[vsnet-campaign 983] V446 Her campaign, again

[Daisaku Nogami <nogami@kwasan.kyoto-u.ac.jp>]

Dear colleagues,

as you might remember we (Boris Gaensicke, Daisaku Nogami, and Matthias 
Schreiber) started an intensive observing campaign on the Cataclysmic 
Variable V446 Her (V~18) last summer (vsnet-campaign 325). You can find
the resulting light curve at 
"http://alpha.uni-sw.gwdg.de/~mschrei/v446her/light.htm";.  

Our interest in this object results from the fact that it is one of the 
very few post novae that shows also regular dwarf nova outbursts. In
contrast to e.g. GK Per, V446 Her has a rather typical orbital period of
4.97h (Thorstensen & Taylor, 2000, MNRAS 312, 629).

Although the obtained light curve is very interesting and indicates the 
presence of "echo" outbursts, it can neither completely confirm nor
disprove our predictions. Hence, we need more observations of this
fascinating object. 

Our aim is again to obtain a *good* contiguous light curve of V446 Her
that covers 2-3 outbursts of the system, in order to compare its outburst
characteristics to those of ``normal'' dwarf novae. We invite those of
you equipped with a CCD camera to obtain a couple of images of V446
Her per night throughout the next four months, say, until the end of
September.  To get a complete coverage (~5-10 measurements per day), it
is crucial that we find collaborators in several continents. The
resulting light curve will be published in a refereed journal,
including all contributors as co-authors.

We hope that you will (again) join us in the study of this extremely
interesting object. If you decide to do so, please find some
technical notes below.

Thank you very much for your attention.

Cheers and clear skies,
Matthias Schreiber, Boris Gaensicke, and Daisaku Nogami
Universitaets-Sternwarte Goettingen
Germany


Technical notes: 


1) For your convenience, we have set up a Web directory 

    http://vsnet.uni-sw.gwdg.de/~boris/outgoing/V446Her/

containing a finder chart (V446Her_5x5.gif, V446Her_5x5.ps, 5'x5').
You also find a photometric sequence of comparison stars in the field
(from Henden & Honeycutt, 1997, PASP 109, 441; see the file
V446Her_sequence).  The chart of the comparison stars is available as 
V446Her_comp.gif or V446Her_comp.ps.

1) Please just use V-filter.  

3) V446 Her has two nearby (~3.5") visual companions with somewhat
fainter magnitudes (Honeycutt et al. 1998; see the files
V446Her_zoom.gif and V446Her_zoom.ps).  Depending on the seeing
conditions, these three stars may not be resolved. In order to have
homogenous measurements, please compute the magnitude of *all three
stars together*, we will then correct for the contribution of the two
field stars later.

4) Please send us (v446her@uni-sw.gwdg.de) your measurements on a
regular base, so that we can monitor the progress of the project. In
addition, it would be very helpful if you could send us the original CCD
frames, so that we can archive all the observations in a single
location (and, if desired, make them available to the contributors of
the campaign).

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