Zwicky Transient Facility (ZTF) Identified a Thousand New Objects

ZTF, based at the Palomar Observatory, found a variety of amazing phenomena in the night sky, including 50 near-Earth asteroids and 1,100 new supernovae.

Have you ever wondered about the secrets of the night sky? Do you want to know what lies in the empty space around stars? The Zwicky Transient Facility in San Diego County has figured out some answers for you through a sky-survey camera in Southern California. It identified numerous new objects ranging from binary-star systems to supernovae and from near-Earth asteroids to black holes.

Key Information about ZTF

ZTF is a public-private partnership between a consortium of nine different institutions of the world and the National Science Foundation. The last 6 papers of this collaboration describe the discoveries of these amazing objects and phenomena. In addition to that, these papers include wealthy information about data mining, sorting, and alert systems of the ZTF. One of these papers explains the alert system for notifying the researching teams of possible new objects or significant changes to existing objects. Maria Patterson, a Data Scientist, is the Lead Author of this paper. Similarly, Eric Bellm, a Research Assistant Professor at the University of Washington who is also the Survey Scientist of ZTF, is the Lead Author of the paper which described the major findings of the survey since its beginning in March 2018. Bellm said,

“The ZTF mission is to identify changes in the night sky and alert the astronomical field of these discoveries as quickly as possible. The results and specifications reported in these six papers demonstrate that the ZTF has in place a pipeline to identify new objects, as well as analyze and disseminate information about them quickly to the astronomy community.”   

He further mentioned that instant alerts are needed to make sure that follow-up observations of individual objects are arranged by other observatories.

Amazing Capabilities of ZTF

The digital camera of the ZTF has 16 charge-coupled devices that enable it to achieve its survey goals. It is mounted on the Samuel Oschin Telescope at Palomar Observatory and can cover an area of about 240 times the size of the moon in a single image. Consequently, it can capture the entire night sky that is visible from the Northern Hemisphere in just one night. Just Imagine!

The images taken by the ZTF belong to a number of private as well as public entities including the National Science Foundation. Bellm acknowledged that the volume of data generated by this survey has led to a completely new approach to data analysis and alerts. According to the science teams, it has captured more than a billion stars from the Milky Way alone. The ZTF can find new objects by comparing the new images to the older ones. For instance, it can observe the brightening of a star and a new supernova, which has just lightened up for the first time. Bellm referred to the extensive data needed for this survey in the following words:

“Every image that the ZTF takes contributes to at least one survey. We needed to put an automated alert system in place that would inform the relevant survey teams — in near-real time — of every potential change or new object that the ZTF would uncover, which could be more than a million in a single night.”

Automated Alert System

Mario Juric, an Associate Professor of Astronomy with the eScience Institute, helped Patterson and Bellm to develop the automated alert system in the ZTF. They used a couple of open-source technologies, called Avro (a Framework to serialize data for transmission and storage) and Kafka (a real-time data-streaming platform), for crafting this amazing system.

Since its deployment in June last year, it has successfully generated and distributed up to 1.2 million alerts each night. The ZTF has shared all the discovered changes with its survey partners, who are using machine-learning classification methods to sort these alerts. Bellm talked about the significance of the ZTF with regards to the Large Synoptic Survey Telescope (expected to begin in 2022 and will generate 10 million signals every night) by saying,

“We are very pleased with the opportunities that the ZTF mission has provided us. It is reassuring to know that we have the tools at hand today that are useful not only for ongoing surveys at the ZTF but also future missions like the LSST.”