Pluto Imaging Challenge: Images   

Ken Graun Images

 ISO 400 Negative Film 101-mm/1091-mm efl, Tele Vue-NP101 APO refractor  
[click image for full-size original]
Ken Graun Pluto 2003 Film TV-NP101small
September 26, 2 & 28, 2003

Equipment: Tele Vue Optics TV-NP101 (ob: 4" / 101mm, native f.l.: 540mm) and  2x Barlow onto ISO 400 negative film guided by SBIG ST-4 autoguider through  AP 155 Starfire EDF as guidescope. . 
Exposure/Processing: 20-minutes tracked
Location: Tucson, AZ, USA
Notes from the Imagers: Clyde Tombaugh discovered Pluto in early 1930 after taking two exposures of the same section of the sky 6 days apart. It was not by accident that he found the 9th planet for his job was to systematically image the area of the sky around the ecliptic in the hopes of finding the long sought and elusive 'Planet X.' When he was not photographing, he was comparing pairs of plates to find a 'star' that moved between them. Clyde took 60 minutes exposures using a 13-inch (3 lens element), f/5.3 refractor called an astrograph (an astrograph is a telescope that has a wide field of view). The Lowell Observatory does not have any information about the film speed of the original 14x17 inch glass plates used, but after seeing copies of the original discovery plates, I estimate that the film speed was no higher than 50, probably 25 or lower.

In Clydešs honor, I imaged Pluto on emulsion, using off-the-shelf ISO400 negative film, with a 4-inch Tele Vue, TV NP101 refractor working at f/10.8 (used a barlow). My Astro-Physics 155 F7 Starfire EDF served as the guidescope with an attached ST-4 autoguider. The biggest advantage I had over Clyde is knowing exactly where Pluto is located and I obtained this information from the Astronomical Calendar 2003 by Guy Ottewell. Pluto was around magnitude 13.8 at the time I took these pictures. The 13-inch astrograph had 10 times more light gathering capability than my 4-inch refractor but todayšs modern films far surpass those of 1930 so I was able to easily image our smallest planet in just 20 minutes.

-- ken graun

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