[vsnet-alert 16729] 1RXS J041924.8+653006 outburst (13.9m)

[Denis Denisenko]

MASTER-Kislovodsk has detected an optical transient in Camelopardalis
MASTER OT J041923.57+653004.3 which is related to the ROSAT X-ray
source 1RXS J041924.8+653006 (0.050+/-0.012 cnts/s, HR1=0.90+/-0.20,
HR2=0.75+/-0.16). The variability was detected by me back in December
2006 when I have started endless work on identifying new cataclysmic
variables among the poorly studied ROSAT sources. 1RXS
J041924.8+653006 was #6 in the very first list of northern sources
with 0 identification candidates in the correlation catalogue (with #3
in that list being 1RXS J020929.0+283243 which turned out to be Deeply
Eclipsing CV in Triangulum)!

1RXS J041924.8+653006 was a tough target. No large-amplitude
variability was detected at quiescence. It was abandoned for a few
years. Then a spectrum was obtained by Alexey Tkachenko with the 1.5-m
Russian-Turkish Telescope, but I have left IKI for Sternberg Astronomy
Institute, and it was never published. The spectrum is showing very
strong He II 4686 line (about 1.5 times stronger than H-beta!), so
that made me think it is a polar (or an intermediate polar) with a
long orbital period. Now we have enough observations with MASTER-Amur
and MASTER-Kislovodsk to see it is a dwarf nova. Unfortunately two
previous outbursts were not detected by automated processing routines.

The object was found in outburst by Pavel Balanutsa. It was published
in ATel #5688 together with two other MASTER transients. Here are the
details about MASTER OT J041923.57+653004.3 = 1RXS J041924.8+653006:

1RXS J041924.8+653006
  20131223.911  13.87C  MASTER-Kislovodsk
  20131223.912  13.87C  MASTER-Kislovodsk
  20131223.913  13.88C  MASTER-Kislovodsk
  20131223.944  13.84C  MASTER-Kislovodsk
  20131223.945  13.89C  MASTER-Kislovodsk
  20131223.946  13.81C  MASTER-Kislovodsk

Color-combined DSS finder chart (note the date!):
http://master.sai.msu.ru/static/OT/J0419+6530-comps.jpg (10'x9' FOV)
MASTER discovery and reference images:
http://master.sai.msu.ru/static/OT/041923.57653004.3.png

Object IDs in other catalogs:
USNO-A2.0 1500-03665468 (04 19 23.58 +65 30 04.1 R=16.7 B=18.5)
USNO-B1.0 1555-0091928 (04 19 23.576 +65 30 04.28 B1=18.76 R1=16.39
B2=16.61 R2=16.84 I=14.35)
2MASS J04192359+6530042 (J=14.48 H=13.98 K=13.71)

Red colors suggest the large contribution from the secondary and the
long orbital period. So don't expect superhumps here. On the other
hand, the variable may be very interesting because of the strong He II
line in spectrum. Follow up observations are encouraged!

Denis Denisenko
Member of MASTER team at SAI MSU