Summary: A pair of coronal mass ejections (CMEs) hit Earth's magnetosphere on April 11th, triggering a severe G4-category geomagnetic storm that lasted from 1500 UT to 1800 UT (11a.m. and 2p.m. EDT). Activity subsided a little after that, but a strong geostorm continued well into the next day and spawned impressive high-latitude auroras. The CMEs were hurled into space by a pair of explosions: an M8-class flare on April 9th followed by a X2-class flare on April 10th -- both from sunspot group 9415. The April 10th CME was a fast-moving cloud that caught its predecessor on the way to Earth, resulting perhaps in a cannibalistic combination of the two.

Unless otherwise stated, all images are copyrighted by the photographers.

	Photographer, Location	Images	Comments
	Thad V'Soske, Anza-Borrego Desert State Park, southern California	#1	This photo is remarkable because of its southern latitude, only 19 km north of the California-Mexico border. Photo details: Fuji Superia 800, 4 min (2 flashes), Zuiko 21mm f/2 @ f/2.8 April 11, 2001
	Jan Lameer, Terschelling, The Netherlands	#1, #2, #3, #4	J. Lameer: "I use the bicycle for transporting my photo equipment to dark locations in the woods. It is 40 years old and was formerly used by a baker to bring bread around." Photo details: Kodak Portra 800 film with exposures between 20 and 40 secs. April 11-12, 2001
	Garth Arsenault, Prince Edward Island, Canada	#1, #2, #3, #4, #5, #6, more	G. Arsenault: "Great show last night! The bridge is the Confederation Bridge which spans 13 kilometers connecting Prince Edward Island and New Brunswick, Canada. It is the longest bridge over ice covered waters in the world." April 11, 2001
	Chris Grohusko, near the border dividing New Mexico and Texas, USA	#1, #2, #3, #4, #5, #6, #7, #8	Photo details: Fujichrome Professional Provia 400 ASA, Pentax K1000 camera with 28mm at f/2.8 on B setting. Exposure times for most shots ranged from 30 to 90 sec. April 11, 2001
	Pete Urwin, Cleish Hills, Fife, Scotland	#1, #2, #3, #4, #5	P. Urwin: "What a sublime display. It lasted four hours." Photo details: Nikon FM2, 24mm Nikkor w/a lens 400asa film. 40-50 seconds at f2.8 April 11, 2001
	Harald Edens, Wijdenes, The Netherlands	#1, #2, #3, #4, #5, #6, more	H. Edens: "This aurora was not as spectacular as the display as I saw one year ago (6/7 Apr. 2000), but close! Clouds cleared just in time for me to see and photograph a burst of auroral activity between 21:30 and 22:00 UT, with beautiful red and blueish rays reaching up to the zenith." April 11, 2001
	Morton Henderson, Glasgow, Scotland	#1, #2, #3, #4	M. Henderson: "The sky wasn't particularly transparent, but this was a much more impressive display than my only other experience last October. These pictures were taken with an Olympus OM-1 camera and 35mm lens. Exposures were approx 15-20 seconds on Fuji Superia 800 film." April 12, 2001
	Stefan Stumpf, northwest Germany	#1, #2	Photo details: Olympus C2020Z digital camera, f2.0, 18mm (with converter), ISO 400, 16 sec. April 11-12, 2001
	Henrik Nordvig, Denmark	#1, #2, #3, #4, #5, #6, #7, #8, #9, #10, #11, #12	H. Nordvig: "I experienced two activity peaks, the first from 21:15 UT to 21:45 UT, the second from 23:45 UT to 00:10 UT. This was absolutely the most stunning auroral display I have ever seen." April 11, 2001
	Bob Neitman and Ed & Marilyn Johnson, near Fairbanks, Alaska	#1, #2, #3, #4, #5, #6, #7, #8, #9	B. Neitman: "As soon as we saw the great aurora forecast on spaceweather.com, we raced to Alaska from southern California for this spectacular event. It was awesome and we'll definitely be back!"
	Jouni Jussila, Oulu, Finland	#1, #2, #3	J. Jussila: "This was an extreamly beautiful night with strong red emissions -- the most powerful red I've never seen." Photo settings: Canon 24mm F/1.4 and Fuji Provia 400F (RHP III) @ 400 ASA. ~8 sec exposures. April 11, 2001 (2115 - 2230 UT)
	Dominic Cantin, Quebec, Canada	#1, #2, #3, more	Photo details: 28 mm @ f 2.8 , 25 seconds , Konica Centuria 800. April 12, 2001 (6:30 - 7:30 UT)
	Mark Shipley, Leyland, England	#1	M. Shipley: "It isn't often we get to see the Northern Lights over England!" Photo details: Canon EOS D30, Shooting Mode Program AE, Tv (Shutter Speed) 20, Av (Aperture Value) 3.5 , Exposure Compensation +2, ISO Speed 400, Lens 19.0 - 35.0 mm, Focal Length 19.0 mm April 11, 2001 (2244 UT)
	Ulrich Rieth, Mainz, Germany	#1, #2, #3, #4, #5, more	U. Reith: "Picture #1 is the dream of every aurora observer. It shows a wonderful partial corona, which is extremely rare down here at middle latitudes. I took all of these with a Canon SLR camera and a 28mm f/2.8 lens. The film was Fuji Superia 800 color print." April 11, 2001
	Jan Volkers, Bergen aan Zee, The Netherlands	#1, #2, #3, #4	J. Volkers: "Yesterday evening I saw my first-ever aurora. It was stunning!" Photo details: Minolta 7000 camera, 18 years old! Fuji Superia 400 ASA film. Shutterspeed 30 sec. April 11, 2001 (2300 local time)
	Herman Harperink, Almelo, The Netherlands	#1	Herman Harperink captured this image thirty minutes past local midnight on April 12, 2001.
	Frédéric Merlin, Fontaine-notre-dame, France	#1, #2, #3, #4, #5	Photo details: Canon EOS 500, (35mm F/D 4) and KODAK 800 ISO. Exposure times ~30s. April 11, 2001