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IMO Meteor Shower Calendar 2002

compiled by Alastair McBeath and Rainer Arlt based on information in IMO Monograph No.2: Handbook for Visual Meteor Observers, edited by Jürgen Rendtel, Rainer Arlt and Alastair McBeath, IMO, 1995, additional material extracted from reliable data analyses produced since, and comments provided by Rainer Arlt. Layout by André Knöfel. Prepared for WWW by Sirko Molau IMO's Meteor Shower Calendar for 2002 contains the following items:

Introduction

Welcome to the 2002 International Meteor Organization (IMO) Meteor Shower Calendar. The year provides a mixture of Moon-free and Moon-affected major showers, with the Orionids and the potentially storm-rate Leonids especially badly moonlit, though the Perseids and alpha-Centaurids enjoy darker skies. It's a good year too for checking up on uncertain and minor sources like the gamma-Normids (March), June Lyrids, Pegasids (July), the Taurids (November) and the host of minor streams in early December, amongst others. Do not forget that monitoring of meteor activity should ideally be carried on throughout the rest of the year too, however! We appreciate that this is not practical for many observers, and this Calendar was devised as a means of helping observers deal with reality by highlighting times when a particular effort may most usefully be employed. Although we include timing predictions for all the more active night-time and daytime shower maxima, based on the best available data, please note that in many cases, such maxima are not known more precisely than to the nearest 1° of solar longitude (even less accurately for the daytime radio showers, which have only recently begun to receive regular attention again). In addition, variations in individual showers from year to year mean past returns are at best only a guide as to when even major shower peaks can be expected, plus as some showers are known to show particle mass-sorting within their meteoroid streams, the radio, telescopic, video, visual and photographic meteor maxima may occur at different times from one another, and not necessarily just in these showers. The majority of data available are for visual shower maxima, so this must be borne in mind when employing other observing techniques.

The heart of the Calendar is the Working List of Visual Meteor Showers, thanks to regular updating from analyses using the IMO's Visual Meteor Database, the single most accurate listing available anywhere today for naked-eye meteor observing. Even this can never be a complete list of all meteor showers, since there are many showers which cannot be properly detected visually, and some which only photographic, radar, telescopic, or video observations can separate from the background sporadic meteors, present throughout the year.

The IMO's aims are to encourage, collect, analyze, and publish combined meteor data obtained from sites all over the globe in order to further our understanding of the meteor activity detectable from the Earth's surface. Results from only a few localized places can never provide such total comprehension, and it is thanks to the efforts of the many IMO observers worldwide since 1988 that we have been able to achieve as much as we have to date. This is not a matter for complacency, however, since it is solely by the continued support of many people across the whole world that our steps towards constructing a better and more complete picture of the near-Earth meteoroid flux can proceed. This means that all meteor workers, wherever they are and whatever methods they use to record meteors, should follow the standard IMO observing guidelines when compiling their information, and submit their data promptly to the appropriate Commission for analysis.

Visual and photographic techniques remain popular for nightly meteor coverage (weather permitting), although both suffer considerably from the presence of moonlight. Telescopic observations are much less popular, but they allow the fine detail of shower radiant structures to be derived, and they permit very low activity showers to be accurately detected. Video methods continue to be dynamically applied as in the last few years, and are starting to bear considerable fruit. These have the advantages, and disadvantages, of both photographic and telescopic observing, but are increasing in importance. Radio receivers can be utilized at all times, regardless of clouds, moonlight, or daylight, and provide the only way in which 24-hour meteor observing can be accomplished for most latitudes. Together, these methods cover virtually the entire range of meteoroid sizes, from the very largest fireball-producing events (using all-sky photographic patrols or visual observations) through to tiny dust grains producing extremely faint telescopic or radio meteors.

However and whenever you are able to observe, we wish you all a most successful year's work and very much look forward to receiving your data. Clear skies!

January to March

Of the major streams active in the first quarter of the year, the northern-hemisphere Quadrantids (maximum due around January 3, 18h UT) lose out to the gibbous Moon, waning from full on 2001 December 30, though the southern-hemisphere alpha-Centaurids in early February are Moon-free. The minor streams too enjoy mixed fortunes. The minor delta-Cancrids are well-placed for observers in mid January, but the very weak delta-Leonids (peaking near February 24) are lost to full Moon, for instance. Also underway from late January to mid April is the diffuse ecliptical stream complex of the Virginids, probably producing several low, and poorly-observed, maxima in March or early April. Mid-March sees a perfectly moonless spell for checking on the gamma-Normids, whose details are most uncertain. Daylight radio shower peaks are theoretically due from the Capricornids/Sagittarids around February 1, 14h UT, and the chi-Capricornids on February 13, 15h UT. Recent radio results suggest the Cap/Sgr maximum may variably fall up to 2 or 3 days later than this however, while activity near the expected chi-Capricornid peak has tended to be slight and perhaps a day or so later in 1999-2000. Both showers have radiants >10°-15° west of the Sun at maximum, so cannot be regarded as visual targets even from the southern hemisphere.

delta-Cancrids

Active       : January 1-24;
Maximum      : January 17 (lambda = 297°);
ZHR          = 4;
Radiant      : alpha = 130°, delta = +20°;
Radiant drift: see Table 6;
V            = 28 km/s;
r            = 3.0;
TFC          : alpha = 115°, delta = +24° and
               alpha = 140°, delta = +35° (beta>40° N);
               alpha = 120°, delta = -03° and
               alpha = 140°, delta = -03° (beta<40° N).

Figure 1: Radiant position of the delta-Cancdrids

This minor stream of predominantly faint meteors is well-suited to telescopic observations, with a large, complex, diffuse radiant that probably consists of several sub-centers. Visual observers should assume a minimum radiant size of roughly 20° in alpha by 10° in delta about the radiant point given above. This type of large, loose radiant area is similar to the Virginids, and the delta-Cancrids are probably an early part of the Virginid activity. Recent observations have suggested the peak may occur close to lambda = 291° (2002 January 11), though ZHRs do not rise above 3-4 even then. New Moon on January 13 means either peak time will be moo