[vsnet-alert 5074] (fwd) V446 Her observing campaign

[Taichi Kato <tkato>]

     We have received the following call for observations.  Please use
vsnet-campaign for communication between VSNET collaborators.
(V446 Her is an old nova, but the purpose is more or less related to
usual dwarf nova studies).

Date: Fri, 7 Jul 2000 12:13:37 +0200 (MET DST)
From: "Boris T. Gaensicke" <boris@uni-sw.gwdg.de>
Subject: V446 Her

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Dear colleagues, 

we plan for this summer an intensive campaign on the post nova V446
Her (V~18). Our interest in this object arouse as it is one of the 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). 

While the work of Honeycutt et al. (1998, ApJ 495, 933) reveals an
outburst period of ~23d with an amplitude of ~1.5mag, their RoboScope
observations could not cover in detail the rise and the decline of the
outbursts.

Our aim is 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 three 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 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.

Boris Gaensicke, Matthias Schreiber, 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.

2) 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.

3) 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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