IMO Meteor Shower Calendar 1997

compiled by Alastair McBeath

based on data in IMO Monograph No.2: Handbook for Visual Meteor Observers,
edited by Jürgen Rendtel, Rainer Arlt and Alastair McBeath, IMO, 1995, and
contributions from Paul Roggemans. Layout by André Knöfel.

Prepared for UseNet, CompuServe and AstroNet by André Knöfel

prepared for WWW by Sirko Molau

IMOs Meteor Shower Calendar for 1997 contains the following items:



Introduction

   
     Welcome to the 1997 International Meteor Organization (IMO) Meteor Shower   
     Calendar. In response to suggestions from radio workers, we have included   
     information on the predicted timing of the more active night-time and   
     daytime shower maxima this year, based on the best available data. It   
     should be noted, however, that in many cases, such maxima are not known   
     more precisely than to the nearest 1deg of solar longitude (even less   
     accurately for the daytime radio showers, which have received little   
     attention in recent years), and 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. In addition, several showers are known to   
     show particle mass-sorting within their meteoroid streams, which means that   
     radio, telescopic, 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. In an   
     ideal world, of course, we would like to see global monitoring of the   
     meteor activity the Earth encounters throughout the year whenever   
     conditions permit, to enable us to better understand the meteoroid flux in   
     the near-Earth vicinity. This Calendar was devised as a means of helping   
     observers to deal with reality, where such protracted observing is often   
     not possible, in highlighting times when a particular effort may most   
     usefully be employed.   
        
     The heart of the Calendar is the Working List of Visual Meteor Showers,   
     thanks to regular 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 meteor   
     activity near the Earth 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 still less popular,   
     although 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 have been dynamically applied 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 alreadyincreasing 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

   
     The first quarter of the year brings primarily low activity showers,   
     including the first of the year's main diffuse ecliptical stream complexes,   
     the Virginids, active from late January to mid-April. The two better   
     showers, the Quadrantids, visible from the northern hemisphere in early   
     January, and the alpha-Centaurids, a sometimes good southern hemisphere   
     shower in early February, are both free from moonlight in 1997, along with   
     the minor delta-Cancrids in mid-January and the gamma-Normids in mid-March.   
     Two daylight radio peaks are due from the Capricornids/Sagittarids around   
     07h UT on February 1, and the -Capricornids on February 13, probably around   
     08h UT. Neither radio shower has been well-observed in recent times, and as   
     both have radiants under 10-15° west of the Sun at maximum, they cannot   
     be regarded as visual targets even from the southern hemisphere.   
        
     


Quadrantids

   
     Active  : January 1-5;   
     Maximum  : January 3, 11h UT (lambda = 283.16°);   
     ZHR   = 120 (can vary around 60-200);   
     Radiant  : alpha = 230°, delta = +49°;   
     Radiant drift: see Table 3;   
     diameter  : 5° at maximum;   
     V   = 41 km/s;   
     r   = 2.1 at maximum, but variable;   
     TFC   : alpha = 242°, delta = +75° and   
         alpha = 198°, delta = +40° (beta>40° N);   
     PFC   : before 00h local time alpha = 150°, delta = +70°;   
         after 00h local time alpha = 180°, delta = +40° and   
         alpha = 240°, delta = +70° (beta>40° N).   
        
     Figure 1: Radiant position of the Quadrantids   
        
     [image:843]   
        
     The year starts well for northern hemisphere watchers, with a reasonably   
     good return of the Quadrantids, since the Moon will be a waning crescent   
     in eastern Virgo and western Libra on January 3-4, and will give its worst   
     problems only late in the night. The shower's radiant lies in northern   
     Bootes, which makes it circumpolar for many northern locations, but it   
     attains a useful elevation for observations only after local midnight or   
     so, and is at its highest towards morning twilight. It is an interesting   
     challenge to try spotting the occasional long-pathed shower member from the   
     southern hemisphere around dawn, but sensible watching cannot be carried   
     out from such locations.   
        
     The maximum time given above is based on the best-observed return of the   
     shower ever analysed, from IMO 1992 data, a repeat of which time in 1997   
     would be excellent news for North American watchers. The peak itself is   
     short-lived, and can be easily missed in just a few hours of poor winter   
     weather in the north, which may be why the ZHR level apparently fluctuates   
     from year to year, but some genuine variability is probably present too. An   
     added level of complexity comes from the fact that mass-sorting of   
     particles across the meteoroid stream makes fainter objects (radio and   
     telescopic meteors) reach maximum up to 14 hours before the brighter   
     (visual and photographic) ones, so observers should be alert throughout the   
     shower!   
        
     Past observations have suggested the radiant is very diffuse away from the   
     maximum, contracting notably during the peak itself, although this may be a   
     result of the very low activity normally seen away from the hours near   
     maximum. Photographic observations from January 1-6 would be particularly   
     welcomed by those investigating this topic, using the PFCs given above,   
     along with telescopic, video and visual plotting results.   
        
     


delta-Cancrids

   
     Active  : January 1-24;   
     Maximum  : January 17 (lambda = 297°);   
     ZHR   = 4;   
     Radiant  : alpha = 130°, delta = +20°;   
     Radiant drift: see Table 3;   
     size   : alpha = 20° x delta = 10°;   
     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 2: Radiant position of the delta-Cancdrids   
        
     [image:52]   
        
     This minor stream is especially suited to telescopic observations, with its   
     large, complex radiant area that may consist of several sub-centers, and   
     many of its meteors are faint. It is likely that this shower is an early   
     part of the Virginid activity, which generally becomes more obvious in   
     March and April. The delta-Cancrid ZHR is unlikely to rise much above 3-4,   
     but the long winter nights in the northern hemisphere provide a good   
     opportunity to see what occurs, particularly this year, with the Moon at   
     first quarter for the shower's peak. The radiant is above the horizon for   
     almost the entire night, whether your site is north or south of the   
     equator, with moonset around local midnight.   
        
     


alpha-Centaurids

   
     Active  : January 28-February 21;   
     Maximum  : February 7, 10h UT (lambda = 318.7°);   
     ZHR   = variable, usually around 6, but may reach 25+;   
     Radiant  : alpha = 210°, delta = 59°;   
     Radiant drift: see Table 3;   
     radius  : 4°;   
     V   = 56 km/s;   
     r   = 2.0.   
        
     Figure 3: Radiant position of the alpha-Centaurids   
        
     [image:657]   
        
     The alpha-Centaurids are one of the main southern hemisphere high points in   
     the opening months of the year, producing many very bright, even fireball-   
     class objects (meteors of at least magnitude -3). Their peak ZHR is normally   
     around 5-10, but in 1974 and again in 1980, bursts of only a few hours   
     duration that yielded activity closer to 20-30 were detected. As we have no   
     means of telling when another such event might happen, photographic,video   
     and visual observers are urged to be alert, especially this year, since the   
     new Moon on February 7 perfectly favours the maximum. Thanks to their   
     brilliance, even a normal alpha-Centaurid return is worth looking out for,   
     and almost one-third routinely leave fine persistent trains after them. The   
     radiant is nearly circumpolar for much of the sub-equatorial Earth, and is   
     at a useful elevation from late evening onwards.   
        
     


gamma-Normids

   
     Active  : February 25-March 22;   
     Maximum  : March 13, (lambda = 353°);   
     ZHR   = 8;   
     Radiant  : alpha = 249°, delta= -51°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 56 km/s;   
     r   = 2.4;   
     TFC   : alpha = 225°, delta = -26° and   
         alpha = 215°, delta = -45° (beta< 15° S).   
        
     Figure 4: Radiant position of the gamma-Normids   
        
     [image:658]   
        
     gamma-Normid meteors are very similar to the sporadics in appearance, and   
     for most of their activity period, their ZHR is virtually undetectable   
     above this background rate. The peak itself is normally quite sharp, with   
     ZHRs of 3+ noted for only a day or two to either side of the maximum. There   
     are suggestions that the activity may vary somewhat at times, with   
     occasional broader, or less obvious, maxima having been reported in the   
     past. Post-midnight watching yields best results, when the radiant is   
     rising to a reasonable elevation from southern hemisphere sites, which is   
     good news in 1997, as the Moon is a waxing crescent that will have set long   
     before this time on March 13. All forms of observation can be carried out   
     for them, although most northern observers will see nothing from the   
     shower.   
     

April to June

Meteor activity picks up around the April-May boundary, with showers like the Lyrids, pi-Puppids and eta-Aquarids, albeit only this latter source is free from moonlight this year. For radio observers, the expected UT maxima for the April showers are as follows: April Piscids (possibly periodic daylight shower) -- April 20d 07h; Lyrids -- April 22d 03h; pi-Puppids -- April 23d 14h; delta-Piscids (very short daylight shower) -- April 24d 07h. During May and June, most of the activity is in the daytime sky, with six shower peaks due in this time. Although a few shower members from the o-Cetids and Arietids have been reported from tropical and southern hemisphere sites visually in previous years, sensible activity calculations cannot be carried out from such observations. These daylight showers have the following predicted UT maximum times in 1997: epsilon-Arietids -- May 9d 05h; May Arietids -- May 16d 06h; o-Cetids -- May 20d 05h; Arietids -- June 7d 09h; zeta-Perseids -- June 9d 08h; beta-Taurids -- June 28d 08h. The ecliptical complexes continue with some late Virginids and the best from the minor Sagittarids in May-June.


eta-Aquarids

   
     Active  : April 19-May 28;   
     Maximum  : May 5, 22h UT (lambda = 45.5°);   
     ZHR   = 60 (occasionally variable);   
     Radiant  : alpha = 338°, delta = -01°;   
     Radiant drift: see Table 3;   
     radius  : 4°;   
     V   = 66 km/s;   
     r   = 2.7;   
     TFC   : alpha = 319°, delta = +10° and   
         alpha = 321°, delta = -23° (beta<20° S).   
        
     Figure 5: Radiant position of the eta-Aquarids   
        
     [image:665]   
        
     This is a fine, rich stream associated with Comet 1P/Halley, like the   
     Orionids of October, but it is visible for only a few hours before dawn   
     essentially from tropical and southern hemisphere sites. Occasional meteors   
     have been reported from further north, and the shower would benefit from   
     increased observer activity generally. The fast and often bright meteors   
     make the wait for radiant-rise worthwhile, and many events leave glowing   
     persistent trains after them. A relatively broad maximum -- sometimes with   
     a variable number of submaxima -- usually occurs in early May, and ZHRs are   
     generally above 30 for almost a week centred on the main maximum, based on   
     IMO observations between 1988-1995. With new Moon on May 6, the shower is   
     ideally-placed for watchers in 1997. All forms of observing can be used to   
     study it, with radio work allowing activity to be followed even from   
     northern sites throughout the daylight morning hours. The radiant   
     culminates at about 08h local time.   
     


July to September

   
     Minor shower activity continues apace from near-ecliptic sources throughout   
     this quarter, first from the Sagittarids, then the Aquarid and Capricornid   
     showers (discussed below with the Piscis Austrinids; only the Northern   
     iota-Aquarid maximum loses out particularly to moonlight this year), and   
     finally the Piscids into September. Other low activity showers are apparent   
     too, such as the Pegasids and July Phoenicids, but the kappa-Cygnids lose   
     out to the near-full Moon on August 17. Then there are the Aurigid showers   
     from late August through to October. The major northern hemisphere event is   
     always the Perseids in August, of course. For daylight radio observations,   
     the interest of May-June has waned, but there remains the visually-   
     inaccessible gamma-Leonids (peak due August 25d 08h UT), and a tricky   
     visual shower, the Sextantids (maximum expected September 27d 08h UT). The   
     latter has the waning crescent Moon near its radiant at maximum in 1997,   
     and will rise less than an hour before dawn in either hemisphere.   
        
     


Pegasids

   
     Active  : July 7-13;   
     Maximum  : July 10 (lambda = 108°);   
     ZHR   = 3;   
     Radiant  : alpha = 340°, delta = +15°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 70 km/s;   
     r   = 3.0;   
     TFC   : alpha = 320°, delta = +10° and   
         alpha = 332°, delta = +33° (beta>40° N);   
         alpha = 357°, delta = +02° (beta<40° N).   
        
     Figure 6: Radiant position of the Pegasids   
        
        
     [image:667]   
        
     Watching this very short-lived minor shower is not easy, as a few cloudy   
     nights mean its loss for visual observers, but with the Moon a waxing   
     crescent for its peak this year, everyone -- particularly those in the   
     northern hemisphere -- should attempt to cover it. The shower is best-seen   
     in the second half of the night, by when the Moon will have set, though the   
     maximum ZHR is generally low. With its swift, faint meteors, telescopic   
     observers should be in action too.   
        
     


July Phoenicids

   
     Active  : July 10-16;   
     Maximum  : July 14 (lambda = 111°);   
     ZHR   = variable 3-10, usually around 2;   
     Radiant  : alpha = 032° , delta = -48°;   
     Radiant drift: see Table 3;   
     radius  : 7°;   
     V   = 47 km/s;   
     r   = 3.0;   
     TFC   : alpha = 041°, delta = -39° and   
         alpha = 066°, delta = -62° (beta<10° N).   
        
     Figure 7: Radiant position of the July Phoenicids   
        
     [image:58]   
        
     This minor shower can be seen from the southern hemisphere, from where it   
     only attains a reasonable elevation above the horizon after midnight. This   
     means 1997 is a good year to watch it, with the waxing gibbous Moon at   
     maximum setting as the radiant becomes more suitably--placed. Activity can   
     be quite variable visually, and indeed observations show it is a richer   
     radio meteor source (possibly also telescopically too, but more results are   
     needed). Recent years have brought ZHRs of around 2, when the winter   
     weather has allowed any coverage at all. Perhaps 1997 will be a good year   
     for them?   
        
     


Piscis Austrinids and Aquarid/Capricornid Complex

   
     


Piscis Austrinids

   
     Active  : July 15-August 10;   
     Maximum  : July 28 (lambda = 125°);   
     ZHR   = 5;   
     Radiant  : alpha = 341°, delta = -30°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 35 km/s;   
     r   = 3.2;   
     TFC   : alpha = 255° to 0°, delta = 0° to +15°,   
         choose pairs separated by about 30° in alpha (beta<30° N).   
        
        
        
     


Southern delta-Aquarids

   
     Active  : July 12-August 19; Maximum: July 28, 00h UT (lambda = 125°);   
     ZHR   = 20;   
     Radiant  : alpha = 339°, delta = -16°;   
     Radiant drift: see Table 3;   
     radius  : 5°; V = 41 km/s; r = 3.2;   
     TFC   : alpha = 255° to 0°, delta = 0° to +15°,   
         choose pairs separated by about 30° in alpha (beta<30° N).   
        
     Figure 9,11: Radiant position of the Alpha Capricornids and the Southern and Northern delta-Aquarids   
     [image:668]   
        
     


alpha-Capricornids

   
     Active  : July 3-August 15;   
     Maximum  : July 30 (lambda = 127° );   
     ZHR   = 4;   
     Radiant  : alpha = 307°, delta = -10°;   
     Radiant drift: see Table 3;   
     radius  : 8°;   
     V   = 23 km/s;   
     r   = 2.5;   
     TFC   : alpha = 255° to 0°, delta = 0° to +15°,   
         choose pairs separated by about 30° in alpha (beta<30° N).   
     PFC   : alpha = 300°, delta = +10° (beta>45° N),   
         alpha = 320°, delta = -05° (beta = 0° to 45° N),   
         alpha = 300°, delta = -25° (beta<0° S.)   
        
     Figure 8,10: Radiant position of the Piscis Austrinids and the Southern and Northern iota-Aquarids   
        
     [image:669]   
        
     


Southern iota-Aquarids

   
     Active  : July 25-August 15;   
     Maximum  : August 4 (lambda = 132°);   
     ZHR   = 2;   
     Radiant  : alpha = 333°, delta = -15°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 34 km/s;   
     r   = 2.9;   
     TFC   : alpha = 255° to 0°, delta = 0° to +15°,   
         choose pairs separated by about 30° in alpha (beta<30° N).   
        
     


Northern delta-Aquarids

   
     Active  : July 15-August 25;   
     Maximum  : August 8 (lambda = 136°);   
     ZHR   = 4;   
     Radiant  : alpha = 335° , delta = -05°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 42 km/s;   
     r   = 3.4;   
     TFC   : alpha = 255° to 0°, alpha = 0° to +15°,   
         choose pairs separated by about 30° in alpha (beta<30° N).   
        
     The Aquarids and Piscis Austrinids are all rich in faint meteors, making   
     them well-suited to telescopic work, although enough brighter members exist   
     to make visual and photographic observations worth the effort too,   
     primarily from more southerly sites. Radio work can be used to pick up the   
     Southern delta-Aquarids especially, as the most active of these showers.   
     The alpha-Capricornids are noted for bright -- sometimes fireball-class --   
     events, which, combined with their low apparent velocity, can make some of   
     these objects among the most impressive and attractive an observer could   
     wish for. A possible minor enhancement of alpha-Capricornid ZHRs to around   
     10 was noted in 1995 by European IMO observers, although the Southern   
     delta-Aquarids were the only one of these streams previously suspected of   
     occasional variability.   
        
     Such a concentration of radiants in a small area of sky means that   
     familiarity with where all the radiants are is essential for accurate   
     shower association for all nights being observed on. Visual watchers in   
     particular should plot all potential stream members seen in this region of   
     sky rather than trying to make shower associations in the field. The only   
     exception is when the Southern delta-Aquarids are near their peak, when   
     from southern hemisphere sites in particular, rates may become too high for   
     accurate plotting.   
        
     All the above listed shower maxima are reasonably free from lunar-light   
     interference in 1997, since all five fall between last quarter Moon in late   
     July and first quarter Moon in mid August. As the radiants are above the   
     horizon for much of the night, there is ample scope for extended observing   
     sessions.   
        
     


Perseids

   
     Active  : July 17-August 24;   
     Maxima  : August 12, 06h UT (lambda = 139.6°) and   
         August 12, 18h UT (lambda = 140.1°);   
     ZHR   : primary peak = variable 150-400, secondary peak = 100;   
     Radiant  : alpha = 046°, delta = +57°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 59 km/s;   
     r   = 2.6;   
     TFC   : alpha = 019°, delta = +38° and   
         alpha = 348°, delta = +74° before 2h local time;   
         alpha = 043°, delta = +38° and   
         alpha = 073°, delta = +66° after 2h local time (beta>20° N);   
     PFC   : alpha = 300°, delta = +40°,   
         alpha = 000°, delta = +20° or   
         alpha = 240°, delta = +70° (beta>20° N).   
        
     Figure 12: Radiant position of the Perseids   
        
     [image:61]   
        
     The Perseids have become the single most exciting and dynamic meteor shower   
     in recent times, with outbursts producing EZHRs of 400+ in 1991 and 1992,   
     around 300 in 1993, 220 in 1994 and around 160 in 1995 at the shower's   
     primary maximum, which this year is expected to fall around 06h UT on   
     August 12. The peak may be encountered up to four hours before this time,   
     however, judging by past variations in the densest stream core. The return   
     of the Perseids' parent comet 109P/Swift-Tuttle in late 1992 was almost   
     certainly responsible for producing these recent outbursts, although the   
     material was probably laid down at the comet's previous perihelion passage,   
     in 1862. Whether the moon-free 1996 Perseid peak will continue the   
     decreasing trend in the primary maximum's rates remains to be seen as this   
     is written, but conditions are reasonable for trying to cover the 1997   
     event, as the waxing gibbous Moon will set soon after midnight for most   
     northern hemisphere observers on August 12, by when the shower radiant will   
     be at a very healthy elevation. Europe or the eastern seaboards of North   
     America should be the places to be, if the shower's primary peak keeps to   
     time. The "traditional" maximum is expected around 18h UT on August 12,   
     well-placed for sites in the Far East and eastern Asia particularly.   
        
     Visual and photographic observers should need little encouragement to cover   
     this stream, but telescopic watching near the main peak would be valuable   
     in confirming or clarifying the possibly multiple nature of the Perseid   
     radiant, something not detectable visually. Video observations would be   
     very helpful in this respect too. Radio data would naturally enable early   
     confirmation, or detection, of a perhaps otherwise unobserved outburst if   
     the timing proves unsuitable for land-based sites. The only negative aspect   
     to the shower is the impossibility of covering it from the bulk of the   
     southern hemisphere.   
        
     


alpha- and delta-Aurigids

   
     


alpha-Aurigids

   
     Active  : August 25-September 5;   
     Maximum  : August 31, 23hUT (lambda = 158.6°);   
     ZHR   = 10;   
     Radiant  : alpha = 084°, delta = +42 ;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 66 km/s;   
     r   = 2.5.   
     TFC   : alpha = 052°, delta = +60°,   
         alpha = 043°, delta = +39° and   
         alpha = 023°, delta = +41° (beta>10° S).   
        
     


delta-Aurigids

   
     Active  : September 5 - October 10;   
     Maximum  : September 8 (lambda = 166°);   
     ZHR   = 6;   
     Radiant  : alpha = 060° , delta = +47°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 64 km/s;   
     r   = 3.0.   
     TFC   : alpha = 052°, delta = +60°,   
         alpha = 043°, delta = +39° and   
         alpha = 023°, delta = +41° (beta>10° S).   
        
     Figure 13: Radiant position of the alpha- and delta-Aurigids   
        
     [image:670]   
        
     These are both essentially northern hemisphere showers, and are in need of   
     more observations. Despite occurring close to one another in time, and   
     radiating from the same constellation, they are separate streams. The   
     alpha-Aurigids are the more active, with short, unusual bursts giving EZHRs   
     of about 30-40 in 1935, 1986 and 1994, although they have not been   
     regularly observed until very recently, so other outbursts may have been   
     missed. The delta-Aurigids produce lower rates of generally fainter   
     meteors, and have yet to be well-seen in more than an occasional year.   
        
     1997 provides a fine opportunity to improve our knowledge of the showers,   
     since new Moon on September 2 means dark skies will prevail for much of the   
     night for both maxima. Telescopic data to confirm the radiants -- and   
     possibly observe the telescopic beta-Cassiopeids simultaneously -- would be   
     especially useful, but photographs, video records and visual plotting would   
     be welcomed too. The shower radiants are at a useful elevation from roughly   
     23h-00h onwards, so protracted watching is distinctly possible.   
     

October to December

Ecliptical minor shower activity reaches what might be regarded as a peak in early to mid November, with the Taurid streams in action, but before then we have the Orionids (whose central peak of several submaxima, October 21d 07h UT, is badly affected by a waning gibbous Moon, as are the minor epsilon-Geminids). Around October 9d 17h UT, any Draconid activity this year might be detected, when the Moon is at first quarter, but it is likely to be 1998, when Comet 21P/Giacobini-Zinner returns to perihelion, that we have the best chance to see any noticeable activity from this source. The Leonids (maximum due November 17, 15h UT) and the Geminids (peak: December 13, 22h UT) both lose out to bright moonlight in 1997, along with several of the late-year low-activity showers, such as the alpha-Monocerotids (those checking for another outburst at the time of 1995's should be alert around November 21d 13h UT), Monocerotids, sigma-Hydrids and Coma Berenicids. By contrast, the chi-Orionids, Phoenicids, the early part of the weak Puppid-Velid complex and Ursids during December are all rather better-placed with regard to the Moon.


Taurids

   
     


Southern Taurids

   
     Active  : October 1-November 25;   
     Maximum  : November 5 (lambda = 223°);   
     ZHR   = 5;   
     Radiant  : alpha = 050°, delta = +13°;   
     Radiant drift: see Table 3;   
     size   : alpha = 20° x delta = 10°;   
     V   = 27 km/s;   
     r   = 2.3;   
     TFC   : Choose fields on the ecliptic and around 10° E or W of the   
         radiants (beta>40° S).   
        
     


Northern Taurids

   
     Active  : October 1-November 25;   
     Maximum  : November 12 (lambda = 230°);   
     ZHR   = 5;   
     Radiant  : alpha = 058°, delta = +22°;   
     Radiant drift: see Table 3;   
     size   : alpha = 20° x delta = 10°;   
     V   = 29 km/s;   
     r   = 2.3;   
     TFC   : Choose fields on the ecliptic and around 10° E or W of the   
         radiants (beta>40° S).   
        
     Figure 14: Radiant position of the Northern and Southern Taurids   
        
     [image:67]   
        
     These two streams forms a complex associated with Comet 2P/Encke. Defining   
     their radiants is best achieved by careful visual or telescopic plotting,   
     photography or video work, since they are large and diffuse. The brightness   
     and relative slowness of many shower meteors makes them ideal targets for   
     photography, while these factors coupled with low, steady combined Taurid   
     rates makes them excellent targets for newcomers to practice their plotting   
     techniques on. The activity of both streams produces an apparently plateau-   
     like maximum for about ten days in early November, and the shower has a   
     reputation for producing some superbly bright fireballs at times, although   
     seemingly not in every year. 1995 produced an impressive crop of brilliant   
     Taurids between late October and mid-November, for instance, and the last   
     few days of October with the opening ones of November seem especially   
     likely to yield Taurid fireballs, from past analyses. New Moon on October   
     31 means this period, and the Southern Taurid maximum are notably favoured   
     with dark skies in 1997.   
        
     The near-ecliptic radiants for both shower branches mean all meteoricists   
     can observe the streams, with the northern hemisphere somewhat better-   
     placed, from where suitable radiant zenith distances obtain for much of the   
     lengthening late autumnal nights. Even in the southern hemisphere, a good   
     3-5 hours' watching around local midnight is possible with Taurus well   
     above the horizon, however.   
        
     


chi-Orionids

   
     Active  : November 26-December 15;   
     Maximum  : December 2, (lambda = 250),   
     ZHR   = 3;   
     Radiant  : alpha = 082°, delta = +23°;   
     Radiant drift: see Table 3;   
     radius  : 8°;   
     V   = 28 km/s;   
     r   = 3.0;   
     TFC   : alpha = 083°, delta = +09° and   
         alpha = 080°, delta = +24° (beta>30° S).   
        
     Figure 15: Radiant position of the chi-Orionids   
        
     [image:859]   
        
     This weak visual stream is moderately active telescopically, although a   
     number of brighter meteors have been recorded by professional photographic   
     patrols in the past too. The shower has a double radiant (at least), but   
     the southern branch has been rarely detected. The chi-Orionids may be a   
     continuation of the ecliptic complex after the Taurids cease to be active.   
     The radiant used here is a combined one, suitable for visual work, although   
     telescopic or video observations should be better-able to determine the   
     exact radiant structure. November's new Moon favours the shower with dark   
     skies this year, and the radiant, actually in eastern Taurus at the   
     shower's peak, is well on display for all watchers throughout the night.   
        
     


Phoenicids

   
     Active  : November 28-December 9;   
     Maximum  : December 6, 08h UT (lambda = 254.25°);   
     ZHR   = variable, usually 3 or less, may reach 100;   
     Radiant  : alpha = 018°, delta = -53°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 18 km/s;   
     r   = 2.8;   
     TFC   : alpha = 040°, delta = 39° and   
         alpha = 065°, delta = 62° (beta<10° N).   
        
     Figure 16: Radiant position of the Phoenicids   
        
     [image:70]   
        
     Only one impressive Phoenicid return has so far been reported, that of its   
     discovery in 1956, when the ZHR was around 100. Three other potential   
     bursts of lower activity have been reported, but never by more than one   
     observer, under uncertain circumstances. IMO observers noted rates barely   
     at the visual detection limit between 1988-1995, making the normal current   
     activity virtually nonexistent. This may be a periodic shower, however, and   
     more observations of it are needed by all methods. Radio workers may find   
     difficulties, as radar echoes from the 1956 event were only 30 per hour,   
     perhaps because these low-velocity meteors produce too little radio-   
     reflecting ionization. Observing conditions this year are reasonable for   
     all southern hemisphere watchers, with a waxing crescent Moon a problem   
     only in the evening hours. This is a little unfortunate, since the radiant,   
     although well on view for most of the night, culminates at dusk, but it   
     should not be regarded as a major deterrent.   
        
     


Ursids

   
     Active  : December 17-26;   
     Maximum  : December 22, 11h UT (lambda = 270.7°);   
     ZHR   = 10 (occasionally variable up to 50);   
     Radiant  : alpha = 217°, delta = +76°;   
     Radiant drift: see Table 3;   
     radius  : 5°;   
     V   = 33 km/s;   
     r   = 3.0;   
     TFC   : alpha = 348°, delta = +75° and   
         alpha = 131°, delta = +66° (beta>40° N);   
         alpha = 063°, delta = +84° and   
         alpha = 156°, delta = +64° (beta 30° to 40° N);   
        
     Figure 17: Radiant position of the Ursids   
        
     [image:672]   
        
     A northern hemisphere shower which has been very poorly-observed, although   
     at least two major outbursts have occurred in the past half-century or so,   
     in 1945 and 1986, and several other rate enhancements, recently in 1988 and   
     1994, have been reported too. Other similar events could easily have been   
     missed due to poor weather or too few observers active. All forms of   
     observation can be used for the shower, since many of its meteors are   
     faint, but with so little work carried out on the stream, it is impossible   
     to be precise in making statements about it.   
        
     Its radiant is circumpolar from most northern sites (thus fails to rise for   
     most southern ones), though it culminates after daybreak, and is highest in   
     the sky later in the night. The waning Moon, just past last quarter, will   
     be a minor nuisance this year when the radiant is approaching its highest,   
     but with observations at a premium, that should not put off prospective   
     watchers.   
        
     


Abbreviations

   
     alpha, delta: Coordinates for a shower's radiant position, usually at   
     maximum; is right ascension, is declination. Radiants drift across the   
     sky each day due to the Earth's own orbital motion around the Sun, and   
     this must be allowed for using the details in Table 3 for nights away   
     from the listed shower maxima.   
        
     r: Population index, a term computed from each shower's meteor magnitude   
     distribution. r = 2.0-2.5 is brighter than average, while r above 3.0 is   
     fainter than average.   
        
     lambda: Solar longitude, a precise measure of the Earth's position on its   
     orbit which is not dependent on the vagaries of the calendar. All lambda are   
     given for the equinox 2000.0.   
        
     v: Atmospheric or apparent meteoric velocity given in km/s. Velocities range   
     from about 11 km/s (very slow) to 72 km/s (very fast). 40 km/s is roughly   
     medium speed.   
        
     ZHR: Zenithal Hourly Rate, a calculated maximum number of meteors an ideal   
     observer would see in a perfectly clear skies with the shower radiant   
     overhead. This figure is given in terms of meteors per hour. Where meteor   
     activity persisted at a high level for less than an hour, or where   
     observing circumstances were very poor, an estimated ZHR (EZHR) is used,   
     which is less accurate than the normal ZHR.   
        
     TFC and PFC: suggested telescopic and photographic field centers   
     respectively. beta is the observer's latitude ("<" means "south of" and ">"   
     means "north of"). Pairs of telescopic fields must be observed, alternating   
     about every half hour, so that the positions of radiants can be defined. The   
     exact choice of TFC or PFC depends on the observer's location and the   
     elevation of the radiant.   
        
        
     


Tables

   
     Table 1: Lunar phases for 1997.   
        
     New   First   Full   Last   
     Moon   Quarter  Moon   Quarter   
                January 2   
     January 9  January 15  January 23  January 31   
     February 7 February 14 February 22 March 2   
     March 9  March 16  March 24  March 31   
     April 7  April 14  April 22  April 30   
     May 6   May 14   May 22   May 29   
     June 5  June 13  June 20  June 27   
     July 4  July 12  July 20  July 26   
     August 3  August 11  August 18  August 25   
     September 2 September 10 September 16 September 23   
     October 1  October 9  October 16  October 23   
     October 31 November 7  November 14 November 22   
     November 30 December 7  December 14 December 21   
     December 29   
        
     
Table 2: Working list of visual meteor showers. Details in this Table correct according to the best information available in April 1996. Contact the IMO's Visual Commission for more information. Maximum dates in parentheses indicate reference dates for the radiant, not true maxima. Some showers have ZHRs that vary from year to year. The most recent reliable figure is given here, except for possibly periodic showers that are noted as "var." = variable. Shower Activity Maximum Radiant Period Date lambda alpha delta ° ° ° Quadrantids Jan 01-Jan 05 Jan 03 283.16 230 +49 delta-Cancrids Jan 01-Jan 24 Jan 17 297 130 +20 alpha-Centaurids Jan 28-Feb 21 Feb 07 318.7 210 -59 delta-Leonids Feb 15-Mar 10 Feb 24 336 168 +16 gamma-Normids Feb 25-Mar 22 Mar 13 353 249 -51 Virginids Jan 25-Apr 15 (Mar 24)(004) 195 -04 Lyrids Apr 16-Apr 25 Apr 22 032.1 271 +34 pi-Puppids Apr 15-Apr 28 Apr 23 033.5 110 -45 eta-Aquarids Apr 19-May 28 May 05 045.5 338 -01 Sagittarids Apr 15-Jul 15 (May 19)(059) 247 -22 Pegasids Jul 07-Jul 13 Jul 10 108 340 +15 July Phoenicids Jul 10-Jul 16 Jul 13 111 032 -48 Pisces Austrinids Jul 15-Aug 10 Jul 28 125 341 -30 Southern delta-Aquarids Jul 12-Aug 19 Jul 28 125 339 -16 alpha-Capricornids Jul 03-Aug 15 Jul 30 127 307 -10 Southern iota-Aquarids Jul 25-Aug 15 Aug 04 132 334 -15 Northern delta-Aquarids Jul 15-Aug 25 Aug 08 136 335 -05 Perseids Jul 17-Aug 24 Aug 12 139.6 046 +58 kappa-Cygnids Aug 03-Aug 25 Aug 17 145 286 +59 Northern iota-Aquarids Aug 11-Aug 31 Aug 19 147 327 -06 alpha-Aurigids Aug 25-Sep 05 Aug 31 158.6 084 +42 delta-Aurigids Sep 05-Oct 10 Sep 08 166 060 +47 Piscids Sep 01-Sep 30 Sep 19 177 005 -01 Draconids Oct 06-Oct 10 Oct 09 196.49 262 +54 epsilon-Geminids Oct 14-Oct 27 Oct 18 205 102 +27 Orionids Oct 02-Nov 07 Oct 21 208 095 +16 Southern Taurids Oct 01-Nov 25 Nov 05 223 052 +13 Northern Taurids Oct 01-Nov 25 Nov 12 230 058 +22 Leonids Nov 14-Nov 21 Nov 17 235.16 153 +22 alpha-Monocerotids Nov 15-Nov 25 Nov 21 239.32 110 +03 chi-Orionids Nov 26-Dec 15 Dec 02 250 082 +23 Phoenicids Nov 28-Dec 09 Dec 06 254.25 018 -53 Puppid-Velids Dec 01-Dec 15 (Dec 07)(255) 123 -45 Monocerotids (Dec) Nov 27-Dec 17 Dec 08 257 100 +08 sigma-Hydrids Dec 03-Dec 15 Dec 11 260 127 +02 Geminids Dec 07-Dec 17 Dec 13 262.0 112 +33 Coma Berenicids Dec 12-Jan 23 Dec 19 268 175 +25 Ursids Dec 17-Dec 26 Dec 22 270.7 217 +76
Shower v r ZHR IMO km/s Code Quadrantids 41 2.1 120 QUA delta-Cancrids 28 3.0 4 DCA alpha-Centaurids 56 2.0 6 ACE delta-Leonids 23 3.0 2 DLE gamma-Normids 56 2.4 8 GNO Virginids 30 3.0 5 VIR Lyrids 49 2.9 15 LYR pi-Puppids 18 2.0 var. PPU eta-Aquarids 66 2.7 60 ETA Sagittarids 30 2.5 5 SAG Pegasids 70 3.0 3 JPE July Phoenicids 47 3.0 var. PHE Pisces Austrinids 35 3.2 5 PAU Southern delta-Aquarids 41 3.2 20 SDA alpha-Capricornids 23 2.5 4 CAP Southern iota-Aquarids 34 2.9 2 SIA Northern delta-Aquarids 42 3.4 4 NDA Perseids 59 2.6 200 PER kappa-Cygnids 25 3.0 3 KCG Northern iota-Aquarids 31 3.2 3 NIA alpha-Aurigids 66 2.5 10 AUR delta-Aurigids 64 3.0 6 DAU Piscids 26 3.0 3 SPI Draconids 20 2.6 var. GIA epsilon-Geminids 70 3.0 2 EGE Orionids 66 2.9 20 ORI Southern Taurids 27 2.3 5 STA Northern Taurids 29 2.3 5 NTA Leonids 71 2.5 40+ LEO alpha-Monocerotids 65 2.4 var. AMO chi-Orionids 28 3.0 3 XOR Phoenicids 18 2.8 var. PHO Puppid-Velids 40 2.9 10 PUP Monocerotids (Dec) 42 3.0 3 MON sigma-Hydrids 58 3.0 2 HYD Geminids 35 2.6 110 GEM Coma Berenicids 65 3.0 5 COM Ursids 33 3.0 10 URS
Table 3: Radiant positions during the year in alpha and delta. COM DCA Jan 0 186 +20 112 +22 QUA Jan 5 190 +18 116 +22 231 +49 Jan 10 194 +17 121 +21 Jan 20 202 +13 130 +19 ACE VIR Jan 30 200 -57 157 +16 DLE Feb 10 214 -60 165 +10 155 +20 GNO Feb 20 225 -63 172 +6 164 +18 225 -53 Feb 28 178 +3 171 +15 234 -52 Mar 10 186 0 180 +12 245 -51 Mar 20 192 -3 256 -50 Mar 30 198 -5 Apr 10 SAG LYR PPU 203 -7 Apr 15 224 -17 263 +34 106 -44 ETA 205 -8 Apr 20 227 -18 269 +34 109 -45 323 -7 Apr 25 230 -19 274 +34 111 -45 328 -5 Apr 30 233 -19 332 -4 May 5 236 -20 337 -2 May 10 240 -21 341 0 May 20 247 -22 350 +5 May 30 256 -23 Jun 10 265 -23 Jun 15 270 -23 Jun 20 275 -23 Jun 25 280 -23 Jun 30 284 -23 CAP JPE Jul 5 289 -22 285 -16 SDA 338 +14 Jul 10 293 -22 PHE 289 -15 325 -19 NDA 341 +15 PER PAU Jul 15 298 -21 032 -48 294 -14 329 -19 316 -10 012 +51 330 -34 Jul 20 299 -12 333 -18 319 -9 SIA 018 +52 334 -33 Jul 25 303 -11 337 -17 323 -9 322 -17 023 +54 338 -31 Jul 30 KCG 308 -10 340 -16 327 -8 328 -16 029 +55 343 -29 Aug 5 283 +58 NIA 313 -8 345 -14 332 -6 334 -15 037 +57 348 -27 Aug 10 284 +58 317 -7 318 -6 349 -13 335 -5 339 -14 043 +58 352 -26 Aug 15 285 +59 322 -7 352 -12 339 -4 345 -13 050 +59 Aug 20 286 +59 327 -6 AUR 356 -11 343 -3 057 +59 Aug 25 288 +60 332 -5 076 +42 347 -2 065 +60 Aug 30 289 +60 337 -5 082 +42 DAU Sep 5 088 +42 055 +46 SPI Sep 10 060 +47 357 -5 Sep 15 066 +48 001 -3 Sep 20 071 +48 005 -1 Sep 25 NTA STA 077 +49 009 0 Sep 30 021 +11 023 +5 ORI 083 +49 013 +2 Oct 5 025 +12 027 +7 085 +14 089 +49 GIA Oct 10 029 +14 031 +8 088 +15 095 +49 262 +54 Oct 15 034 +16 035 +9 091 +15 EGE Oct 20 038 +17 039 +11 094 +16 099 +27 Oct 25 043 +18 043 +12 098 +16 104 +27 Oct 30 047 +20 047 +13 101 +16 109 +27 Nov 5 053 +21 052 +14 105 +17 Nov 10 058 +22 056 +15 LEO AMO Nov 15 062 +23 060 +16 150 +23 113 -5 Nov 20 067 +24 064 +16 XOR 153 +21 117 -6 Nov 25 072 +24 069 +17 075 +23 121 -7 MON PUP PHO Nov 30 080 +23 HYD 091 +8 120 -45 014 -52 Dec 5 COM GEM 085 +23 122 +3 096 +8 122 -45 018 -53 Dec 10 169 +27 108 +33 090 +23 126 +2 100 +8 125 -45 022 -53 Dec 15 173 +26 113 +33 094 +23 130 +1 URS 104 +8 128 -45 Dec 20 177 +24 118 +32 217 +75
Table 4: Working list of daytime radio meteor streams. The "Best Observed" columns give the approximate local mean times between which a four-element antenna at an elevation of 45° receiving a signal from a 30-kW transmitter 1000 km away should record at least 85% of any suitably positioned radio- reflecting meteor trails for the appropriate latitudes. Note that this is often heavily dependent on the compass direction in which the antenna is pointing, however, and applies only to dates near the shower's maximum. Shower Activity Max lambda Radiant Best Observed Rate Date 2000.0 al. de. 50°N 35°S ° ° ° Cap/Sagittarids Jan 13-Feb 04 Feb 02 312.5 299 -15 11h-14h 09h-14h medium chi-Capricornids Jan 29-Feb 28 Feb 14 324.7 315 -24 10h-13h 08h-15h low Piscids (Apr.) Apr 08-Apr 29 Apr 20 030.3 007 +7 07h-14h 08h-13h low delta-Piscids Apr 24-Apr 24 Apr 24 034.2 011 +12 07h-14h 08h-13h low epsilon-Arietids Apr 24-May 27 May 08 048.7 044 +21 08h-15h 10h-14h low Arietids (May) May 04-Jun 06 May 16 055.5 037 +18 08h-15h 09h-13h low o-Cetids May 05-Jun 02 May 19 059.3 028 -4 07h-13h 07h-13h medium Arietids May 22-Jul 02 Jun 07 076.7 044 +24 06h-14h 08h-12h high zeta-Perseids May 20-Jul 05 Jun 09 078.6 062 +23 07h-15h 09h-13h high beta-Taurids Jun 05-Jul 17 Jun 28 096.7 086 +19 08h-15h 09h-13h medium gamma-Leonids Aug 14-Sep 12 Aug 25 152.2 155 +20 08h-16h 10h-14h low Sextantids Sep 09-Oct 09 Sep 27 184.3 152 0 06h-12h 06h-13h medium


Useful addresses

   
     For more information on observing techniques, and when submitting results,   
     please contact the appropriate IMO Commission Director:   
        
     Fireball Data Center : André Knöfel, Saarbrückerstraße 8,   
     (FIDAC)     D-40476 Düsseldorf, Germany.   
           (e-mail: fidac@imo.net)   
        
     Photographic Commission: Marc de Lignie, Prins Hendrikplein 42,   
           NL-2264 SN Leidschendam, the Netherlands.   
           (e-mail: photo@imo.net)   
        
     Radio Commission:   Temporarily vacant   
        
     Telescopic Commission: Malcolm Currie, 25 Collett Way, Grove, Wantage,   
           Oxon. OX12 0NT, UK.   
           (e-mail: tele@imo.net)   
        
     Visual Commission:  Rainer Arlt, Berliner Straße 41, D - 14467 Potsdam,   
           Germany   
           (e-mail: visual@imo.net)   
        
     For further details on IMO membership, please write to:   
           Ina Rendtel, IMO Treasurer, Gontardstraße 11   
           D-14471 Potsdam, Germany.   
           (e-mail: treasurer@imo.net)   
        
     Please try to enclose return postage when writing to any IMO officials,   
     either in the form of stamps (same country only) or as an International   
     Reply Coupon (I.R.C.--available from main postal outlets). Thank you!