Experimenting with filters for splitting Antares

[pjsmith_6198]

Splitting Antares is very difficult and I've never had any luck doing it.  The problem being the separation between primary and secondary is only 2-3 arc seconds and Antares A is much brighter than Antares B (mag 1.2 to mag 5.4).  Also being so low above the horizon doesn't help either.  So I thought I would try different filters to filter out most of the brightness of the primary to make the secondary easier to see.

Antares B is class B2 or B3 which is blue white.  So I would use Astronomik OIII, H-Beta and UHC filters to see if any of helped.   I was using my 12 inch dob with 10mm/7mm/5mm XW's and 9mm/7mm Fuji ortho's and 10mm/6mm BCOs.  I tested different combinations of EPs and filter over 3 sessions. The seeing varied average to better than average but not great.  Transparency was average to below average each night. Bad transparency might actually help it helps reduce the glare.   My best view of Venus was looking through clouds.  Each night I checked and tweaked collimation if needed. 

Using no filters I failed to split Antares with any of the EP's I was using.  Using a 2x barlow didn't help.   Seeing was not good enough to go beyond 300x on any night.  

The performance of the OIII and H-Beta filters were similar.   Both tightened up the focus considerably compared to using no filters.   Antares was still difficult to split but on the nights of better seeing I was able to tell there were 2 stars there and splitting in moments of better seeing.  It was slightly easier to split with the ortho's than the XW's.  However I would get more eye strain with the ortho's. The XW's were more comfortable to use.   

I wasn't expecting much from the UHC filter because along with passing the OIII and H-Beta bands, it passes most of the H-alpha.   So if you look at a bright star you see both greenish blue  and magenta color.   I  thought that to much red would pass and Antares A would still over power Antares B.  What happened was the image focused to a small bluish point touching a larger magenta point.  The blue point was approximately at 8 O'clock position compared to the magenta point.

I viewed Arcturus using the same EP/UHC filter.   I saw both blue and red but they didn't resolve into blue and magenta points.  Just one containing both colors.

I viewed the Double-Double Epsilon 1 and 2 in Lyra because they have about the same separation.  These resolved with both colors but mostly blue with the same separation and orientation as with no filter.  I was harder to split them using the UHC filter than no filter because they were fainter.

I split Cor Carli with the UHC but the separation was wide enough that they looked like normal stars with the UHC.   No blue and magenta.

My conclusion is Antares is easier to split using a OIII or H-Beta filter than using no filter.   Antares is easiest to split with a UHC filter which passes the H-alpha band because the stars resolve into a magenta primary and blue secondary.   This probably only works for blue and red doubles.  

Has anybody tried this before?  I thought using the OIII or H-beta would help somewhat but I didn't expect the UHC would be so easy.   

Thanks,

Phil

 

[IB20]

Interesting, I think I’ve read similar on Cloudy Nights. I’ve had a few goes at Antares this season but the atmosphere hasn’t played ball so far. Despite thinking I have fleetingly detected the companion it’s so swamped from the shimmering primary that it’s never a certainty. 

I must give this method a go! 👍🏻

[markse68]

On 05/06/2022 at 06:57, pjsmith_6198 said:

Has anybody tried this before?

nope- but I will! I so want to split Antares. Thanks for the suggestion!

Mark