{
  "bibcode": "2019GCN.24130....1A",
  "body": "Authors: Tomas Ahumada (UMD), S. Bradley Cenko (NASA GSFC), Michael W.\nCoughlin (Caltech), Eric C. Bellm (UW), Leo P. Singer (NASA GSFC), Shaon\nGhosh (UWM), Mansi M. Kasliwal (Caltech), Shreya Anand (Caltech), Igor\nAndreoni (Caltech), Scott Adams (Caltech), Matt Hankins (Caltech), Varun\nBhalerao (IITB), Harsh Kumar (IITB), V. Zach Golkhou (UW) on behalf of the\nZTF and GROWTH collaborations and the KPED team\n\nWe observed the localization region of the short GRB190406B (trigger\n576241792) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi\nsatellite with the Palomar 48 inch telescope equipped with the 47 square\ndegree Zwicky Transient Facility (ZTF) camera. We obtained a series of r-\nand g-band images covering 268 square degrees beginning at 08:01 UT on 2019\nApril 08 (44:52 hours after the burst trigger time). This corresponds to ~\n44% of the probability enclosed in the intersection of the GBM and IPN\nlocalization regions. We revisited the region on 2019 April 11, starting at\n08:03 UT (116:54 hours after the burst trigger time) and we covered the\nsame ~ 44% of the probability region.\n\nThe images were processed through the ZTF reduction and image subtraction\npipelines at IPAC to search for potential counterparts. 240\nhigh-significance transient and variable candidates were identified by our\npipeline in the area observed, 236 of which had previous detections with\nZTF in the days and weeks prior to the GRB trigger time (e.g., supernovae,\nactive galactic nuclei).\n\nFurther follow-up of 4 transients was obtained with the Kitt Peak EMCCD\nDemonstrator (KPED) on the Kitt Peak 84-inch telescope on April 12.\nAdditionally, we obtained follow-up spectroscopy of 2 candidates with the\nDouble Spectrograph (DBSP) on Palomar 200��� the nights of April 12. The\ncandidates are listed below, however no photometric evolution or spectral\nclassification was consistent with an optical counterpart.\n\n----------------------------------------------------------------------------------------------------------------------------\n\n       ZTF ID            RA DEC         last non-detection discovery   KPED\nClass\n\n----------------------------------------------------------------------------------------------------------------------------\n\n\n                                 deg deg date in 2019       April 08 April\n12\n\n----------------------------------------------------------------------------------------------------------------------------\nZTF19aapgbri    275.504094 +55.964483    04-07 r<20.41    g = 21.36\n  g=20.76        SN Ia\nZTF19aapgdcn  285.158686 +69.881810     04-04 r<19.49    g = 20.67   g=21.74\n       SN Ia\n\nZTF19aapfxqv     276.915046 +65.626121    04-04 r<17.61    g=20.67\n  g=20.67    SN*\n\nZTF19aapwbgo   278.519641 +57.057325    04-07 r<20.35    g=21.61   g=22.36\n   SN*\n\n-------------------------------------------------------------------------------------------------------------------------\n\n*Classification from photometric data points.\n\n\nThe median 5 sigma upper limit for an isolated point source in our images\nwas r > 21.5 and g > 21.8 mag for the observations made on April 8 26 and r\n> 21.9 and g > 21.6 mag for the observations made on April 11.\n\nZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266\n<http://www.astronomerstelegram.org/?read=11266>), and includes IPAC; WIS,\nIsrael; OKC, Sweden; JSI/UMd, USA; UW, USA; DESY, Germany; NRC, Taiwan; UW\nMilwaukee, USA and LANL USA. ZTF acknowledges the generous support of the\nNSF under AST MSIP Grant No 1440341. Alert distribution service provided by\nDIRAC@UW. Alert filtering is being undertaken by the GROWTH marshal system,\nsupported by NSF PIRE grant 1545949.",
  "circularId": 24130,
  "createdOn": 1555625212000,
  "email": "tahumada@astro.umd.edu",
  "subject": "GRB 190406B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 576241792)",
  "submitter": "Tomas Ahumada at U. of Maryland  <tahumada@astro.umd.edu>",
  "eventId": "GRB 190406B"
}