Eta Aquarids : may 5/6, 2000

By Marco Langbroek

One of the major streams of the year, but only well observable from the southern hemisphere. In the northern hemisphere, usefull observations are only possible below 40d latitude North, during the last hour of the night. The stream originates from comet P/Halley and is the twin-stream of the Orionids in October. Like the Orionids, the meteors are very fast (~66 km/s). The radiant is located at RA 338d, dec. -1d at maximum, in the lower part of the small asterix of Aquarius (known as the 'Mercedes' by Dutch observers).
ZHR-values given for this stream differ between as low as 35 and as high as 100. The stream is suspect of showing erratic shortlived outbursts from time to time.
Although serious observations are out of the question, some observers at high northern latitudes have made it into a sport to catch the odd Aquarid deep in twilight. At the Latitude of The Netherlands (52d N), the radiant has an altitude of only 2 degrees (!) when twilight starts, and is still below 10 degrees when twilight becomes too strong to continue observing. Still, meteors of the stream can be seen. Rudolf Veltman was perhaps the first to observe an eta Aquarid from The Netherlands in 1983. In 1995, Koen Miskotte and I spend three mornings hunting untill deep into twilight, harvesting 4 possible streammembers. In 1996, a stroke of good fortune brought me 3 eta aquarids in one morning twilight session. This year, conditions are excellent: no moonlight will interfere.

Because the weather in large areas of western Europe is excellent a major observing campaign is organised at this very moment.
Team Delphinus will observe from their well known location in Biddinghuizen, team VSP/EPS-Lattrop will observe from a new location somewhere in the vicinity of the Public Observatory Lattrop and other teams are joining too.

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Marco Langbroek and Casper ter Kuile