{
  "bibcode": "2023GCN.33898....1A",
  "circularId": 33898,
  "createdOn": 1685503947519,
  "submitter": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
  "subject": "LIGO/Virgo/KAGRA S230527ch: Zwicky Transient Facility observations",
  "body": "Akash Anumarlapudi (UWM), Tomas Ahumada (CIT), Viraj Karambelkar (CIT),\nRobert Stein (CIT), Gaurav Waratkar (IITB), Anirudh Salgundi (IITB),\nVishwajeet Swain (IITB), Theophile du Laz (CIT), Igor Andreoni (UMD),\nMichael Coughlin (UMN), Mansi Kasliwal (CIT), Varun Bhalerao (IITB), Simeon\nReusch (DESY), Jannis Necker (DESY), Shreya Anand (CIT), Eric Bellm (UW),\nD. Perley (LJMU), D. Kaplan (UWM), S.B. Cenko (UMD) report on behalf of the\nZTF and GROWTH collaborations:\n\n\nWe observed the localization region of LVC trigger S230527ch as part of\nroutine Zwicky Transient Facility (ZTF; Graham et al., 2019; Bellm et al.,\n2019) survey operations. We obtained images in the r, i, and g bands\nbeginning at ~9 hours after the burst trigger time and covering ~20% of the\nprobability enclosed in the localization region (18 % with galactic\nlatitude |b|>10, 2 % with |b|<10).\n\n\nWe queried the ZTF alert stream using Kowalski (Duev et al. 2019) through\nFritz (Coughlin et al. 2023) and emgwcave (Karambelkar et al. in prep),\nAMPEL (Nordin et al. 2019), and ZTFReST (Andreoni & Coughlin et al., 2021).\nWe required at least 2 detections separated by at least 15 minutes to\nselect against moving objects. Furthermore, we cross-match our candidates\nwith the Minor Planet Center to flag known asteroids, reject stellar\nsources (Tachibana and Miller 2018), and apply machine learning algorithms\n(Mahabal et al. 2019). We require that no spatially coincident ZTF alerts\nwere issued before the detection time of the LVC trigger. We also run\nforced photometry on ZTF images (Masci et al. 2019) and ATLAS images (Tonry\net al. 2018, Smith et al. 2020) and require no detections before the LVC\ntrigger.\n\n\nTwo sources passed our criteria and are inside the 95% error region:\n\n|-----------------------------------------------------------------------------------------------------\n| id           | alias                |       ra  |     dec      |     mjd\n    | mag±err (ab)   | filter   | comments                      |\n|-----------------------------------------------------------------------------------------------------------------\n| ZTF23aamnsjs | AT2023jtu            | 280.2040  | -20.6598     |\n60094.23830 | 19.20±0.14     | r        |\n| ZTF23aamdode | AT2023jpc            | 257.1902  | 8.9143       |\n60092.3303  | 17.83±0.01     | r        | likely a CV based on spectrum    |\n|----------------------------------------------------------------------------------------------------------------\n\nWe obtained a spectrum of AT2023jpc with the SEDM spectrograph on the\n60-inch telescope at Palomar Observatory (Blagorodnova et al. 2017). The\nspectrum shows a blue, featureless continuum indicating that this transient\nis a cataclysmic variable (CV).\n\nFurther follow-up of this localization region will continue as part of\nregular survey operations.\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. GROWTH acknowledges generous support of the NSF under PIRE Grant\nNo 1545949. Alert distribution service provided by DIRAC@UW (Patterson et\nal. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019)\nand Kowalski (Duev et al. 2019). GROWTH India telescope is located at the\nIndian Astronomical Observatory (Hanle), operated by the Indian Institute\nof Astrophysics (IIA). GROWTH-India project is supported by SERB and\nadministered by IUSSTF, under grant number IUSSTF/PIRE\nProgram/GROWTH/2015-16 and IUCAA.\n",
  "eventId": "LIGO/Virgo/KAGRA S230527ch"
}