[vsnet-chat 1680] Errors in star catalog

[Seiichi Yoshida <seiichi@muraoka.info.waseda.ac.jp>]

MISAO Project Announce Mail (Mar. 10, 1999)

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

In the last MISAO Project Announce Mail issued on Mar. 5, 1999, the
list of MISAO catalog errors, not detected at all but recorded in the
catalog, was published, 

Then Dr. Arne Henden pointed out that since the wavelengths are
different between images of the MISAO Project and the GSC or USNO-A1.0
catalogs, such stars not detected in the MISAO Project cannot be
always stated as errors in star catalogs (Thank you so much, Arne).

The policy to determine MISAO catalog errors is in principle, to pick 
up stars not detected at all during five or more nights and the
magnitude recorded in star catalog is 1.0 mag or more brighter than
the limiting magnitude. Here, the limiting magnitude is what output
by the PIXY system, so it is usually about 1.5-2.0 mag brighter than
the faintest magnitude of the image (the magnitude of the faintest
star). Therefore, even if a star is actually a bit fainter, it cannot
be selected by mistake as a MISAO catalog error when the magnitude
difference is less than 2.5 mag.

However, some stars can be selected by mistake as MISAO catalog errors 
in the following cases.

- Faint nebulae or clusters.
    In the MISAO Project, nebulae and clusters are removed by
    referring to such catalogs as NGC2000, IRAS PSC, etc. But there
    are many faint galaxies not listed in those catalogs. Because
    galaxies are recorded brighter in the GSC or USNO-A1.0 in general, 
    they may be compiled as MISAO catalog errors by mistake. In
    addition, the magnitude estimation of nebulae and clusters by the
    PIXY system tends to become fainter than that of normal stars. So
    they may be judged as catalog errors more.
- Wavelength difference.
    Some stars become several magnitude fainter than the value
    recorded in star catalog.
- Variable stars.

Since faint nebulae and clusters always appear fainter than recorded
in star catalog, they are always output as candidates of catalog
errors by the PIXY system. Therefore, the MISAO Project decides to
compile such faint objects into MISAO faint objects catalog (MisF).
In principle, when an object was not detected at all during five or
more nights but exists as a very faint object actually, much fainter
than recorded in star catalog, it will be registered as MisF object.

Actually, among the MISAO catalog errors published in the announce
mail on Mar. 5, MisE.UA1.00001 is a real object. It is very faint and
cometary, so it should be a galaxy.

I guess some of the MISAO catalog errors will be revealed as real
objects after this. Then such an object will be registered as a MISAO
faint object and the code of MisF object is inserted in the list of
MISAO catalog errors.

The list of MISAO faint objects are available at the URL:

  http://vsnet.info.waseda.ac.jp/muraoka/members/seiichi/misao/public/MisF

The MISAO faint objects registered hitherto are as follows.

MisF -- Faint cometary objects discovered by the MISAO Project.

ID        R.A.      Decl.     Mag
------------------------------------
MisF00001 065826.60 +410846.3 17
MisF00002 063924.48 +474631.7 17
MisF00003 063517.84 +474914.0 16
MisF00004 062840.10 +480357.7 16
MisF00005 012113.39 +200905.7 15
MisF00006 012132.02 +195229.9 15
MisF00007 132151.60 -174014.9 17
MisF00008 004247.64 +404431.1 17
MisF00009 185840.78 +432806.6 17
MisF00010 165854.29 -174434.5 14
MisF00011 165853.82 -174434.4 14

By the way, 16 errors in the GSC and 19 errors in the USNO-A1.0 are
discovered after the announce mail on Mar. 5. 

Dr. Arne Henden also pointed out that the R.A. and Decl. should be
recorded in the list. So the recent list contains R.A. and Decl. of
all objects. The lists of the MISAO catalog errors are available at
the URL:

  http://vsnet.info.waseda.ac.jp/muraoka/members/seiichi/misao/public/MisE.GSC
  http://vsnet.info.waseda.ac.jp/muraoka/members/seiichi/misao/public/MisE.UA1

P.S.
The past MISAO project announce mails are available at:
  http://vsnet.info.waseda.ac.jp/muraoka/members/seiichi/misao/

--
Seiichi Yoshida
Muraoka Lab., Waseda University, Japan
seiichi@muraoka.info.waseda.ac.jp
http://vsnet.info.waseda.ac.jp/muraoka/members/seiichi/index.html

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