Re: Phobos, Deimos and more challenges


Paul
 

Phobos is currently magnitude 11.8, which puts it in the same ballpark as Enceladus.  I have never found Enceladus easy in my 8" Dob, but I have had intermittent glimpses of it a few times. Enceladus has a larger maximum separation, but there are those rings, so I'm not sure how the difficulty of seeing Phobos would compare to the difficulty of seeing Enceladus. I guess I'll just have to try and see it for myself.  I don't have an eyepiece with a focal plane outside the barrel, though. Maybe this is a reason to pick up a Kellner or RKE. 

I have seen Sirius' companion (The Pup) twice now. Both times at very high mag and fantastic seeing, and both times it took me quite a while to be sure I was seeing it. Once I saw it, it seemed much more obvious. The same way I often feel when I manage to find Venus with unaided eyes during daylight . Oh and I should mention that I saw it twice and that was in about 2000 attempts (maybe more)  :-o

Other similarly fun ones are Antares and Propus.


 




On Thu, Apr 3, 2014 at 6:14 PM, Roy Diffrient <mail@...> wrote:
 

I remember that!!  What a fun time! And IIRC we saw both Deimos and, eventually, Phobos.

Occulting eyepieces have been discussed here previously, but it's been awhile.  I don't know of one for sale commercially either, but one can be fairly easily made_if_you have an eyepiece with the focal plane outside the barrel (such as Kellner, RKE types).  Most modern eyepieces (such as Naglers) locate the focal plane inside, somewhere in the middle of the optics -- The occulting element must be at the focal plane to function properly.  The easiest way to DIY this may be to start with a cross-hair eyepiece (where the cross-hairs are available at the bottom of the barrel), and gently stick a carefully-cut piece of opaque black plastic tape (or eq.) on the cross-hairs so that about half the field is blocked off.  Then add a PowerMate or some Barlows to boost the magnification.  Amazing how it boosts the contrast of a faint object near a blocked-off bright one.

Roy

Sent from my iPod

On Apr 3, 2014, at 5:23 PM, <kent@...> wrote:

Right you are, Ted. It was at Tuckahoe MD, October 2005. We showed it to Roy Diffrient, Robert Hitt, Danka Prilepkova and "14-year old" C.J. Wood.


Kent Blackwell


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