Archive for August 2015

M16 – Open Cluster plus Nebula in Serpens: Pencil Sketches, Notes and Image

August 29, 2015

Pencil sketch using a blank 5 x 8 notecard, with the colors inverted using a scanner

Scanned Image 162410001

Original pencil sketch with natural colors


August 2015 – Observer’s Challenge Report:  Click on the following link. 


M16 – NGC 6611:  Open cluster and nebula in Serpens, often called “The Eagle”  
Date: October 1996
Telescope: 10-inch reflector
Sketch: Magnification 57x and field of view 1.1º
Conditions: Transparency Poor – NELM 5.0
Location: Moderately light polluted backyard

About 30 mostly faint stars could be counted, with a greater concentration on the NNW edge. A pair of 8th magnitude stars located on the W side. A faint and small triangle of mostly equal stars located just outside the nebula on the NNE edge. The nebula is mostly faint. When using averted vision and patience, the nebula makes a cross shape, as seen in the following pencil sketch. Easily seen with an 8 x 50 finder appearing as a faint nebulous patch.

My backyard is a poor location to observe this object, as ambient lighting from a couple unshielded streetlights are located in close proximity to my observing site. This object would be best observed from a true dark site and with the use of an O-III or UHC filter.

3.5-inch Maksutov-Cassegrain 
Date: September 1997
Magnification: 52x

About 15 stars counted, with a prominent double star located on the western edge. The surrounding nebula is very faint and appears without a definite shape, encompassing the cluster. A faint and small triangle of stars is located on N edge.

Roger Ivester

Following image by Dr. James Dire of Hawaii:

“My image of M16 was taken with a 4-inch apochromatic refractor at f/6.3. The exposure was 90 minutes with an SBIG ST-2000XCM single shot color CCD camera. Even with this small aperture, dark dusty pillars of gas are easily seen. These are the types of pillars magnificently imaged and made famous by the Hubble Space Telescope. The red glowing hydrogen gas does take the shape of an eagle. Faint glowing gases extending beyond The Eagle are part of a larger complex, which includes the neighbor M17 nebula.”  JD


Pencil sketch by Jaakko Saloranta of Finland using a 4.5-inch Newtonian reflector @ 101x with a FOV of 30 arc minutes:


Chaple’s Arc and the Cygnus Fairy Ring

August 14, 2015
  • Date of observation:  August 13th 2015
  • Transparency:  Poor – Very high humidity  
  • Seeing:  Excellent
  • Telescope:  10-Inch f/4.5 Reflector

I located and recognized immediately using a 32mm eyepiece @ 36x with a 1.8º FOV.  The first star I noticed was double star h1470, with the primary being a ruddy or rust color.  

When increasing the magnification, using a 20 mm eyepiece @ 57x with a 1º FOV, at least eight or more pairs of double stars, making a circle could be seen and separated.  This beautiful ring of doubles are framed very nicely within the 1º field.  A fabulous and most interesting asterism. Dimensions: 40 x 40 arc minutes.    

A pencil sketch by the writer using a blank 5 x 8 notecard with the colors inverted using a scanner.

Scanned Image 160890002

Now for the complete story of Chaple’s Arc, and how the Cygnus Fairy Ring came to being…

The following is an excerpt from an article by Glenn Chaple and posted by “Skyscrapers, Inc.” 

“Forgive me for the apparent ego trip, but this month I’m going to introduce you to an amazing little asterism called “Chaple’s Arc.” I stumbled upon the Arc in the mid-1970s while looking for the double star h1470. Instead of one double, I found four arranged in an arc 1/2° across. So smitten was I by its extraordinary appearance that I eventually wrote about it in the September 1980 issue of Deep Sky Monthly. New York amateur astronomer John Pazmino viewed the group and dubbed it “Chaple’s Arc.”

A quarter century later, I decided to introduce the Arc to a much larger audience by featuring it in my “Observing Basics” column in Astronomy. To my amazement, I saw the same group described in the British magazine Sky at Night. The writer called it the “Fairy Ring.” Uh-oh! Had I missed something?

After a little detective work and an assist from Sky and Telescope’s Sue French, I learned that the Arc had been seen by Utah amateur astronomer Kim Hyatt in the early 1990s. Like me, he found it during a search for h1470. Because he was using a larger telescope than I had, he was able to view some faint pairs that, along with my four, formed a ring of double stars. Not knowing about Chaple’s Arc, he and a friend christened it the Fairy Ring.”   Glenn Chaple/Skyscrapers, Inc. 

Chaple’s Arc:  Image by Mario Motta:  August 29th 2022  

I attached two images, first a wide field centered on the arc or fairy ring. Note in the wide-field that it has a surprise “dark dust lane” immediately above and below the circle of double stars, and in the south edge of the field is a faint nebula glowing.
This was taken with my 6-inch f/7.6 refractor, that gives a 1.0 x 1.4 degree field of view with my ZWO ASI6200 camera. 
One can see the ring of double stars, but also many other double stars in this interesting field.
This was 10 stacked 10 second images, lightly processed only, to hone in to the Chaple Arc.  I also cropped the image to highlight the arc (ring) itself. 
Glenn, I am including you in this email, in case you don’t have an image of your immortality in the sky… 🙂   Mario Motta 

Open Cluster’s NGC 752, NGC 7243, and NGC 7789

August 10, 2015

NGC 752 – Open Cluster in Andromeda

Date: October 27th 1994 – Location:  North Carolina Foothills

Conditions:  Poor; NELM 4.5 – Telescope: 10-inch f/4.5 reflector – Magnification: 20mm Erfle EP @ 57x FOV: 1º

Notes: Naked eye object with a dark sky. A very large open cluster easily fills a 1º eyepiece field of view. Approximately 75 or more stars could be counted. Two prominent bright stars, one being yellow and the other reddish or rust lies to the SSW. This cluster is mostly irregularly round with many chains of stars crossing throughout.

NGC 7243 – Open Cluster in Lacerta Date: September 30th 1994 – Location:  North Carolina Foothills

Conditions:  Fair; NELM 5.0 – Telescope: 10-inch f/4.5 reflector – Magnification: 20mm Erfle EP @ 57x FOV: 1º

Notes: Very irregularly shaped, fairly loose open cluster. Double star Struve 2890 with both stars at mag 8.5 lies in the center. A dark lane crosses the central region.

NGC 7789 – Open Cluster in Cassiopeia – Date: December 20th 1994 – Location:  North Carolina Foothills 

Conditions:  Good; NELM 5.5; Telescope: 10-inch f/4.5 reflector; Magnification: 16mm University Optics Konig EP @ 71x and FOV:  0.92º

Notes:  Circular chains or patterns of stars. This cluster is large, very rich and condensed. Beautiful and refreshing after looking at faint objects.

Roger Ivester