ZTF welcomes new partners
The campuses of our new partner institutions - ISTA, Austria (left) and UNC, USA (right).
Last year, ZTF received additional funding from the National Science Foundation for two more years. This funding and individual contributions from the partnerships will allow ZTF to work in tandem with Vera Rubin Observatory, enabling new scientific studies of the dynamic universe that could not be tackled by any of the observatories alone.
The ZTF partnership operates as a public-private consortium with funding contributions from its partners. While we are seeing some partners leave the phase 3 of ZTF, we are excited to welcome new ones. Assistant professor Ilaria Caiazzo from the ISTA institute in Vienna, Austria will lead the variables science working group in ZTF. Assistant professor Igor Andreoni at the UNC in the USA will collaborate closely with the multi-messanger astrophysics group in ZTF. Our continued partners are University of Maryland, College Park, USA; University of Wisconsin, Milwaukee, USA; Drexel University, USA; Cornell University, USA; University of California, Berkeley; and IPAC/Caltech.
Daniel Perley (LJMU), Adam Miller (Northwestern University), Michael Coughlin (UMN) and Eric Bellm (UW) will be associate members of the partnership with in-kind contributions in software, operations and survey science.
ZTF tallies more than 10,000 supernovae
The Zwicky Transient Facility has opened up new scientific horizons in transient astronomy with the largest supernova survey to date.
Seven years ago, an international collaboration of astronomers installed a state-of-the-art camera on a robotic telescope at the Palomar Observatory near San Diego. Today, the Zwicky Transient Facility holds the largest census of cosmic supernovae - flashes of light in the sky that tell us of stars dying in spectacular explosions.
“There are trillions of stars in the universe, and about every second, one of them explodes. ZTF detects hundreds of these explosions per night and a handful are then confirmed as supernovae. Systematically doing this for seven years has led to the most complete record of confirmed supernovae to date,” says Christoffer Fremling, a staff astronomer at Caltech who leads ZTF’s Bright Transient Survey (BTS) program that was dedicated to the supernova search.
Video Spotlight
The man behind the 2024 Shaw Prize
In May last year, the Shaw Prize Foundation announced the recepients of their prestigious awards in Astronomy, Life Science and Medicine and Mathematics. Shri Kulkarni, a professor of astronomy and planetary sciences at Caltech and the principal investigator of the Zwicky Transient Facility was the laureate in Astronomy, the award recognizing his significant contributions to time-domain astronomy and our understanding of the transient universe.
Shri Kulkarni took the idea of automating the discovery of transients and turned it into reality with the PTF, iPTF and now ZTF international partnerships. Each phase of the project expanded the capabilities of the observing facilities and last year, ZTF was the first group to aanounce fully automated discovery process from detection to announcement to the wider community thanks to machine learning and AI algorithms. Currently, the ZTF manages the largest supernova survey, the Bright Transient Survey, which recently announced it has recorded more than 10000 objects.
This video will take us behind the scene of the Shaw Prize glamour and reveal who Shri Kulkarni is, what has fueled his ambition and dedication to science and who has supported him along the way.
ZTF Public Data Release 23
This is the final public data release from ZTF for the ZTF-O4 extension which covered the period between Sept 2023 and Dec 2024. Thanks to continuing funding from the National Science Foundation ZTF will continue operations in 2025 and 2026. Public releases will continue in the next two year. Their frequency and data products are currently being defined. Stay tuned for update on our website or our X account @ztfsurvey.
This release adds 4 months of observations to the twenty-second data release, up to 31 October 2024 for the public portion of the survey, and private survey time prior to 30 June 2023. The products include 61.3 million single-exposure images, 178 thousand co-added images, accompanying source catalog files containing 937 billion source detections extracted from those images, and 4.97 billion light curves constructed from the single-exposure extractions.
Science Highlights
The ELEPHANT alert pipeline for astronomical transients
In this paper, authors present the ExtragaLactic alErt Pipeline for Hostless AstroNomical Transients (ELEPHANT), a framework for filtering hostless transients in astronomical data streams. Initial results show that ELEPHANT is an effective strategy to filter extragalactic events within large and complex astronomical alert streams. This study confirms the feasibility and usefulness of developing specially crafted pipelines that enable a variety of scientific studies based on large-scale surveys.
Variability of Central Stars of Planetary Nebulae
Bhattacharjee, Soumyadeep et al.,
Authors have undertaken a systematic study of optical photometric variability of cataloged Central Stars of Planetary Nebulae (CSPNe), using the epochal photometric data from the Zwicky Transient Facility (ZTF). By applying appropriate variability metrics, they arrive at a list of 94 significantly variable CSPNe. Based on the timescales of the light-curve activity, these are classifed broadly into short- and long-timescale variables.
A study of Type Ia supernovae using their host environment
In this paper, authors make use of two-dimensional image decomposition to model the host galaxies of SNe Ia. They model elliptical galaxies as well as disk/spiral galaxies with or without central bulges and bars. This allows for the categorisation of SN Ia based on their morphological host environment, as well as the extraction of intrinsic galaxy properties corrected for both cosmological and atmospheric effects.
ZTF Faces
Brodie Popovic
(IN2P3, France)
I am from the sunshine state itself, Florida! Though I typically just tell people North Carolina, since it is where I spent the last 6 years of my life.
Read On
Theophile du Laz
(Caltech, USA)
I come from Paris, in France. I grew up and mostly studied there before I started traveling to different corners of the world.
Read OnZTF Science Vlog
The ZTF vlog brings you the latest ZTF results presented by the authors themselves.
Automated supernova classification
In this science vlog, PhD student at Caltech Yashvi Sharma present a new system for automated classifiction of supernova dubbed CCSNscore. The system uses machine learning to combine detection and light curve data from ZTF with classification data from the SEDM to automatically assign a probability score for supernova discoveries.
Community science with ZTF
We highlight scientific publications from individuals and groups outside of the ZTF partnership that use ZTF public data
Tuning into spatial frequency space: Satellite and space debris detection in the ZTF alert stream
[Abstract]
A significant challenge in the study of transient astrophysical phenomena is the identification of bogus events, with
human-made Earth-orbiting satellites and debris remain a key contaminant. Existing pipelines effectively identify
satellite trails but can miss more complex signatures, such as collections of dots known as satellite glints. In
the Rubin Observatory era, the scale of the operations will increase tenfold with respect to its precursor, the
Zwicky Transient Facility (ZTF), requiring crucial improvements in classification purity, data compression,
pipeline speed and more. We explore the use of the 2D Fast Fourier Transform (FFT) on difference images as a
tool to improve satellite detection algorithms. Adopting the single-stamp classification model from the
Automatic Learning for the Rapid Classification of Events (ALeRCE) broker as a baseline, we adapt its
architecture to receive a cutout of the FFT of the difference image, in addition to the three (science,
reference, difference) ZTF image cutouts (hereafter stamps). We study different stamp sizes and resolutions
for these four channels, aiming to assess the benefit of including the FFT image, especially in scenarios
with data compression and processing speed requirements (e.g., for surveys like the Legacy Survey of Space
and Time). The inclusion of the FFT improved satellite detection accuracy, with the most notable increase
observed in the model with the smallest field of view (16''), where accuracy rose from 66.9% to 79.7% (a
statistically significant improvement of ~13% with a 95% confidence interval of 7.8% to 17.8%). This
result demonstrates the effectiveness of FFT in compressing relevant information and extracting features
that characterize satellite signatures in larger difference images. We show how FFTs can be leveraged to
cull satellite and space debris signatures from alert streams.
ZTF is supported by the National Science Foundation and a collaboration including the following universities
: University of
Maryland, College Park, USA; University of Wisconsin,
Milwaukee, USA; Drexel University, USA; Cornell University, USA; University of California, Berkeley; University of North Caroline Chapel Hill, USA;
Institute of Science and Technology, Austria;
IPAC, Caltech, USA; Caltech, USA. Operations are conducted
by COO, IPAC and University of Washington.
Any opinions, findings, and conclusions or
recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the National Science Foundation.