region_from_exposure

lsst.analysis.ap.region_from_exposure(exposure, padding=5.0)

Compute a cone (ra, dec, radius) covering an exposure’s sky footprint.

The cone is the smallest circle centered on the exposure’s bounding-box center that contains all four corners, expanded by padding arcseconds. A circumscribing circle (rather than the exact polygon) keeps the resulting ADQL robust: CIRCLE is universally supported by TAP services, whereas POLYGON support and winding conventions vary.

Parameters

exposurelsst.images.MaskedImage or lsst.afw.image.Exposure

Image whose sky projection and bounding box define the region, such as an lsst.images.VisitImage. A legacy exposure is converted with as_masked_image.

paddingfloat, optional

Margin to add around the footprint, in arcseconds.

Returns

rafloat

Cone center right ascension, in degrees (ICRS).

decfloat

Cone center declination, in degrees (ICRS).

radiusfloat

Cone radius, in degrees.

Raises

ValueError

If the image has no WCS, or padding is negative.