Hi all!

I just posted the following observation to sci.astro.amateur:

Observed Hale-Bopp from Sunnyvale CA from about 5:40 AM to 6:30 AM local time with a 10" F5.6 Orion dobsonian.

The comet was about 1/2 degree away from Gamma Sagitta and its pearly white contrasted prettily with the ruddy color of the star. At 41x the comet had a bright pseudo-nucleus and graceful "MacDonald's" arch coma sweeping back behind the comet ("downwind") and becoming a diffuse milky-white tail extending a little over a degree before fading into a light-polluted sky.

The southern "arch" of the coma was somewhat brighter than the north arch, suggesting I might see something interesting at higher magnification. But since I had just brought my telescope out from indoors, tube convection currents were rioting and I would get no clear view of the nucleus until the fan could cool the mirror.

By 6 AM I was able to use higher magnifications to examine the pseudo-nucleus, an almost point-like region of brightly glowing gas surrounding the true dirty iceball nucleus. As tube currents began to subside, Its true shape began to emerge. I first appeared like a tiny disk with a "bite" taken out of its downwind side. For a moment I wondered if there was some dark component obscuring the nucleus.

After a few more minutes I realized that what I thought was a disk was actually a tiny L-shaped crescent with the corner of the L facing sunward. A few minutes later it became apparant that the north tip of the crescent was itself a bright star-like point. By this time it was about 6:15 and the tail was no longer visible in the brightening sky. At six thirty, I turned to Mars - but that's another story!

I would like to think that it was changing as I observed it, but it is also possible that it was pretty much the same throughout the session and that the observed changes were due to gradually improving seeing (tube currents) and mind-eye acuity.

So what was it? My guess is that it was a curved jet of gas originating from the nucleus located at one end of the "L". Why was it curved? The crescent was symmetric with respect to the direction towards the sun, so that strongly suggests that it was due to the solar wind. But if that is so, how can the coma be many times larger than the crescent? In other words, if the solar wind can bend that jet so sharply, how can any gas get as far sunward of the comet as the sunward boundary of the coma? Another possibility is that the Jet was pointed earthward and that forshortening increased both apparant curvature and brightness of the jet. But that seems an unlikely occurance. Finally, perhaps the curvature is from the rotation of the nucleus.

Can anyone corroborate these observations? Has anyone seen a similar jet?

Best regards, Jim Harford

	May those who love us, love us
	And those that don't love us,
	May God turn their hearts,
	And if he doesn't turn their hearts
	May he turn their ankles
	So we'll know them by their limping
		[an old gaelic blessing]