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THE ASTRONOMER Electronic Circular No 836 1994 May 02 15.25UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke,
Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074
INTERNET: GMH at AST.STAR.RL.AC.UK or GMH at GXVG.AST.CAM.AC.UK
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BC UMA
Taichi Kato, Kyoto University, Japan e-mails:
Makoto Iida, Nagano, Japan reports that he has finally detected
long-awaited superhumps in suspected SU UMa-type dwarf nova BC UMa,
which is presently undergoing one of its rare outbursts.
>From a series of 40 unfiltered CCD exposures taken between
Apr. 28.476 and 28.615 UT he has detected clear superhumps with an
amplitude of 0.3 mag.
A preliminary period analysis gives the best estimate of the
superhump period of 0.0607 day, which would place this object
similar to SU UMa members with ultrashort orbital periods like
HV Vir (P=0.05818 day) and SW UMa (P=0.05833 day).
Available results to date:
JD= 2449000
UT Date UT Dec JD Estimate mpv mv Cl I Surname
28/04/94 0.476 470.98 12.8 2 M Iida
28/04/94 0.515 471.02 13.2 M Iida
28/04/94 0.517 471.02 12.6 S Takahashi
28/04/94 0.530 471.03 12.7 M Koshiro
28/04/94 0.559 471.06 13.0 M Iida
28/04/94 0.603 471.10 12.7 M Iida
28/04/94 0.859 471.36 12.7 P Schmeer
28/04/94 0.938 471.44 12.7 P Schmeer
28/04/94 0.962 471.46 12.0 G Poyner
29/04/94 0.542 472.04 12.8 M Koshiro
29/04/94 0.876 472.38 L-2;M+7 12.9 2 W Worraker
30/04/94 0.542 473.04 12.6 S Takahashi
30/04/94 0.885 473.38 L-2 12.9 1 G Poyner
30/04/94 0.896 473.40 H(2)L(1)V 13.0 1 G Hurst
01/05/94 0.918 474.42 H(2)L(3)V 13.6 2 G Hurst
Several observers report difficulty with the sequence and as it
appears necessary to ultimately re-reduce the estimates, we ask
that observers send us their full estimate if not already logged
and also in all future observations. Please also quote the date
and source of the chart in use. Professional astronomers confirm
that following our alert via E-Circular, they are currently
using the IUE on this object. Please continue intensive coverage.
IR LYRAE
Tony Vanmunster, Landen, Belgium has detected an outburst of this
possible UG-type variable located at: RA 18h22m09s DEC +39 17'
(1950) which is catalogued in the GCVS as having a range of
14.6-16.0p. Available results:
1994 Apr 28.94UT, 14.3 (Vanmunster)
28.97UT, 14.0 (P.Van Cauteren, Aartselaar, Belgium)
30.99UT, 13.8 (G.Poyner, Birmingham, UK)
Guy M Hurst
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Date: Mon, 2 May 1994 16:56:05 +0100 (BST)