Variable Star AB Cas

[Dave Smith]

Finally got to do some astronomy again. Variable Star AB Cas. The gap is where I did a meridian flip and things did not play ball for a while. I did take readings for a further hour but the sky was deteriorating.

 

I find the shape of this curve a little strange - any ideas why?

 

Dave

[MarsG76]

Something I was wondering for a while on and off....How exactly do you measure magnitude of stars?

 

[Merlin66]

Image acquisition software like AstroArt have a "Photometry" feature which allows you accurately measure the star magnitude.

 

[MarsG76]

16 minutes ago, Merlin66 said:

Image acquisition software like AstroArt have a "Photometry" feature which allows you accurately measure the star magnitude.

 

So without software there isn't a way to determine star brightness?

 

[Dave Smith]

I use charts from the aavso to locate the star and suitable comparison stars. I use SGPro to get my scope (Megrez90) pointing at the target and to take suitable exposures. In this case it was 10s. It is vital that the target star and the comparison stars are not saturated. I then use the free software MUNIWIN to do the analysis. Muniwin can produce files in the correct format to upload to the BAA database or to the aavso database. There is loads of advice on the BAAVSS website and also a page that gives predictions of when a minimum will occur. If you need any more detail just let me know.

Dave

[Merlin66]

Dave,

I hadn't come across the MUNIWIN program - great resource.

 

[DHEB]

12 hours ago, MarsG76 said:

So without software there isn't a way to determine star brightness?

 

No. You can also make visual estimations, by comparing the magnitude of your target star with that of a set of comparison stars whose magnitudes are given in charts. You can check the AAVSO or the BAAVSS sites for these charts.