Hi all, I received a message from Juergen Rendtel (jrendtel@aip.de) of the International Meteor Organization. I've included a few excerpts below. If you want a text with the complete discussion that was held on the meteor-observing mailing list, let me know, I'll send it to you privately. It's a bit too long to be sent to SeeSat-L. Suffice it to say that Mr. Rendtel contacted me (and I contact you) because no explanation has been found yet. > Bright diffuse atmospheric phenomenon at night > > When turning on the fireball patrol camera this morning (1996 Nov 8) > I observed an unusual bright diffuse light high in the sky (almost > overhead). While it was overcast most of the night, I found that the > clouds started to disappear at 03:50 MET (02:50 UT). However, there > were slowly moving cirrus clouds as well as a few fast moving cumulus > clouds. > At 03:55 I was about to open the shutter of the camera, and I saw > `something diffuse' near zenith, i.e. north of Gemini. At a first > glance it appeared like the moon shining through thick cirrus or so. > (In fact, the moon was still close to the horizon.) I estimate the total > brightness of the phenomenon as -1...-2 mag, while I was able to > see stars up to +3/+4 with the naked eye. The object was elongated > (about 1 deg wide, 6-7 deg long), showed no motion, and even in a > 10x50 binocular there was no structure to be seen. I took a few > photos between 04:02 MET and 04:14 MET. After 04:10 the brightness > decreased remarkably, and (also due to thicker cirrus again) it > disappeared after 04:15 MET. There was a little `knot-like' structure > around 04:12 visible in the binocular. > The position was near RA=100 deg, Decl=+40 deg, i.e. elevation 80 deg, > azimuth 15 deg (az. counted from S=0 deg). > > I observed a similar phenomenon also from Potsdam, Germany (52.4 deg N, > 13.0 deg E) on 1987 Dec 21, 20:15 MET, and I checked my log book for this > entry. Here are some comparisons: > > Date 1996 Nov 8 1987 Dec 21 > Time 03:55 - 04:15 MET 20:15 - 20:35 MET > Position (elev.) 80 deg 85 deg > Size 1 deg x 7 deg 1 deg x 5 deg > Brightness when > first seen -1/-2 mag +1 mag > Remarks gradually fading gradually fading > position `fixed' position `fixed' > `knots' after some time no structure (visually + phot.) > photographed 2 photos of the fireball patrol > camera > > After the 1987 observation I first thought it was a persistent meteor train. > But because of the remarkable stability of the shape and the duration I was > very sceptical. Unfortunately, this was observed when the cloud cover just > started to break, so no photo of the fireball patrol camera from the period > prior to the observation is available. This is the same in the new case. There > is one difference: the appearance of the knot-like structure for some minutes. > So, was this a persistent train of a fireball? Other ideas? Accidentially (?) > both phenomena appeared close to the zenith - indicating a terrestrial origin? > I don't expect an aurora-like phenomenon, because the Sun was quiet at this > time and the geomagnetic coefficient Kp was very low. > > I am afraid there are no corresponding observations since the conditions were > quite poor for astro-observers, and accidential eye-witnesses are unlikely > seen the time. > > In the literature I found one old note which possibly refers to a > similar observation (I have to check the source, but it was in > `Astronomische Nachrichten'). > > Juergen Rendtel Cheers, Bart