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Alert Classification for the ALeRCE Broker System: The Real-time Stamp Classifier

Carrasco-Davis, R. and Reyes, E. and Valenzuela, C. and Förster, F. and Estévez, P. A. and Pignata, G. and Bauer, F. E. and Reyes, I. and Sánchez-Sáez, P. and Cabrera-Vives, G. and Eyheramendy, S. and Catelan, M. and Arredondo, J. and Castillo-Navarrete, E. and Rodríguez-Mancini, D. and Ruz-Mieres, D. and Moya, A. and Sabatini-Gacitúa, L. and Sepúlveda-Cobo, C. and Mahabal, A. A. and Silva-Farfán, J. and Camacho-Iñiquez, E. and Galbany, L. (2021) Alert Classification for the ALeRCE Broker System: The Real-time Stamp Classifier. Astronomical Journal, 162 (6). Art. No. 231. ISSN 0004-6256. doi:10.3847/1538-3881/ac0ef1.

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We present a real-time stamp classifier of astronomical events for the Automatic Learning for the Rapid Classification of Events broker, ALeRCE. The classifier is based on a convolutional neural network, trained on alerts ingested from the Zwicky Transient Facility (ZTF). Using only the science, reference, and difference images of the first detection as inputs, along with the metadata of the alert as features, the classifier is able to correctly classify alerts from active galactic nuclei, supernovae (SNe), variable stars, asteroids, and bogus classes, with high accuracy (∼94%) in a balanced test set. In order to find and analyze SN candidates selected by our classifier from the ZTF alert stream, we designed and deployed a visualization tool called SN Hunter, where relevant information about each possible SN is displayed for the experts to choose among candidates to report to the Transient Name Server database. From 2019 June 26 to 2021 February 28, we have reported 6846 SN candidates to date (11.8 candidates per day on average), of which 971 have been confirmed spectroscopically. Our ability to report objects using only a single detection means that 70% of the reported SNe occurred within one day after the first detection. ALeRCE has only reported candidates not otherwise detected or selected by other groups, therefore adding new early transients to the bulk of objects available for early follow-up. Our work represents an important milestone toward rapid alert classifications with the next generation of large etendue telescopes, such as the Vera C. Rubin Observatory.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Carrasco-Davis, R.0000-0003-4673-8791
Reyes, E.0000-0003-3455-9358
Valenzuela, C.0000-0001-5306-1390
Förster, F.0000-0003-3459-2270
Estévez, P. A.0000-0001-9164-4722
Pignata, G.0000-0003-0006-0188
Bauer, F. E.0000-0002-8686-8737
Reyes, I.0000-0003-3627-0216
Sánchez-Sáez, P.0000-0003-0820-4692
Cabrera-Vives, G.0000-0002-2720-7218
Eyheramendy, S.0000-0003-4723-9660
Catelan, M.0000-0001-6003-8877
Arredondo, J.0000-0002-2045-7134
Castillo-Navarrete, E.0000-0002-3648-3839
Ruz-Mieres, D.0000-0002-1292-2374
Moya, A.0000-0002-7003-5087
Mahabal, A. A.0000-0003-2242-0244
Galbany, L.0000-0002-1296-6887
Additional Information:© 2021. The American Astronomical Society. Received 2020 June 30; revised 2021 June 23; accepted 2021 June 25; published 2021 November 5. The authors acknowledge support from the National Agency of Research and Development's Millennium Science Initiative through grant IC12009, awarded to the Millennium Institute of Astrophysics (RC, ER, CV, FF, PE, GP, FEB, IR, PSS, GC, SE, Ja, EC, DR, DRM, MC) and from the National Agency for Research and Development (ANID) grants: BASAL Center of Mathematical Modelling AFB-170001 (CV, FF, IR, ECN, CS, ECI) and Centro de Astrofísica y Tecnologías Afines AFB-170002 (FEB, PSS, MC); FONDECYT Regular #1171678 (PE), #1200710 (FF), #1190818(FEB), #1200495 (FEB), #1171273 (MC), #1201793(GP); FONDECYT Postdoctorado #3200250 (PSS); FONDECYT Iniciación #11191130 (CV); Magíster Nacional 2019 #22190947 (ER). This work was funded in part by project CORFO 10CEII-9157 Inria Chile (PS). The authors acknowledge financial support from the Spanish Ministry of Science, Innovation, and Universities (MICIU) under the 2019 Ramón y Cajal program RYC2019-027683 (LG). Software: Aladin (Bonnarel et al. 2000), Apache ECharts 25 , Apache Kafka 26 , Apache Spark (Zaharia et al. 2016), ASTROIDE (Brahem et al. 2018), Astropy (Astropy Collaboration et al. 2013), catsHTM (Soumagnac & Ofek 2018), Dask (Rocklin 2015), Jupyter 27 , Keras (Chollet et al. 2018), Matplotlib (Hunter 2007), NED (Steer et al. 2016), Pandas (McKinney 2010), Prometheus 28 , Python 29 , scikit-learn (Pedregosa et al. 2011), Simbad-CDS (Wenger et al. 2000), Tensorflow (Martín et al. 2015), Vue 30 , Vuetify 31 , PostgreSQL 32 .
Funding AgencyGrant Number
Iniciativa Científica Milenio del Ministerio de EconomíaIC12009
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1171678
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1200710
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1190818
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1200495
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1171273
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1201793
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3200250
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)11191130
Magster Nacional 201922190947
Corporación de Fomento de la Producción (CORFO)10CEII-9157
Ramón y Cajal ProgrammeRYC2019-027683
Subject Keywords:Astroinformatics; Astrostatistics; Convolutional neural networks; Active galactic nuclei; Supernovae; Variable stars; Small solar system bodies; Classification; Surveys; Transient detection; Time domain astronomy
Issue or Number:6
Classification Code:Unified Astronomy Thesaurus concepts: Astroinformatics (78); Astrostatistics (1882); Convolutional neural networks (1938); Active galactic nuclei (16); Supernovae (1668); Variable stars (1761); Small solar system bodies (1469); Classification (1907)
Record Number:CaltechAUTHORS:20210204-092803262
Persistent URL:
Official Citation:R. Carrasco-Davis et al 2021 AJ 162 231
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107920
Deposited By: George Porter
Deposited On:05 Feb 2021 20:55
Last Modified:08 Nov 2021 18:46

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