compiled by Alastair McBeath
based on contributions from Rainer Arlt, Jürgen Rendtel and Paul Roggemans
layout by André Knöfel
prepared for Usenet, Astronet and Compuserve by André Knöfel
prepared for WWW by Sirko Molau
IMOs Meteor Shower Calendar for 1996 contains the following items:
- Introduction
- Highlights January to March
- Highlights April to June
- Highlights July to September
- Highlights October to December
- Abbreviations
- Tables
- Working list of visual meteor showers
- Radiant positions during the year in alpha and delta
- Lunar phases for 1996
- Working list of daytime radio meteor streams
- About the International Meteor Organization
- Useful addresses
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!
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.
Active : January 1-24;
Maximum : January 16 (lambda = 297°);
ZHR = 4;
Radiant : alpha=130°, delta=+20° ;
Radiant drift: <Delta>alpha=+0.7°, <Delta>delta=-0.2°;
Radius : in alpha=10°, in delta=5° ;
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
[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 3-5, 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.
Active : February 15-March 10;
Maximum : February 25 (lambda = 336°);
ZHR = 2;
Radiant : alpha=168°, delta=+16°;
Radiant Drift: <Delta>alpha=+0.9°, <Delta>delta=-0.3°;
Radius : 5°;
V = 23 km/s;
r = 3.0;
TFC : alpha=140°, delta=+37° and alpha=151°, delta=+22°.
Figure 2: Radiant position of the delta-Leonids
[image:53]
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.
Active : April 16-25;
Maximum : April 21, 21h UT (lambda = 32.1°);
ZHR : variable-up to 90, usually 15;
Radiant : alpha=271°, delta=+34°;
Radiant drift: <Delta>alpha=+1.1°, <Delta>delta=0.0°;
Radius : 5°;
V = 49 km/s;
r = 2.9;
TFC : alpha=262°, delta=+16° and alpha=282°, delta=+19° (beta>10° S).
Figure 3: Radiant position of the Lyrids
[image:54]
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.
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.
Active : July 7-13;
Maximum : July 11 (lambda = 108°);
ZHR = 3;
Radiant : alpha=340°, delta=+15°;
Radiant drift: <Delta>alpha=+0.8°, <Delta>delta=+0.2°;
Radius : 5°;
V = 70 km/s;
r = 3.0;
TFCs: alpha=320°, delta=+10° and alpha=332°, delta=+33° (beta>40° N);
alpha=357°, delta=+02° (beta<40° 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.
Active : July 10-July 16;
Maximum : July 14 (lambda = 111°);
ZHR = variable 3-10;
Radiant : alpha=32°, delta=-48°;
Radiant drift: <Delta>alpha=+1.0°, <Delta>delta=+0.2°;
Radius : 7°;
V = 47 km/s;
r = 3.0;
TFC : alpha=041°, delta=-39° and alpha=066°, delta=-62° (beta<10° 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?
Active : July 17-August 24;
Maximum : August 12, 00hUT (lambda=139.6°) and
August 12, 12hUT (lambda=140.1°);
ZHR : primary peak = variable 200-400, secondary peak = 100;
Radiant : alpha=46°, delta=+58°;
Radiant drift: <Delta>alpha=+1.4°, <Delta>delta=+0.2°;
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 (>20° N);
PFC : alpha=300°, delta=+40°, alpha=000°, delta=+20° or
alpha=240°, delta=+70° (beta> 20° N).
Figure 4: 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 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.
Active : August 3-25;
Maximum : August 18 (lambda= 145°);
ZHR = 3;
Radiant : alpha=286°, delta=+59°;
Radiant drift: <Delta>alpha=+0.2°, <Delta>delta=+0.1°;
Radius : 6°;
V = 25 km/s;
r = 3.0;
PFC : alpha=330°, delta=+60° and alpha=300°, delta=+30°
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.
Active : November 14-21;
Maximum : November 17, 17h UT (lambda=235.7°);
ZHR : periodic--up to storm levels, recently 15-20;
Radiant : alpha=153°, delta=+22°;
Radiant drift: <Delta>alpha=0.7°, <Delta>delta=-0.4°,
Radius : 5°;
V = 71 km/s;
r = 2.5;
TFC : alpha=140°, delta=+35° and alpha=129°, delta=+06° (beta>35° N); or
alpha=156°, delta=-03° and alpha=129°, delta=+06° (beta<35° N).
PFC : alpha=120°, delta=+40° before 0h local time (beta>40° N),
alpha=120°, delta=+20° before 4h local time;
alpha=160°, delta= 00° after 4h local time (beta>0° N),
alpha=120°, delta=+10° before 0h local time;
alpha=160°, delta=-10° after 0h local time (beta<0° N),
Figure 5: Radiant position of the Leonids
[image:68]
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.
Active : December 03-15;
Maximum : December 11, (lambda=260°),
ZHR = 2
Radiant : alpha=127°, delta=+02°;
Radiant drift: <Delta>alpha=0.7°, <Delta>delta=-0.2°;
Radius : 5°;
V = 58 km/s;
r = 3.0;
TFC : alpha=095°, delta=00° and alpha=160°, delta=00°
(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 10° 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.
Active : December 7-17;
Maximum : December 13, 16h UT (lambda=262.0°);
ZHR = 110;
Radiant : alpha=112°, delta=+33°,
Radiant drift: <Delta>alpha=+1.0°, <Delta>delta=-0.1°;
Radius : 5°;
V = 35 km/s;
r = 2.6;
TFC : alpha=087°, delta=+20° and
alpha=135°, delta=+49° before 23h local time;
alpha=087°, delta=+20° and
alpha=129°, delta=+20° after 23h local time (beta>40° N);
alpha=120°, delta=-03° and alpha=084°, delta=+10° (<40° N).
PFC : alpha=150°, delta=+20° and alpha=060°, delta=+40° (>20° N);
alpha=135°, delta=-05 and alpha=080°, delta=0° .
Figure 6: Radiant position of the Geminids
[image:72]
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 1° 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: Working list of visual meteor showers. 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
° ° ° °
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
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 +10 155 +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
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 PER PAU
Jul 15 298 -21 294 -14 329 -19 316 -10 12 +51 330 -34
Jul 20 299 -12 333 -18 319 -9 SIA 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
alpha, delta, <Delta>alpha, <Delta>delta: Coordinates for a shower's radiant
position, usually at maximum; alpha is right ascension, and delta is
declination. <Delta> 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 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 ZHR
Date 2000.0 alpha delta 50°N 35°S
° ° °
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 Balatonfoeldvar, 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.
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: starex@tron.gun.de)
Photographic Commission: Acting Director
Jürgen 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!