The Zwicky Transient Facility (ZTF) is currently in a phase of extended operations overlapping with the fourth gravitational-wave observing run conducted by the LIGO-Virgo-KARGA collaboration. During this phase, ZTF is conducting monthly three-night experiments where ZTF’s observing strategy can be reimagined to accomplish certain science goals (Ahumada et al. 2023-349, Ahumada et al. 2024-59, Qin et al. 2024-96, Qin et al. 2024-123, Ho et al. 2024-135, Vanderbosch et al. 2024-172). The alerts generated during these ZTF experiments are public and delivered to brokers through the standard ZTF public alert stream.
The next ZTF experiment will focus on discovering infant SNe (~days after explosion). This search is scheduled from August 9th to August 11th 2024 (PDT), which crucially precedes an HST “Flexible Thursday” on August 15th. The new HST Flexible Thursdays program allows for quicker response to target of opportunity triggers than previously possible. UV and optical spectra will be obtained for the most promising infant Type II SN candidate(s) through HST program 17507 (PI Jacobson-Galán).
The ZTF observing strategy will be broadly similar to standard ZTF extragalactic observations: two 30 second visits per field per night (one each in g and r band) over fields away from the Galactic plane. We additionally limit the fields observed to those which overlap with HST visibility. Planned fields will be listed on this document once finalized.
Promising candidates will be vetted with the SED Machine (Blagorodnova et al. 2018) and other facilities. Many candidates will receive autonomous follow-up triggered by BTSbot (Rehemtulla et al. 2024) in a fashion similar to the BTSbot-nearby program (Rehemtulla et al. 2024-140). We encourage additional follow-up and classification of all transients discovered during this experiment.
ZTF is supported by the National Science Foundation under Grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley, the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University, Cornell University, Northwestern University and Drexel University.
Zwicky Transient Facility access for N.R., S.S., and A.M. was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171.
BTSbot runs on Kowalski (Duev et al. 2019), an alert broker and data system for ZTF, and autonomously submits triggers to SEDM using Fritz, a SkyPortal instance (Coughlin et al. 2023).
Comments
The ZTF observing strategy
The ZTF observing strategy for the experiment has changed slightly due to fewer-than-expected ZTF fields which overlap with HST visibility. We will now obtain 60 second exposures for every visit. Any time remaining after completing the ~140 fields which overlap with HST visibility will be spent on other extragalactic fields with the same strategy. All field numbers can be found in the document linked in the AstroNote.