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The Zwicky Transient Facility: Data Processing, Products, and Archive

Masci, Frank J. and Laher, Russ R. and Rusholme, B. and Shupe, D. L. and Groom, Steven and Surace, J. and Jackson, Edward and Monkewitz, Serge and Beck, R. and Flynn, David and Terek, Scott and Landry, Walter and Hacopians, Eugean and Desai, Vandana and Howell, Justin and Brooke, Timothy Y. and Imel, D. and Wachter, Stefanie and Ye, Quan-Zhi and Lin, Hsing-Wen and Cenko, S. B. and Cunningham, Virginia and Rebbapragada, U. D. and Bue, B. D. and Miller, Adam A. and Mahabal, Ashish and Bellm, Eric C. and Patterson, Maria T. and Jurić, Mario and Golkhou, V. Zach and Ofek, Eran O. and Walters, Richard and Graham, Matthew J. and Kasliwal, Mansi M. and Dekany, Richard G. and Kupfer, T. and Burdge, Kevin B. and Cannella, C. and Barlow, Thomas and Van Sistine, Angela and Giomi, Matteo and Fremling, Christoffer and Blagorodnova, N. and Levitan, David and Riddle, Reed and Smith, Roger and Helou, G. and Prince, Thomas A. and Kulkarni, S. R. (2019) The Zwicky Transient Facility: Data Processing, Products, and Archive. Publications of the Astronomical Society of the Pacific, 131 (995). Art. No. 018003. ISSN 0004-6280. doi:10.1088/1538-3873/aae8ac.

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The Zwicky Transient Facility (ZTF) is a new robotic time-domain survey currently in progress using the Palomar 48-inch Schmidt Telescope. ZTF uses a 47 square degree field with a 600 megapixel camera to scan the entire northern visible sky at rates of ~3760 square degrees/hour to median depths of g ~ 20.8 and r ~ 20.6 mag (AB, 5σ in 30 sec). We describe the Science Data System that is housed at IPAC, Caltech. This comprises the data-processing pipelines, alert production system, data archive, and user interfaces for accessing and analyzing the products. The real-time pipeline employs a novel image-differencing algorithm, optimized for the detection of point-source transient events. These events are vetted for reliability using a machine-learned classifier and combined with contextual information to generate data-rich alert packets. The packets become available for distribution typically within 13 minutes (95th percentile) of observation. Detected events are also linked to generate candidate moving-object tracks using a novel algorithm. Objects that move fast enough to streak in the individual exposures are also extracted and vetted. We present some preliminary results of the calibration performance delivered by the real-time pipeline. The reconstructed astrometric accuracy per science image with respect to Gaia DR1 is typically 45 to 85 milliarcsec. This is the RMS per-axis on the sky for sources extracted with photometric S/N ≥ 10 and hence corresponds to the typical astrometric uncertainty down to this limit. The derived photometric precision (repeatability) at bright unsaturated fluxes varies between 8 and 25 millimag. The high end of these ranges corresponds to an airmass approaching ~2—the limit of the public survey. Photometric calibration accuracy with respect to Pan-STARRS1 is generally better than 2%. The products support a broad range of scientific applications: fast and young supernovae; rare flux transients; variable stars; eclipsing binaries; variability from active galactic nuclei; counterparts to gravitational wave sources; a more complete census of Type Ia supernovae; and solar-system objects.

Item Type:Article
Related URLs:
URLURL TypeDescription
Masci, Frank J.0000-0002-8532-9395
Laher, Russ R.0000-0003-2451-5482
Rusholme, B.0000-0001-7648-4142
Shupe, D. L.0000-0003-4401-0430
Groom, Steven0000-0001-5668-3507
Surace, J.0000-0001-7291-0087
Desai, Vandana0000-0002-1340-0543
Imel, D.0000-0002-6118-7396
Ye, Quan-Zhi0000-0002-4838-7676
Lin, Hsing-Wen0000-0001-7737-6784
Cenko, S. B.0000-0003-1673-970X
Cunningham, Virginia0000-0003-2292-0441
Rebbapragada, U. D.0000-0002-2560-3495
Bue, B. D.0000-0002-7856-3570
Miller, Adam A.0000-0001-9515-478X
Mahabal, Ashish0000-0003-2242-0244
Bellm, Eric C.0000-0001-8018-5348
Patterson, Maria T.0000-0002-4753-3387
Jurić, Mario0000-0003-1996-9252
Golkhou, V. Zach0000-0001-8205-2506
Ofek, Eran O.0000-0002-6786-8774
Walters, Richard0000-0002-1835-6078
Graham, Matthew J.0000-0002-3168-0139
Kasliwal, Mansi M.0000-0002-5619-4938
Dekany, Richard G.0000-0002-5884-7867
Kupfer, T.0000-0002-6540-1484
Burdge, Kevin B.0000-0002-7226-836X
Cannella, C.0000-0003-2667-7290
Van Sistine, Angela0000-0003-4131-173X
Fremling, Christoffer0000-0002-4223-103X
Blagorodnova, N.0000-0003-0901-1606
Riddle, Reed0000-0002-0387-370X
Smith, Roger0000-0001-7062-9726
Helou, G.0000-0003-3367-3415
Prince, Thomas A.0000-0002-8850-3627
Kulkarni, S. R.0000-0001-5390-8563
Additional Information:© 2018. The Astronomical Society of the Pacific. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2018 July 14; accepted 2018 October 15; published 2018 December 7. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. Major funding has been provided by the U.S National Science Foundation under Grant No. AST-1440341 and by the ZTF partner institutions: the California Institute of Technology, the Oskar Klein Centre, the Weizmann Institute of Science, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron, the University of Wisconsin-Milwaukee, and the TANGO Program of the University System of Taiwan. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The High Performance Wireless Research & Education Network (HPWREN; is a project at the University of California, San Diego and the National Science Foundation (grant numbers 0087344 (in 2000), 0426879 (in 2004), and 0944131 (in 2009)). This work has made use of data from the European Space Agency (ESA) mission Gaia (,processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This work has also made use of the Pan-STARRS1 (PS1) Surveys (http://ps and the PS1 public science archive ( Facilities: PO:1.2 m - , PO:1.5m - .
Group:Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility, Astronomy Department
Funding AgencyGrant Number
ZTF partner institutionsUNSPECIFIED
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:astronomical databases: miscellaneous – catalogs – methods: data analysis – techniques: image processing – techniques: photometric
Issue or Number:995
Record Number:CaltechAUTHORS:20181207-084047467
Persistent URL:
Official Citation:Frank J. Masci et al 2019 PASP 131 018003
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91561
Deposited By: George Porter
Deposited On:07 Dec 2018 21:22
Last Modified:16 Nov 2021 03:42

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