Where the survey has detections. Click any cell to search it — the
cell becomes a polygon search over its own RA/Dec bounds, which is
the region the cell's count was taken over, so the two agree up to the 5,000-row
limit every search has. The search arrives with every column filter row
free, so you can narrow the cell by snr or mjd
without giving anything up; it used to spend four of the five saying where the cell
was.
Two things that link does not do. A polygon is not a cone, so a cell holding more than 5,000 detections reports “5,000 shown, and more matched” rather than the exact number on its tooltip — counting every match is affordable only under a cone's capped radius. And a cell that is both large and very dense can be refused rather than answered: a polygon's cost is estimated per row lying under it, so the 10° cell covering this catalog's densest patch comes out above the limit the portal answers without a cone. A smaller cell size is the answer — every cell at 1°, 2° and 5° is answered here. Hiding the fixture does not help, because the estimate counts the rows scanned rather than the rows kept, and neither does asking for fewer rows.
1,002,279 detections in 25 cells of 2.0°. Sky with at least one detection: at most 96 square degrees, or 0.2% of the sky. Mostly empty is the correct picture for now.
That is an upper bound, not a measured footprint. It is the area of the 1.0° grid squares that hold a detection, so a single detection claims a whole square and the sky actually observed can be orders of magnitude smaller — for the ZTF stand-in patch it is. The grid stays fixed at 1.0° whichever cell size you pick below, so the figure does not move when only the picture does. Measuring a real footprint needs the exposure outlines, which the stand-in data does not carry.
The large even block spanning RA 180–190°, Dec 10–20° is the synthetic test fixture — a million uniformly random points, not observations of anything. Real ZTF stand-in detections are the small bright cell near RA 185°, Dec 15°. Hide the fixture to see only real ingests.
Cells are RA/Dec rectangles, so they are not equal-area — a cell near a pole covers
much less sky than one at the equator. Fine for finding coverage, not for comparing
densities across declination. Same data as JSON: /api/sky?bin=2.0