[vsnet-alert 10389] New CV from 1RXS catalog

[Denis Denisenko]

Dear all,

We have just reported the discovery of a new cataclysmic variable in 
Ophiuchus to The Astronomer's Telegram (ATel #1640, 
<http://www.astronomerstelegram.org/?read=1640>).  This is an eclipsing 
polar with a period of 1.68089 hr (100.853 min).  The star's average 
brightness has jumped by 1.0m (from 17.1 to 16.1) between May 31st and 
June 13th, and is still growing (15.7 as of July 27).  It will be 
interesting to follow the general trend in a few next months.

The data in RK catalogue format follow:

J1808+1010   *               18 08 35.8 +10 10 30 1 NL  AM           
15.7   17.0   17.1   18.4              
0.070037                                  1

J1808+1010               = USNO-A2.0 0975-10560872
J1808+1010               = USNO-B1 1001-0317189
J1808+1010               = 2MASS 18083580+1010298

This is the first in a series of cataclysmic variables I have identified 
among the ROSAT X-ray sources during the last year.  There are at least 
6 (six) more CVs waiting for publication, including one dwarf nova 
17.5-13.5m and two very interesting objects with unusually high X-ray to 
optical flux ratio and both long-term and fast variability.  One of them 
may be AM CVn system, the other - possibly neutron star or black dwarf 
transient.  For this one (J1808+1010) we have managed to determine the 
orbital period using "merely" a 30-cm telescope.  The others are fainter 
and require larger scopes to uncover their nature.  For two objects 
currently visible I have asked for observations on 1.5-m telescope in 
Turkey, but RTT150 observing schedule is very dense, and I'm discovering 
more new interesting objects than it can explore. ;-)

As a by-product of searching for X-ray source identifications, I have 
found many new quasars still not published anywhere, a few white dwarfs, 
several common proper motion (CPM) pairs of nearby red dwarfs and at 
least five new RS CVn stars (see PZP 8, 25, 
<http://www.astronet.ru/db/varstars/msg/1227871>).  Btw, there are also 
two new RRAB variables in the field of J1808+1010 to be published in PZP 
soon. :-)

Discovering the new variables is fun, exciting and - believe it or not - 
easy!  Some days I have five or even ten new ones!

Best regards,

Den in Moscow
--
Denis V. Denisenko
Space Research Institute
Profsoyuznaya st., 84/32
117997, Moscow, Russia
denis at hea.iki.rssi.ru