Over 1,100 supernovae and 50 near-Earth objects have been discovered through a new survey

The Tzwicki Transient Phenomena facility located at the Plumer Observatory serves as an alert system that informs researchers in the relevant fields in real time about the discovery of new objects or changes in known objects in the sky

Casual sky watchers may look at the black spaces between the stars and think there is only an empty flute, but the night sky hides many secrets from the naked eye.
Less than a year after its mission began, the Southern California Sky Survey Camera shows just how full the sky is. The Zwicky Transient Facility (ZTF) at the Plummer Observatory, not far from San Diego, has detected more than 1,100 supernovae and 50 near-Earth asteroids, as well as binary star systems and black holes. The facility is operated by Caltech but is a public and private partnership that includes nine more secrets.
The collaboration of all ZTF member universities resulted in the publication of 6 papers describing these discoveries, as well as analysis obtained from data mining for screening and warning systems, in the Journal of the Astronomical Society of the Pacific.

Eric Belm, a ZTF survey scientist and research assistant in astronomy at the University of Washington is the lead author of a paper describing the technical systems of the ZTF and the main findings since the facility began operating on March 20, 2018. Another study, led by Maria Patterson formerly of the University of Washington and now at the DIRAC Institute—and is Describes the ZTF alert system used to notify scientists worldwide of possible new objects in the sky or significant changes in existing objects.
"ZTF's mission is to detect changes in the night sky to alert astronomers studying the specific field to the discoveries relevant to them as quickly as possible," said Belem, also from the DIRAC Institute. "The findings of the six papers show that the ZTF has the ability to serve as a pipeline to identify new objects as well as analyze data and rapidly alert the astronomy community.
Science teams need quick alerts so they can, if necessary, arrange for follow-up observations of individual objects by other observers, Belem added. The ZTF achieves its survey goals with 16 cameras that allow it to cover the entire visible sky in one night. One image from the camera covers an area 240 times larger than the size of the moon. So far the facility has photographed the billion stars in our galaxy alone. By comparing the new images with the old ones, the ZTF can detect new objects, such as a supernova brightening for the first time, or changes in existing objects, such as a star brightening in brightness.

The ZTF undertakes surveys for public bodies such as the National Science Foundation, as well as private bodies. The sheer volume of data generated by the ZTF required a new approach to data analysis and alerts, according to Belem.

"Each image that the ZTF took is relevant to some kind of survey, so we were required to develop an automatic alert system that would notify the relevant researchers in near real time of any potential changes in existing objects or new objects. Patterson, Balem and other scientists from the University of Washington, Lubham Mario Jurich, Senior Professor of Astronomy and Systems Information at the eScience Institute - they led the efforts to design the automatic notification system within the ZTE Two open source technologies were used - Kafka, which is a platform for real-time data flow, and Ebro - a system for transferring and storing data. The system, which was first unveiled in June 2018, successfully created and distributed up to 1.2 million alerts per night, with each alert automatically sent to researchers in the field to which it belongs.

"Through these alert systems, the ZTF shares any changes it finds with our survey partners," said Belem. "They get every bit of data."
The survey partners, in turn, operate computerized classification systems and other analytical tools to sort the alerts. According to Belem, the ZTF alerting system is proven ground for "real-time automated astronomical" missions, such as the "Large Synoptic Survey Telescope." LSST, which is expected to begin its survey of the sky in 2022, will produce about 10 sorties of alerts per night, about 10 times the maximum alert volume of ZTE, but the current survey can create the infrastructure for an alert system, which will be upgraded for the LSST.