TASS magnitude for visual observations of comets

[Seiichi Yoshida <comet@aerith.net>]

Dear colleagues,

Observing comets fainter than 12 mag visually, the magnitude in the
Tycho-2 Catalogue can be inaccurate sometimes.

In the case of the southern sky, we can use the ASAS-3 V magnitude as
comparison stars. However, in the case of the northern sky, observers
have been using the non-recommended GSC magnitude.

But Reinder J. Bouma pointed out that we can get the accurate V
magnitude in the northern sky using the TASS MarkIV data.

The TASS MarkIV data contains all stars brighter than 14 mag in the
northern hemisphere. Using both the ASAS-3 and the TASS data, we can
get the accurate comparison stars down to 14 mag of whole sky.

In the following web pages, I introduce how to look up the TASS MarkIV
data.

  Investigate about Star
  http://www.aerith.net/misao/guide/research.html

  Usage of The TASS MarkIV Engineering Run Database
  http://www.aerith.net/misao/guide/research/TASS.html

Well, in the following web page, I also introduce how to look up the
ASAS-3 data.

  Usage of The All Sky Automated Survey
  http://www.aerith.net/misao/guide/research/ASAS.html

Best regards,

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