[LVAS] September Observer's Challenge - The Helix Nebula - NGC-7293

[Fred Rayworth]

MONTHLY OBSERVER’S CHALLENGE
Las Vegas Astronomical Society
 
Compiled by:
Roger Ivester, Boiling Springs, North Carolina
&
Fred Rayworth, Las Vegas, Nevada
 
September 2009
NGC-7293 (The Helix Nebula)
 
Introduction
The purpose of the observer’s challenge is to encourage the pursuit of visual observing.  It is open to everyone that is interested, and if you are able to contribute notes, drawings, or photographs, we will be happy to include them in our monthly summary.  Observing is not only a pleasure, but an art.  With the main focus of amateur astronomy on astrophotography, many times people tend to forget how it was in the days before cameras, clock drives, and GOTO.  Astronomy depended on what was seen through the eyepiece.  Not only did it satisfy an innate curiosity, but it allowed the first astronomers to discover the beauty and the wonderment of the night sky.
Before photography, all observations depended on what the astronomer saw in the eyepiece, and how they recorded their observations.  This was done through notes and drawings and that is the tradition we are stressing in the observers challenge.  By combining our visual observations with our drawings, and sometimes, astrophotography (from those with the equipment and talent to do so), we get a unique understanding of what it is like to look through an eyepiece, and to see what is really there.  The hope is that you will read through these notes and become inspired to take more time at the eyepiece studying each object, and looking for those subtle details that you might never have noticed before.  Each new discovery increases one’s appreciation of the skies above us.  It is our firm belief that careful observing can improve your visual acuity to a much higher level that just might allow you to add inches to your telescope.  Please consider this at your next observing session, as you can learn to make details jump out.  It is also a thrill to point out details a new observer wouldn’t even know to look for in that very faint galaxy, star cluster, nebula, or planet.
NGC-7293
            NGC-7293, otherwise known as the Helix Nebula, or more recently, the Eye of God is a planetary nebula in Aquarius.  It is a notoriously difficult object to see visually, and many have missed it completely even in larger telescopes.  It has been listed in catalogues with no magnitude, as with diffuse nebulae, but has also been shown to have magnitudes from 7.2 up to 13.5.  The latter is the most realistic brightness as the nebula is half the diameter of the full moon and is quite diffuse.  However, it has been seen in binoculars and depending on the conditions, can be seen with almost any telescope.  For significant details, a larger scope is preferred.
            The closest and largest of the planetaries (D=500LY), with an apparent size half that of the moon, it is large enough to fill the view of many eyepieces.  In appearance, it is similar to a much larger version of the Ring Nebula and has similarities to the Dumbbell Nebula in structure.  It presents an excellent challenge.
            There are many features within the nebula including the 13 mag central star as well as several others peppered throughout.  There is the central area which may appear dark or washed out.  There are several rings, or thickened areas as the nebula spreads from the center.  It is also one of the first planetaries known to have knots of gas in it.  These features are what to look for along with the overall shape.
Walter Scott Houston, Deep-Sky Wonders, Selections and Commentary by Stephen O'Meara.
WSH:  “Magnitude of about 6, but its large apparent diameter, nearly half that of the Moon, spreads the light out and makes it a difficult object visually.  I recently saw the Helix with a 4-inch Clark refractor, and was certain that it was glimpsed in a 2-inch finder.  Burnham notes in his Celestial Handbooks that it can be spied in binoculars.  Small telescopes in relatively poor skies seldom reveal color.  Ted Komorowski told of a gray disc easily visible in his 8-inch f/7.5 at 56X.”
Note:  The 8-inch F/7.5 scope is currently housed at the Williams Observatory on campus at Gardner-Webb University in Boiling Springs, North Carolina.  Over the years, it has come to be known as the Komorowski Comet scope.  Ted was a member of the Charlotte Amateurs during the 60's and later (Roger Ivester).
WSH:  “The nebula's central hole was sighted by only a few observers, who included Michael Pleinis, Aberdeen, South Dakota (4-and 6-inch telescopes), and Mark Grunwald, Mishawaka, Indiana, among others.”