[vsnet 2052] Magnitude data collaboration between projects

[Seiichi Yoshida <comet@aerith.net>]

MISAO Project Announce Mail (August 29, 2000)

Hello. I am Seiichi Yoshida working on the MISAO project.

It has passed about one and a half of year since the discovery of the
first variable star on the MISAO Project. Now the number of MISAO
variable (MisV) stars is about to reach to 1000.

Unfortunately, most of the MisV stars have a few observations and the
profiles such as variable type, period, etc., are uncertain, because
it has not passed long time since the MISAO Project started.

However, some of the MisV stars were observed not only in the MISAO
Project but also by outside people or projects. As a result, there are
some stars whose period was determined, which was uncertain only based 
on the MISAO's data, or whose interesting behavior was revealed.

The light curves of all MisV stars also observed by outside people or
projects are available at the following web page.

  MisV Stars Light Curve
  http://www.aerith.net/misao/data/curve.html

We received the MisV observations from the following outside people. 

  Arne A. Henden		MisV0001 (*1)
  Guy M Hurst			MisV0884
  Mike Collins			MisV0884
  Patrick Schmeer		MisV0508
  Seiichiro Kiyota		MisV0001, MisV0955, MisV0956

  *) The image itself was offered.

The details on MisV0001 was reported in the announce mail issued on
Apr. 19, 1999. The 390 day period was obtained based on the Kiyota's
observations.

Mike Collins and Guy M Hurst reported me the interesting
observations. They said that MisV0884 was too faint, fainter than 11
mag, when it was bright as 9.3 mag in the MISAO Project observations.
Especially, Hurst's observations was with unfiltered CCD, as same as
the MISAO observations, so it cannot be explained by the color of the
star. Maybe it is a strange variable star.

Some MisV stars are in the well-observed fields, near by M27, near by
recent novae, etc. If you find MisV stars on your images, and measure
the magnitude, please report it to the public.

There are some working projects which are taking CCD images of all
sky, accumulate magnitude data of stars, and search variable stars,
besides the MISAO Project. The two projects, TASS (The Amateur Sky
Survey) and ASAS (The All Sky Automated Survey), publish the
observation data to the web.

Some MisV stars were observed in their patrol images. In the "MisV
Stars Light Curve" web page, the light curve including the TASS and
ASAS data are available. Most of the TASS data were researched by
Michael Richmond. The identifications with ASAS stars were researched
by John Greaves.

  ASAS	MisV0270, MisV0271, MisV0430, MisV0492, MisV0533, MisV0823, 
	MisV0826, MisV0836, MisV0852, MisV0911
  TASS	MisV0009, MisV0130, MisV0138, MisV0142, MisV0143, MisV0144,
	MisV0161, MisV0162, MisV0164, MisV0165, MisV0250, MisV0351, 
	MisV0352, MisV0430, MisV0573, MisV0696, MisV0701, MisV0740, 
	MisV0824

One of them, MisV0009 shows an interesting light curve. The TASS
I-band observations show both the slow fading and short-time
eclipse-like fading. The eclicpse-like event occurred between 2450995
and 2451022 (JD), with a large amplitude as maximum 10.2 mag and
minimum 12.4 mag. But while TASS I-band observations were detecting
the slow fading, TASS V-band observations show it was constant, or
maybe slightly brightening. Including the MISAO observations and
excluding the eclipse-like event, it looks like a slow variability
with a rough period of 500 days.

Richmond also pointed out that the four stars, MisV0429, MisV0697,
MisV0698 and MisV0699, was not recorded in the TASS project, although 
they are in the TASS patrol fields observed many times. It may be
because the maximum brightness observed in the MISAO Project are faint 
as 12.8 mag, 13.3 mag, 13.7 mag, 13.8 mag respectively. But it maybe
imply the rapid brightening and fading.

There are many ASAS data of MisV stars also observed in the ASAS
project. The periodic variability evidently appears in the light
curve. Most of them were revealed as Mira type or SR type variable
stars with a long period. But the period of MisV0911 is uncertain,
although the light curve looks quasi-periodic. 

As mentioned above, data collaboration between projects can yield
valuable information. In the MISAO Project, the magnitude of new
variable stars discovered by outside searchers or projects are also
measured and reported to the VSNET, not only searching MisV stars.

There are some MisV stars whose strange behavior were detected only
based on the MISAO Project. In case of MisV0073, the unfiltered CCD
observations suggest that short-period variability with about 20 day
period. But the difference between unfiltered CCD magnitude and CCD
magnitude with IR-blocking filter suggests that MisV0073 is a red
variable star.

However, there are not data enough to determine the type or features
of those stars with strange behaviors still now. It is also an
important work of the MISAO Project to accumulate magnitude data
continuously after this, not only to discover new variable stars. 

By the way, the catalog of 2MASS (The Two Micron All Sky Survey) was
published recently. Taichi Kato researched the identifications between 
the 2MASS data and MisV stars and revealed many MisV stars are
recorded in the 2MASS catalog as bright objects. It means most of the
MisV stars are red variables. Taichi Kato also found that the position 
of MisV0041 was inaccurate, based on the identification with 2MASS
data.

As mentioned above, investigation of catalogs can reveal the type of
variable stars or help to find mistakes. The number of all sky surveys 
increases after this and many catalogs will be published in the
future. The catalogs based on the amateur activities like the MISAO
Project can be also published. Therefore, researches on catalogs will
be one of the important works in astronomy. In the MISAO Project,
Taichi Kato and John Greaves research various catalogs for
identifications with the MisV stars.

P.S.
The past MISAO project announce mails are available at:
  http://www.aerith.net/misao/

--
Seiichi Yoshida
comet@aerith.net
http://www.aerith.net/

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