Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 11/22/2014 - 19:59
When I create a regualr chart for Eps Aur it show mag. for Copella and comparison starts 32, 38, 43. But when when I do a binocular chart all it shows are the 4.7 comparison star even though 32, 38 , 43 and a couple of other are in the field of view (FOV)? I'm using the "A" chart scale and "Binocular Chart"?
Thanks,
David
David,
When you use the VSP to secure an "A" scale chart for Eps Aur you will note the following:
NOTE: epsilon Aurigae is a bright star that requires a very large field of view that is beyond the normal plotting capabilities of VSP.
Click here for a chart we recommend for visual observing of epsilon Aurigae.
The VSP is limited to a FOV of no more than 20 degrees (1200 arcmin). The chart that the "click here" creates is well over 20 degrees and was created for the citizensky program.
There is no physical way to include the 19 & 26 (very important) comps into a 20 degree fov with this target and therefore I suspect that could very well be why this target was never originally included in the Binocular Charts list:
http://www.aavso.org/aavso-binocular-progra
One a star is included in that list a special code is then added to the comps intended for that target so that a Binocular chart can then be specially created.
As Eps Aur is not in the Binocular program, at the moment, that is why you do not get the comps you are inquiring about as they lack the speical code for this purpose.
I have written to Mike Simonsen to ask him if he wants to include this target within the Binocular program... however, as previously mentioned the 26 could not be included and I note the 32 might be somewhat variable and have also asked Sebastian to take a look at this.
One of us will let you know whether or not Eps Aur will be included as a binocular target on the existing list.
Per Ardua Ad Astra,
Tim Crawford, CTX
Sequence Team
Thanks for the
Tim,
Thanks for the clarification.
That make sense.
David (JDAC)
David,
For all the reasons Tim explained, eps Aur is not included in the AAVSO Binocular Program, so VSP will not plot Binocular charts for it. That is why we created a special chart just for it. All of the stars in the 10 star and 11 star tutorials are best observed naked eye with the special charts in those pdf documents.
http://www.aavso.org/10-star-training
Besides the fact that many of the useful comps would never fit on a 1200 arc minute chart, eps Aur is not a great target anyway; except for once every 27 years when it goes into eclipse. By 2036 (the next eclipse) we may have a better solution. For now, if you want to observe stars in the tutorials, please use the tutorial charts.
Mike Simonsen
AAVSO
Are you implying that so-called stable variables are not worth observing???!!
Thanks for the
Steve,
Thanks for the clarification.
David
Well, when I started variable star observing, I wanted to see some variations from week to week, or better, day after day. I took up R Leo and beta Lyrae for this, and avoided Algol.
Algol has a period of about two days, but the eclipse itself is is just 9 hours. So the chances of seeing one (without planning in catching one) were fairly slim. I guess I wanted to avoid the situation where I'd stare at a star that is known to vary, and yet see nothing. It doesn't take long to just lose interest in the activity alltogether.
27 years between eclipses is a long time. While monitoring eps Aur during its maximum might reveal some faint fluctuations, it will probably take a very good eye to detect them. So sure, one can observe stable variables, but this is a decision one should take only after aknowledging that there's a really good chance he/she won't see any change at all. Make it an informed decision, basically.