Electronic Telegram No. 3164
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


V1647 ORIONIS
     J. P. Ninan, D. K. Ojha, K. K. Mallick, S. K. Ghosh, and J. S. Joshi,
Tata Institute of Fundamental Research (TIFR), Mumbai; and B. C. Bhatt, Indian
Institute of Astrophysics, Bangalore, report a slow dimming of the young
eruptive star V1647 Ori (cf. IAUCs 8284, 8354, 8396, 8600, 8681, 8694, 8968,
8969, 9006, 9079; CBETs 1596, 2104, 2647) from long term optical and
near-infrared (NIR) photometric observations made with the 2-m IUCAA Girawali
Telescope (+ IFOSC spectrograph and TIFR Near Infrared Camera, TIRCAM2) at
Girawali (Pune) and the 2-m Himalayan Chandra telescope (+ HFOSC spectrograph
and NIR camera) at Hanle (Ladakh).  Representative optical magnitudes of
V1647 Ori are:  2008 Sept. 28 UT, V = 18.95 +/- 0.03, R = 17.01 +/- 0.01, I =
14.96 +/- 0.01; 2012 Jan. 17, V = 19.21 +/- 0.04, R = 17.26 +/- 0.02, I =
15.24 +/- 0.02.  During the period 2009-2012, the source brightness shows a
linear dimming trend of about 0.3 mag in the R and I bands.  This linear
dimming trend is also present in the brightness of a Herbig-Haro object
illuminated by the source.  The observations during the period Jan.-Feb. 2012
show an increase in dimming rate, but it can be confirmed only after the
source becomes visible once again in 2012.  A similar trend is also seen in
the following NIR magnitudes:  2009 Oct. 24 UT, J = 10.71 +/- 0.05, H = 8.88
+/- 0.05, K = 7.44 +/- 0.02 (using NIR camera); 2011 Dec. 4, J = 11.24 +/-
0.1, H = 9.25 +/- 0.1, K =  8.08 +/- 0.1 (using TIRCAM2).  The source
brightness has therefore dimmed by about 0.5 mag in the NIR bands during the
period 2009-2011.  V1647 Ori has undergone an unexpected second outburst in
2008 after the first outburst in late 2003, which lasted for about 2 years
until early 2006 (Ojha et al. 2006, MNRAS 368, 825; Aspin et al. 2009, Ap.J.
692, L67; Aspin et al. 2011, A.J. 142, 135, and references therein).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2012 CBAT
2012 July 4                      (CBET 3164)              Daniel W. E. Green