Posted tagged ‘Challenge Reports’

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:


M 101 Galaxy in Ursa Major – Face-on spiral with low surface brightness.

September 6, 2014


Pencil sketch with inverted colors

Rogers M-101 3

Original sketch:


Trapezium Stars In The Great Orion Nebula

March 2, 2012

Trapezium Sketch -1

Observer’s Challenge complete report:

Theta 1 “The Trapezium”

March 1977:  4 1/4-inch f/10 spherical mirror, Edmund Scientific reflector @ 80x – Beautiful view of all four primary stars.  I could never see the E star with this scope.

February 1993:  10-inch f/4.5 reflector (using 4-inch off-axis stop-down mask) @ 254x – Seeing fair to good.  Could see the “E” star, but not easy. 

12-22-95:  80-mm f/15 refractor – All four stars appear as a beautiful white.

12-23-95:  10-inch f/4.5 reflector @ 120x – Conditions and seeing not good. Could see only the four primary stars.

March 1997:  3.5-inch Maksutov @ 135x – Seeing good, could see four stars.  On one occasion, I thought that I could see the “E” star, but very difficult, using averted vision. 

12-26-99:  10-inch f/4.5 reflector @ 142x – Fair to good.  All six stars visible, E and F fairly easy. 

12-26-99:  4-inch apochromatic f/7 refractor @190x –  Must look carefully to see the “E” star, which appears red.

12-26-99:  4-inch achromatic f/9.8 refractor @ 224x –  Can see fleeting glimpse of “E” star, but not constant.

January 2012:  76-mm Celestron FirstScope; Model 21024 Dobsonian @ 50x –  All four stars visible…nice crisp view. 

January 2012:  100-mm Orion SkyScanner @ 67x – All four stars visible, excellent view…slightly brighter than the 76-mm

02-24-2012:  4-inch f/9.8 refractor @ medium to high power. Seeing fair to poor, could not see E nor F.

02-25-2012:  10-inch f/4.5 reflector @ medium to high power.  Seeing only fair with tube currents, no E or F stars.

Roger Ivester