Year 1 of the ZTF high-cadence Galactic plane survey: Strategy, goals, and early results on new single-mode hot subdwarf B-star pulsatos

Thomas Kupfer, Thomas A. Prince, Jan Van Roestel, Eric C. Bellm, Lars Bildsten, Michael W. Coughlin, Andrew J. Drake, Matthew J. Graham, Courtney Klein, Shrinivas R. Kulkarni, Frank J. Masci, Richard Walters, Igor Andreoni, Rahul Biswas, Corey Bradshaw, Dmitry A. Duev, Richard Dekany, Joseph A. Guidry, J. J. Hermes, Russ R. LaherReed Riddle

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


We present the goals, strategy, and first results of the high-cadence Galactic plane survey using the Zwicky Transient Facility (ZTF). The goal of the survey is to unveil the Galactic population of short-period variable stars, including short-period binaries, and stellar pulsators with periods less than a few hours. Between 2018 June and 2019 January, we observed 64 ZTF fields resulting in 2990 deg2 of high stellar density in the ZTF-r band along the Galactic plane. Each field was observed continuously for 1.5 to 6 h with a cadence of 40 sec. Most fields have between 200 and 400 observations obtained over 2-3 continuous nights. As part of this survey, we extract a total of ≈230 million individual objects with at least 80 epochs obtained during the high-cadence Galactic plane survey reaching an average depth of ZTF-r ≈ 20.5 mag. For four selected fields with 2-10 million individual objects per field, we calculate different variability statistics and find that ≈1-2 per cent of the objects are astrophysically variable over the observed period. We present a progress report on recent discoveries, including a new class of compact pulsators, the first members of a new class of Roche lobe filling hot subdwarf binaries as well as new ultracompact double white dwarfs and flaring stars. Finally, we present a sample of 12 new single-mode hot subdwarf B-star pulsators with pulsation amplitudes between ZTF-r = 20-76 mmag and pulsation periods between P = 5.8-16 min with a strong cluster of systems with periods ≈6 min. All of the data have now been released in either ZTF Data Release 3 or Data Release 4.

Original languageEnglish (US)
Pages (from-to)1254-1267
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Jul 1 2021

Bibliographical note

Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.


  • binaries (including multiple): close
  • stars: oscillations (including pulsations)
  • surveys
  • white dwarfs


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