Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 04/30/2020 - 23:10
Hey all,
I've been using the binocular charts for the binocular program with great success. However, while playing around with VSP I noticed that if I plot a chart with the same settings (field size, mag limits) as suggested by the Binocular Star spreadsheet, but I don't mark it as a binocular chat, I will get often quite a few more comparison stars.
Is there a preferred reason to stick with the specific Binocular charts or is it okay if I opt for the regular charts with more comparison stars, especially for sparse fields?
--Michael in Houston (RMW)
Hi, I think it depends to some extent on which star(s) you are doing. A faint binocular variable - say, about 9th magnitude would probably benefit from a (b) scale chart. Using VSP you can limit the faintest magnitude you need, so all those 11th-mag stars on a standard b chart won't show up if you set the limiting mag to (for example) 9.5!
Hi Michael,
The stars in the Binocular program have had sequences specially created for observing them. By using the Binocular chart option in VSP you will end up with the sequence stars chosen by the Sequence Team for that particular star.
Most of these charts have large fields of view and thus crowding may be a problem in some fields, where lots of comparison stars will show up in a "regular" chart, stars not relevant to the variable in question.
The stars showing up using the Binocular chart option are supposed to be the best comp stars available and the sequences should be complete. At least that's what we tried to do when creating these charts.
If you happen to find a gap in some sequence, you can report it through CHET suggesting the comp star you want us to include in the binocular chart. But be sure it is really needed.
Cheers,
Sebastian
That does make sense....I did a b chart in Cygnus....oops....that is a lot of stars in a 7 degree FOV. :D