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The IPAC Image Subtraction and Discovery Pipeline for the intermediate Palomar Transient Factory

Masci, Frank J. and Laher, Russ R. and Rebbapragada, Umaa D. and Doran, Gary B. and Miller, Adam A. and Bellm, Eric and Kasliwal, Mansi and Ofek, Eran O. and Surace, Jason and Shupe, David L. and Grillmair, Carl J. and Jackson, Ed and Barlow, Tom and Yan, Lin and Cao, Yi and Cenko, S. Bradley and Storrie-Lombardi, Lisa J. and Helou, George and Prince, Thomas A. and Kulkarni, Shrinivas R. (2017) The IPAC Image Subtraction and Discovery Pipeline for the intermediate Palomar Transient Factory. Publications of the Astronomical Society of the Pacific, 129 (971). Art. No. 014002. ISSN 0004-6280.

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We describe the near real-time transient-source discovery engine for the intermediate Palomar Transient Factory (iPTF), currently in operations at the Infrared Processing and Analysis Center (IPAC), Caltech. We coin this system the IPAC/iPTF Discovery Engine (or IDE). We review the algorithms used for PSF-matching, image subtraction, detection, photometry, and machine-learned (ML) vetting of extracted transient candidates. We also review the performance of our ML classifier. For a limiting signal-to-noise ratio of 4 in relatively unconfused regions, bogus candidates from processing artifacts and imperfect image subtractions outnumber real transients by ≃10:1. This can be considerably higher for image data with inaccurate astrometric and/or PSF-matching solutions. Despite this occasionally high contamination rate, the ML classifier is able to identify real transients with an efficiency (or completeness) of ≃97% for a maximum tolerable false-positive rate of 1% when classifying raw candidates. All subtraction-image metrics, source features, ML probability-based real-bogus scores, contextual metadata from other surveys, and possible associations with known Solar System objects are stored in a relational database for retrieval by the various science working groups. We review our efforts in mitigating false-positives and our experience in optimizing the overall system in response to the multitude of science projects underway with iPTF.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Masci, Frank J.0000-0002-8532-9395
Laher, Russ R.0000-0003-2451-5482
Rebbapragada, Umaa D.0000-0002-2560-3495
Miller, Adam A.0000-0001-9515-478X
Bellm, Eric0000-0001-8018-5348
Kasliwal, Mansi0000-0002-5619-4938
Ofek, Eran O.0000-0002-6786-8774
Surace, Jason0000-0001-7291-0087
Shupe, David L.0000-0003-4401-0430
Grillmair, Carl J.0000-0003-4072-169X
Yan, Lin0000-0003-1710-9339
Cao, Yi0000-0002-8036-8491
Cenko, S. Bradley0000-0003-1673-970X
Storrie-Lombardi, Lisa J.0000-0002-5987-5210
Helou, George0000-0003-3367-3415
Prince, Thomas A.0000-0002-8850-3627
Kulkarni, Shrinivas R.0000-0001-5390-8563
Additional Information:© 2016 The Astronomical Society of the Pacific. Received 2016 August 5; accepted 2016 September 27; published 2016 December 8. This work was funded in part by the iPTF and ZTF projects at the California Institute of Technology. iPTF is a partnership led by the California Institute of Technology and includes the Infrared Processing & Astronomical Center; Los Alamos National Laboratory; University of Wisconsin at Milwaukee; Oskar-Klein Center of the University of Stockholm, Sweden; Weizmann Institute of Sciences, Israel; University System of Taiwan, Taiwan; the Institute for Physics & Mathematics of the universe, Japan; Lawrence Berkeley National Laboratory and the University of California, Berkeley. ZTF is funded by the National Science Foundation under grant no. AST-144034. M.M.K. acknowledges support from the National Science Foundation PIRE GROWTH award. A.A.M. acknowledges support for this work by NASA from a Hubble Fellowship grant: HST-HF-51325.01, awarded by STScI, operated by AURA, Inc., for NASA, under contract NAS 5-26555. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The pipelines use a number of software packages from other institutions and past projects (see Table 1), for which we are indebted. Portions of the analysis presented here made use of the Perl Data Language (PDL) developed by K. Glazebrook, J. Brinchmann, J. Cerney, C. DeForest, D. Hunt, T. Jenness, T. Lukka, R. Schwebel, and C. Soeller and can be obtained from PDL provides a high-level numerical functionality for the Perl scripting language (Glazebrook & Economou 1997). We thank the anonymous referee for valuable comments that helped improve the quality of this manuscript. Facility: PO:1.2m.
Group:Infrared Processing and Analysis Center (IPAC), Palomar Transient Factory, Astronomy Department
Funding AgencyGrant Number
Intermediate Palomar Transient Facility (iPTF)UNSPECIFIED
Zwicky Transient Facility (ZTF), CaltechUNSPECIFIED
NASA Hubble FellowshipHST-HF-51325.01
NASANAS 5-26555
Subject Keywords:methods: analytical – methods: data analysis – methods: statistical – techniques: image processing – techniques: photometric
Issue or Number:971
Record Number:CaltechAUTHORS:20160817-123122578
Persistent URL:
Official Citation:Frank J. Masci et al 2017 PASP 129 014002
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69707
Deposited By: Joy Painter
Deposited On:17 Aug 2016 21:21
Last Modified:09 Mar 2020 13:19

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