LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate
Abstract
ENGRAVE targeted 9 fields containing 17 high-probability host galaxies for S190814bv, based on the LALInference skymap (LIGO Scientific Collaboration and Virgo Collaboration, GCN 25333), with deep VLT/HAWK-I imaging over two epochs in a search for intrinsically faint, near infrared transient sources. As part of this search, we observed the host galaxy 2MASX J00472894-2526263 of the Canada-France-Hawaii Telescope (CFHT) candidate reported by Ruan et al. (GCN 25443). The observations were conducted between 06:55 and 07:14 UT on 2019-08-16 and a second epoch between 04:32 and 04:50 UT on 2019-08-21, approximately 1.4 and 6.3 d after S190814bv, respectively (600 s exposure per epoch in the Ks filter). The source is detected in both epochs with AB magnitudes of 21.0 +- 0.1 and 20.9 +- 0.1, respectively (based on preliminary photometry calibrated against the 2MASS catalogue). This field was also covered serendipitously by the ESO/VISTA survey telescope in the Ks band during the science verification program. The CFHT candidate is detected in images from 2009-10-23 and 2009-10-30. We measure a brightness around 0.5 mag fainter in the historic data compared to the HAWK-I measurement. This confirms some level of long-term variability, consistent with the report by Ruan et al. (GCN 25443). The lack of variability between the two VLT/HAWK-I images and especially the archival detection suggest that this object is unrelated to S190814bv. We acknowledge the ESO observing staff at Paranal, in particular S. Brillant, J. Corral-Santana, B. Haussler, C. Opitom, F. J. Selman, and T. Szeifert. Based on observations collected by the ENGRAVE collaboration at the European Southern Observatory under ESO program 0103.D-0722 (for further information on ENGRAVE see http://www.engrave-eso.org/). The VISTA data were secured under science verification program 60.A-9285(A). We acknowledge valuable help with the archival VISTA data by Carlos Gonzalez-Fernandez (CASU / IoA Cambridge). [GCN OPS NOTE(23aug19): Per author's request, The "Drout" references in the 1st and 3 paragraphs were changed to "Ruan".]
- Publication:
-
GRB Coordinates Network
- Pub Date:
- August 2019
- Bibcode:
- 2019GCN.25447....1J