SHENANDOAH ASTRONOMICAL SOCIETY
ANCIENT ASTERISM RENAMED
By Herman Heyn
Before dawn, March 23, 1986, as it was gliding westward through SGR, I photographed Comet Halley with myself in the foreground wearing a yellow Halley's t-shirt of my own design which I was then
advertising in Sky & Telescope (S&T) and Astronomy (A) magazines. To the comet's left in my photo appears a small, four stars group arrayed like a slightly askew Latin cross (aka crucifix). Immediately I thought this group was sufficiently eye-catching to rate named asterism status. By 2006, having noticed no reference to it in any astronomy publication, I decided to dub it "Herman's Cross". (While the names of the 88 constellations are IAU sanctioned, names of asterisms are fair game. Within the 88, anyone can name any star group whatever he/she likes. Its currency rests on the community's acceptance.)
Besides in my own photo, the group appears in Halley's photos in the June '86 S&T (pp. 560-61). It is between SGR and CAP on A's late summer-fall sky maps but not on S&T's. Its four, 4th magnitude stars are Omega, 59, 60, and 62 SGR. To help me stake my claim, my longtime, California astrofriend, Derek Wallentinsen, put my story and photo on line.
Tom Bisque of Software Bisque added it to his own asterisms list.
Subsequent to staking my claim I discovered that, after all, the group has a history. In his Rambling Through the Skies
George Lovi notes that in ancient China it was known as Kou, the Dogs. In his classic compendium STAR NAMES, Richard Hinckley Allen writes that Ptolemy (2nd. cen. A.D.) called the group Terabellum, the Quadrangle. Searching through antique sky atlases in Baltimore's Peabody Library, the most recent sky map labeling I could find for it (Terebellum) is in Joannis Bode's Uranographia of 1801. In the here and now, however, under Terebellum you will see a detailed description of the four stars on Wikipedia. Possibly, had I known of these earlier incarnations, I would have reevaluated the Herman's Cross idea, but I didn't, so now the ball is rolling!
Herman's Cross is centered at RA 20h, dec. -27 degrees. It is 1-deg. wide and 2.5-deg. high. (Crux is 4.5 x 6.5-deg.) When on Front Royal's meridian it is 24-deg. above the horizon. Considering its low altitude and light pollution, binoculars are the best way to spot it. While it can be difficult to spot by eye, the group is
amazingly photogenic, showing up in many published astrophotos. Check out the one on p. 57 of July 09's S&T, where it is 1/2-inch in from the left edge. If you spot my asterism next summer, please let me know how it is faring. As well, when you notice a little knot of four stars between SGR and CAP on a sky map or in an astrophoto, remind yourself, "Hey, there's Herman's Cross!"