A First Catalog of Variable Stars Measured by the Asteroid Terrestrial-impact Last Alert System (ATLAS)

Abstract

The Asteroid Terrestrial-impact Last Alert System (ATLAS) carries out its primary planetary defense mission by surveying about 13000 deg 2 at least four times per night. The resulting data set is useful for the discovery of variable stars to a magnitude limit fainter than r ∼ 18, with amplitudes down to 0.02 mag for bright objects. Here we present a Data Release One catalog of variable stars based on analyzing the lightcurves of 142 million stars that were measured at least 100 times in the first two years of ATLAS operations. Using a Lomb-Scargle periodogram and other variability metrics, we identify 4.7 million candidate variables. Through Space Telescope Science Institute, we publicly release lightcurves for all of them, together with a vector of 169 classification features for each star. We do this at the level of unconfirmed candidate variables in order to provide the community with a large set of homogeneously analyzed photometry and avoid pre-judging which types of objects others may find most interesting. We use machine learning to classify the candidates into fifteen different broad categories based on lightcurve morphology. About 10% (427,000 stars) pass extensive tests designed to screen out spurious variability detections: we label these as 'probable' variables. Of these, 214,000 receive specific classifications as eclipsing binaries, pulsating, Miratype, or sinusoidal variables: these are the 'classified' variables. New discoveries among the probable variables number 315,000, while 141,000 of the classified variables are new, including about 10,400 pulsating variables, 2,060 Mira stars, and 74,700 eclipsing binaries.

PG 1610+062: a runaway B star challenging classical ejection mechanisms

“…A.11. The oscillation period reported by Heinze et al (2018), 4.336721 days, is nicely confirmed here. However, due to the very scarce sampling, alias frequencies at 1 − ν osc , 1 + ν osc , and 2 − ν osc are almost as likely as ν osc itself (see Fig.…”

“…PG 1610+062 lies right inside the instability domain of slowly pulsating B (SPB) stars (see, e.g., Moravveji 2016) and is thus expected to pulsate if it is a MS star. The ATLAS variable star catalog (Heinze et al 2018) indeed classifies it as a candidate variable star. Because this classification is based on a purely automated procedure, we decided to reanalyze the ATLAS data to test the robustness of the results.…”

THOR 42: A touchstone ∼24 Myr-old eclipsing binary spanning the fully-convective boundary

“…Although the photometry is of poorer quality than Catalina or ASAS-SN, they found a period of 6.08 d which may be an alias (6.08 d/0.8589 d = 7.08). Finally, Heinze et al (2018) included J0552−0044 in their catalogue of variable stars from the first data release of the Asteroid Terrestrial-impact Last Alert System (ATLAS; Tonry et al 2018a). ATLAS observed J0552−0044 in two non-standard bandpasses; cyan (4200-6500 Å) and orange (5600-8200 Å).…”

Physical Parameters of Late-type Contact Binaries in the Northern Catalina Sky Survey

“…The sample of known CBs was recently significantly increased thanks to new data from several sky surveys that provide high-cadence, long-term, high-precision photometric observations in a range of passbands, including, e.g., the Catalina Sky Survey (CSS; Marsh et al 2017), the Wide-field Infrared Survey Explorer catalogue (WISE ; Chen et al 2018b), the All-Sky Automated Survey for Supernovae (ASAS-SN; Jayasinghe et al 2018), the Northern Sky Variability Survey (NSVS; Gettel et al 2006), and the Asteroid Terrestrial-impact Last Alert System (ATLAS; Heinze et al 2018). As sample sizes increased, researchers have taken advantage of the data from various surveys and constructed genuine CB samples for further statistical study (Rucinski 1995;Norton et al 2011;Marsh et al 2017).…”