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Lion Nebula SH2-132 - RC71

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Posts Made By: Dave Mitsky

February 12, 2006 11:52 AM Forum: Deep Sky Observing

Do anyone know anything about..

Posted By Dave Mitsky
I observed NGC 6067 (as well as all the other objects on the Astronomical League's Southern Sky Telescopic List) from Huatajata, Bolivia in July, 2004, but I don't have my notes at hand.

http://www.seds.org/~spider/ngc/ngc.cgi?n6067

I can't recall if I viewed the other three objects during my trips there in 2001 and 2004.

Dave Mitsky

February 16, 2006 09:54 AM Forum: Equipment Talk

Broadband vs. narrowband

Posted By Dave Mitsky
You may find these articles of interest:

http://www.cloudynights.com/item.php?item_id=63

http://pages.sbcglobal.net/raycash/filters.htm

http://sciastro.net/portia/advice/filters.htm

Dave Mitsky

February 23, 2006 09:13 AM Forum: Beginning Astronomy?

Mercury Tonite

Posted By Dave Mitsky
Here's a shot of Mercury that I took on Tuesday evening with my Canon Digital Rebel.

Dave Mitsky

March 3, 2006 06:40 PM Forum: After Dark

Ground Telescopes Useless by 2050

Posted By Dave Mitsky
By that date, there won't be a dark site remaining anywhere on the Earth anyway. sad

Dave Mitsky

March 8, 2006 02:44 PM Forum: Deep Sky Observing

The core of M31

Posted By Dave Mitsky
It sounds like you're describing M31's "stellar" core...

Dave Mitsky

March 14, 2006 07:28 AM Forum: Deep Sky Observing

Atmosphere limits/diminshing returns for more aperture

Posted By Dave Mitsky
Gary,

I typically use magnifications of up to two or more times the figure you stated with scopes ranging up to 17 inches and sometimes larger so I can't agree with your premise.

Dave Mitsky

March 14, 2006 03:23 PM Forum: Deep Sky Observing

Max magnificationg for galaxy viewing

Posted By Dave Mitsky
Mike,

As Clifton mentioned, magnification is a function of aperture. Exit pupil, however, is not. I typically use exit pupils of 2.7mm (162x) to 1.7mm (259x) and sometimes 1.3mm (324x) when using the ASH 17" f/15 classical Cassegrain to observe galaxies. Obviously, these are not galaxies of large apparent size.

Having a large telescope with a drive permits high magnifications to be employed, when required, in this pursuit.

Dave Mitsky

March 14, 2006 03:30 PM Forum: Deep Sky Observing

Max magnificationg for galaxy viewing

Posted By Dave Mitsky
As to your second question, many DSO observers prefer high quality wide-field or super wide-field eyepieces like the Tele Vue Panoptics and Naglers, the Meade UWA line, the Pentax XW (and now defunct XL), and so on, because they often are using undriven Dobs. A simpler design like an ortho may actually provide a marginally better view but the small apparent field of such a design is a bit of a drawback for DSO observing. For planetary observing, small apparent fields are not necessarily troublesome.

Dave Mitsky

March 14, 2006 03:47 PM Forum: Deep Sky Observing

Max magnificationg for galaxy viewing

Posted By Dave Mitsky
You should read what Roger Clark, an expert on vision and deep-sky observing, has to say on this topic at http://clarkvision.com/visastro/m51-mag/index.html

There's also an excellent discussion by Mel Bartels at http://www.bbastrodesigns.com/aa/visual.html

A quote from the above:

"John Dobson was the first large aperture observer to point out the advantages of high magnifications. Al Nagler, and Brian Skiff, among others, have recommended high magnifications. By increasing magnification, you are decreasing sky background brightness, and making the object larger in apparent size, both crucial to detectability. For small extended objects, you may exceed the old double star observers' rule of 50x per inch of aperture."

The section on sensitivity and contrast at http://www.mailbag.com/users/ragreiner/eyeperception.html is worth reading.

In case you don't know, the easiest way to determine exit pupil is to divide the focal length of the eyepiece by the f/ratio of the telescope it's being used with.

Dave Mitsky

March 16, 2006 10:06 AM Forum: After Dark

messier marathon

Posted By Dave Mitsky
For more on marathoning see

http://www3.telus.net/lmcnish/darksky/messierplanner.htm (I like the ordering of Phil Harrington's list.)

http://www.reflector.org/MESSIER.HTM

http://www.messiermarathon.com/

Dave Mitsky

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