[vsnet-j 1937] V838 Mon outburst discovery story

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

V838 Mon outburst discovery story

　アウトバースト発見時の生々しい様子が掲載されていますので転載します。

V838 Mon outburst  - discovery story by MEDUZA observers

Almost all nights in January 2002 were cloudy. However, during the last
week of January the temperature has unusually increased. From Jan. 28 to
Feb. 3 the historical temperature records (1884) were overcome in the
Czech Republic. It had a secondary effect: on Feb. 2 (Saturday) many
observers wanted to observe variable stars - finally!
  The first MEDUZA observer who discovered unusual brightness of V838 Mon
was Ladislav Smelcer from Valasske Mezirici Observatory. He has been
observing mostly long period variable stars (especially Miras) since the
end of 1998. On Feb. 2, 18h 47min UT he had done CCD V filtered
observation of V838 Mon showing it at magnitude 8.17. It was so surprising
that he immediately called another observer to confirm this. 
  L. Smelcer contacted one of the best MEDUZA observers Lubos Brat from
Pec pod Snezkou. On Feb. 2, L. Brat had been observing variable stars and
had planned to observe stars from Monoceros when L. Smelcer suddenly
called him. Brat's visual estimate on 19:19 UT confirmed the unexpected
outburst - V838 Mon was at magnitude 8.80 mag (note: diferrence between
CCD+V and visual observations is due to the large B-V index of variable
star). L. Brat immediately called Ondrej Pejcha and Petr Sobotka, who had
been observing variables at N. Copernicus Observatory and planetarium in
Brno. After that, L. Brat ran to his house (ski tourist center Alena) and
sent alerts to VSNET and MEDUZA discussion mailing list. 
  Feb 2. was the first CCD night in life of O.Pejcha. P.Sobotka was
training him how to manipulate with telescope and CCD camera. When the
night came, they had been doing VRI photometry of some symbiotic variable
star. Then they turned the telescope on V838 Mon and took frame in I
filter with 40cm Newtonian telescope. When the frame appeared they
screamed "Ohh!" In the middle of the frame was saturated circle with
diameter of 1/10 of field! They let down the exposition time, so the star
was not saturated, but other stars were too faint to compare. Hence, they
changed filter to V and on 17:45 UT the V838 Mon seemed to be a normal (it
looked normal, they did not reduce this frame). They thought: "since
discovery of N. J. Brown, the star had been slowly decreasing, so why
should we do another observations? It is too boring for us". And they
turned telescope to some RR Lyr star. 
  On 19:25 UT, L. Brat called them and was really exhilarated. He said
what had happened and O. Pejcha and P. Sobotka almost killed themselves
that they had stopped observations of V838 Mon! They immediately turned the
telescope to V838 Mon again and on 19:33 UT started run in V filter with
20-second exposures. P. Sobotka's visual estimate on 20:12 UT 8.73 mag and
O. Pejcha's on 20:13 UT 8.63 mag confirmed Brat's alert.
  P. Sobotka and O. Pejcha reduced their first V frame made on 17:45 UT
and find out brightness at 8,23 mag. During acquisition of new images they
had been simultaneously reducing data which made them able to see the
brightening in real time. On 22:15 UT they sent their report to IAUC. One
hour later, they plot the light curve for the first time and saw
unbelievable brightening with rate of 0,1 mag per hour!!! In this exciting
night three other MEDUZA observers send their observations to
VSNET. P.A.Dubovsky (visual), K.Hornoch (CCD+R) and L.Kral (CCD+R,
visual).
  Thanks to up-to-date technologies as cell phone and email, the
information about outburst had been distributed to the majority of world
observers and many observations were made during the same night around
the whole world. Many thanks to all visual and CCD observers and thanks to
VSNET alert mailling list!!!

Petr Sobotka, Ondrej Pejcha, Ladislav Smelcer and Lubos Brat