Note: This web page is preliminary, not citable, and for discussion purposes only
WIND detected a magnetic cloud which reached the Earth at roughly 14 UT on 27 May 1996, with a shock arriving earlier in the day. The event was followed by a high-density "corotating stream" similar to the cloud events of October 1995 and January 1997. The event resulted in a considerable amount of geomagnetic activity.
According to my notes, a filament which was at (N 15.2 E 10.05 P 25.26) at 15:11 UT on the 21st of May appears to have lifted off somewhere around 17:00 UT on the 21st. According to GOES data, there was a really minor X-ray event at that time, followed by a very quiet period for several days.
Probably the easiest two to compare are the Sac Peak h-alpha images from the 21st and the 22nd.
The lack of activity in LASCO, EIT, and GOES makes (currently) the apparent filament eruption of the 21st the best candidate on the sun for any sort of disturbance.
Here is a table of data sources and the "filament status" at the time:
EIT apparent eruption in progress at 04:00 UT 22 May 1996 Sac peak filament there at 13:37 21 May 1996 Big Bear gone at 14:04 22 May 1996 Big Bear gone at 16:26 22 May 1996 Space Environment Lab there at 14:05 21 May 1996 Holloman there at 16:51 21 May 1996 Mees gone at 17:39 21 May 1996 Mees gone at 17:09 21 May 1996 Kitt peak gone at 19:39 21 May 1996 Kitt peak there at 16:51 21 May 1996From this data, I estimate that the filament erupted close to 17:00 UT on 21-May-1996.
WIND Key Parameters:May 27, 1996
Celias Proton Monitor Data:Carrington Rotation 1909: 5 May - 1 June 1996
The solar wind velocity was slightly less than 400 km/sec during the event, indicating that a disturbance would take about 4.5 days to reach Earth. Tracing back, a disturbance which first reached Earth at 12 UT on the 27th travelling 380 km/sec would have originated at around 21 UT on the 22nd. If the speed were 450 km/sec, the estimated date would be 15 UT on the 23rd.
GOES X-ray Flux:May 20-23, 1996
May 20, 1996:Sac Peak halph 19960520_2016
May 21, 1996:Nobeyama radio 19960521_0000
May 22, 1996:Big Bear caiik 19960522_1839
May 23, 1996:Big Bear caiik 19960523_1738
May 24, 1996:Holloman halph 19960524_0060
May 25, 1996:Holloman halph 19960525_1257
SOHO had a momentum management maneuver on the 24th, and so the LASCO data was sparse for the 21st and 22nd of May. The LASCO CME list reports a "faint loop with core" out of the southeast on the 22nd, but nothing else until the 24th. The Mauna Loa CME list is "temporarily off line" so I'll have to actually contact a human... As far as EIT goes, you don't get a much quieter sun.
In case you were wondering how to get a prompt response out of Joe Gurman, try saying
something like "nothing much was going on in EIT."
With minimal effort, you can see that the filament is more prominent (no pun intended) and perhaps the span of it is larger as well.
This page was created 30 January 1997.
This page was revised on 30 January 1997.
Barbara J. Thompson