by Jay Reynolds Freeman
An eight-day Moon and suburban lighting make deep-sky viewing marginal, but it's amazing what a difference aperture makes. I was anxious for more operational experience with my newly completed 10-inch Dobson, which had first light a few days ago, so on May 11, 2000, I hauled it out into my yard in Palo Alto again. At least the bright Moon had one benefit -- I was not nearly as fussy as usual to set up in the puddles of darkness cast where trees intercept the street lights.
I used a 12 mm Brandon (106x) for most of the evening, though I switched once to a 32 mm Brandon (40x) for star-hopping. The Moon itself was very nice. I used the Archimedes area to line up the finder, and noted through the main telescope that further to the west (all lunar directions are Selenographic), the curved wrinkle ridges east of center in the Imbrium Basin showed up well. On the southerly part of the disc, the Straight Wall area showed wonderfully; the little patch crossing the line of the wall at one end gave the whole the appearance of a giant scimitar abandoned on the lunar surface.
Working close to the Moon is a good test of how well a telescope deals with scattered light. The Beehive -- M44 -- and its neighbor in Cancer, M67, were both well resolved, and the background there didn't look appreciably brighter than elsewhere in the sky. The 6x30 finder was working hard in the moon glow -- it only showed stars to perhaps a bit past 6th magnitude, which left all too many blank places in the sky. In darker conditions, though, that's plenty of aperture -- I only use a little larger finder, a 10x40, on my Celestron 14.
Thinking about what else was well placed, I turned to Ursa Major, and quickly found M40 -- an unobtrusive double star near delta UMa, that is perhaps the least at home on Messier's list of all the objects there. I have looked at this wide pair with instruments down to 7x50 binoculars, and though I can't always claim to have resolved it, I have never had the impression that it was nebulous, or composed of a vast swarm of stars. Next I moved to the opposite corner of the bowl of the dipper, and to my considerable surprise succeeded in chasing down the Owl Nebula, M97. It took averted vision and jiggling the tube to find it for certain, but there it was. I have seen the Owl in suburban settings before, but never with so much Moon. Nearby M108 was easier. I made a stab at M51, but it was too close to the zenith to maneuver the tube, as were the other Messier objects in Canes Venatici.
Hercules was far enough out of the light near the horizon to chase down M13. At 106x, the cluster had a sprinkling of individual stars clear across the unresolved mass of fainter ones. I shall have to try more magnification on a darker night. M5 seemed more compact and more concentrated, a noticeably different object, also with individual stars clear across it.
I took a break from Messier hunting to try a few easy double stars: Mizar was wide open, with Alcor on the other side of the field. Polaris was easy, and although epsilon Lyrae was sufficiently low to be blurred intermittently by seeing, 106x showed both components of the double-double well split when conditions momentarily settled.
I closed the evening by chasing down M81 and M82. The elongated nuclear area of the former was easily visible -- no surprise, it has high surface brightness. M82 was a ghost of its usual self, but I could trace the familiar elongated shape and get a hint of the irregular scalloping at its edges.
What fun to chase Messier objects when the Moon is bright. If the weather holds, perhaps I will try some more during the next few days.