Special Notice #89: Rare Outburst of 0103+59 HT Cas

January 10, 2008

Coordinates: RA 01:10:12.98 Dec. +60:04:35.9 (2000.0)

AAVSO observer Glenn Chaple, Townsend, MA, reports that the UGSS+EA type dwarf nova HT Cas is in outburst for the first time since February 2002, with his visual observation of 13.6 on January 10.0076 UT. Makoto Uemura and colleagues at Hiroshima University (vsnet-alert 9807) confirmed the outburst with an observation of 14.02V on January 10.5278 UT. This outburst looks to be a normal, brief outburst, probably lasting only 2-3 days.

Mike Simonsen and Gary Poyner announced the outburst on cvnet-discussion and baavss-alert, respectively.

This star has an irregular history of outbursts. According to observations in the AAVSO International Database, all but one from 1979 to date have been brief and have reached maximum brightness between 12.3 and 13.3, occurring in Jan 1979, Mar 1980, Aug 1985, Feb 1987, Nov 1989, Nov 1995, Mar 1997, Mar 1998, Jul 1999, Apr 2001 (possible outburst), Feb 2002, Apr 2003 (possible outburst, single observation). On January 12, 1985, HT Cas had a bright, long outburst, reaching visual magnitude 10.7 and remaining brighter than 15.2 until January 24.

HT Cas is in VSX (http://www.aavso.org/vsx/). Charts may be generated using VSP (http://www.aavso.org/observing/charts/vsp/). Note that CCD observers should use the photometry table provided in VSP.

HT Cas, with an orbital period of approximately 01hr 46 min, shows deep eclipses on the order of 1-2.5 magnitudes. Very frequent observations and precise reporting of times are essential. Hiroyuki Maehara (via vsnet-alert 9808) provides an eclipse ephemeris for HT Cas (geocentric, based on Feline et al. 2005) from the elements:

Min HJD = 2443727.937290(8) + 0.07364720309(7) E

JD Date Time(UT)
2454476.08206 2008/01/10 13:58:10
2454476.15572 2008/01/10 15:44:13
2454476.22937 2008/01/10 17:30:17
2454476.30302 2008/01/10 19:16:20
2454476.37667 2008/01/10 21:02:24
2454476.45032 2008/01/10 22:48:27
2454476.52398 2008/01/11 00:34:31
2454476.59763 2008/01/11 02:20:34
2454476.67128 2008/01/11 04:06:38
2454476.74493 2008/01/11 05:52:41
2454476.81858 2008/01/11 07:38:45
2454476.89223 2008/01/11 09:24:49
2454476.96589 2008/01/11 11:10:52
2454477.03954 2008/01/11 12:56:56
2454477.11319 2008/01/11 14:42:59
2454477.18684 2008/01/11 16:29:03
2454477.26049 2008/01/11 18:15:06
2454477.33414 2008/01/11 20:01:10
2454477.40780 2008/01/11 21:47:13
2454477.48145 2008/01/11 23:33:17
2454477.55510 2008/01/12 01:19:20
2454477.62875 2008/01/12 03:05:24
2454477.70240 2008/01/12 04:51:27
2454477.77606 2008/01/12 06:37:31
2454477.84971 2008/01/12 08:23:34
2454477.92336 2008/01/12 10:09:38
2454477.99701 2008/01/12 11:55:41
2454478.07066 2008/01/12 13:41:45
2454478.14431 2008/01/12 15:27:48
2454478.21797 2008/01/12 17:13:52
2454478.29162 2008/01/12 18:59:55
2454478.36527 2008/01/12 20:45:59
2454478.43892 2008/01/12 22:32:02
2454478.51257 2008/01/13 00:18:06
2454478.58623 2008/01/13 02:04:09
2454478.65988 2008/01/13 03:50:13
2454478.73353 2008/01/13 05:36:16
2454478.80718 2008/01/13 07:22:20
2454478.88083 2008/01/13 09:08:23
2454478.95448 2008/01/13 10:54:27
2454479.02814 2008/01/13 12:40:30
2454479.10179 2008/01/13 14:26:34
2454479.17544 2008/01/13 16:12:38
2454479.24909 2008/01/13 17:58:41
2454479.32274 2008/01/13 19:44:45
2454479.39640 2008/01/13 21:30:48
2454479.47005 2008/01/13 23:16:52
2454479.54370 2008/01/14 01:02:55
2454479.61735 2008/01/14 02:48:59
2454479.69100 2008/01/14 04:35:02
2454479.76466 2008/01/14 06:21:06
2454479.83831 2008/01/14 08:07:09
2454479.91196 2008/01/14 09:53:13
2454479.98561 2008/01/14 11:39:16
2454480.05926 2008/01/14 13:25:20
2454480.13291 2008/01/14 15:11:23
2454480.20657 2008/01/14 16:57:27
2454480.28022 2008/01/14 18:43:30
2454480.35387 2008/01/14 20:29:34
2454480.42752 2008/01/14 22:15:37