[vsnet-alert 7621] XZ Eri: flashing superhumps and eclipses!

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

XZ Eri: flashing superhumps and eclipses!

Dear Colleagues,

   We have received new data from Greg Bolt.  The data on January 29
very clearly show the emergence of narrow eclipses (depth ~0.4 mag) and
superhumps.  This observation has clearly confirmed that XZ Eri is one
of rare short-period SU UMa-type dwarf novae showing deep eclipses even
during a superoutburst.  The light curve (will be posted on the VSNET
page later) resembles that of DV UMa.

   From two-night observations, we obtained a superhump period of
0.06289(6) d, which is 2.7% longer than the orbital period.  If this
period holds during the entire superoutburst, the fractional superhump
excess is unusually large for this orbital period.  However, this value
needs to be treated with care, since there is increasing amount of
evidence that some SU UMa-type dwarf novae show rapid period changes
during the early stage of a superoutburst.

   Preliminary eclipse predictions are given below.  Because of the
uncertainty of the period, and the systematic and random variations
of the eclipse timings during a superoutburst, the ephemeris will have
a substantial (minutes?) errors.  I will update the ephemeris when
new period determination becomes possible.

   The campaign has been very successful.  We have received and obtained
a large amount of data, and have received successful reports.  The present
report only illustrates a very early part of the entire analysis!

   Please continue observing XZ Eri as densely as possible - our experience
shows that maximum recommended integration time is 60-90 s, in order to
catch the eclipse profile (a shorter integration time is naturally preferred
for a larger instrument).  Good luck with your observation!

  Eclipse ephemeris (UT, geocentric).

  20030127 00:11:57
  20030127 01:40:05
  20030127 03:08:13
  20030127 04:36:21
  20030127 06:04:29
  20030127 07:32:37
  20030127 09:00:45
  20030127 10:28:53
  20030127 11:57:01
  20030127 13:25:09
  20030127 14:53:17
  20030127 16:21:25
  20030127 17:49:34
  20030127 19:17:42
  20030127 20:45:50
  20030127 22:13:58
  20030127 23:42:06

  20030128 01:10:14
  20030128 02:38:22
  20030128 04:06:30
  20030128 05:34:38
  20030128 07:02:46
  20030128 08:30:54
  20030128 09:59:03
  20030128 11:27:11
  20030128 12:55:19
  20030128 14:23:27
  20030128 15:51:35
  20030128 17:19:43
  20030128 18:47:51
  20030128 20:15:59
  20030128 21:44:07
  20030128 23:12:15

  20030129 00:40:23
  20030129 02:08:31
  20030129 03:36:40
  20030129 05:04:48
  20030129 06:32:56
  20030129 08:01:04
  20030129 09:29:12
  20030129 10:57:20
  20030129 12:25:28
  20030129 13:53:36
  20030129 15:21:44
  20030129 16:49:52
  20030129 18:18:00
  20030129 19:46:09
  20030129 21:14:17
  20030129 22:42:25

  20030130 00:10:33
  20030130 01:38:41
  20030130 03:06:49
  20030130 04:34:57
  20030130 06:03:05
  20030130 07:31:13
  20030130 08:59:21
  20030130 10:27:29
  20030130 11:55:38
  20030130 13:23:46
  20030130 14:51:54
  20030130 16:20:02
  20030130 17:48:10
  20030130 19:16:18
  20030130 20:44:26
  20030130 22:12:34
  20030130 23:40:42

  20030131 01:08:50
  20030131 02:36:59
  20030131 04:05:07
  20030131 05:33:15
  20030131 07:01:23
  20030131 08:29:31
  20030131 09:57:39
  20030131 11:25:47
  20030131 12:53:55
  20030131 14:22:03
  20030131 15:50:11
  20030131 17:18:19
  20030131 18:46:28
  20030131 20:14:36
  20030131 21:42:44
  20030131 23:10:52

  20030201 00:39:00
  20030201 02:07:08
  20030201 03:35:16
  20030201 05:03:24
  20030201 06:31:32
  20030201 07:59:40
  20030201 09:27:49
  20030201 10:55:57
  20030201 12:24:05
  20030201 13:52:13
  20030201 15:20:21
  20030201 16:48:29
  20030201 18:16:37
  20030201 19:44:45
  20030201 21:12:53
  20030201 22:41:01

  20030202 00:09:09
  20030202 01:37:18
  20030202 03:05:26
  20030202 04:33:34
  20030202 06:01:42
  20030202 07:29:50
  20030202 08:57:58
  20030202 10:26:06
  20030202 11:54:14
  20030202 13:22:22
  20030202 14:50:30
  20030202 16:18:39
  20030202 17:46:47
  20030202 19:14:55
  20030202 20:43:03
  20030202 22:11:11
  20030202 23:39:19

Regards,
Taichi Kato
VSNET Collaboration team

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