Extremely rare superoutburst of V592 Her

(visual and CCD light curves)

(superhumps detected by Garradd)

(CCD image provided by Masi)

(CCD image provided by Garradd, object had faded to mag 19 on Sep. 22)

Superhump period analysis

(PDM theta-diagram, first detection by Garradd and all CCD data since then, respectively).

(vsnet-alert 2066)
(vsnet-alert 2067)

Dear colleagues,

V592 Her bright! Confirmation needed.

V592 Her 19980826.82 12.0

Observer Timo Kinnunen (KNN.VSNET)
         Espoo, Finland

Instr.   44.5 cm f/4.5 refl.

(vsnet-alert 2070)

Cograntulations!!! The long-awaited outburst, if confirmed.

This object is most likely a WZ Sge-type dwarf nova with the largest outburst amplitude (more than 10 mag!). All sorts of observations (high-speed photometry, spectroscopy, astrometry etc.) are more urgently needed.

More details will follow later. Hope someone can confirm the event in the meantime.

Taichi Kato

(vsnet-alert 2071)

V592 Her was discovered by Richter as a possible nova in 1968, later suspected to be a dwarf nova (or a X-ray nova).

This object has been discussed several times in VSNET:

from [vsnet-alert 89]
>   A PostScript file for V592 Her is also available (herv592.ps in the same
> directory).  This chart contains faint comparison stars down to V=17.8.
> Note that the quiescent identification by Duerbeck should be replaced by
> more recent one published in IBVS (sorry I don't remember the number).
> Our chart is based on this correct identification.  V592 Her is also
> suspected to be a WZ Sge-type dwarf nova with a very long recurrence
> time and an exceptionally large (~10 mag) outburst amplitude.  Other
> classifications, however, can not be ruled out.  Please keep a close watch.
IBVS 293 lists the 1968 outburst observation:
      JD       mag
  2440033.50 <17 pg
       37.45 <17
       37.50 <17
       38.44  13.0
       38.45  12.5
       38.50  12.5
       39.45  12.3
       39.45  12.4
       39.45  14.0 (mpv)
       39.50  12.4
       40.46  12.4
       59.40  14.9
       60.42  14.9
       65.39  14.7
       66.41  14.8
       66.46  14.8
       66.50  14.9
       66.53  14.9
       67.41  15.0
       67.46  15.0
       67.50  14.9
       68.42  16.0
       69.49 <16.5
       69.53 <16.5
Richter suggested the blue nature of the object, based on the comparison between mpv and mpg measures on JD 2440039.45.

Further outburst was discovered on photographs (IBVS 3619) taken on 1986 May 12, at mag 13.6. The limited coverage of this 1986 outburst made the conclusion of the outburst nature diffucult. The star has been intensively monitored by visual observered since.

Observers are strongly encourage to follow the object as in the case of AL Com and EG Cnc, both of which showed double-humped "orbital superhumps" during the earliest stage of the outbursts. Try continuous time-series CCD photometry, as long as you can (take as many frames as possible), with an exposure time of 10-20 sec depending on the instruments. Be sure to include an appropriate comparison star in the same field, and sure to avoid saturation, esp. for V592 Her.

AL Com and EG Cnc:


Looking forward to hearing your successful observations!

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