Equal Doubles countdown
Posted 22 January 2020 - 02:38 PM
Can anyone provide a list of nearly equal magnitude doubles (meaning the two stars in a given pair are equal) that go from 5" down to 1" separation (not likely I'll need that but might as well be optimistic). Bonus points if you have them in 0.5" intervals.
Of course it will only be fun if they can all be seen in the sky in a single two hour session.
More bonus points if you can do four sets, one per season.
My bias is for northern hemisphere but I don't want to exclude those currently enjoying summer.
Thanks for reading.
Posted 23 January 2020 - 03:22 PM
I agree; use stelledoppie.it, and use the Advanced search to tweak parameters for mag. primary and secondary, delta mag. (use"between"), separation (use "between") and constellation.
Just for fun, I did it for Orion; got a mag. 8 pair 5" apart (approx.), a mag. 7 pair 3" apart and a mag. 6 pair 1" apart.
(see last 3 entries in each row below (separation, mag. primary, mag. secondary)):
Show V1804 Ori Ori 05 23 06 +01 03 25 STF 700 2017 48 4 4.80 7.69 7.89
Show Ori 132060 05 23 51 -00 51 60 WNC 2 A,BC 2018 122 158 3.10 6.87 6.96
Show 52 Ori Ori 113150 05 48 00 +06 27 14 STF 795 2017 173 220 1.00 5.99 6.03
Posted 23 January 2020 - 06:47 PM
Thank you both. I get on and play around soon. If you find any particular favorite set after you get a chance to look at them please post.
Posted 27 January 2020 - 06:35 AM
The book 'Observing and Measuring Double Stars', edited by Bob Argyle, has lists of such pairs recommended as resolution tests for apertures ranging from binoculars to 60cm. In the first edition they are arranged by aperture, in the second by RA.
I'm not sure if these are online anywhere but I could scan. As even the second edition is a few years old now the PA/sep data needs a check/ update but they're a great starting point.
Posted 27 January 2020 - 10:22 AM
Perfect. Thanks for the suggestion.