[vsnet-alert 14486] 1RXS J165032.3-242643 = ASAS 165033-2426.9 outburst

[Denis Denisenko]

D. Denisenko (IKI/SAI MSU) and K. Sokolovsky (ASC Lebedev/SAI MSU) report:

In April 2011 we have identified the faint ROSAT source 1RXS
J165032.3-242643 with a previously unknown dwarf nova in Ophiuchus
from the difference of the star's magnitudes in USNO-B1.0 catalogue:

USNO-B1.0 0655-0378052
16 50 32.639 -24 26 58.77  pmRA=0  pmDE=0 B1=14.56 R1=14.53 B2=17.71
R2=16.52 I=15.25

The object was obviously in outburst on the POSS-I Red plate taken on
1952 Aug. 22.

We have then analysed 13 available Palomar/NEAT images from five
nights in 2001-2002. The variable was detected in the bright (14.1C)
outburst on three images on 2002 June 04.

Furthermore, at least 9 previous outbursts were detected by ASAS-3,
but not reported anywhere before us:

http://www.astrouw.edu.pl/cgi-asas/asas_variable/165033-2426.9,asas3,0,0,500,0,0

The brightest two of them were on 2004 May 03 (13.41V) and on 2002
Aug. 13 (13.42V).

Inspection of photographic plates from Moscow collection at SAI MSU
has revealed additional archival outbursts on the following dates:
1960 July 22-29 (13.6-14.0B), 1981 July 03 (13.6B), 1988 June 04
(13.8B) and June 16 (14.0B).

One of us (D.D.) has started monitoring the variable with the Bradford
Robotic Telescope back in 2011. The following unfiltered magnitudes
with the Red zeropoint were measured:

  YYYYMMDD(UT)   mag  observer
  20110504.141   160C (Bradford Robotic Telescope)
  20110529.111   159C (Bradford Robotic Telescope)
  20120424.163   138C (Bradford Robotic Telescope)

USNO-A2.0 0600-21843070 (16 50 24.32 -24 25 12.8 R=13.2 B=13.8) was
used as a comparison star. It is labeled as B=13.8 on the 10x10'
finder chart at http://pics.livejournal.com/bigdenru/pic/000cpz6h

The current outburst was detected on the very first image of the field
obtained just 5 days after the Galaxy camera was back online. Many
thanks to BRT staff and IAC engineers who have replaced the faulty
power supply!

The animation of BRT images of J1650.5-2426 at quiescence and in
outburst is available at
http://pics.livejournal.com/bigdenru/pic/000ckdkx/

The new variable is present in 2MASS catalogue with the following
coordinates and magnitudes:
2MASS 16503263-2426592
16 50 32.634 -24 26 59.20 J=13.823+/-0.030 H=13.485+/-0.030 K=13.401+/-0.040
DENIS (not Denis Denisenko!) gives I=15.42+/-0.04 and J=14.61+/-0.14
for this star.

Photometric time series are encouraged.

Denis in Moscow
(on leave from Space Research Institute for MASTER team in Sternberg
Astronomical Institute at MSU)