American Association of Variable Star Observers (AAVSO)
Sun, 10/29/2023 - 13:50

Hi, I'm sure this has been asked before but I couldn't find it or at least did know the right phrase for the query. 

I'm a new observer.  Winter is coming and I do have a nice warm space in my house to run the telescope outside.

Can visual magnitudes be done this way either on screen or from a calibrated mono image?  

I'm not geared up for CCD photometry yet and am in no rush to do so.


American Association of Variable Star Observers (AAVSO)
Hi Terrence

Sounds like you…

Hi Terrence

Sounds like you have a camera on a telescope outside.

You may be very close to doing common differential photometry.

Would a mentor help? Try emailing a request for a mentor here: 



American Association of Variable Star Observers (AAVSO)
Thanks Ray

I took the CCD course this spring and the visual with "Professor" Pox later.  I wanted to start visualreporting this summer but with work and the weather I just spent the  limited time observing the tutorial stars, no reports.

I'm not ready to jump into CCD photometry yet.  Still need a couple gadgets to do it and would like to do visual for a while first.  

That's why I was curios if doing it by image was acceptable through the winter.  If you get a good image of a star and comps paying attention factors taught in the CCD course, seems like it could be done.

Thanks again,



American Association of Variable Star Observers (AAVSO)
I think that decision is…

I think that decision is above my pay-grade Terry. But there is a parallel.

Solar observers maintain sunspot counts visually rather than let a computer count them. The method is taught to observers so that the  counts are done the way that they have always been done. No kinks in the 400 year solar cycle graph.

I suppose that you could estimate magnitudes from your CCD, but your eye has a measurable different response than a CCD, and different CCDs have different response from 300 to 1100 nanometers. You likely would get different magnitudes when using visual vs visual-from-CCD or visual-from-video monitor. You could do a good sampling (100 to 1000?) of measurements both ways and compare them. Best done by two observers to avoid some bias.

Sounds like a lot of trouble though, better to buy what you need to do CCD work.

Binoculars on a lawn chair wrapped in blankets works for visual in the winter.