We amateurs speak of our “grab and go” instruments, smaller lightweight, that are easy to set up and transport. After borrowing three catadioptric telescopes weighing up to 65 lbs (30 kg)—and buying one of them—from the local club, portability was a consideration for me for all of my recent purchases. But “grab and go” does not work well for me. I like to do a lot of reading, planning, and arithmetic before I go out. And I prefer to be out for three or four hours, not just one. I got that opportunity. And last night’s work will allow me to plan better for my next viewing.
I started with the intent to find M13 the Hercules Cluster, M51 the Pinwheel Galaxy, and the stunning double Albireo. I obtained only the last. The first two would have been new for me. I have seen Albireo often in the past (though not recently for the time of night, the poor seeing, and my neighbor’s trees). I also revisited other targets. For myself, I find that comforting, like meeting with friends. At 2145 hours CDT I started by aligning on Mizar-Alcor. I worked out the arithmetic for the field of view (
Then I went hunting for
I sketched its location and returned to it with different eyepiece arrangements. With the 32mm ocular and 2X Barlow almost all of the neighborhood was in the field of view. I counted about 30 stars, most easily about the same magnitude, but others dimmer that appeared clearer with averted vision. Just after midnight (0005 hrs), I used the 8mm with 2X Barlow to home in on the center of the cluster. Then (0010 hrs) I compounded the 32mm with the 5X focal extender to again count the stars there: about 24 the first time, about 30 the second. Boosting the magnification to 250X with the 13mm and 5X extender I found the focus difficult despite the additional helical threads on the right-angle focal adapter.
I turned to Jupiter (0023) with the same 13mm 5X arrangement. It was big, with subtle brown and gray bands, but grainy with poor resolution. Still, the eye adapts and we see mostly with the brain. Ronald Stoyan “The Visual Astronomer” (not secure https, but here anyway http://visualastronomer.com/) says that no magnification is wasted and that the eye adapts to take advantage of moments of best seeing. Despite that encouragement I think that it is better to perceive details in clearer though smaller presentations.
Taking a break on the chaise longue with a binocular (12x42 Bushnell), Albireo was an easy find as was the “first double” Epsilon Lyrae. Mostly, I just looked up at the sky without the glasses. At 0059 with a modest 17mm ocular (38.8X) alone and then the 17mm with 2X Barlow, I viewed Albireo down to its “Airy disks” of tightest focus. I noted the yellow and blue members of the visual (not physical) pair.
Epsilon Lyrae is the “double double.” What the naked eye perceives as a single star, is easily a pair with the smallest of instruments. William Herschel is accepted as the first to have recorded the double-double in August 1779 (Burnham, page 1151). It is a favorite with amateur observers. All four stars are accepted as “white” though Burnham credits others with assigning colors “greenish-white and bluish white… red tint… yellow and ruddy.” At the highest power 8mm with 5X (ridiculous 400X), I noted them (larger first) as yellow and blue (northwest) and white and yellow (southeast). Just to note, also: at 253X (13mm with 5X), they filled two-thirds of the field of view though were not much improved. (Going back through my log entries, I recorded the same colors on 20 November 2020.)
That was my night. I can now prepare more accurate templates for recording these same targets again.