TITLE: GCN CIRCULAR NUMBER: 27057 SUBJECT: LIGO/Virgo S191213g: AT2019wxt Wendelstein optical observations DATE: 20/02/13 13:47:49 GMT FROM: Ulrich Hopp at U Observatory Munich Ulrich Hopp, Matthias Kluge, Claus Goessl, Christoph Ries, Michael Schmidt (University Observatory Munich, LMU, Munich Germany) AT2019wxt = PS19hgw was reported as a potential optical counterpart for the LIGO/Virgo S191213g target at RA = 01:55:41.94, Dec = +31:25:04.4, McBrien et al. 2019 (GCN26485). Follow-up photometry pointed towards a blue and fastly faiding object (Huber et al. 2019, GCN 26577). Follow-up spectroscopy favored the identification as a supernova similar to SN2011fu of type SN IIb (Valeev et al. 2019, GCN 26591 and references therein). We here present three channel optical and near-infrared photometry in g', i' and J taken with the 3KK camera (Lang-Bardl et al., 2016, SPIE 9908) mounted at the 2m telescope of the Wendelstein Observatory (University of Munich). Five epochs were obtained from shortly after detection until about 20 days after maximum. A further image set was taken after the SN faded below our detection limit. That image served for difference image photometry of the SN to minimize the impact of the host galaxy light on the SN photometry. The SN location is within the disk of the spiral host galaxy KUG 0152+311. On our images, the SN appears to be in a inter-arm area of the spiral galaxy. Eigth comparison stars within the detector field served as magnitude reference for our aperture photometry. Magnitudes were obtained through the CDS Strassbourg portal from SDSS DR9 (g', i') and 2MASS (J) catalogs. Errors in the below table include the statistical error of the SN measurement and of the zero-point determination. Date UT g' +/- i' +/- J +/- exp.time sec 2019 12 18 19.78 0.08 20.10 0.09 20.26 0.08 1560 2019 12 19 19.83 0.11 19.84 0.09 19.18 0.11 2340 2019 12 21 20.10 0.06 19.83 0.06 18.96 0.10 1560 2019 12 29 22.77 0.05 20.92 0.06 19.75 0.11 1560 2020 01 06 23.68 0.08 22.64 0.07 20.69 0.12 1560 2020 01 14 <24.0 <22.7 <21.0 Our data around the maximum agree with previously reported optical photometry (e.g. CGN 26485, 26500, 26503, 26517, 26577). Only one NIR observation was reported so far (D'Avanco et al. 2019 GCN 26499). Our data show that the object was very blue in the maximum phase but turned to a much redder color during the decline. The decline was fast with a rate of delta mag/5d 1.12 in g', 0.80 in i', and 0.54 in J, respectively. Our decline rates confirm the early estimate of Huber et al. in g' and i' obtained shortly after maximum. These rates are much faster than the decline of SN2011fu (see Kumar et al. 2013 MNRAS 431, 308). *************************************************************************** * Dr. Ulrich Hopp * *************************************************************************** * Universitaetssternwarte Muenchen * Tel.: + 89 2180 5997 * * Scheiner Str. 1 * Fax.: + 89 2180 6003 * * D 81679 Muenchen * Tel.-MPE: + 89 30000 3913 * * Germany * email: * * und * hopp@usm.uni-muenchen.de * * MPI f. Extraterrestische Physik * hopp@usm.lmu.de * * Postfach 1312 * hopp@mpe.mpg.de * * 85741 Garching * * *************************************************************************** * http://www.usm.lmu.de/people/hopp/hopp.html * ***************************************************************************