[vsnet-alert 10429] V745 Sco at present

[Berto Monard]

In view of all the recent 'negative' observation reports on V745 Sco, I would like to state that this recurrent nova has actually been quite bright lately as shown in the table (starting Sep 2005):

V745 SCO  	2453627.209		15.7	CR		MLF
V745 SCO  	2453766.602		15.0	CR		MLF
V745 SCO  	2453800.635		[17.5	CR		MLF
V745 SCO  	2453810.639		[17.0	CR		MLF
V745 SCO  	2453825.567		[17.5	CR		MLF
V745 SCO  	2453829.646		17.0	CR		MLF
V745 SCO  	2453833.600		16.2	CR		MLF
V745 SCO  	2453837.582		16.2	CR		MLF
V745 SCO  	2453848.658		[16.0	CR		MLF
V745 SCO  	2453853.548		16.5	CR		MLF
V745 SCO  	2453860.658		15.7	CR		MLF
V745 SCO  	2453919.223		15.4	CR		MLF
V745 SCO  	2453978.213		15.2	CR		MLF
V745 SCO  	2454002.225		15.6	CR		MLF
V745 SCO  	2454013.225		15.2	CR		MLF
V745 SCO  	2454175.569		16.1	CR		MLF
V745 SCO  	2454214.591		15.1	CR		MLF
V745 SCO  	2454263.562		15.2	CR		MLF
V745 SCO  	2454273.535		15.6	CR		MLF
V745 SCO  	2454345.333		15.8	CR		MLF
V745 SCO  	2454418.225		15.6	CR		MLF
V745 SCO  	2454513.629		15.0	CR		MLF
V745 SCO  	2454546.648		15.0	CR		MLF
V745 SCO  	2454549.578		14.7	CR		MLF
V745 SCO  	2454562.509		15.0	CR		MLF
V745 SCO  	2454574.657		15.1	CR		MLF
V745 SCO  	2454592.432		14.9	CR		MLF
V745 SCO  	2454601.562		15.0	CR		MLF
V745 SCO  	2454604.617		14.8	CR		MLF
V745 SCO  	2454609.617		14.8	CR		MLF
V745 SCO  	2454611.299		14.7	CR		MLF
V745 SCO  	2454617.259		14.8	CR		MLF
V745 SCO  	2454619.530		14.7	CR		MLF
V745 SCO  	2454626.255		14.4	CR		MLF
V745 SCO  	2454631.204		14.6	CR		MLF
V745 SCO  	2454645.408		14.9	CR		MLF
V745 SCO  	2454654.223		14.8	CR		MLF
V745 SCO  	2454668.390		14.5	CR		MLF
V745 SCO  	2454679.189		14.6	CR		MLF
V745 SCO  	2454685.209		14.6	CR		MLF
V745 SCO  	2454686.243		14.7	CR		MLF

Note that CR magnitudes are unfiltered CCD and considering a V-R of this star around 1.2 (red light originating mainly from the M4 secondary), CR magnitudes are effectively in between R and I magnitudes, a bit more towards R still.

Recent observations in CCD-V showed V745 Sco to be also bright in visual light (but unfortunately still just out of reach of visual observers) as per table:

SCOV745		2454658.30		16.00	CCD-V		MLF
SCOV745		2454677.30		15.90	CCD-V		MLF
SCOV745		2454681.30		16.20	CCD-V		MLF

The obvious next step for me to do was timeseries (unfiltered) photometry, the ideal target until RU Hor would rise.
As it turned out V745 Sco is not like most other Z And systems (if at least it is one..), but shows prominent changes over 0.5 mag with possibly some flickering. Its light curve is very similar to that of magnetic CVs like EX Hya and others.  
This means that there is a quite significant variability definitely not originating from the secondary. Possibly it is a dq system which is now in the active state. 

Follow up observations will be done at CBA Pretoria. It's not impossible that a period of 0.106d was detected on the first observing night. Possibly it is the orbital period of the WD. Let's await further data.

The possible connection DQ Her and (recurrent) nova will certainly please certain astrophysicists...

Best regards,

Berto Monard
Bronberg Observatory / CBA Pretoria