{
  "bibcode": "2019GCN.25447....1J",
  "body": "J. Japelj (Univ. of Amsterdam), Z. Jin (PMO), E. Kankare (Univ. Turku), \nE. Kool (OKC), A. J. Levan (Radboud Univ.), K. Maguire (TCD), D. B. \nMalesani (DTU Space), S. Mattila (Univ. Turku), B. Milvang-Jensen \n(DAWN/NBI), T. Reynolds (Univ. Turku), N. B. Sabha (Univ. Innsbruck), A. \nSagues Carracedo (Stockholm Univ.), report on behalf of the ENGRAVE \ncollaboration:\n\nENGRAVE targeted 9 fields containing 17 high-probability host galaxies \nfor S190814bv, based on the LALInference skymap (LIGO Scientific \nCollaboration and Virgo Collaboration, GCN 25333), with deep VLT/HAWK-I \nimaging over two epochs in a search for intrinsically faint, near \ninfrared transient sources. As part of this search, we observed the host \ngalaxy 2MASX J00472894-2526263 of the Canada-France-Hawaii Telescope \n(CFHT) candidate reported by Ruan et al. (GCN 25443).\n\nThe observations were conducted between 06:55 and 07:14 UT on 2019-08-16 \nand a second epoch between 04:32 and 04:50 UT on 2019-08-21, \napproximately 1.4 and 6.3 d after S190814bv, respectively (600 s \nexposure per epoch in the Ks filter). The source is detected in both \nepochs with AB magnitudes of 21.0 +- 0.1 and 20.9 +- 0.1, respectively \n(based on preliminary photometry calibrated against the 2MASS catalogue).\n\nThis field was also covered serendipitously by the ESO/VISTA survey \ntelescope in the Ks band during the science verification program. The \nCFHT candidate is detected in images from 2009-10-23 and 2009-10-30. We \nmeasure a brightness around 0.5 mag fainter in the historic data \ncompared to the HAWK-I measurement. This confirms some level of \nlong-term variability, consistent with the report by Ruan et al. (GCN \n25443).\n\nThe lack of variability between the two VLT/HAWK-I images and especially \nthe archival detection suggest that this object is unrelated to S190814bv.\n\nWe acknowledge the ESO observing staff at Paranal, in particular S. \nBrillant, J. Corral-Santana, B. Haussler, C. Opitom, F. J. Selman, and \nT. Szeifert. Based on observations collected by the ENGRAVE \ncollaboration at the European Southern Observatory under ESO program \n0103.D-0722 (for further information on ENGRAVE see \nhttp://www.engrave-eso.org/). The VISTA data were secured under science \nverification program 60.A-9285(A). We acknowledge valuable help with the \narchival VISTA data by Carlos Gonzalez-Fernandez (CASU / IoA Cambridge).\n\n[GCN OPS NOTE(23aug19): Per author's request, The \"Drout\" references\nin the 1st and 3 paragraphs were changed to \"Ruan\".]",
  "circularId": 25447,
  "createdOn": 1566482783000,
  "email": "malesani@space.dtu.dk",
  "subject": "LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate",
  "submitter": "Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>",
  "eventId": "LIGO/Virgo S190814bv"
}