complied data from VSNET reports
(vsnet-alert 273, G. Poyner)
Bill Worraker (Didcot, UK) has reported an outburst of HT Cas, which is monitored as part of the TA/BAA Recurrent Objects Programme. I have just confirmed the outburst. Details....
Nov 17.9049 UT mv=13.4 Worraker, 26cm Seq. TA 17.9132 mv=13.4 Poyner, 40cm Seq. TA
There is no need to emphasise the importance of this outburst!
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We Ouda-team observed HT Cas on Nov 15 with a CCD with V filter attached to a 60-cm reflector. HT Cas was found to be already somewhat brighter than usual quiescent level at that time with an averaged level of V=16.14 outside eclipses. An eclipse was observed approximately centered at HJD24450037.147, with a duration of 12 min which is apperently longer than mentioned (~6 min) by Welsh (vsnet message #317). No evidence of orbital hump was observed.
For follow-up observers, a PostScript finding chart with V-magnitude is available at :
The forecast time of eclipses of HT Cas are listed below
(times are geocentric). YYMMDD hh:mm:ss (UT) 951118 05:16:20 951118 07:02:23 951118 08:48:27 951118 10:34:30 951118 12:20:33 951118 14:06:36 951118 15:52:39 951118 17:38:43 951118 19:24:46 951118 21:10:49 951118 22:56:52 HJD (mid-eclipse) = 2443727.93721 + 0.0736472039E And the table of comparison stars are listed below. AAVSO Misselt(1995) VSNET (Alert 217) V B-V approx. V ---------------------------------------------- 95 101 104 106 109 11.88 +0.59 11.84 (113) 115 124 127 134 13.62 +0.85 136 anon 13.92 +0.85 13.90 just south of HT Cas 143 14.33 +1.59 14.23 anon 14.61 +1.02 14.62 west to AAVSO (109) 151 14.70 155 15.19 +1.86 15.19 156 15.02 anon 15.58 +1.79 15.57 faint star just SE to HT Cas 159 15.82 163 16.18 166 15.91
Needless to say, close monitoring is highly encourged.
Hajime Baba and Ouda-team
Eclipse observations at Ouda
A total of high quality 1081 V-band CCD frames of HT Cas were obtained by a 60-cm reflector at Ouda Station (Kyoto University) with a typical time resolution of 23s (20s exposure + 3s dead time). A prelimary analysis gives following mid-eclipse times (heliocentric correction has not been applied intentionally). Magnitudes were determined using V=11.88 star by Misselt (1995).
JD (Geo) eclipse center outside eclipse depth 2450039.86757 14.45 V 13.16 V 1.29 V 40.01482 14.45 13.17 1.28 40.08851 14.50 13.22 1.28 40.16218 14.57 13.26 1.31 40.23583 14.72 13.29 1.43
Eclipses last ~12 min. The above data seem to indicate HT Cas has already started a rather rapid decline at a rate of ~0.5 mag/day. However, broad hump features (amplitude ~0.05 mag) around 2450040.108 and 2450040.190 may be indicative of the appearance of superhumps. Further observations are strongly encouraged.
Ouda team (Daisaku Nogami and Hajime Baba observing)
A story of this night ..
Start of a rapid decline
We Ouda Team observed HT Cas on Nov 19.47. The object seems to be declining. Based on our CCD image on CRT, we estimate that the magnitude out of eclipse is V~13.7 mag, which is about 0.6 mag fainter than that of Nov 18. This indicates that this outbutst seems to be a normal one ?
Further monitoring is highly encourged !
Hajime Baba and Daisaku Nogami
Ouda Team ( at observatory )
Eclipse observation by Makoto Iida
This image contains consecutive eight panels, from the upper left to the lower right as time proceeds. HT Cas is the northern component of an aggregate of three stars at the center of each panel. The fourth panel represents the center of an eclipse. The images were taken by a 16-cm reflector with an ST-6 CCD camera. (Courtesy of Makoto Iida)
Outburst image by the Ouda team
CCD photometry by Nick James
Attached to this e-mail is a postscript graph showing two consecutive eclipses of HT Cas. Photometry was unfiltered using a Sony CCD and 30cm Newtonian and the brightness of HT Cas was measured relative to the nearby GSC 4030.00719. Eclipse duration was 550 sec in each case and the times of minima were:
1995 November 19, 18:24:20 UTC (JD 2450041.26690) 1995 November 19, 20:10:30 UTC (JD 2450041.34063)
These agree very well with predictions based on Kato's vsnet-alert 277 message.
The sample period in the following plot is approximately 25s (20s exposure + 5s read-out). My location is Chelmsford, UK.
More information, including a CCD image of the field is available on the pages of The Astronomer at http://www.demon.co.uk/astronomer/htcas.html
Regards Nick James.
get a full message containing a PS file
Dear HT Cas observers,
HT Cas seems to have stopped fading. The post-outburst object is now staying about 1 mag brighter than its "high-state" quiescence. Nightly averaged preliminary magnitudes outside eclipses are below:
mid-UT mag S.D. N band ----------------------------------- 951118.618 13.27 0.075 904 V 951119.505 13.98 0.086 71 V 951120.534 15.55 0.130 91 V 951121.554 15.89 0.141 477 V 951122.494 15.93 0.210 303 V (S.D.: for a single point)
The light curves on Nov. 21 and 22 show broad undulations with a time- scale of few hours, together with short-term flickering and QPOs. Although the averaged system brightness has changed little these two nights, the shapes of eclipses have changed considerably; the system is now exhibiting rather sharp ingresses and egresses which are usually observed in quiescence.
Ouda team (Taichi Kato, observing)
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