AAVSO NEWS FLASH - No. 8
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
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* * * AAVSO NEWS FLASH * * *
Subject: DI UMa, ER UMa, HL CMa No. 8
March 27, 1996
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DI URSAE MAJORIS
We have been informed by T. Kato and the Ouda team (Japan) via vsnet-alert
#374 that the observations at Ouda station indicate that the dwarf nova
type (SU UMa subclass) cataclysmic variable DI UMa is undergoing a bright
outburst. The Ouda team reports that their time resolved V-band CCD
photometry on March 25/26 revealed superhumps with a period of 79.9 minutes,
establishing this star to be a SU UMa star with ultrashort orbital period.
The AAVSO d and e scale charts of DI UMa are available on our FTP site:
ftp.aavso.org(198.116.78.2), in /pub/charts
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ER URSAE MAJORIS
The outburst of ER UMa (see AAVSO News Flash No. 7) continues as indicated
by the following observation:
UT JD Mag. Observer
MAR 26.810 2450169.31 12.5 (L. T. Jensen, Denmark)
I thank my colleague Paula Szkody for informing us that ER UMa is indeed
an SU UMa type star. It is the third member of a group (namely ER UMa,
RZ LMi, V1159 Ori and now DI UMa) that have supercycles that are very short.
They have observed superhumps during their superoutbursts and orbital periods
below the period gap. The characteristic of this group is the short (18 - 45
days) interval between superoutbursts in comparison to hundreds of days for
the rest of SU UMa stars.
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HL CANIS MAJORIS
The dwarf nova type (Z Cam subclass) cataclysmic variable HL CMa is in
outburst as indicated by the following observations:
UT JD Mag. Observer
MAR 13.024 2450155.524 12.5 (J. McKenna, USA)
MAR 22.1507 2450164.6507 <13.0 (W. Dillon, USA)
MAR 23.1097 2450165.6097 <13.0 (Dillon)
MAR 26.822 2450169.322 11.8 (L. T. Jensen, Denmark)
MAR 27.0368 2450169.5368 11.9 (M. Dombrowski, USA)
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Please monitor these stars closely and phone-in, fax, or e-mail your
observations to the AAVSO.
CCD observers are particularly encouraged to monitor the outbursts of
DI UMa and ER UMa (recommended every three minutes) in search of superhumps.
Good observing!
Janet A. Mattei
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AAVSO NEWS FLASH is a new electronic publication of the AAVSO intended
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activity. The basis of the data in this publication will be the
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