IAUC 6731 (September 3rd 1997) reported the discovery of a new Cataclysmic variable apparently in outburst in Cygnus by the BAO (Beijing Astronomical Observatory) team J.-y. Hu, Y.-l. Qiu, W.-d. Li, and A. Esamdin, Urmqi Astronomical Station. The discovery was made on August 28th during a BAO supernova survey using a 0.60-m telescope. The R magnitudes given for Aug 28 and 31 were 13.3 & 13.5 respectively. The position measured from the USNO A1.0 catalogue is R.A. = 19h 27m 11s.63, Decl. = +54° 17' 51".5 (2000.0), with R and B magnitudes of 19.9 and 20.3. IAUC 6731 comments “A spectrogram obtained with the 2.16-m telescope at Xinglong Station on Aug. 31 shows typical features of cataclysmic variables during outburst, with absorption Balmer lines and weak He I lines (including a feature at 447.1 nm).”
The first visual observations of this new CV in outburst were made by the
German observer Jochen Pietz and the Director on September 4.820 UT (mv=13.5)
and 4.892 UT (mv=13.4) respectively. The two images shown below are taken
from
a) Digitised Sky Survey (no object shown)
b) the star in outburst, Nick James, September 5.861, CCD+V 240s integration time.
Weak superhumps were eventually detected by Rudolf Novak (Nicholas Copernicus Observatory), and by Tonny Vanmunster (CBA Belgium) on September 6/7, thus categorising this new object as a UGSU type star.
Following a short period at maximum brightness, the star dipped, only to rise again to a second supermaximum reminiscent of the AL Com outburst in April 1995. This second superoutburst displayed superhumps of a more prominent nature (0.1mag). Vanmunster reports on CVC 155 that CBA data analysed by Joe Patterson reveals a unique superhump period of high precision, namely 0.05672 ± 0.00006 d. To the disappointment of many, a third brightening did not materialise. A chart is available from Guy Hurst, and hopefully a BAAVSS chart for this new UGSU star will be available soon.
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Left; Digitised Sky Survey Image. Below; Outburst image by Nick James. |
