[Lvas] Virgo Cluster Observing Tecnique

[roger ivester]

This is a follow-up from yesterday's discussion regarding the "Virgo Cluster" which is pretty much centered around M-84 and M-86. 

 

My friend and book author, Tom Lorenzin...author of 1000+ The Amateur Astronomer's Field Guide to Deep-Sky Observing pointed out the nine galaxies one evening. I could hardly wait to to observe this group. Tom called this 1° degree field of galaxies "The Nonet".

 

The galaxies comprised in this group are E to W;  NGC-4435, 4438, 4425, 4407, 4406 (M-86) 4413, 4387, 4388, 4374 (M-84).

 

I will send a scanned copy of my sketch with each galaxy identified to all if there is anyone who would like to have it for identification purposes. 

 

I will also submit a detailed description of each in the final observing report...hopefully along with observing notes from many others. 

 

I found it necessary to use an unusual technique to observe this group. I don't normally use my RA motor for tracking but in this case it was necessary. I hand guide almost all the time. With polar alignment I do not find it objectionable to slightly nudge the scope in RA to keep the object in view.

 

Some of the galaxies are too faint to be seen at the low power of 57x. I had to use a 20mm UO Erfle to get a 1.1° degree field as I had mentioned in the previous e-mail.

 

I found it necessary to look at a photograph of this group and use a minimum of 114x ...maybe up to 150x to see and study the fainter galaxies. I would then draw them in their appropriate location and also to the proper scale as compared to the brighter ones. 

 

With a 10-inch telescope it is necessary to use over 100x to "just see" galaxies that are fainter than 12th magnitude...most of the time. Of course it depends on the concentration and surface brightness of the galaxy, and of course sky conditions.

 

John, your with your 10-inch f/12.5 Maksutov with a focal length of 3175 mm's it is going to be hard for you to get a 1° degree field. You may want to use your eyepiece with the greatest field and then use a photograph as I do and try moving the scope to the location of each galaxy. Memorizing from the photo where they should be in relationship to M-84 and M-86. I would love to hear your results.

 

Fred, your 16-inch should show this entire group nicely using your 38mm Q70 2-inch. With your focal ratio of 1828 mm's you should be able to place all galaxies in your 48x magnification. The greater light gathering ability of your 16-inch versus my 10-inch should be significate and you should be able to see all the fainter galaxies at the lower power. Like John I can hardly wait for your report. 

 

48x/70° AF = 69 arc mins or a 1.15° degree FOV. 

 

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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