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[vsnet-chat 2839] Re: CH UMa
- Date: Thu, 20 Apr 2000 03:28:06 +0200
- To: vsnet-chat@kusastro.kyoto-u.ac.jp, aah@nofs.navy.mil, b.sumner@bom.gov.au, Patrick Schmeer <extpasc@rz.uni-sb.de>
- From: Patrick Schmeer <p.schmeer@mx.uni-saarland.de>
- Subject: [vsnet-chat 2839] Re: CH UMa
- In-Reply-To: <200004192054.AA23089@runner.nofs.navy.mil>; from aah@nofs.navy.mil on Wed, Apr 19, 2000 at 01:54:33PM -0700
- References: <200004192054.AA23089@runner.nofs.navy.mil>
- Sender: owner-vsnet-chat@kusastro.kyoto-u.ac.jp
I don't think there is a problem with Arne's astrometry. He obtained
the following position for CH UMa at quiescence:
R.A. 10h07m00.81s Decl. +67o32'47.7" (J2000.0)
His photometry: V= 14.933, B-V= 0.691
Bruce Sumner commented:
"The quiescence magnitude quoted above is the minimum value determined
from three nights of photometry. However the B-V value is too red for
a dwarf nova, and it is possible that CH UMa is hidden under this red
star."
DX And, however, is even redder at quiescence. Arne obtained a B-V
value of 0.897 for that dwarf nova. CH UMa and DX And are btw very
similar in several respects: magnitude range 11-15, mean cycle length
about 1 year, often slow rise to maximum.
B-V values of more than 0.5 are not uncommon for SS Cyg-type dwarf
novae with relatively long orbital periods. Another example is RU Peg
with B-V= 0.633 (Arne Henden).
Regards,
Patrick
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