VWDB — statistics

STAND-IN DATA. This catalog contains 2,279 ZTF detections and 1,000,000 synthetic fixture rows — NOT Visnjan-Washington observations. Stand-in data is loaded while the VW Data Analysis Pipeline is built. Do not use these measurements for science.

Statistics

The survey's observing record, computed from survey.exposures. These are ZTF's observing statistics, not Visnjan-Washington's — the stand-in notice above applies to every plot here as much as it does to a search result, and the synthetic fixture is excluded by default because its cadence is invented (a perfectly uniform one exposure every 0.01 day), not observed.

Clump by day week month Dates all 2018 2019 2020 2021 2022 2023 2024 2025 Band zg zi zr Synthetic fixture excluded

Exposures

1,339

in 3 bands (zg, zi, zr)

Nights observed

550

2.4 exposures per night

Baseline

7.3 yr

Mar 25, 2018 – Jun 27, 2025

Open-shutter time

11.6 h

summed exposure time

Median depth

21.07 mag

limiting magnitude per exposure

Median airmass

1.12

secant of the zenith angle

Exposures per day

How often the survey observed. A gap is a day it didn't run, not one with nothing to see. Hover a column for its date, its total and how that total divides between bands.

Cumulative exposures

The same data, accumulated — flat stretches are when the survey was not running, which the bar chart above makes easy to miss among the days that did have data. Hover a point for the running total and what it added.

Exposures by filter

How the observing above divides between bands — always the whole split, whichever band is currently picked. Click a slice to show only that band in the charts above.

Revisits and light-curve length

How often the survey comes back to the same object, over the same bands and dates as the charts above. Grouped by ZTF's own association of the stand-in data (ztf_oid), which is the only thing linking one detection to another until phase 2 builds objects — so these describe what the stand-in catalog can support, not a VW data product. Only the 2,279 detections ZTF associated this way are counted, out of 1,002,279 sources in the catalog: a source with no association has no object identity here at all, so it is absent from these charts rather than appearing as a one-point curve.

Objects with a curve

from 2,279 linked detections

Typical curve length

19 points

median over those objects

Typical revisit

1.9 d

median gap between consecutive points

Longest baseline

7.3 yr

first to last point on one object

Time between consecutive detections

The sampling, which is what sets the periods a light curve can recover: a signal shorter than the typical gap is not resolved, and one near a spike in this histogram aliases against it. Log-spaced buckets — revisits run from minutes to years. Hover a row for its share.

Detections per object

How long the curves are. An object with a handful of points has a position and little else — fitting a period or an orbit takes tens of points at least, so it is the bottom rows here that are worth plotting. Plot the best-sampled one (590 points).

Same data as JSON: /api/statistics