Ultra-bright outburst of HT Cam

Representative pulse light curve

Outburst detection

(vsnet-alert 6944)

HT Cam super-ultra-bright outburst!

Finally a New Year Alert!!!

H. Itoh (Tokyo, Japan) reports that HT Cam (a ultra short-period CV; also renowned for its infrequent very brief outbursts) is undergoing an unprecedentedly bright outburst!! All sorts of observations (time-resolved continous photometry, spectroscopy, X-ray observation etc.) are MOST URGENTLY needed. The object is currently the top priority target of the VSNET campaign. Please keep us informed of the progress of your observation!

Visual magnitude estimates by VSOLJ members

object         YYYYMMDD(UT)   mag  code
CAMHT          20011229.680   122  Ioh.VSOLJ
CAMHT          20011229.710   123  Ioh.VSOLJ
CAMHT          20011229.833   122  Ioh.VSOLJ
075701.3 +630600 (2000.0) RXJ0757.0+6306 18.2 CV 
075700.4 +630601 (2000.0) 1RXS_J075700.5+630602 0.152 0.79 0.43
075701.2 +630600 (2000.0) CAMHT XM 17.2 (1.4) B - - -

Very rapid fading

(vsnet-alert 6952)

Arto Oksanen has reported the following magnitude:

we observed HT Cam with Harri Hyvonen here at Nyrola under very bad conditions. Not much light curve but the unfiltered maginitude was:

CAMHT 20011230.9 15.7C AOk

best regards,


Strong modulations!!

(vsnet-alert 6957)

HT Cam: very strong modulation!!

Dear Colleagues,

We have partly analyzed the Kyoto and RIKEN (Torii-san) data. The initial result is surprizing.

Superimposed on the decay, as inferred from visual and other observations, there exist *very strong* (0.4 mag or even larger) short-term modulations. Although exact identification requires further analysis (of the full-night data) and period analysis, the modulations seem to be somehow related to the 8.5-min period reported by Tovmassian. This finding may be indicative of the (possibly transient) IP (intermediate polar) nature of this object. [Note, however, optical photometry during an outburst of DO Dra, did show a similar (lower amplitude) periodicity which does not agree with the spin period].

The large-amplitude short-term modulations are quite unlike any modulations seen during an outburst of any CV. The characteristics are even drastically different from that reportd by Gary W. Billings (vsnet-alert 6953) less than 0.5 d ago! Observers are strongly requested to continue observing this object as intensively as possible, since we may have witnessed a short period of unexpectedly intensive avtivity of this CV.

Taichi Kato
VSNET Collaboration team

(vsnet-alert 6959)

Correction! The period seems to be close to 8 min. [Not likely two-pole accretion].

We have put a representative pulse light curve at:


The amplitude of the pulses reach 0.3-0.4 mag.

Taichi Kato
VSNET Collaboration team

Finding chart provided by Tovmassian

VSNET light curve (requires Java)

Light curve

VSNET data search


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