At 01:00 AM UTC 05/15/2005, I arrived at my OP (Little Mountain Pass, 10 miles east of Salt Lake City, Utah, Latitude N 40.8, Longitude W 111.9) to find the auroral display had already begun. This display was principally a continuous faint homogenous Type C (green) skyglow along the northern horizon from W 20° to N 0° to E 70° between 0° and 30° altitude. Through the course of display, the homogenous glow would partially coalesce into faint discrete rayed arcs. Unusually, Type C skyglow patches formed between 15° to the zenith (90°) in altitude. These lasted between 30-45 secs, with occassional patches lasting for 75 secs. Type C green aurora are caused by highly excited oxygen at 100-200 km above the surface. Only one instance of faint Type D (red) streaking was seen at the far W 20° azimuth. During part of the display, homogenous Type C arcs started to form on the northern horizon. From the 5-10° angle between the north horizon and the base of these proto-arcs, it was estimated the main auroral band was about 1100 kilometers (685 miles) north of N 41° latitude on the U.S. Canadian border at N 46° latitude. Brightness varied from International Brightness Codes I (IBC I equal in brightness to the Milky Way) to IBC II (brightness equal to a moonlight cumulus cloud). For comparison, the contrast between the Aquila dark clouds and the Milky Way disk was visible in the south-east sky. Cassiopeia was rising in the bright glow band along the northern horizon. The principal stars of the constellation figure (alf-del Cas) were visible with eps Cas (3.4v) representing a boundary between the visible and secondary invisible Cas stars like zet Cas (3.6v) and iot Cas (4.5v). One diffuse skyglow patch formed directly over over Lyra. Alf Lyr (Vega, 0.0v) was clearly visible, while gam Lyr (3.2v) and bet Lyr (3.4v) were not. Although fainter and more diffuse than prior aurora seen at this low-latitude site, the unique feature of this display was its total extended duration with multiple transitions. The display lasted about two and one-half hours. The display repeatedly faded in and out. A draft of my full observing log is at: http://members.csolutions.net/fisherka/astronote/observed/CME200505/CME20050... I shot a roll of 35mm film. If any pictures come out, I'll post them at a later time. - Canopus56 (Kurt) Yahoo! Mail Stay connected, organized, and protected. Take the tour: http://tour.mail.yahoo.com/mailtour.html