank you!

#2

Hi Carrie,

According to the DP2 ‘Stage 4’ pipeline graph available at Summary — DP2, the detection on difference images was done by lsst.ip.diffim.detectAndMeasure.DetectAndMeasureTask (code link), with a threshold signal-to-noise ratio of 5 according to Difference image analysis (DIA) — DP2.

The bboxSize column contains the minimum square box size (in pixels) required to fully contain the DETECTED footprint of the diaSource. The alert cutout size is the greater of this cutout size and the configured minimum cutout size (up to a maximum cutout size). Thanks very much.