Photometry - correct star magnitudes for reference stars

[pscharff]

Hello,

I am currently in the process of doing photometry at T CrB. I have made some images of T CrB by using the V-filter.

In Astroart 8 I have set the option for using the APASS DR10 star atlas. I have downloaded the corresponding aera of the sky from this site:
https://www.aavso.org/download-apass-data

In addition to the usage of the internal sky atlas of Astroart I wanted to compare the star magnitudes of the reference stars by using the AAVSO "Variable Star Plotter" tool. The result was, that there are differences in the magnitudes between the VSO and the internal Astroart star atlas.

In Astroart I have choosen the "V" band for the APASS DR10 atlas. In the VSP tool "V" magnitudes are displayed automatically.

So, here is the result:

As you can see, the same star is shown with magnitude +10,06 in Astroart and with magnitude +9,809 in VSP.

Can you please tell me, what is the correct magnitude?

Clear skies,
Patric

[pscharff]

I have already thought about asking this question in the AAVSO forum, because Astroart only shows the magnitudes which are offered by the APASS DR10 star catalog.

Therefore it is not a problem of Astroart.

Patric

[pscharff]

I think, I have found an answer. The same question was allready asked here (third post):
https://www.aavso.org/which-catalog-dif ... photometry

Patric