Hodgson Observatory

This is the first of what may become monthly or semi-monthly reports on serious astronomical observations made at Hodgson Observatory. Rather than issuing a series of individual session reports as in the past, we will spare our readers the details, and give a review of the highlights. More details of these observations are available on request.

Early in November observations of Comet 17P/Holmes occupied our attention using the 203mm f/4.9 Newtonian reflector, 80mm f/11.4 guide refractor, and the 9x50mm finder scope in our Wide-Sky facility. The comet’s expanding bright coma was impressive and has already been reported.

On 2007 November 13 (UT) we had an evening “Trolling Through Triangulum” evening using the 635mm (25-inch) Obsession reflector and the 120mm (3.15-inch) f/8.33 Orion refractor in our Main Observatory. Primary attention was given to the Pinwheel Galaxy (M33) in Triangulum and its highly luminous stellar nursery NGC 604. The latter was easily visible in the 120mm refractor at 20x, and best seen at 201x in the 635mm reflector. At the best moments a very brief twinkling glimpse of two faint stars on the eastern edge of NGC 604 was obtained. At 2.7 million light years distance that is astonishing! (NGC 604 is now on my list of beautiful targets missed by Messier, Caldwell, & O’Meara’s lists. In time I will publish my list.) Later in the evening the galaxies NGC 672 and NGC 925 were seen with the 635mm reflector as faint glows in the sky, but sky conditions were declining, so observing was ended.

Mid- and late-November 2007 observations were largely solar, made in our Wide-Sky Observatory with the 203mm reflector and a full aperture solar filter at 38.5x and 77x. Careful observations of the solar disk were made on November 17, 19, 20, 24, and 26. NO SUNSPOTS WERE SEEN on any of these dates. It has now been more than one month with no sunspots visible, a surprising situation. – Dick Hodgson

The Wide-Sky Observatory at Hodgson Observatory, Beresford, SD, was busy yesterday, 2007 Nov. 2!  In the late morning there was a solar disc observation with the 203mm reflector showing NO SUNSPOTS visible using 38.5x. Are we at sunspot minimum or what?

The evening night sky was clear and dark, calm, and with average seeing and transparency. Temperature was ~ 40F falling to 31F.

COMET 17P/HOLMES.  Comet 17P/Holmes that recently flared up in brightness (probably because of an impact upon its icy-dusty nucleus showering a lot of debris into space) was again observed, this time from 8:01 to 8:21 p.m. CDT (Nov. 3, 01h 01m to 01h 21m UT). The nucleus was a little larger than the last observation on the previous evening, but not significantly changed. The edge of the coma was more sharply toward its NE quadrant, and more diffuse toward the opposite SW quadrant. The distinctive change, best seen with the 203mm reflector at 100x, was the nucleus which was no longer show sharply visible. It took a few minutes of observing for its exact location to be identified — perhaps the veil of the coma is thickening somewhat on our side of the nucleus. Apart from the nucleus the best overall views were made at 38.5x. The 80mm guide refractor and 9x50mm finder scope were also used briefly.

STAR BETA IN GRUS, THE CRANE, DEFINES SOUTHERN LIMIT OF OBSERVATIONS. Observations made from 8:40 to 9:15 p.m. definitively defined the southernmost observable limit from the field at Hodgson Observatory. The 2nd magnitude star Beta Gruis (this is not a typo — it is the genitive (possessive) of Grus in Latin) located at minus 46.8 degrees declination (south of the equator) was distinctly observed from the Wide-Sky observing hut with the 203mm reflector at 38.5x, and, more faintly, with the 9x50mm finder scope. It was not seen naked eye, due to light extinction of ~ 4 or 5 magnitudes. This is an astonishing observation because being located at +42.98 latitude, the geometric southern theoretical horizon would be minus 47.02 degrees. Previous measures indicated that the non-treed hill ridge due south of us was ~ 0.8 to 1.0 degree high, so this would make the hill-top horizon to be ~ minus 46.2 degree. This makes Beta Gruis geometrically invisible. How then was it seen?  The answer is atmospheric refraction, which varies a little with temperature, but is about 35 arc minutes (0.6 degree) in our favor, making minus 46.8 declination just visible. (This is the same star seen the previous night with John Johnson.)  Note: Star Alpha Gruis (Al Na’ir), just slightly farther south was never seen, nor, given the hill ridge, should its observation be possible in the 21st century.

Identification of Beta Gruis was made by going visually from Formalhaut SW in the sky to Gamma Gruis and then telescopically using the 203mm reflector to drop SE to the ridge of the hill.   (See “Sky & Telescope’s Pocket Sky Atlas” charts 78 & 79; “Millennium Star Atlas”, charts 1466 & 1467.)

FURTHER OBSERVATIONS.  In the hour that followed, after a successful one-star alignment of the GoTo system, the 80mm guide refractor and 9x50mm finder scope were used to give brief views of Messier objects 57, 13, 92, 31, and 27, and NGC objects 188 and 889.

On 10/31/07 exactly at midnight witch made it 11/1/07 at 01 minutes the elusive constellation Gourdus Spookis appears only for 1 minute on odd years at this time. Intrepid astronomers Dick and John where on hand to capture the moment! With telescopes pointed in the direction of the fleeting asterism we were rewarded with this image. Hope you enjoy!