This evening (March 22-23) I broke my week-old tradition and got to observe Comet Hyakutake from a dark-sky site. I had been visiting friends in Santa Cruz, California, and had taken along my 90 mm refractor and 7x35 binocular to show them the comet. We were located a few miles to the (true) east of the center of town (that's the direction that most Santa Cruz residents call "south" -- remember, this is California, and we are all flakes), near 17th Avenue, much closer to the beach than to state highway 1. Limiting magnitude (after moonset) at about 0630 UT 23 March, was about 5, and the comet seemed to have a naked-eye integrated visual magnitude marginally fainter than Arcturus -- say, 0.3. The naked-eye tail was easy to about 10 degrees, and could be traced with difficulty to about 20 degrees. View in the binocular was similar. At 25 and 65 diameters, the 90 mm showed the usual strongly condensed coma, slightly pale blue in color, with a notable spike extending a fraction of a degree down the axis of the tail. At 65x, motion of the central part of the coma with respect to the background sky was visible as I watched. My friends were all impressed with the stick-on glow-in-the-dark green stars I had attached to the tube of the Vixen fluorite refractor.

But that wasn't the dark-sky site. On the way home, I drove up highway 1 along the coast west and north of Santa Cruz. Just beyond of Davenport, I turned off on Swanton Road, to get away from the occasional lights of passing cars on highway 1, drove a mile or two, and parked. The time was about 0830 UT. It wasn't the New Mexico high desert, and there was light from the Bay Area cities looming up over the hills to the north, but the limiting magnitude near the zenith was around 6.5, and to my complete surprise and delight I logged the counterglow for the second time in my life. (I had been driving for twenty or so minutes with one eye closed, and dark-adapted for another twenty or so while observing, and I said to myself, gee, that glowing patch can't be the counterglow, the sky is too bright, but when I got home to my charts I found I had been looking exactly at the antisolar point, so...) Anyhow, the comet appeared notably brighter, I was estimating naked-eye integrated magnitude now brighter than Arcturus, say perhaps -0.2. I don't think the brightening was the comet itself; rather, I think that I was integrating over more of the coma, which appeared larger in the darker sky. And after a total of 40 minutes of dark adaptation, I was seeing roughly 30 degrees of tail easily -- all the way from the comet's position adjacent to epsilon Bootis to roughly epsilon Virginis -- and with difficulty making out another ten degrees or so, all the way to roughly eta Virginis. The tail was quite narrow within the first ten degrees or so, then rapidly widened and became fainter. Motion of the comet was easily detectable with the naked eye over intervals of five to ten minutes, by reference to epsilon Bootis. The view in the 7x35 was similar -- perhaps it was not quite so easy to trace the outer extrema of the tail, in the binocular. I did not set up the 90 mm fluorite again.

I continued northward, turned east across the San Francisco Peninsula at highway 84, and stopped again a mile or two in from the coast, at about 0915 UT. The view and magnitude were essentially the same, though the sky was a hair brighter. Continuing back toward Palo Alto, I stopped in a parking lot at the Page Mill Road exit off US 280, at about 1000 UT, and found naked-eye limiting magnitude about 5. The comet had lost a full half magnitude in apparant naked-eye integrated magnitude, and I could not see nearly so much tail. I doubt the comet had gotten coy with me just because I had driven back toward the light pollution; it seems clear that for me at least, naked-eye integrated magnitudes of diffuse objects are brighter in darker sky.