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[vsnet-campaign-news 66] AstroAlert: V893 Sco: outburst of eclipsing dwarf nova
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Relatively Bright Outburst of the Eclpsing Dwarf Nova
V893 Scorpii
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V893 Sco had long been a "lost" variable star since its discovery
announcement. In spite of intensive research by many astronomers,
no one had positively identified the object. In the meantime,
Katsumi Haseda (Variable Star Observers League in Japan) discovered
a variable star on patrol films in the early 1998. Since the position
of the reported object was relatively close to the original position
of V893 Sco, an extensive research on the discovery paper, discovery
plates was undertaken by the collaboration of the VSNET team and the
Moscow (GCVS) team. It became evident that the finding charts published
in the discovery paper were interchanged, and Haseda's variable was
confirmed to be identical with the lost V893 Sco. This story was
published as a paper in IAU Information Bulletin on Variable Stars
(IBVS), No. 4585.
Since V893 Sco was one of bright dwarf novae, several researchers
used large telescopes to reveal the nature of the object. Several
groups independently discovered that the object belongs to a rare
class of short-period cataclysmic variables with eclipses. Only a
limited number of such objects are known, and V893 Sco is the brightest
such object below the period gap of cataclysmic variables. Since almost
all dwarf novae below the period gap are known to be SU UMa-type dwarf
novae, many researchers expect V893 Sco will show superoutbursts, which
have not been securely identified in past observations yet.
References:
Kato et al. 1998, IBVS 4585
Thorstensel 1999, IBVS 4749
Bruch et al. 2000, PASP 112, 237
Matsumoto et al. 2000, Astron. Astrophys. 363, 1029
The present outburst of V893 Sco has become one of the brightest ones
in this year. Although the duration is not yet sufficient to claim the
possibilty of a superoutburst, intensive observations would be helpful
to understand the nature of the current outburst.
YYYYMMDD(UT) mag observer
20010520.750 <146 (B. Monard)
20010521.735 <146 (B. Monard)
20010522.501 <135 (R. Stubbings)
20010522.612 145 (A. Pearce)
20010523.044 148 (B. Monard)
20010523.783 <146 (B. Monard)
20010523.810 148 (A. Pearce)
20010525.438 129 (R. Stubbings)
20010525.771 128 (B. Monard)
20010526.101 123 (B. Monard)
20010526.601 127 (A. Pearce)
Eclipses are predicted to occur around the times listed. CCD (and visual)
observers are strongly recommended to observe the star between +/- 20 min
of the predicted times. Record magnitudes (take CCD frames) as quickly
as possible (requring 10-30 sec time resolution, better than 1 sec timing
accuracy). A search for superhumps can be made by observing the object
throughout the observable time, spanning several hours. If the current
outburst turns out to be a genuine superoutburst, please give it the highest
priority.
V893 Sco is located at: 16h 15m 15s.08, -28o 37' 31".3 (J2000.0)
YYYYMMDD hh:mm:ss (UT, geocentric)
------------------------------------
20010525 00:03:34
20010525 01:52:57
20010525 03:42:20
20010525 05:31:43
20010525 07:21:06
20010525 09:10:29
20010525 10:59:52
20010525 12:49:15
20010525 14:38:38
20010525 16:28:01
20010525 18:17:24
20010525 20:06:47
20010525 21:56:10
20010525 23:45:33
20010526 01:34:56
20010526 03:24:19
20010526 05:13:42
20010526 07:03:06
20010526 08:52:29
20010526 10:41:52
20010526 12:31:15
20010526 14:20:38
20010526 16:10:01
20010526 17:59:24
20010526 19:48:47
20010526 21:38:10
20010526 23:27:33
20010527 01:16:56
20010527 03:06:19
20010527 04:55:42
20010527 06:45:05
20010527 08:34:28
20010527 10:23:51
20010527 12:13:14
20010527 14:02:37
20010527 15:52:00
20010527 17:41:23
20010527 19:30:46
20010527 21:20:09
20010527 23:09:32
20010528 00:58:55
20010528 02:48:18
20010528 04:37:41
20010528 06:27:05
20010528 08:16:28
20010528 10:05:51
20010528 11:55:14
20010528 13:44:37
20010528 15:34:00
20010528 17:23:23
20010528 19:12:46
20010528 21:02:09
20010528 22:51:32
20010529 00:40:55
20010529 02:30:18
20010529 04:19:41
20010529 06:09:04
20010529 07:58:27
20010529 09:47:50
20010529 11:37:13
20010529 13:26:36
20010529 15:16:00
20010529 17:05:23
20010529 18:54:46
20010529 20:44:09
20010529 22:33:32
20010530 00:22:55
20010530 02:12:18
20010530 04:01:41
20010530 05:51:04
20010530 07:40:27
20010530 09:29:50
20010530 11:19:13
20010530 13:08:36
20010530 14:57:59
20010530 16:47:23
20010530 18:36:46
20010530 20:26:09
20010530 22:15:32
20010531 00:04:55
20010531 01:54:18
20010531 03:43:41
20010531 05:33:04
20010531 07:22:27
20010531 09:11:50
20010531 11:01:13
20010531 12:50:36
20010531 14:40:00
20010531 16:29:23
20010531 18:18:46
20010531 20:08:09
20010531 21:57:32
20010531 23:46:55
20010601 01:36:18
20010601 03:25:41
20010601 05:15:04
20010601 07:04:27
20010601 08:53:50
20010601 10:43:14
20010601 12:32:37
20010601 14:22:00
20010601 16:11:23
20010601 18:00:46
20010601 19:50:09
20010601 21:39:32
20010601 23:28:55
20010602 01:18:18
20010602 03:07:41
20010602 04:57:05
20010602 06:46:28
20010602 08:35:51
20010602 10:25:14
20010602 12:14:37
20010602 14:04:00
20010602 15:53:23
20010602 17:42:46
20010602 19:32:09
20010602 21:21:32
20010602 23:10:56
Regards,
Taichi Kato
VSNET Collaboration team
We have been undertaking on photometric campaigns on several super-
outbursting dwarf novae and peculiar variable stars. News and call for
observations on these objects will be issued on our regular weekly
"News from VSNET" bulletins. Those who immediately need information
should make an access to the VSNET website, and click on VSNET campaign
list.
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VSNET (Variable Star Network) is an international variable star observing
network, covering various areas of novae, supernovae, cataclysmic variables
(CVs), X-ray transients, and other classical eruptive, pulsating, and
eclipsing variables. VSNET is one of invited contributing organizations
to the SkyPub AstroAlert system.
VSNET Home Page: http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/
CCD observations of such targets are a relatively easy task for a 20-40cm
telescope; simply take as many CCD frames (with exposure times 10-30 sec)
as possible, spanning several hours per night. The only requirements are
the weather and your patience! If you need more help on the observing
technique, please feel free to ask on the vsnet-campaign list.
We would sincerely appreciate volunteers who would join the VSNET
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