2024-03-25 16:00 UTC: There will be some minor disruption in the week beginning 25 March 2024 as we upgrade our servers. We will let you know when the upgrade is complete.

Forced photometry is now available from the Southern Telescopes (El Sauce, Chile and Sutherland, South Africa). Please be aware that the difference imaging template south of -50 degrees declination was changed during commissioning, so you may get an unexpected discontinuity in your target's difference lightcurve.

ATLAS Forced Photometry

This is the ATLAS forced photometry server, which provides full public access to photometric measurements over the full history of ATLAS survey. After registration, a user can request forced photometry at any position on the sky either for a single position, a list of positions, or moving objects (by MPC name).

ATLAS is a quadruple 0.5m telescope system with two units in Hawaii (Haleakala and Mauna Loa), and one each in Chile (El Sauce) and South Africa (Sutherland). With the installation of the two southern units, we are robotically surveying the whole sky with a cadence of 1 day between -50 and +50 and 2 days in the polar regions, weather permitting. Two filters are used, cyan and orange (denoted c and o; all mags quoted are in the AB system).

As described in Tonry et al. (2018), ATLAS surveys the whole visible sky. On each night, a sequence of 4 x 30 second exposures are taken, spaced over a period of about one hour to provide identification and orbit constraints for near-earth objects (NEOs). Discovery of NEOs and potentially hazardous objects is the main purpose of ATLAS. However the all-sky, frequent coverage, to o ~ 19.5 makes it treasure trove for time domain science. A full description is on the ATLAS homepage at fallingstar.com

The potential for transient object science and variable star science has been described in Smith et al. (2020) and Heinze et al. (2018), respectively. We release all our transient discoveries to the IAU's Transient Name Server.

A forced photometry means that a point-spread-function is calculated for each image based on high signal to noise stars, and a profile fit is forced at the user's input coordinates. The forced measurement can be made on either a target image (e.g. for the measurement of flux of a variable star), or on a difference image (e.g. for a lightcurve point for a transient). Data processing and photometry are described in more detail in Tonry et al. (2018) and Smith et al. (2020).


The data returned are described on the Output page and if you encounter problems, bugs, or would like to make suggestions, please do it through our GitHub issues page.

If you use these data in a publication you must cite Tonry et al. (2018), If you use data for transient time-domain science you must also cite Smith et al. (2020), and if you use it for variable object science, you must cite the Heinze et al. (2018). This web service can be cited as Shingles et al. (2021).

Please also add the acknowledgement:

This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen’s University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile.