In the Time Domain: ZTF Community Survey and Alerts, ANTARES Event Brokering, and the Astronomical Event Observatory Network

Stephen Ridgway NOAO), Cesar Briceno (CTIO), Bryan Miller (Gemini) and Rachel Street (LCOGT)

The Zwicky Transient Facility (ZTF), which achieved first light a few months ago, is now in full swing and producing up to hundreds of thousands of transient alerts per night. The survey is being carried out on the Palomar 48-inch Schmidt telescope using a 47 square degree camera (a mosaic of 16 CCDs with 6Kx6K pixels each). A public-private project supported in part by a National Science Foundation Mid-Scale Innovations Program award, ZTF can survey 3750 deg² per hour to a median depth of R=20.5. A first-light image is reproduced here.

ZTF first light composite image. Right: the full field of view encompassing the belt of Orion. Left: Successive zooms.

The ZTF Public Surveys

Thanks to the MSIP award, 40% of time on ZTF is spent on two public surveys: an all-northern-sky survey with a pair of visits in g and r every 3 nights, and a Galactic Plane survey with nightly visits in g and r.

Transient alerts from the public survey are available now on a daily basis. Pending operation of a community broker, daily alert archives are provided for download (ATEL #11685; see https://ztf.uw.edu/alerts/public/). The ZTF team is also operating a filter to select bright transients for possible supernovae, announcing favorable events via the Transient Name Server (TNS), and in some cases undertaking classification spectroscopy, also to be reported to TNS. ZTF moving object alerts are also being fed to the Minor Planet Center. Las Cumbres Observatory (LCOGT) is now offering an alert server for ZTF, MARS (Make Alerts Really Simple), with user-specifiable filtering capability.

The first ZTF object catalog and image data release is expected at the end of the first survey year (about June 2019).

Proposals for ToO follow-up programs on NOAO facilities are invited and welcome. As a reminder, access to the LCOGT automated telescopes is available via the NOAO TAC for the next few years, also thanks to NSF MSIP support.

ANTARES Event Brokering

The NOAO Community Science and Data Center continues development of the ANTARES transient broker service. An initial ANTARES brokering service for the ZTF alert stream is currently being commissioned, with a release date anticipated during January 2019. This service will begin with simple filters and deploy more complex filtering capabilities in subsequent semesters, with the goal of operating full-featured and scalable implementation in advance of the arrival of the alert stream from the Large Synoptic Survey Telescope (LSST).

Community engagement is welcome in the continuing development of ANTARES. Shared-risk proposals for follow-up observing of ANTARES-filtered alerts on NOAO-scheduled facilities are welcomed for science-verification purposes. For details, please see the NOAO 2019A call for proposals.

Connecting the Time Domain Ecosystem

A number of community reports (e.g., the Elmegreen report “Optimizing the US Ground-based OIR System” and the Kavli Futures symposium “Maximizing Science in the Era of LSST”) have studied the requirements for follow-up of major synoptic surveys and have highlighted the urgent need for systems that integrate brokering, scheduling, follow-up data acquisition, and data reduction, with the capability of coordination among multiple scientists and between collaborations in order to optimize facility use.

NOAO has initiated development of such an integrated follow-up system, initially to connect alerts from ANTARES to follow-up observing programs employing resources available through the NOAO TAC. This project (dubbed AEON, for “Astronomical Event Observation Network”) is a collaboration between NOAO and LCOGT, SOAR and Gemini. In the first phase (release date TBD), the SOAR Goodman spectrograph will be offered via the LCOGT dynamic scheduling service for a fraction of the available nights each semester. Extension to Gemini will follow, and the project can scale to additional facilities. Further details are available in a poster overview.

The ZTF Community Science Advisory Committee

The ZTF Community Science Advisory Committee, which advises the ZTF PI (Shri Kulkarni), welcomes your input and advice at any time. Are you using ZTF alerts? We would like to hear about your experience. Are you not using ZTF alerts even though you would like to? Why not? What data products are you most eager to access?

To provide your input, please contact the committee: Marcel Aguerros (Columbia University), Todd Boroson (LCOGT), Mukremin Kilic (University of Oklahoma), Juna Kollmeier (Carnegie Observatories), Maryam Modjaz (NYY), Marc Pinsonneault (Ohio State University), and Stephen Ridgway (NOAO).

The next major tasks of the CSAC will be to encourage community utilization of ZTF data, aggregate feedback, and advise the project on the evolution of the community survey strategy moving into the second half of the survey. The 2019 AAS meetings will be an opportunity for discussion, and the discussion venue will be announced in these pages.