Affiliation
None
Fri, 06/21/2013 - 13:03
Folks,
I'd like to encourage all visual observers to take part in the AG Dra Observing Campaign that has been posted on the AAVSO web site. AG Dra is a great visual star to observe, having a range of 7.9-10.3. There are 2 bright stars to use as locators on the "b" chart. Even smaller telescopes can do some great science here! Please read the Alert Notice on AG Dra, print off a chart, and go to it!! Good Observing.
Chris Stephan SET
Mahoning Valley Observatory
Braceville, OH
I agree 100% with Chris on this one. AG Dra is a great star. It appears to show some erratic variation on short time scales, and recently seems to be in a fading trend overall. There is a bit of an inconvenient gap in the sequence between 8.3 and 8.9, but that doesn't appear to be in play most of the time. The rest of the sequence (on B scale chart for example), is pretty good.
I like the unpredictable and active stars myself. I haven't observed this one because it is fairly bright, and I choose to go after fainter objects in general with my 12" telescopes. But this one would be an easy target in my 80mm short tube refractor.
Bright, easy to find, good charts and sequence, active and unpredictable and somebody WANTS your data- what else do you want! I'm printing charts for it right now. What the heck...
Thanks Chris, AG Dra has been added to my observing list, perfect for my 80mm piggyback refractor
Yes, this is a good star for finders, like CH Cyg. I can remember following R Vir to about 10.6 with a 7x50 finder a few years back. A good sequence too. And aren't there a couple of suspect variables in the AG Dra field too?
I would point out a "fly in the ointment" regarding this star's observation with small telescopes. While at minimum its immediately surrounding comp stars offer excellent comparisons, when outbursts do occurr the widely spaced arrangement of the needed brighter comp stars has often proven a significant difficulty for observers. Without question, when in outburst AG Dra must be followed with larger, wide-field, binoculars, otherwise estimates clearly do suffer.
J.Bortle (BRJ)
It may be a bit too extreme to say one MUST use wide field binoculars to measure brighter variables! I just estimated AG Dra with my 20" reflector and my estimate came in exactly in line with the others. The issue is not the aperture per se, but whether or not you can effectively utilize the proper comp stars in the same field, or very nearly so. I can always opt to use very low power in my 20", though the exit pupil becomes larger than my iris, there is no issue with the wasted light for such a bright star!
Also, for these bright variables, its perfectly fine to use the Tycho2 with Bessell corrections to find comp stars which may not be on the charts. The Tycho photometric errors at these bright levels is negligible for visual use. For example, you could use TYC 4195-1968-1 at V=8.77 to fill the 83-89 gap a little better, and its only 80' distant.
Mike LMK
[quote=BRJ]
when outbursts do occurr the widely spaced arrangement of the needed brighter comp stars has often proven a significant difficulty for observers. Without question, when in outburst AG Dra must be followed with larger, wide-field, binoculars, otherwise estimates clearly do suffer.
J.Bortle (BRJ)
[/quote]