This page provides information on meteor streams visible from the Northern hemisphere which are active in the current and next month. Information will be frequently updated for that purpose. In addition, information about special events (e.g. stream outbursts) is available if such an event is anticipated. Mentioned stream data and peak locations are based on Astronomy and Astrophysics Vol. 287 (1994), 990-1013 (P. Jenniskens: meteor stream activity I. Annual streams) and subsequent revisions.
ZHR alfa Monocerotids. Dr. Peter Jenniskens (NASA-Ames Research Centre): Meteor Stream Activity; II. Meteor Outbursts. Astronomy and Astrophysics 295, 206-235 (1995)
Contents:General information April and May
Information on the Virginids
Information on the Lyrids
Information on the eta Aquarids
Information on the alpha Scorpids
Information on the omega Scorpids
This page was last modified on April 10, 1998 by Marco Langbroek and Casper ter Kuile
General information April and May
We have now entered the quiet months of the year. Sporadic activity is at its annual low in this time of the year, and streams active are mostly minor streams. Exceptions are the Lyrids late April, and the eta Aquarids early may.
Stream activity in this part of the yearly cycle is still relatively ill surveyed. Many mysterious small streams hide in the sporadic background, and in the Northern hemisphere nights are relatively short. A lot is still unknown, and observational efforts are therefore very valuable. To this author, this is his favorit time of the year for observing. There's still a lot to be discovered, some of the minor streams (e.g. the Scorpiid complex) produce beautifull meteors, night temperatures are pleasant, the starry night sky overwhelming, the bats are out, and frogs join in an enchanting nightly choir.
mu Virginids (April 29/30)
A minor stream part of the large Virginid complex, and one of the better recognizable substreams. Maximum is ill defined and occurs near April 29 (radiant RA 229d, dec. -7d); the stream is also well recognizable however during the Lyrid maximum, when the radiant is located at RA 225d, dec. -5d. It are medium to slow meteors (~30 km/s, similar to Taurids). Maximum ZHR is in the order of 2-3. During maximum, the moon is absent in the second part of the night as the radiant is rising.
Lyrids (April 22/23)
One of the few Northern hemisphere springtime streams that produces a conspicuous activity. The stream has a low level activity extending over a week, and a steep and shortlived maximum taking a few hours. Maximum activity is around ZHR 15. This year, the maximum occurs around 20h UT on April 22. West Asia and Europe therefore will be favoured most. There is little interfering moonlight excpet for the rising slope of activity (new moon April 26): the moon rises only during morning twilight at the night of maximum.
Lyrids are on the edge of medium to fast velocity, ~49 km/s. During maximum the radiant is located at RA 272d, dec. +33d, at the Lyra/Her border.
eta Aquarids (May 6/7)
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.
alpha Scorpids (May 16/17)
Part of a large stream complex, building on the Virginids. Activity is low, the radiant altitudes remain low for the Northern hemisphere, but the streams are recognizable.
The alfa Scoorpiids have a broad activity stretching over 2 to 3 weeks with a peak near May 17. They are mediumfast (35 km/s, like Geminids), often appearing as greenish 'balls with tails'. Radiant is at RA 240d, dec. -25d during maximum, near alfa Sco (drift +1.1d, -0.2d in RA and Dec. per day). Before maximum, moon interferes early in the night, after maximum it is absent (last quarter May 19).
omega Scorpids (June 2/3)
Part of the same complex as the alfa Scorpiids, but with a peak near June 2 and slightly higher activity. Radiant at RA 239d, dec. -20d at maximum (drift +1.0, -0.1 per day). Activity stretches at least two weeks. The meteors are very slow (21 km/s). Some moonlight will interfere with maximum.
|This page was last modified on May 10, 1998 by
Marco Langbroek and Casper ter Kuile