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NIR observations of V404 Cyg with PANIC

ATel #7738; A. W. Shaw, C. Knigge (U. Southampton), K. Meisenheimer (MPIA), J. M. Ibanez (IAA-CSIC)
on 1 Jul 2015; 10:38 UT
Credential Certification: Poshak Gandhi (p.gandhi@soton.ac.uk)

Subjects: Infra-Red, Black Hole, Nova, Transient

Referred to by ATel #: 7751, 7959

We report on NIR photometry of the black hole X-ray transient, V404 Cyg during its current outburst (GCN #17929). The source was observed between 27 Jun 22:47 UT - 29 Jun UT 02:28 with the PANoramic Near Infrared Camera (PANIC) on the 2.2m telescope at the Centro Astronómico Hispano-Alemán (CAHA) on Calar Alto, Spain. 4x5 min integrations were obtained over two nights in each of the J, H and Ks filters (1.2 - 2.2um).

The source shows a steady decline across all wavelengths, with the J-band magnitude decreasing from 11.68 (27 Jun 22:47 UT) to 12.98 (29 Jun 02:13 UT) and a similar response in the H and Ks filters. This significant decrease in NIR flux mirrors that seen at optical wavelengths (ATel #7729; AAVSO light curves), as well as X-rays (ATel #7731) and Radio (ATel #7733). We note that a similar decrease in flux occurred during the 1989 outburst, followed by a partial recovery and a slower decline (Han & Hjellming 1992, ApJ, 400, 304).

57200.95 11.68 11.04 10.40
57201.14 12.56 11.78 11.43
57201.93 12.80 11.98 11.51
57202.09 12.98 12.17 11.78

We intend to continue monitoring V404 Cyg across all wavelengths. Further observations are encouraged.