Author Topic: Double Star Epsilon Canis Majoris  (Read 295 times)

Mark

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Double Star Epsilon Canis Majoris
« on: March 03, 2017, 11:29:21 AM »
I was looking at my old AstroCards, for good double stars in Canis Major.  I saw Epsilon listed, mags 1.6 and 8.1 with a 7.4" separation.  Started looking for any reports of splitting it - don't find any. 

Wikipedia says "The +7.5 magnitude companion star is at 7.5" away with a position angle of 161° of the main star. Despite the relatively large angular distance the components can only be resolved in large telescopes..."

Anyone try this?  I am somewhat surprised at what I'm reading....

mccarthymark

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Re: Double Star Epsilon Canis Majoris
« Reply #1 on: March 03, 2017, 12:21:39 PM »
I've not split it myself (though I will try--wish you posted this earlier! I was out the last three nights splitting challenging doubles from my backyard, with the good seeing we've had).  Searching under the common name Adhara turned up plenty of reports of splits, down to 5-6" scopes
 http://www.cloudynights.com/topic/98926-epsilon-canis-major/
Mark

Mark

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Re: Double Star Epsilon Canis Majoris
« Reply #2 on: March 03, 2017, 02:18:49 PM »
Thanks.... looks like a tough one.  I didn't google the common name - I almost always use the Greek.

Joe Bergeron, who used to be in the Santa Barbara club and would come to CalStar, wrote this:

"In my 92mm refractor it resolves neatly at 120X with good seeing from Florida, but is rarely resolvable from my New York site, which is eighteen degrees farther north."

sgottlieb

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Re: Double Star Epsilon Canis Majoris
« Reply #3 on: March 03, 2017, 09:18:07 PM »
Mark, here are two observations I've made.  I've split it in both 6" and 8" apertures -- even at a low elevation if the seeing was good.  I don't have a good quality small refractor, but I'm sure it can be resolved.  So, Wikipedia is certainly wrong.

6" (2/19/07): mag 1.5 Adhara is a challenging double with a 7.5-mag companion at 7.5" separation.  It was cleanly resolved in moments of steadier seeing (viewed at 15° elevation) at 175x using a 6" mask.

C8 (seen several times in the early 1980's) : difficult pair due to very large mag difference.  Visible with at least 100x and fairly easy at 165x in excellent seeing.