CBA Belgium Observatory
  TK4 (UGSU:) in Lyra - no outburst on November 1st, 2001

 

TK4 Lyr was discovered by T. V. Kryachko of Sternberg Astronomical Institute (Russia) on Moscow archive plates (see IBVS 5058) taken with the 40-cm astrograph. It appears as a blue object on the Palomar prints.

On 2001, October 31.8132 UT, Chris Jones (UK) reported his visual detection of an outburst of the object, and estimated it at mag 14.0 (vsnet-outburst 3022).

I had an unfiltered CCD session of TK4 at CBA Belgium Observatory on 2001, November 1/2, between 17h00m UT and 18h01m UT (i.e. Nov 1.708 and Nov 1.750 UT). I used a 0.35-m f/6.3 reflector and SBIG ST-7 CCD. 

At left is a "stacked" CCD image (10 x 30 sec exposure) showing the TK4 region. 
Based on my Nov 1 session, I have to conclude that the object *definitely* was not visible during my observing interval, down to magnitude 18.0, contrary to some visual observations made around that same time (see vsnet-campaign-dn 1827), that placed the object around mag 14. By the way, the reason for already interrupting the observing session after 1 hour, was exactly because I couldn't positively identify the variable.

The FITS image above has North up. TK4 is located at  RA = 19h13m58.47s, Decl =  +40°44'09.1" (2000.0), and has a magnitude range of 14.9 - <17.2p.


                                                                                                                                    (c) Copyright Tonny Vanmunster, 2001