(Note: A Web page has now been created for this observing campaign.)

BZ UMa may be in outburst or at least a bright state. Confirmation of this outburst is needed and, if real, intensive CCD photometry is needed. Usually BZ UMa flickers between V=16-17 mag during quiescence.

   BZ UMA  JAN 16.3590   14.2   SPK CCD Unfiltered w/R Zeropoint
   BZ UMA  JAN 15.7700  <14.0   VOL                                        
   BZ UMA  JAN 15.7667  <13.7   KWO                                        
   BZ UMA  JAN 15.3620   16.0   SPK CCD Unfiltered w/R Zeropoint
   BZ UMA  JAN 14.2674  <14.0   MUY
   
   KWO - Wolfgang Kriebel - Germany
   MUY - Eddy Muyllaert - Belgium 
   SPK - Patrick Schmeer - Germany
   VOL - Wolfgang Vollmann - Austria

If you notice it brighter than 16, then observations in V with precision of 0.01 magnitude are needed for as long as possible. Please make this a priority target for the next week. The last outburst of BZ UMa was last February and lasted approximately 5 days and reached a peak brightness of ~V=11.5 mag.

BZ UMa shows some signs of belonging to the UGSU subclass of dwarf novae. Its orbital period, mass ratio, outburst amplitude and frequency all suggest it is an UGSU. However, its outbursts do not show superhumps as they should, and it is a bright X-Ray source with abnormally strong Balmer emission lines and other peculiarities in its spectra. BZ UMa could be an intermediate polar (IP) or could be in a class of its own. Our analysis of the data from the February outburst shows signs of activity that are usually associated with IPs. It also has some tantalizing hints of other periodicities that could be very interesting, however the statistical significance of the signal is too weak believe on its own based on our earlier data alone.

The results of the Feb. 2004 campaign last year was published as IBVS #5526 with all observers as coauthors: http://www.konkoly.hu/cgi-bin/IBVS?5526

We also conducted a quiescent campaign last April with interesting results which could be useful combined with new data from this campaign: http://www.aavso.org/news/bzuma.shtml

Most of all, we are looking for evidence of superhumps. But we also need to look for signs of the quasiperiodic oscillations and if it is an IP, a spin period (but that could be wishful thinking).

Please observe in V as long as possible and report your observations to the AAVSO. We need as few gaps in the coverage as possible. Observations will be coordinated through the AAVSO-Photometry Discussion Group: http://mira.aavso.org/pipermail/aavso-photometry/2005-January/thread.html

If the outburst is confirmed, a web page will be made for this campaign and posted to our home page soon.

GOOD LUCK!

Aaron Price
AAVSO