[Lvas] Revised Challenge Objects for June 2009

Tue May 5 06:02:27 PDT 2009

LVAS all,

Some changes with more information that may become important in your attempt to observe the three challenge objects for the month of June.

Roger

Our "Observers Challenge" for June will be M-13. We will be looking for the illusive "propeller" within M-13. Three dark lanes radiating from the central region. See my sketch of Lord Rosse's sketch of about 1850 from Ireland.

WSH brought presented this challenge in "Deep-Sky Wonder's" in Sky & Telescope July 1953. 

In 1980 John Bortle saw the lanes with his 12.5-inch reflector at 176x. Dennis di Cicco at Stellafane in 1981 was surprised by how easily the lanes were seen with the 12-inch f/17 Porter turret telescope at about 180x. However, even knowing their orientation and appearance, he was unable to see them at 95x with a 12-inch that was set up nearby. Sighting the lanes seems to depend upon a careful balance of aperture and magnification. 
Both Bortle and Dennis di Cicco commented on the importance of magnification. Most observers note that they appear best at a magnification of about 200x. Information from "Deep-Sky Wonders" by Walter Scott Houston, selections and commentary by Stephen James O'Meara; Sky Publishing Corporation Cambridge, Massachusetts 1999.   

We will add two galaxies to our monthly challenge, both located in the constellation of Ursa Major. Two very faint galaxies. The first, NGC-4290 at 12.6 magnitude. Messier 40 is a pair of 9th magnitude stars less than 15' E of this galaxy, and the second is the "very faint" NGC-4284 at magnitude 14.7; app. 5' W. of NGC-4290. See my attched sketch to be used as a finders guide. Using my 10-inch reflector with a magnification of 200x I could glimpse the fainter NGC-4284.    

I have observed both of these galaxies from my backyard with my 10-inch reflector. The challenge will be nothing more than to see both of these very faint galaxies. I have notes and descriptions of both. NGC-4284 is one of my faintest galaxies I have observed to date...possibly the faintest.   

On April 3rd 1994, Tom English and I observed both galaxies from my backyard. We could easily see NGC-4290 with the GWU orange tube Celestron C-8, but we could not see the 14.7 mag. NGC-4284. 

We could see both with my 10-inch reflector. Averted vision was required to see the fainter NGC-4284, and we could not hold it constantly. My notes indicate a round shape with a stellar appearance.

We observed that night from 11:00 PM till 3:30 AM local time, stopping only due to the rising of the moon. Conditions were very good with some occasional or intermittent clouds.  We were also observing and estimating the magnitude of a  supernova in the galaxy NGC-4526...magnitude 12.5.  

Good luck with the June objects. 

Roger

    I can see how it might be possible for a man to look down upon the earth and be an atheist, but I cannot conceive how he could look up into the heavens and say there is no God.      Abraham Lincoln

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