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Challenging double near Jup

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#1 Darren Drake

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Posted 02 January 2013 - 09:47 AM

Last night I noticed that a 6th mag star posing as a 5th Jovian moon is actually a challenging red double star. According to Skysafari Pro it a 5.9 and 8.5 mag double with a sep of 2.0 arcseconds. It took the 16 LB to split it last night in okay seeing. The 8 and 12 inchers were not doing it by the time I realized it was a double on the phone Jupiter was above my house and seeing was down but the Lightbridge was in the front yard and seeing was better there. The star is HR 1370.

#2 Asbytec

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Posted 02 January 2013 - 10:22 AM

Yea, it's a fine looking star. Nice red color. I caught it in 8/10 seeing last two nights, and actually just spent time enjoying it.

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.

#3 Cepheus Elf

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Posted 03 January 2013 - 05:26 PM

I didn't realise it was a double when I was looking at Jupiter with my 127 Mak, but it made a fine site at low power....Jupiter looking like it had five moons strung out in a line. I'll have a go with my C9.25 next clear night and see if I can split it.
Clear Skies,
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#4 fred1871

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Posted 03 January 2013 - 05:59 PM

Yes, the look of Jupiter with "five moons strung out in a line" is a very nice effect.

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.

#5 Cepheus Elf

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Posted 03 January 2013 - 06:50 PM

I haven't checked, but is or was this star occulted by Jupiter? I've never seen one, but I guess it would be very interesting to watch a double being occulted!!

#6 Asbytec

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Posted 03 January 2013 - 08:44 PM

It's a nice tight pair with a beautifully red primary, more folks should observe it. Glad to see some interest in it and that Fred has. Good luck, Elf. Not sure about an occultation, would be nice.

#7 Darren Drake

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Posted 03 January 2013 - 10:15 PM

No there will be no occultation.

#8 Darren Drake

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Posted 04 January 2013 - 02:33 PM

I am interested in knowing what is the smallest aperture newt,sct and refractors this challenging double can be seen with. As of now (1/4/13) the star is posing as a 5th Jovian satellite but Jup will soon move on. So since this star is right now so simple to find and placed so high in the sky I thought it would be very interesting to see how various scopes 8 inches and under do on this challenging double. The mags once again are about 5.9 and 8.5 with a sep of about 1.9 arcseconds. I hope to hear some reports on this one over the weekend.....

#9 Ed D

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Posted 04 January 2013 - 03:02 PM

Darren, I didn't split it, but I was using my 6" f/8 and it looked like a single, really beautiful red star. It was a really awesome sight last night. Now that I know what it is I'm going to try splitting it. I'll let you know what happens.

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#10 Darren Drake

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Posted 04 January 2013 - 03:08 PM

I will try a 6 inch f/8 dob at work at the Cernan Space Center tonight as well. I suspect it will be do able if seeing is good but the lights there are terrible....

#11 azure1961p

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Posted 04 January 2013 - 06:20 PM

I was seeing the companion now and again with my binoculars. 8x42 of course. Naturally a 7x50 would be out of its league on a 2" double.

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#12 Gary Osoba

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Posted 04 January 2013 - 08:56 PM

Hi All:

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.

Best Regards,

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#13 azure1961p

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Posted 04 January 2013 - 11:17 PM

It was the extra 0.5mm of aperture that did it.

Pete

#14 Darren Drake

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Posted 05 January 2013 - 07:38 AM

Okay one buddy of mine was unable to split the star with his 4 inch apo last night but his patience was in question as he was dealing with cold and complaining to me for making him do this.

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.

#15 Asbytec

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Posted 05 January 2013 - 08:06 AM

Cool. Knew you would nab it. No luck with a 4". Try and try again, as they say. Well, until the groaning becomes to much. :)

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.

#16 dscarpa

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Posted 05 January 2013 - 02:10 PM

I didn't know it was a double when I was viewing Jupiter for several nights with my WO ZS-110 at 240X-250X. I did look at the star however because of it's location and pretty color and didn't see any sign of a split. Ditto for last night with good seeing at 230X with a 12 Delos in my C9.25 knowing it was a double. I popped in my 8 LVW for 340X and there it was a nice clean split. As a bonus it was a treat to view Jupiter at that power . David

#17 Rutilus

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Posted 05 January 2013 - 04:04 PM

Another C9.25 user here, used a 9mm eyepiece for a nice split.

#18 fred1871

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Posted 05 January 2013 - 08:34 PM

General experience so far seems to be that it needs 300x or a bit over for a split. I used 320x on my 140mm refractor. Next steady night I'll try it again at different powers to see what's possible with a bit less magnification. This kind of double is very much affected by seeing, and I've found some pairs like this look relatively easy one night (exceptional seeing) and pretty difficult at higher powers another night in merely good seeing.

#19 desertrefugee

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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.

#20 Ed D

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Posted 06 January 2013 - 09:05 AM

Last night (1-5-13) I used my 6" f/8 Dob with a few different eyepieces. Conditions just couldn't get any better, that legendary Florida seeing. The icing on the cake was that the star was positioned high in the sky throughout my observing period. The conditions held for almost 3 hours.

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.

Ed D

#21 Asbytec

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Posted 06 January 2013 - 09:50 AM

Well done, Ed. :)

#22 fred1871

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Posted 06 January 2013 - 08:24 PM

Very nice sketch, Ed. And the colours match up with the spectral types of the stars, K3 and B3. Nice colour difference/contrast when the pair shows itself.

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. :cool:

#23 Catapoman

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Posted 06 January 2013 - 08:35 PM

I just came in from observing this double with my TEC-140. It's nearly directly overhead at my location during this observation. I was able to split this double at magnifications of 163x, 196x and 280x. It was easiest at 280x. I tried at 140x, but can't say for certain I was seeing the secondary. I estimate the PA at around 180* +/- 5. Seeing conditions were marginal and quickly turned poor just after my observation. I'll try again on Monday with predicted better seeing.

#24 EJN

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Posted 06 January 2013 - 08:51 PM

I tried it Thursday & Friday night with an 8" f/5 Newtonian, but seeing was too poor.

Tonight, it is easy at 160x in the 8", companion star is definitely blueish.

#25 Asbytec

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Posted 06 January 2013 - 09:46 PM

:goodjob:






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