created: 01-05-2014.

American astronomer Clyde Tombaugh (1907 1997), is best known for his discovery of the plant Pluto while working at Lowell Observatory in Flagstaff Arizona. But, during Tombaugh's search for trans-Neptunian planets, he ran across a number of unknown open star clusters.
Of the five clusters 'discovered' by Tombaugh, four were first observed by him, with a fifth star cluster, Tombaugh-3, being a re-observation of little-known cluster IC166, which at that time, was not included on any of the usual catalogs.

Tombaugh didn't directly discover his clusters visually thru the telescope, but by examining negative photographic plates taken by him between 1938 - 1941, using a 13" astrograph located at Lowell Observatory in Arizonia.

13" Lawrence Lowell Telescope

and Dome at Lowell Observatory used by Clyde Tombaugh:

With the exception of Tombaugh-5, all of the 1st-four star clusters are small, faint, and can be difficult to find.
A visual observer will need a moderate size telescope with a mirror 10" or greater, and a dark-sky location.
Video-observers and CCD imagers will be able to use smaller scopes with exposures of 25 seconds or more.

For detailed descriptions and additional 'finder' photos, see the "Deep Sky" magazine article cited below.
Also,this original article from the Astronomical Society of the Pacific, June 1938.
Three More New Galactic Star Clusters:

Tombaugh-1 and 2 finder chart, located in Canis Major.'

Tombaugh-3 and 4 finder chart, located in Cassiopeia.'

Tombaugh-5 finder chart, located in Camelopardalis.'

On the left side of the webpage is my personal observation list of the
'Tombaugh catalog of star clusters'.

I currently have 5 out of a possible 5 objects visible from my Pittsburgh, PA latitude of around +40.

"Tracking Down the Tombaugh Clusters, by Max Radloff,
'Deep Sky' magazine, page-12, winter 1990/91 issue.
"Earth Centered Universe" by David Lane

Hope you enjoyed the visit. Come again soon!
Larry McHenry,   Pittsburgh, PA. USA

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