Challenging double near Jup
Posted 02 January 2013 - 09:47 AM
Posted 02 January 2013 - 10:22 AM
Didn't notice it was a double. But, at those magnitudes and that separation, what makes it so hard? I was seeing stars in the vicinity of the moons near 12th magnitude.
Maybe I should set back up and try it. But, I was loosing Jupiter in some unsteady air.
Edit: Never mind, answered my own question. That is another unequal, close pair like C Ori. Never saw it while viewing Jupiter at mags around 170x. But, at 260x (12mm HD Ortho 1.6x Barlow) and 320x (6mm TMB II), sure enough there is a companion struggling for attention almost directly south. It sits right outside the first ring in the second minimum (at 1.8" arc.) Really hard to see any color.
Darren, thanks for pointing that one out. Had you not mentioned it, never would have noticed it. It was a beautiful site with Callisto's pale disc just NE in the FOV.
Posted 03 January 2013 - 05:26 PM
Posted 03 January 2013 - 05:59 PM
The double you guys are describing is BU 87, to give it a double star designation.
Current information in the Washington Double Star Catalog (WDS) is mags 6.21 and 8.60 (so probably Tycho magnitudes), at separation 1.9" (2007 measure - the separation has sloooowly increased since discovery in 1873). Angle hasn't changed much, so its no doubt a very long period binary.
And, yes, the combination of magnitude difference and close separation does make it "non-obvious" as a pair. I've split it with my 140mm refractor. As Norme indicates, it needs a bit of power applied to separate the companion. And decent air steadiness, as usual for this kind of pair.
Posted 03 January 2013 - 06:50 PM
Posted 03 January 2013 - 08:44 PM
Posted 04 January 2013 - 02:33 PM
Posted 04 January 2013 - 03:02 PM
Posted 04 January 2013 - 03:08 PM
Posted 04 January 2013 - 06:20 PM
Posted 04 January 2013 - 08:56 PM
I'm primarily a planetary observer, but as noted above could not help but notice the double last night. With a 317.5mm f/5 Zambuto Primary Newtonian equatorially mounted, I saw clean separations starting at about 160X ( I wasn't looking for it when first noticed). As seeing improved, and employing up to 370X utilizing a professional Zeiss Monocentric coupled with a Powermate, there was a chasm between the pair and the minor component appeared yellow in contrast to the red partner. Seeing was 6-7/10. The chasm was estimated at 5X the diameter of the minor star's airy disc, which is about the resolution limit for this instrument so the seeing might have been better than I noted.
Posted 05 January 2013 - 07:38 AM
Another buddy with his superb 8 inch newt was apparently not able to do it but may not have had enough magnification going to do it. I'm quite certain that his scope can do it but he just didn't have a high enough power eyepiece there to do it.
I used an XT 6 at the space center last night and may have glimpsed it but again not enough power was available there as I only had a 7mm available as the highest power and the lights were terrible. Also the night before my C8 did show me the companion star on a shaky balcony but it was difficult.
Posted 05 January 2013 - 08:06 AM
I grabbed it tonight at 320x and 380x. Didn't think I need that high magnification, but it was shocking to actually hold the companion for longer periods up 60x per inch. I stared right at it for several seconds in 7 to 8/10 seeing, variable cloudiness. Actually holding it for a time was a quite striking view.
Posted 05 January 2013 - 02:10 PM
Posted 05 January 2013 - 04:04 PM
Posted 05 January 2013 - 08:34 PM
Posted 06 January 2013 - 01:38 AM
I am interested in knowing what is the smallest aperture newt,sct and refractors this challenging double can be seen with.
I happened onto this pair while observing Jupiter. I popped in here to see if there was any chatter on it and my answer was this thread.
I got a definite split from suburban Phoenix using my ES ED127 at 317x. Clearly notched at 238x, I might split it there with better seeing, but it's doubtful. Seeing was pretty good tonight for Arizona. I'm pretty satisfied to call it a night and move on.
Posted 06 January 2013 - 09:05 AM
At 133x, the lowest mag used, I could tell I was looking at a double but couldn't see the secondary. At 480x, the highest mag used, the image was OK but soft. The usable range of magnifications where I could see the secondary was from 160x to 400x, but the sweet spot was at 240x.
I posted a sketch, listing magnifications and comments, here in the Sketching Forum if anyone is interested. It also shows the colors I observed, the primary appearing orange/red and the secondary appearing a blue/teal color.
BTW, the previous night conditions were not the best and I had a very tough time seeing the secondary star at 400x.
Posted 06 January 2013 - 08:24 PM
As you've noted, the seeing is a big factor - it must have been very good the second night for the 6-inch to show it with the more moderate magnifications you list. And good optics.
Posted 06 January 2013 - 08:35 PM
Posted 06 January 2013 - 08:51 PM
Tonight, it is easy at 160x in the 8", companion star is definitely blueish.