AAVSO: 2004 BZ UMA GLOBAL CAMPAIGN

From Dusk Till Dawn:

 2. INTENSIVE BZ UMA 24-HOUR CAMPAIGN

  In late February, BZ UMa (08:53:44.14 +57:48:41.1 - J2000)  was
visually observed in outburst by Mike Simonsen (SXN). Observers were
notified via MyNewsFlash within minutes if they subscribed to the
SNOBS (Significant or Noteworthy OutBurstS) list and the 
rest were notified via an AAVSO Special MyNewsFlash notice hours later 
when confirmation came in from Tonny Vanmunster (VMT). 4,270 CCD
observations were made by AAVSO observers over four nights. We have
analyzed that data and submitted an IBVS manuscript on the results.  
Responses from the IBVS editors are pending. In the meantime, a draft
copy can be read here: http://www.aavso.org/tmp/bzuma/price-bzuma.pdf

 This project highlighted two important things. First, the problems
caused by gaps in the coverage. Visit the URL below to see the light
curve and the gaps in it:

         http://www.aavso.org/tmp/bzuma/all.png

 Second, it highlighted our lack of understanding of the BZ UMa
system. BZ UMa shows some signs of belonging to the UGSU subclass 
of dwarf novae¹. 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.

 In an effort to shed more light on this system we are coordinating
an intensive observing campaign of BZ UMa at quiescence. We would
like to get as many observations as possible during this period to
try and create a precise 24-hour light curve with as few gaps as 
possible.

  We are targeting the evenings of April 19th - April 20 (UTD)  as
our primary day and April 17th - 18th (UTD) as a preliminary day. If
you can only do one evening, choose April 19th-20th because we have
time that evening on a professional Mauna Kea telescope to help fill
in the Pacific gap. We realize that it is a Monday and some of our
observers can not observe all night. However, please try to observe
both days. This allows us to look for variations of a longer
timescale and gives us some extra coverage. Note that all times are
UT. We may setup a chat room for observers to hang out in during
these long runs.

  Basically what we need is for you to observe from your local dusk
until dawn on the nights of April 17th and 19th. 

 We have two professional observatories who will help if weather
permits. Arne Henden at the US Naval Observatory in Flagstaff 
and also Karen Meech (University of Hawaii) who will be able 
to observe from Mauna Kea.

 BTW, we need more coverage in Asia and the Pacific. If you have any 
friends in the area with a CCD please forward this to them!

 BZ UMa at quiescence is quite faint, varying between V=16-17. We 
need integrations to be as short as possible because some of the 
flaring and periodicity we are looking for is on very short time 
scales (minutes). So we're calling for UNFILTERED observations. If 
you have a small aperture, consider binning your pixels if your 
seeing allows you to do that without taking a significant hit in 
precision.

                           ******
  If you think you can participate please e-mail aaronp@aavso.org
with which of the two days (17th and/or 19th) are available to you
and your timezone. A list of participants and their location will be 
kept on the web site (see below for URL).
                           ******

 A CCD Views Special Edition will be issued no later than 00 UT
Friday, April 16th with the exact campaign times. 

 In the next two weeks please begin making observations of BZ UMa
with your system. Use this time to find the best combination of
exposure time and accuracy. In general, aim for 0.02 mag precision.
But if you cannot reach that without taking a very long exposure then
we can do with less precision. Test your system to determine the best
you can do. If you have questions please e-mail your results to the
aavso-photometry discussion group for advice. German-Equatorial users 
make note of BZ UMa's transit time at your location so you can keep 
the "flip-gap" as small as possible.

 Arne Henden has calibrated this field. His data is plotted on the
AAVSO f-scale charts at this URL:
   http://www.aavso.org/cgi-bin/searchcharts3.pl?name=bz%20uma

 Use any comparison star and check star that you see on the chart. 
The 131 is a good color match. Some of them have close companions so 
be careful to keep stars out of your annuli.

 Please upload your data to the AAVSO for these snapshot sessions.  
They will be useful in establishing a baseline of activity for BZ UMa
before the campaign begins.

 In a two-hour unfiltered observing run on March 20, Bruce Gary (GBL)  
detected variations of up to 0.3 mag on a time scale of around an
hour. Do not expect to find these variations in your data but be
prepared for *any* kind of variation or oscillation.

 A To-Do Checklist:

 1. Send an e-mail to aaronp@aavso.org with your timezone if you 
    think you can participate.
 2. Practice taking at least 1 BZ UMa observation each time you are 
    observing up until April 17 (UTD).
 3. On at least one night, spend some time on BZ UMa taking 
    unfiltered exposures and finding the best way to get precision 
    photometry with as short of exposures as possible.
 4. Stock up on coffee, tea, pizza, etc and be prepared to observe 
    April 17 and April 19 (UTD). 

 As we analyze the data we will keep anyone who participated in the
campaign updated. Observers who get more than an hour of data with
SNR>40 during the campaign or who otherwise provide significant help
will be coauthors on any paper we publish.

 A web page for this campaign will be maintained at:

          http://www.aavso.org/news/bzuma.shtml

 Public discussion will take place on aavso-photometry discussion 
group: http://www.aavso.org/mailman/listinfo/aavso-photometry

 ¹ Visit our February, 2000 Variable Star of the Month for more 
information about UGSU dwarf novae: 
              http://www.aavso.org/vstar/vsots/0200.shtml

From Dusk Till Dawn:
The 2004 BZ UMa Global CCD Observing Campaign

CCD Views Announcement

Schedule of Events

Participating Observers & Their Locations

From Dusk Till Dawn: The 2004 BZ UMa Global CCD Observing Campaign

CCD Views Announcement

Schedule of Events

Participating Observers & Their Locations

From Dusk Till Dawn:
The 2004 BZ UMa Global CCD Observing Campaign