{
  "body": "Harsh Kumar (IITB), Vishwajeet Swain (IITB), Anirudh Salgundi (IITB), Aswin\nSuresh (IITB), Tomas Ahumada (CIT), Viraj Karambelkar (CIT), Robert Stein\n(CIT), Theophile du Laz (CIT), Igor Andreoni (UMD), Michael Coughlin (UMN),\nMansi Kasliwal (CIT), Simeon Reusch (DESY), Jannis Necker (DESY), Shreya\nAnand (CIT), report on behalf of the ZTF collaboration:\n\nWe observed the localization region of the short GRB 230513A (trigger\n705709044, GCN 33793) detected by the Gamma-Ray Burst Monitor (GBM) on the\nFermi satellite with the Palomar 48 inch telescope equipped with the 47\nsquare degree Zwicky Transient Facility (ZTF) camera. We obtained a series\nof g- and r-band images covering 410 square degrees beginning at\n2023-05-14T03:42:31.003 (5 hours after the burst trigger time). This\ncorresponds to ~72% of the probability enclosed in the Earth-occultation\ncorrected GRB localization map. Each exposure was 300 seconds, reaching\ng-band and r-band median depths of 22.2 mag and 22.0 mag respectively. The\nimages were processed in real-time through the ZTF reduction and image\nsubtraction pipelines at IPAC (Masci et al. 2019).\n\nWe queried the ZTF alert stream using Kowalski (Duev et al. 2019) through\nFritz (Coughlin et al. 2023) and AMPEL (Nordin et al. 2019). We required at\nleast 2 detections separated by at least 15 minutes to select against\nmoving objects. Furthermore, we cross-match our candidates with the Minor\nPlanet Center to flag known asteroids, reject stellar sources (Tachibana\nand Miller 2018), and apply machine learning algorithms (Mahabal et al.\n2019). We require that no spatially coincident ZTF alerts were issued\nbefore the detection time of the GBM trigger. Close to 120 sources were\ntime and spatially coincident with the burst, most of them showing g-r ~ 0\nmag and a slow evolution. We highlight the sources that show red colors\n(i.e. g-r > 0.3 mag) in the table below, and we encourage follow up.\n\n\nZTF name , AT name , UT first alert , t-t0 , filter , mag , error\n-----------------------------------------------------------------------------------------------\nZTF23aajklxl , AT 2023ilp , 2023-05-14 03:42:31.003 , 0.23 , r , 21.44 ,\n0.14\nZTF23aajkqkc , AT 2023ilq , 2023-05-14 03:58:01.998 , 0.24 , r , 20.59 , 0.1\nZTF23aajkuyh , AT 2023ilr , 2023-05-14 04:18:53.001 , 0.25 , r , 21.56 ,\n0.13\nZTF23aajlbzl , AT 2023ils , 2023-05-14 04:46:40.002 , 0.27 , g , 21.61 ,\n0.15\nZTF23aajktjd , AT 2023ilt , 2023-05-14 04:13:34.003 , 0.25 , r , 21.77 ,\n0.17\n\n\nZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,\nUSA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,\nGermany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;\nIITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.\nZTF acknowledges the generous support of the NSF under AST MSIP Grant No\n1440341.\nGROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.\nAlert distribution service provided by DIRAC@UW (Patterson et al. 2019).\nAlert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski\n(Duev et al. 2019). GROWTH India telescope is located at the Indian\nAstronomical Observatory (Hanle), operated by the Indian Institute of\nAstrophysics (IIA). GROWTH-India project is supported by SERB and\nadministered by IUSSTF, under grant number IUSSTF/PIRE\nProgram/GROWTH/2015-16 and IUCAA.\n\n\n\n\n-- \nTomás Ahumada (he/him)\nPh.D. Candidate\nDepartment of Astronomy\nUniversity of Maryland, College Park\nNASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661\nB.Sc. Astronomy, Pontificia Universidad Católica de Chile\n",
  "subject": "GRB 230513A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)",
  "eventId": "GRB 230513A",
  "createdOn": 1684112815026,
  "submitter": "Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>",
  "circularId": 33801,
  "bibcode": "2023GCN.33801....1K"
}