From: starex@tron.GUN.de (Andre Knoefel) Subject: IMO Meteor Shower Calendar 1996 Date: 17 Aug 95 13:00:00 +0200 International Meteor Organization 1996 Meteor Shower Calendar =========================== compiled by Alastair McBeath based on contributions from Rainer Arlt, Juergen Rendtel and Paul Roggemans. Layout by Andre Knoefel prepared for UseNet, CompuServe and AstroNet by Andre Knoefel Introduction ============ Welcome to the 1996 International Meteor Organization (IMO) Meteor Calendar. Regular users of the Calendar will notice one or two changes to this year's version. Most notably, we have completely revised the working list of visual meteor showers, using the most recent data available in the IMO's Visual Meteor Database. This has meant that some showers have been removed from the list entirely, since they have not been observed at all in recent times (in some cases, this may reflect a questionable shower failing to be detected, in others showers which have received too little attention in the past eight years), but in most cases, it simply means the shower parameters have been amended slightly. This is particularly true for the dates some showers are active between, as well as their peak activity. The result is that the working list of visual showers is the single most accurate listing available anywhere today for naked-eye meteor observing. It will 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, telescopic, or video observations can separate from the background sporadic meteors, present throughout the year. The IMO aims 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 solely by the support of many people across the whole world that our continuing steps towards constructing a true and complete picture of the near-Earth meteoroid flux can proceed. The new working list is the latest step in this direction. 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 (see end of this file) for analysis. Visual and photographic techniques have long been popular, and allow nightly meteor coverage (weather permitting), although both suffer considerably from the presence of moonlight. Telescopic observations are far less popular, though 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 are now starting to be taken up, and these have the advantages, and disadvantages, of both photographic and telescopic observing, but are certain to increase in importance in the future. 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. All of these methods used together cover virtually the entire range of meteoroid sizes, with sufficient overlap between them to allow both accurate positional data and activity levels to be derived, 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. Although ideally meteor data should be collected at all times when conditions permit throughout the year, such protracted monitoring is often not possible, thus the Calendar provides a ready means of helping to determine when a particular effort may be most usefully made for those with a restricted observing schedule. 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. 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, both suffer severely from moonlight in 1996. The minor delta-Leonids, are free from moonlight in late February, but perhaps the best-placed minor shower this quarter is the delta- Cancrids. delta-Cancrids -------------- Active: January 1-24; Maximum: January 16 (lambda = 297deg); ZHR = 4; Radiant: alpha=130deg, delta=+20deg ; Radiant drift: alpha=+0.7deg, delta=-0.2deg; Radius in alpha=10deg, in delta=5deg ; V = 28 km/s; r = 3.0; TFC: alpha=115deg, delta=+24deg and alpha=140deg, delta=+35deg (beta>40deg N); alpha=120deg, delta=-03deg and alpha=140deg, delta=-03deg (beta<40deg N). 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 3-5, but the long winter nights in the northern hemisphere provide a good opportunity to see what occurs, particularly this year, with the Moon just four days before new 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. delta-Leonids ------------- Active: February 15-March 10; Maximum: February 25 (lambda = 336deg); ZHR = 2; Radiant: alpha=168deg, delta=+16deg; Radiant Drift: alpha=+0.9deg, delta=-0.3deg; Radius: 5deg; V = 23 km/s; r = 3.0; TFC: alpha=140deg, delta=+37deg and alpha=151deg, delta=+22deg. This minor stream is also probably part of the early Virginid activity. Its weak activity, with predominantly faint meteors, is a prime candidate for telescopic investigation. Visual observers must make very accurate plots of the meteors to distinguish them from the nearby Virginids and the sporadics. Northern hemisphere sites have a distinct advantage for covering this stream, whose radiant is well on view for most of the night, near the "Sickle" or "Head" of Leo, but southern hemisphere watchers should not ignore it, since they are better-placed to note many of the other Virginid radiants. With the Moon just before first quarter at the shower's maximum, the second half of the night will be dark enough to allow useful watching. April to June ============= Meteor activity picks up around the April-May boundary, with showers like the Lyrids (detailed below), pi-Puppids and eta-Aquarids (their maximum is just after full Moon this year, however), before switching to the daylight sky, for the most active radio showers of the year in May and June, showers like the omicron-Cetids, Arietids, zeta-Perseids and beta-Taurids. The ecliptical complexes continue with some late Virginids and the best from the minor Sagittariids in May-June. Lyrids ------ Active: April 16-25; Maximum: April 21, 21h UT (lambda = 32.1deg); ZHR: variable-up to 90, usually 15; Radiant: alpha=271deg, delta=+34deg; Radiant drift: alpha=+1.1deg, delta=0.0deg; Radius: 5deg ; V = 49 km/s; r = 2.9; TFC: alpha=262deg, delta=+16deg and alpha=282deg, delta=+19deg (beta>10deg S). The Lyrids are best viewed from the northern hemisphere, but they are observable from most sites either north or south of the equator, and are suitable for all forms of observation. Maximum rates are attained for only about an hour or two at best, and can be rather erratic at times. In recent years, activity of around 15 meteors per hour has been seen, but on some occasions much higher rates have been noted. The most recent such event was in 1982 when American observers recorded a very short-lived peak ZHR of 90. This unpredictability means the Lyrids are always a shower to watch, since we cannot tell when another unusual return may happen. As the shower's radiant rises during the night, watches can be usefully carried out from about 22.30 local time onwards. This year, their peak falls with a thin waxing crescent Moon which will have set from most sites by the time the radiant is at a useful elevation above the horizon. The predicted peak should favour Asian sites if correct, but variations in the stream could mean this is not the case in actuality. July to September ================= Minor shower activity continues from near-ecliptic sources throughout this quarter, first from the Sagittariids, then the Aquarid and Capricornid showers (the best of which, the Southern delta-Aquarids and alpha- Capricornids, lose out to full Moon near their maxima towards the end of July this year. The Northern delta- and iota-Aquarid peaks are better in this regard, with maxima around August 9 and 20 respectively), and finally the Piscids into September. Other low activity showers are apparent too, such as the kappa-Cygnids, and the Aurigid showers from late August through to October (the delta-Aurigid peak around September 9 is best-placed of these in 1996). The major northern hemisphere event is always the Perseids in August, of course, although before we cover that, we highlight two other minor streams first. Pegasids -------- Active: July 7-13; Maximum: July 11 (lambda = 108deg); ZHR = 3; Radiant: alpha=340deg, delta=+15deg; Radiant drift: alpha=+0.8deg, delta=+0.2deg; Radius: 5deg V = 70 km/s; r = 3.0; TFCs: alpha=320deg, delta=+10deg and alpha=332deg, delta=+33deg (beta>40deg N); alpha=357deg, delta=+02deg (beta<40deg N). 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 slim waning 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, and the maximum ZHR is generally low. With its swift, faint meteors, telescopic observers should be in action too. July Phoenicids --------------- Active: July 10-July 16; Maximum: July 14 (lambda = 111deg); ZHR = variable 3-10; Radiant: alpha=32deg, delta=-48deg; Radiant drift: alpha=+1.0deg, delta=+0.2deg; Radius: 7deg ; V = 47 km/s; r = 3.0; TFC: alpha=041deg, delta=-39deg and alpha=066deg, delta=-62deg (beta<10deg N). This minor shower can only be seen from the southern hemisphere, from where it only attains a reasonable elevation above the horizon after midnight. This means there will be some slight interference in covering it this year from the waning Moon, but the Moon is only four days from new at the shower's maximum. Activity is 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 3-5, when the winter weather has allowed any coverage at all. Perhaps 1995 will be a good year for them? Perseids -------- Active: July 17-August 24; Maximum: August 12, 00hUT (lambda=139.6deg) and August 12, 12hUT (lambda=140.1deg); ZHR: primary peak = variable 200-400, secondary peak = 100; Radiant: alpha=46deg, delta=+58deg; Radiant drift: alpha=+1.4deg, delta=+0.2deg; Radius: 5deg ; V = 59 km/s; r = 2.6; TFC: alpha=019deg, delta=+38deg and alpha=348deg, delta=+74deg before 2h local time; alpha=043deg, delta=+38deg and alpha=073deg, delta=+66deg after 2h local time (>20deg N); PFC: alpha=300deg, delta=+40deg, alpha=000deg, delta=+20deg or alpha=240deg, delta=+70deg (beta> 20deg N). The Perseids have become the single most exciting and dynamic meteor shower in recent times, with outbursts producing ZHRs over 400 in both 1991 and 1992, around 300 in 1993 and 220 in 1994 at the shower's primary maximum, which this year is expected to fall around, or possibly before, midnight UT on August 12. The return of the Perseids' parent comet P/Swift-Tuttle in late 1992 was almost certainly responsible for producing these outbursts, although the material was probably laid down at the comet's previous perihelion passage, in 1862. Whether the moonlight-affected return of 1995 will continue the decreasing trend in the primary maximum's rates remains to be seen as this is written, but with new Moon just two days after both Perseid maxima in 1996, conditions are ideal for European observers to record what occurs. The "traditional" maximum is expected around 12h UT on August 12 this year, which should be good news for watchers in Northern and Central America. The time of primary maximum has proved variable by up to several hours in the last few years, and its short-lived nature means that observers must be alert throughout the northern hemisphere right over the expected peak times. 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 possible multiple nature of the Perseid radiant, something not detectable visually. Video observations would be very helpful in this respect too, the Perseids being a particularly good shower to test new equipment set-ups on, with plenty of meteors expected for several nights over the peaks. 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. kappa-Cygnids ------------- Active: August 3-25; Maximum: August 18 (lambda= 145deg); ZHR = 3; Radiant: alpha=286deg, delta=+59deg; Radiant drift: alpha=+0.2deg, delta=+0.1deg; Radius: 6 ; V = 25 km/s; r = 3.0. PFC: alpha=330deg, delta=+60deg and alpha=300deg, delta=+30deg New Moon on August 14 almost ideally favors this minor shower this year, although it can be considered accessible only to watchers north of the equator. Its r-value suggests telescopic observers may benefit from its presence, though visual and photographic workers should note that occasional slow fireballs from this source have been reported too. Its apparently stationary radiant results from its close proximity to the ecliptic north pole in Draco. There has been some suggestion of a variation in its activity at times, perhaps coupled with a periodicity in fireball sightings, but we are a long way from even beginning to understand all the nuances of this stream - provide us with more data, please! 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 (quite badly affected by a waxing gibbous Moon in 1996, as are the minor epsilon-Geminids). Of greater interest are the Leonids in November and the Geminids in December, but there are plenty of other low activity showers active, both north and south of the equator which will benefit from December's new Moon - such as the December Phoenicids, Puppids- Velids, December Monocerotids and sigma-Hydrids. By contrast, the Coma Berenicids and Ursids later in December lose out to the increasingly full Moon. Leonids ------- Active: November 14-21; Maximum: November 17, 17h UT (lambda=235.7deg); ZHR : periodic--up to storm levels, recently 15-20; Radiant: alpha=153deg, delta=+22deg; Radiant drift: alpha=0.7deg, delta=-0.4deg, Radius: 5deg; V = 71 km/s; r = 2 5; TFC: alpha=140deg, delta=+35deg and alpha=129deg, delta=+06deg (beta>35deg N); or alpha=156deg, delta=-03deg and alpha=129deg, delta=+06deg (beta<35deg N). PFC: alpha=120deg, delta=+40deg before 0h local time (beta>40deg N), alpha=120deg, delta=+20deg before 4h local time; alpha=160deg, delta= 00deg after 4h local time (beta>0deg N), alpha=120deg, delta=+10deg before 0h local time; alpha=160deg, delta=-10deg after 0h local time (beta<0deg N), The Leonid stream is perhaps most famous for its periodic storms occurring at roughly 33-year intervals when its associated comet, P/Tempel-Tuttle, returns to perihelion. This situation is due to happen again in the years 1998-2000, and Leonid activity showed the first signs of an increase in 1994. Bright moonlight prevented the computation of accurate ZHRs, but best estimates imply rates of around 60+ per hour. A repeat of this activity at the same time in 1996 should be best-seen by observers in the Far East and Australia. Clearly, we have the best opportunity ever to follow what further changes in the Leonids occur in the coming years more fully than has been previously possible, and to take advantage of these circumstances a special International Leonid Watch project has been set up with IMO help to coordinate world-wide professional and amateur Leonid studies. All observing methods should be pursued to ensure that no detail is missed. Data collection began in 1991, and is intended to continue into the next century. In 1996, circumstances are very good, since the waxing crescent Moon will have set from most places well before the Leonid radiant rises (at around local midnight for most locations north or south of the equator). Data by all observing methods is required. sigma-Hydrids ------------- Active: December 03-15; Maximum: December 11, (lambda=260deg), ZHR = 2 Radiant: alpha=127deg, delta=+02deg; Radiant drift: alpha=0.7deg, delta=-0.2deg; Radius: 5; V = 58 km/s; r = 3 0; TFC: alpha=095deg, delta=00deg and alpha=160deg, delta=00deg (all sites, after midnight only). Although first detected in the 1960s by photography, sigma-Hydrids are typically swift and faint, and rates generally low, often close to the visual detection limit. Since their radiant, just to the southwest of the "head" asterism of Hydra, a little over 10deg east of Procyon (alpha Canis Minoris), is near the equator, all observers can cover this shower, whose peak this year is only a day after new Moon. Although the radiant rises in the late evening hours from most sites, it is best viewed after local midnight right up until dawn. All observations would be welcomed, especially those made well before the Geminids' peak, since our knowledge of the shower's early activity is very poor. Geminids -------- Active: December 7-17; Maximum: December 13, 16h UT (lambda=262.0deg); ZHR = 110; Radiant: alpha=112deg, delta=+33deg, Radiant drift: alpha=+1.0deg, delta=-0.1deg; Radius: 5; V = 35 km/s; r = 2.6; TFC: alpha=087deg, delta=+20deg and alpha=135deg, delta=+49deg before 23h local time; alpha=087deg, delta=+20deg and alpha=129deg, delta=+20deg after 23h local time (beta>40deg N); alpha=120deg, delta=-03deg and alpha=084deg, delta=+10deg (<40deg N). PFC: alpha=150deg, delta=+20deg and alpha=060deg, delta=+40deg (>20deg N); alpha=135deg, delta=-05 and alpha=080deg, delta=0deg . One of the finest annual showers presently observable, their entire activity period is virtually free from lunar interference this year, providing a splendid opportunity to observe throughout the shower. Southern hemisphere observers suffer to a degree, as the radiant is low or below the horizon before midnight, but this is a splendid stream of often bright, medium-speed meteors, and well-rewards even these watchers. The peak has shown slight signs of variability in time and maximum rates, and the true maximum may fall a few hours before or after the time noted above. It is likely that Asian and European sites will be the better locations to view the 1996 maximum from. In terms of ZHRs, in 1993 the peak level was around 140, whereas in the late 1980s, 100 was more common. Some mass-sorting across the stream means that fainter telescopic meteor rates are at their highest almost 1deg of solar longitude ahead of the visual peaks mentioned earlier, and telescopic results show these meteors radiate from an elongated region, with up to three possible sub-centers. Further data for this topic would naturally be most valuable, though all forms of observing method can be employed for the Geminids. Table 1: Details in this Table were correct according to the best information available in August 1995. Contact the IMO's Visual Commission for more information. Shower Activity Maximum Radiant Period Date lambda alpha delta Radius [deg] [deg] [deg] [deg] Quadrantids Jan 01-Jan 05 Jan 04 282.7 230 +49 5 delta-Cancrids Jan 01-Jan 24 Jan 16 297 130 +20 10x5 alpha-Centaurids Feb 01-Feb 21 Feb 07 318 210 -59 4 delta-Leonids Feb 15-Mar 10 Feb 25 336 168 +16 5 gamma-Normids Feb 25-Mar 22 Mar 14 353 249 -51 5 Virginids Jan 25-Apr 15 Mar 25 004 195 -04 15x10 Lyrids Apr 16-Apr 25 Apr 22 032.1 271 +34 5 eta-Aquarids Apr 19-May 28 May 06 045.5 339 -01 4 Sagittariids Apr 15-Jul 15 May 20 059 247 -22 15x10 Pegasids (Jul) Jul 07-Jul 13 Jul 11 108 340 +15 5 Pisces Austrinids Jul 15-Aug 10 Jul 28 125 341 -30 5 Southern delta-Aquarids Jul 12-Aug 19 Jul 28 125 339 -16 5 alpha-Capricornids Jul 03-Aug 15 Jul 30 127 307 -10 8 Southern iota-Aquarids Jul 25-Aug 15 Aug 05 132 334 -15 5 Northern delta-Aquarids Jul 15-Aug 25 Aug 09 136 335 -05 5 Perseids Jul 17-Aug 24 Aug 12 140.1 46 +58 5 kappa-Cygnids Aug 03-Aug 25 Aug 18 145 286 +59 6 Northern iota-Aquarids Aug 11-Aug 31 Aug 20 147 327 -06 5 alpha-Aurigids Aug 25-Sep 05 Sep 01 158.6 84 +42 5 delta-Aurigids Sep 05-Oct 10 Sep 09 166 60 +47 5 Piscids Sep 01-Sep 30 Sep 20 177 5 -01 5 epsilon-Geminids Oct 14-Oct 27 Oct 20 207 102 +27 5 Orionids Oct 02-Nov 07 Oct 21 208 95 +16 10 Southern Taurids Oct 01-Nov 25 Nov 03 220 50 +13 10x5 Northern Taurids Oct 01-Nov 25 Nov 13 230 58 +22 10x5 Leonids Nov 14-Nov 21 Nov 18 235.2 153 +22 5 alpha-Monocerotids Nov 15-Nov 25 Nov 20 237 117 -06 5 chi-Orionids Nov 26-Dec 15 Dec 02 250 82 +23 8 Phoenicids (Dec) Nov 28-Dec 09 Dec 05 253 18 -53 5 Puppid-Velids Dec 01-Dec 15 Dec 06 255 123 -45 10 Monocerotids (Dec) Nov 27-Dec 17 Dec 10 259 102 +08 5 sigma-Hydrids Dec 03-Dec 15 Dec 11 260 127 +02 5 Geminids Dec 07-Dec 17 Dec 14 262.0 112 +33 5 Coma Berenicids Dec 12-Jan 23 Dec 19 268 175 +25 5 Ursids Dec 17-Dec 26 Dec 22 270.7 217 +76 5 Periodically and occasionally active showers pi-Puppids Apr 15-Apr 28 Apr 24 33.5 110 -45 5 Phoenicids (July) Jul 10-Jul 16 Jul 14 111 32 -48 7 Draconids Oct 06-Oct 10 Oct 10 196.5 262 +54 2 Table 1 (cont.) Shower v r ZHR IMO km/s Code Quadrantids 41 2.1 120 QUA delta-Cancrids 28 3.0 4 DCA alpha-Centaurids 56 3.0 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 eta-Aquarids 66 2.7 60 ETA Sagittariids 30 2.3 5 SAG Pegasids (Jul) 70 3.0 3 JPE Pisces Austrinids 41 3.2 5 PAU Southern delta-Aquarids 41 3.2 20 SDA alpha-Capricornids 25 2.5 4 CAP Southern iota-Aquarids 34 2.9 2 SIA Northern delta-Aquarids 42 3.4 4 NDA Perseids 59 2.6 100 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 epsilon-Geminids 71 3.0 3 EGE Orionids 66 2.9 25 ORI Southern Taurids 27 2.3 5 STA Northern Taurids 29 2.3 5 NTA Leonids 71 2.5 var. LEO alpha-Monocerotids 60 2.7 5 AMO chi-Orionids 28 3.0 3 XOR Phoenicids (Dec) 22 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 Periodically and occasionally active showers pi-Puppids 18 2.0 PPU Phoenicids (July) 47 3.0 PHE Draconids 20 2.6 GIA Table 2: Radiant positions during the year in alpha and delta. COM DCA Jan 0 186 +20 112 +22 QUA Jan 5 190 +18 116 +22 230 +40 Jan 10 194 +17 121 +21 Jan 20 198 +15 130 +19 ACE VIR Jan 30 200 -57 157 +16 DLE Feb 10 214 -60 165 +10 145 +24 GNO Feb 20 225 -63 172 +6 154 +21 225 -53 Feb 28 178 +3 161 +18 234 -52 Mar 10 186 0 169 +15 245 -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 May 5 236 -20 May 10 240 -21 May 20 247 -22 May 30 256 -23 Jun 10 265 -23 Jun 15 270 -23 Jun 20 275 -23 Jun 25 280 -23 Jun 30 284 -23 JPE CAP Jul 5 289 -22 338 +14 285 -16 SDA Jul 10 293 -22 341 +15 289 -15 325 -19 NDA SIA PER PAU Jul 15 298 -21 294 -14 329 -19 316 -10 311 -18 12 +51 330 -34 Jul 20 299 -12 333 -18 319 -9 317 -17 18 +52 334 -33 Jul 25 303 -11 337 -17 323 -9 322 -17 23 +54 338 -31 Jul 30 KCG 308 -10 340 -16 327 -8 328 -16 29 +55 343 -29 Aug 5 283 +58 NIA 313 -8 345 -14 332 -6 334 -15 37 +57 348 -27 Aug 10 284 +58 317 -7 318 -6 349 -13 335 -5 339 -14 43 +58 352 -26 Aug 15 285 +59 322 -7 352 -12 339 -4 345 -13 50 +59 Aug 20 286 +59 327 -6 AUR 356 -11 343 -3 350 -12 57 +59 Aug 25 288 +60 332 -5 76 +42 347 -2 355 -11 65 +60 Aug 30 289 +60 337 -5 82 +42 DAU Sep 5 88 +42 55 +46 SPI Sep 10 60 +47 357 -5 Sep 15 66 +48 1 -3 Sep 20 71 +48 5 -1 Sep 25 NTA STA 77 +49 9 0 Sep 30 21 +11 23 +5 ORI 83 +49 13 +2 Oct 5 25 +12 27 +7 85 +14 89 +49 GIA Oct 10 29 +14 31 +8 88 +15 95 +49 262 +54 Oct 15 34 +16 35 +9 91 +15 EGE Oct 20 38 +17 39 +11 94 +16 99 +27 Oct 25 43 +18 43 +12 98 +16 104 +27 Oct 30 47 +20 47 +13 101 +16 109 +27 Nov 5 53 +21 52 +14 105 +17 Nov 10 58 +22 56 +15 LEO AMO Nov 15 62 +23 60 +16 150 +23 113 -5 Nov 20 67 +24 64 +16 XOR 153 +21 117 -6 Nov 25 72 +24 69 +17 75 +23 121 -7 MON PUP PHO Nov 30 80 +23 HYD 91 +8 120 -45 14 -52 Dec 5 COM GEM 85 +23 122 +3 96 +8 122 -45 18 -53 Dec 10 169 +27 108 +33 90 +23 126 +2 100 +8 125 -45 22 -53 Dec 15 173 +26 113 +33 94 +23 130 +1 URS 104 +8 128 -45 Dec 20 177 +24 118 +32 217 +75 Abbreviations alpha, delta, alpha, delta: Coordinates for a shower's radiant position, usually at maximum; alpha is right ascension, and delta is declination. indicates the change in either alpha or delta per day after the peak; + and - signs should be reversed to calculate radiant positions before this date. Table 2 provides a useful check for your calculation. The radius gives the radiant size to be assumed for shower association. Large radiant complexes have two radii for extensions in and respectively. 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. Storm rates are usually well in excess of 1000 meteors per hour. Radio ZHRs are based on corrected echo rates, so give only a rough guide as to what visual activity could be seen in the absence of daylight. 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. Table 3: Lunar phases for 1996. New First Full Last Moon Quarter Moon Quarter January 5 January 13 January 20 January 27 February 4 February 12 February 18 February 26 March 5 March 12 March 19 March 27 April 4 April 10 April 17 April 25 May 3 May 10 May 17 May 25 June 1 June 8 June 16 June 24 July 1 July 7 July 15 July 23 July 30 August 06 August 14 August 22 August 28 September 4 September 12 September 20 September 27 October 4 October 12 October 19 October 26 November 3 November 11 November 18 November 25 December 3 December 10 December 17 December 24 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 45deg 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 ZHR Date 2000.0 alpha delta 50degN 35degS [deg] [deg] [deg] Cap/Sagittarids Jan 13-Feb 04 Feb 02 312.5 299 -15 11h-14h 09h-14h 15 chi-Capricornids Jan 29-Feb 28 Feb 14 324.7 315 -24 10h-13h 08h-15h 5 Piscids (Apr.) Apr 08-Apr 29 Apr 20 030.3 7 +7 07h-14h 08h-13h delta-Piscids Apr 24-Apr 24 Apr 24 034.2 11 +12 07h-14h 08h-13h epsilon-Arietids Apr 24-May 27 May 08 048.7 44 +21 08h-15h 10h-14h Arietids (May) May 04-Jun 06 May 16 055.5 37 +18 08h-15h 09h-13h omicron-Cetids May 05-Jun 02 May 19 059.3 28 -4 07h-13h 07h-13h 15 Arietids May 22-Jul 02 Jun 07 076.7 44 +24 06h-14h 08h-12h 60 zeta-Perseids May 20-Jul 05 Jun 09 078.6 62 +23 07h-15h 09h-13h 40 beta-Taurids Jun 05-Jul 17 Jun 28 096.7 86 +19 08h-15h 09h-13h 25 gamma-Leonids Aug 14-Sep 12 Aug 25 152.2 155 +20 08h-16h 10h-14h Sextantids Sep 09-Oct 09 Sep 27 184.3 152 0 06h-12h 06h-13h 30 About the International Meteor Organization =========================================== Founded in 1988, the International Meteor Organization (IMO) is an international scientific non- profit making organization with members all over the world. The IMO was created in response to an ever growing need for international cooperation of amateur meteor work. As such, the IMO's main objectives are to encourage, support and coordinate meteor observing, to improve the quality of amateur observations, to disseminate observations and results to other amateurs and professionals and to make global analyses of observations received world-wide. Unlike other branches of astronomy, such as variable star observing, international coordination of amateur meteor work has never really existed, which is a pity, since meteor work is an area of astronomy to which amateurs with little more than a good practical knowledge of the constellations in the sky can make a valuable contribution. Astronomical enthusiasts who wish to participate in significant scientific programs concerning meteor phenomena will therefore find IMO membership very rewarding. Starting regular meteor observations requires neither long training nor special skills. Providing you follow the IMO guidelines carefully, only a few weeks of practice should be sufficient to allow you to produce valuable observations. Just a few hours of sky-watching every month will soon contribute to the study of the dust complex in our Solar System! The IMO's main instrument to achieve its goals is its bimonthly journal WGN. All IMO members receive this journal. Annually, it contains over 220 pages of general meteor news, observing program guidelines, reports and analyses of observations, and more general articles on meteoric phenomena, some of them by professionals in the field. WGN also makes membership worthwhile to those readers who wish to keep in touch with meteor science, without being an actual meteor observer. The IMO also organizes, or provides assistance to the organization of, International Meteor Con- ferences, publishes handbooks, composes observing programs, collects observations and feeds them to international databases in order to analyze them quickly. IMO also maintains good contacts with professional meteor astronomers, many of whom are very interested in the work and results in WGN. The need for international cooperation in meteor work has existed for a long time. In 1979, the first International Meteor Weekend was held near Bonn, Germany. Since then up to 1988, similar meetings were held every one to two years in Belgium, Germany or the Netherlands. Each weekend was more successful than the previous one; an ever growing number of countries was represented and the 1986 and 1988 meetings even saw professional attendance. At the same time, international contacts also grew beyond Europe, although these were mainly kept up through the personal corre- spondence of numerous active meteor amateurs. As a result of this internationalization of amateur astronomy, WGN, originally Werkgroupniews, a circular in Dutch for observers in Belgium and the Netherlands, grew into a truly international journal in English with contributions from all over the world. It was decided at the 1988 International Meteor Conference in Oldenzaal, the Netherlands, that an International Meteor Organization should be founded with WGN as its principal journal. In less than a year, about 100 meteor workers from Europe, North-America, the former Soviet-Union, Australia and Japan, among them several professionals, were prepared to act as founding members for this organization. In order to guarantee its truly international character, the IMO obtained legal status as an international scientific non-profit making organization. The organization's constitution was approved at the 1989 International Meteor Conference in Balatonföldvár, Hungary. During the first years of its existence, the IMO has already managed to get world-wide recognition from amateurs as well as professionals, including Commission 22 (Meteors) of the International Astronomical Union. New initiatives are taken at an ever growing pace. All branches of meteor work are now being internationally coordinated. Finally, both the quantity and quality of articles submitted to WGN keeps growing. Useful addresses ================ For more information on observing techniques, and when submitting results, please contact the appropriate IMO Commission Director: Fireball Data Center (FIDAC): Andre Knoefel, Saarbruecker Strasse 8, D-40476 Duesseldorf, Germany. e-mail: starex@tron.gun.de Photographic Commission: Acting Director Juergen Rendtel, Gontardstrasse 11, D-14471 Potsdam, Germany. e-mail: jrendtel@aip.de Radio Commission: Temporarily vacant. Telescopic Commission: Malcolm Currie, 25 Collett Way, Grove, Wantage, Oxon. OX12 0NT, UK. e-mail: mjc@ast.star.rl.ac.uk Visual Commission: Rainer Arlt, Berliner Strasse 41, D-14467 Potsdam, Germany. e-mail: 100114.1361@compuserve.com For further details on IMO membership, please write to: Ina Rendtel, IMO Treasurer, Gontardstrasse 11, D-14471 Potsdam, Germany. e-mail: jrendtel@aip.de 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! (c) '95 by International Meteor Organization