IMO Meteor Shower Calendar 2008

Introduction

compiled by Alastair McBeath

Based on information in IMO Monograph No. 2: Handbook for Visual Meteor Observers, edited by Jürgen Rendtel, Rainer Arlt and Alastair McBeath, IMO, 1995, as amended by the commentaries in WGN 34:3 (June 2006), pp. 71 — 84, with subsequent corrections, plus additional material extracted from reliable data analyses produced since. Particular thanks are due to Jeff Brower, David Entwistle, Roberto Gorelli and Jérémie Vaubaillon for valuable discussions in respect of several potential events in 2008.

Welcome to the 2008 International Meteor Organization (IMO) Meteor Shower Calendar. The meteor year ahead starts well for the stronger showers, with moonless maxima for the Quadrantids, α-Centaurids, η-Aquarids and δ-Aquarids, but things go somewhat awry in August with the Perseids peaking near full Moon, while the Orionids in October, the Leonids in November and the Geminids in December are even worse-placed. However, the Draconid epoch should still be partly observable, while the late October to early November spell, which may bring another 'swarm' enhancement from the Taurids, is Moon-free, as too is the Ursid peak towards year's end. There are minor showers to be monitored as well, and ideally, meteor observing should be carried out throughout the year to check on all the established sources, and for any new ones. We appreciate this is impractical for most people, so the Shower Calendar has been helping to highlight times when a particular effort might most usefully be employed since 1991.

The heart of the Calendar is the Working List of Visual Meteor Showers, Table 5, which as many of you will appreciate, completed its most recent thorough overhaul by IMO analysts in 2006, to help it remain the single most accurate listing available anywhere today for naked-eye meteor observing. Of course, for all its accuracy, it is a Working List, so is continually subject to further checks and corrections, based on the best data we have. Consequently, more changes have been made this time, to amend some minor inconsistencies in the 2007 version. Please be sure to use the information here when preparing for your observing in 2008, as even some of the stronger showers like the Perseids and Leonids have had minor adjustments made to their radiant locations.

Apart from these visually-observable showers, there are many others weakly active throughout the year which only still-imaging, video, radar or telescopic observations can separate from the omnipresent background sporadics, possibly including some of those recently removed from the visual showers' list. There is also a set of showers with radiants too near the Sun to be observed by the various optical methods, which can be detected only by forward-scatter radio or radar observations. Some of these showers are given in Table 7, the Working List of Daytime Radio Meteor Streams. The IMO's aims are to encourage, collect, analyze, and publish combined meteor data obtained from sites all over the globe, to help better our understanding of the meteor activity detectable from the Earth's surface. Thus, we encourage these more specialist forms of observing too, so all meteor workers, wherever you are and whatever methods you use to record meteors, should follow the standard IMO observing guidelines when compiling your information, and submit those data promptly to the appropriate Commission for analysis. Thanks to the efforts of the many IMO observers worldwide since 1988 that have done this, we have been able to achieve as much as we have to date, including keeping the shower listings vibrant. This is not a matter for complacency however, since it is solely by the continued support of many people across the planet that our steps towards constructing a better and more complete picture of the near-Earth meteoroid flux can proceed.

Although timing predictions are included below on all the more active night- time and daytime shower maxima, as reliably as possible, it is essential to understand that in many cases, such maxima are not known more precisely than to the nearest 1° of solar longitude (even less accurately for the daytime radio showers, which have received little regular attention until quite recently). In addition, variations in individual showers from year to year mean past returns are only a guide as to when even major shower peaks can be expected. The information given here may be updated after the Calendar is published, so be sure to watch for alerts on the Internet (including on IMO-News) and in WGN, the IMO's bimonthly journal. Some showers are known to show particle mass-sorting within their meteoroid streams, so the radar, radio, still-imaging, telescopic, video and visual meteor maxima may occur at different times from one another, and not necessarily just in those showers. The majority of data available are for visual shower maxima, so this must be borne in mind when employing other observing techniques.

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!

Antihelion Source

The biggest change in the 2006 upgrade of the Visual Working List was the removal of most of those minor near-ecliptic sources that previously seemed to 'chase' one another around the sky throughout the year, such as the Virginids of February-March, and many of the July-August Aquarid showers. They were replaced with a large, diffuse radiant area, whose size is taken to be roughly α = 30° by δ = 15°, centred around 12° east of the solar opposition point on the ecliptic. Such a location names it as the 'Antihelion Source', abbreviated as 'ANT'. This has been done as it seems to give a better description of the actual observed activity than the cluster of previous, often supposedly variable, very minor sources in this part of the sky. At present, we think the July-August α-Capricornids (CAP), and particularly the δ-Aquarids (SDA), should remain discretely observable visually from the ANT, so they have been retained in the Working List, but time and plenty of observations will tell, as ever! Later in the year, the strength of the twin Taurid showers (STA and NTA) means the ANT should be considered inactive while the Taurids are underway, from late September to late November. To assist observers, a set of charts showing the location for the ANT and any other nearby shower radiants is included here, to compliment the numerical positions of Table 6, while comments on the ANT's location and likely activity are given in the quarterly summary notes.

January to March

A waning crescent Moon favours the northern-hemisphere Quadrantids in early January, while the new Moon is still better for the probable southern-hemisphere α-Centaurid peak in February. Mid-March brings a reasonable to very good minor γ-Normid return too, for similarly southern places. The Antihelion Source's radiant centre starts January in south-east Gemini, and crosses Cancer during much of the month, before passing into southern Leo for most of February. It then slips through southern Virgo during March. Likely ANT ZHRs will be <2, though IMO analyses suggest there may be an ill-defined minor peak with ZHRs ~ 2 to 3 around solar longitude ~ 286° — 293° (January 7 to 14 in 2008, well-timed for the new and waxing crescent Moon, if so), and ZHRs could be ~ 3 for most of March. The late January to early February spell, during which several new, swift-meteor, minor showers, radiating from the Coma-Leo-Virgo area have been suggested in some recent years, unfortunately has a full Moon for the potential core period, January 20 — 27. Theoretical approximate timings (rounded to the nearest hour) for the daytime radio shower maxima this quarter are: Capricornids/Sagittarids — February 2, 03h UT; and χ-Capricornids — February 14, 04h UT. Recent radio results suggest the Cap/Sgr maximum may variably fall sometime between February 1 — 4 however, while activity near the expected χ-Capricornid peak has tended to be slight and up to a day late. Both showers have radiants < 10° — 15° west of the Sun at maximum, so cannot be regarded as visual targets even from the southern hemisphere.

Quadrantids (QUA)

Active:January 1 — 5
Maximum:January 4 - 06h40m UT (λsol = 283°16)
ZHR = 120 (can vary ~ 60 — 200)
Radiant:α = 230°; δ = +49°
Radiant drift:see Table 6
vinf = 41 km/s; r = 2.1 at maximum but variable
TFC: α = 242°; δ = +75° and α = 198°; δ = +40° (β > 40° N)
IFC: before 0h local time α = 150°; δ = +70°
after 0h local time α = 180°; δ = +40° and
α = 240°; δ = +70° (β > 40° N)

A virtually moonless maximum of the Quadrantids opens the northern meteor watchers' year very well, with a waning crescent Moon, four days from new, which rises only around or after 04h at mid northern latitudes, so it will be little nuisance. From many northern locations, the shower's radiant is circumpolar, in northern Boötes, but it attains a useful elevation only after local midnight, rising higher in the sky towards morning twilight. Consequently, eastern North American longitudes east to those of extreme western Europe and North Africa will be the most favoured places to catch the shower's best, if the peak keeps to time. An interesting challenge is to try spotting the occasional long-pathed shower member from the southern hemisphere around dawn, but sensible Quadrantid watching cannot be carried out from such places.

The maximum timing given above is based on the best-observed return of the shower ever analysed, from IMO 1992 data, confirmed by radio results in most years since 1996. The peak itself is normally short-lived, and can be easily missed in just a few hours of poor northern-winter weather, which may be why the ZHR level apparently fluctuates from year to year, but some genuine variability is probably present too. For instance, visual ZHRs in 1998 persisted for over two hours at their best. An added level of complexity comes from the fact that mass-sorting of particles across the meteoroid stream may make 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. A few, but apparently not all, years since 2000 seem to have produced a, primarily radio, maximum following the main visual one by some 9 — 12 hours. Visual confirmation of any repeat near this time in 2008 would fall ideally for sites from East Asia east to sites around the eastern North Pacific Ocean.

Past observations have suggested the QUA radiant is diffuse away from the maximum, contracting notably during the peak itself, although this may be a result of the very low activity outside the hours near maximum. Still-imaging and video observations from January 1 — 5 would be particularly welcomed by those investigating this topic, using the IFCs and TFCs given above, along with telescopic and visual plotting results.

α-Centaurids (ACE)

Active:January 28 — February 21
Maximum:February 8 17h UT (λsol = 319°2)
ZHR = variable; usually ~ 5 but may reach 25+
Radiant: α = 211° δ = -59°
Radiant drift: see Table 6
vinf = 56 km/s; r = 2.0

In theory, the α-Centaurids are one of the main southern summer high points, from past records supposedly producing many very bright, even fireball-class, objects (meteors of at least magnitude -3), commonly with fine persistent trains. However, peak ZHRs recently have been found as 5 or less in the few sketchy reports available, though in 1974 and 1980, bursts of only a few hours' duration apparently yielded activity closer to 20 — 30. As with many southern hemisphere sources, we have more questions than answers at present, nor do we have any means of telling when, or if, another stronger event might happen. Thus imaging and visual observers are urged to be alert at every opportunity. The radiant is nearly circumpolar for much of the sub-equatorial inhabited Earth, and is at a useful elevation from late evening onwards. New Moon falls almost perfectly for the predicted peak, an ideal chance for anyone favoured by clearer skies.

γ-Normids (GNO)

Active: February 25 — March 22
Maximum: March 13 (λsol = 353°)
ZHR = 4
Radiant: α = 239° δ = -50°
Radiant drift: see Table 6
vinf = 56 km/s; r = 2.4
TFC: α = 225° δ = -26° and α = 215° δ = -45° (β < 15° S)

γ-Normid meteors seem to be 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 has been reported as quite sharp, with ZHRs of 3 to 4 often noted for only a day or two to either side of the maximum. Activity may vary somewhat at times, with occasional broader, or less obvious, maxima having been noted in the past. Limited data since 1999 have suggested the possibility of a maximum at some, albeit short-lived, stage between λsol ~ 350° — 357°, equivalent to 2008 March 10 — 17, while video information from the same period found the earlier radiant position to be no longer applicable. The details given here are now to be preferred. Post-midnight watching yields best results, when the radiant is rising to a reasonable elevation from southern hemisphere sites (the radiant does not rise for many northern ones). The shower badly needs more regular observation, and March's waxing Moon, at first quarter on March 14, means 2008 would be an excellent year to start. All observing techniques can be employed.

April to June

Meteor activity picks up towards the April-May boundary, with badly moonlit shower peaks in late April from the Lyrids (between 21h UT on April 21 to 08h UT on April 22, with probably better rates the closer the peak falls to ~ 05h UT on April 22) and π-Puppids (but see below), then the perfectly moonless η-Aquarids in early May, followed a few days later by a new Working List minor shower, the η-Lyrids. Later in May and throughout June, most of the meteor action switches to the day sky, with six shower maxima expected during this time. Although occasional meteors from the o-Cetids and Arietids have been claimed as seen from tropical and southern hemisphere sites visually in past years, ZHRs cannot be sensibly calculated from such observations. For radio observers, the theoretical UT peaks for these showers are as follows: April Piscids — April 20, 03h; δ-Piscids — April 24, 03h; ε-Arietids — May 9, 02h; May Arietids — May 16, 03h; o-Cetids — May 20, 01h; Arietids — June 7, 05h; ζ-Perseids — June 9, 04h; β-Taurids — June 28, 04h. Signs of most of these were found in radio data from 1994 — 2007, though some are difficult to define individually because of their proximity to other radiants. There seems to be a modest recurring peak around April 24, perhaps due to combined rates from the first three showers listed here, for instance, while the Arietid and ζ-Perseid maxima tend to blend into one another, producing a strong radio signature for several days in early to mid June. There are indications these two June shower maxima now each occur up to a day later than indicated above. The Antihelion Source should be relatively strong, with ZHRs of 3 to 4 found in recent investigations through till mid April, and again around late April to early May, late May to early June, and late June to early July. At other times, the ZHR seems to be below ~ 2 to 3. The radiant area drifts from south-east Virgo through Libra in April, then across the northern part of Scorpius to southern Ophiuchus in May, and on into Sagittarius for much of June. For northern observers, circumstances for checking on any potential June Lyrids (not currently on the Working List, but possibly producing some weak activity, if at all, around June 15) are very unfavourable this year, with a waxing gibbous Moon visible virtually all night then for most mid latitude sites. Conditions are much better for possible June Boötid hunting.

π—Puppids (PPU)

Active: April 15 — 28
Maximum: April 23 10h UT (λsol = 33°5 — but see below)
ZHR = periodic - up to around 40
Radiant: α = 110° δ = -45°
Radiant drift: see Table 6
vinf = 18 km/s r = 2.0
TFC: α = 135° δ = -55° and α = 105° δ = -25° (β < 20° N)

Despite the very poor lunar circumstances for observing this shower in 2008, we urge all who can to do so, because this is a young stream produced by Comet 26P/Grigg-Skjellerup, and the comet is at perihelion on 2008 March 23, just a month before the Earth passes nearest to the stream orbit. Activity has only been detected from this source since 1972, with notable, short-lived, shower maxima of around 40 meteors per hour found in 1977 and 1982, both years when the parent comet was at perihelion. Before 1982, little activity had been seen at other times, but in 1983, a ZHR of ~ 13 was reported, perhaps suggesting material has begun to spread further along the comet's orbit, as theory predicts. Comet Grigg-Skjellerup's perihelion in 2002 November produced nothing meteorically significant the following April, but this time's closer approach may yield something more interesting. There are no guarantees of course, but even registering a negative return this year would be valuable information, and regular monitoring of the shower epoch generally is vital, as past coverage has commonly been patchy, so other short-lived maxima could have been missed. Apart from the timing suggested above, Jérémie Vaubaillon has found three stream trails may pass close enough to the Earth to produce some activity, though these seem likely to consist of small particles only, perhaps producing meteors too faint for visual observation. The three trails were laid down in 1937, 1942 and 1947, and should be encountered between ~ 22h50m — 23h20m UT on April 22. The ZHR from each component may be ~ 10, ~ 4 and ~ 10 respectively, albeit possibly only for radio observers, unless we are fortunate.

The π-Puppids are best-seen from the southern hemisphere, with useful observations mainly practical there before midnight, as the radiant is very low to setting after 01h local time. Even on April 23, the waning gibbous Moon will rise about as astronomical twilight is ending from mid-southern latitudes, thus the dark-sky observing window is virtually nil. Covering whatever happens is important however, so visual watchers must just make the best of things, and face away from the Moon, and not too close to the radiant, if clear skies manifest. Sites best-placed to catch the predicted maxima timings, if they prove accurate, should be from east Brazil east to Africa on April 22, and across the southern Pacific Ocean, including the eastern one-third of Australia and all of New Zealand on April 23. So far, visual and radio data have been collected on the shower, but the slow, sometimes bright nature of the meteors makes them ideal subjects for imaging too. No telescopic or video data have been reported in any detail as yet.

η-Aquarids (ETA)

Active: April 19 — May 28
Maximum: May 5 18h UT (λsol = 45°5)
ZHR = 70+ (periodically variable ~ 40 — 85)
Radiant: α = 338° δ = -01°
Radiant drift: see Table 6
vinf = 66 km/s; r = 2.4
TFC: α = 319° δ = +10° and α = 321° δ = -23° (β < 20° S)

A fine, rich stream associated with Comet 1P/Halley, like the Orionids of October, but one visible for only a few hours before dawn, essentially from tropical and southern hemisphere sites. Some useful results have come even from sites around 40° N latitude in recent years however, and occasional meteors have been reported from further north, but 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. While the radiant is still low, η-Aquarids tend to have very long paths, which can mean observers underestimate the angular speeds of the meteors, so extra care is needed when making such reports.

A relatively broad maximum, sometimes with a variable number of submaxima, usually occurs in early May. Fresh IMO analyses in recent years, based on data collected between 1984 — 2001, have shown that ZHRs are generally above 30 between about May 3 — 10, and that the peak rates appear to be variable on a roughly 12-year timescale. The next highest rates should fall towards 2008 — 2010, if this Jupiter-influenced cycle is borne-out, thus ZHRs should be around 70 or more in 2008, according to this idea. The unexpectedly strong Orionid return of 2006 October adds a degree of extra uncertainty over what may be possible from this shower too, and new Moon on May 5 makes this a perfect year for checking. A more recent analysis of IMO video results has led to a slight amendment in the radiant drift, though the radiant at maximum is unchanged. All forms of observing can be used to study the shower, with radio work allowing activity to be followed even from many northern latitude sites throughout the daylight morning hours. The radiant culminates at about 8h local time.

ε-Lyrids (ELY)

Active: May 3 — 12
Maximum: May 8 18h UT (λsol = 48°4)
ZHR = 3
Radiant: α = 287° δ = +44°
Radiant drift: see Table 6
vinf = 44 km/s; r = 3.0
TFC: α = 325° δ = +40° or α = 285° δ = +15° and
α = 260° δ = +30° (β > 10° S)

This new introduction to the Working List is associated with Comet C/1983 H1 IRAS-Araki-Alcock, though it appears to be only a weak meteoric source. Most of the observational data on it so far has been based on imaging results. The radiant position is likely to be somewhere near the point given above at the presumed maximum, but may be some degrees from it. Recent IMO video results found a radiant centred near α = 290°, δ = +42°, for example, so other than video work careful visual or telescopic plotting will be needed to separate any potential ε-Lyrids from the sporadics. The radiant drift remains unmeasured, but was supposed to be 1° parallel to the ecliptic. The proposed radiant area is usefully on-view all night from the northern hemisphere (primarily), and the thin waxing crescent Moon will be setting by midnight for mid-northern latitudes on May 8, so will not be a significant problem for checking on any possible activity.

June Boötids (JBO)

Active: June 22 — July 2
Maximum: June 27 02h30m UT (λsol = 95°7)
ZHR = variable: 0 — 100+
Radiant: α = 224° δ = +48°
Radiant drift: see Table 6
vinf = 18 km/s; r = 2.2
TFC: α = 156° δ = +64° and α = 289° δ = +67° (β = 25° — 60° N)

This source was reinstated on the Working List after its unexpected return of 1998, when ZHRs of 50 — 100+ were visible for more than half a day. Another outburst of similar length, but with ZHRs of ~ 20 — 50 was observed on 2004 June 23, a date before definite activity had previously been recorded from this shower. Consequently, in the latest upgrade of the List, the shower's start date has been altered to try to ensure future activity so early is caught, and we encourage all observers to routinely monitor throughout the expected activity period, in case of fresh outbursts. Prior to 1998, only three more probable returns had been detected, in 1916, 1921 and 1927, and with no significant reports between 1928 and 1997, it seemed likely these meteoroids no longer encountered Earth. The dynamics of the stream were poorly understood, although recent theoretical modelling has improved our comprehension. The shower's parent Comet 7P/Pons-Winnecke has an orbit that now lies around 0.24 astronomical units outside the Earth's at its closest approach. It was last at perihelion in 2002, and is next due on September 26 this year. Clearly, the 1998 and 2004 returns resulted from material shed by the comet in the past, which now lies on slightly different orbits to the comet itself. Dust trails laid down at various perihelion returns during the 19th century seem to have been responsible for the last two main outbursts. There were no predictions in force for possible activity in 2008 at the time of writing, but conditions for checking are quite favourable from the mid-northern latitudes where the radiant is best-seen. Last quarter Moon, though rising by midnight on June 26/27 from such locations, should be only a small problem after it appears, though the prolonged — in some places continuous — twilight means the summer nights are short anyway. The radiant is usefully accessible virtually all night, and all observing techniques can be employed.

July to September

With the former minor showers of the Pegasids and July Phoenicids having proven undetectable in the latest full IMO analyses, and so deleted from the Working List, this leaves just the Antihelion Source active and more or less visually identifiable for most of July, while its radiant area moves steadily through eastern Sagittarius and across northern Capricornus into south-west Aquarius. Results suggest the Source may not be especially recognisable after the first few days however, as ZHRs for most of the month seem < 2. Activity appears to improve somewhat, with ZHRs ~ 2 to 3, by late July and through the first half of August. This level of ZHRs may make it more practical to still identify the moonless α-Capricornid maximum, despite that radiant's overlap with the Antihelion Source's.

The Southern δ-Aquarids are strong enough, and the Piscis Austrinids have a radiant probably distant enough from the ANT area, that both should still be separable from it, particularly from the southern hemisphere. By the best from the major, and partly moonlit, Perseids, ANT ZHRs will likely have dropped back below 2 again, as the radiant tracks on through Aquarius, and into western Pisces by the α-Aurigid maximum on the August-September boundary. Only the κ-Cygnid peak is completely lost this August, as their peak is just the day after full Moon, on August 17.

Both the newly-renamed September Perseids (formerly the δ-Aurigids) and what we now term the δ-Aurigids proper, separated into two showers, even though they follow one another directly on exactly the same radiant drift track, have maxima that should be recordable in September, skies permitting. For most of September, ANT rates can still be detected from the radiant in Pisces, albeit probably no better than 2 — 3, but remember that from September 25, Antihelion meteors are no longer to be recorded as such, as both Taurid showers take over the near-ecliptic shower baton until late November.

For daylight radio observers, the interest of May-June has waned, but there remain the visually-impossible γ-Leonids (peak towards August 25, 04h UT, albeit not found in recent radio results), and a tricky visual shower, the Sextantids. Their maximum is expected on September 27, around 04h UT, but may possibly occur a day earlier. In 1999 a strong return was detected at λsol ~ 186°, equivalent to 2008 September 28, while in 2002, the September 27 peak was not found, but one around September 29 — 30 was! It seems plausible that several minor maxima in early October may also be due to this radio shower. New Moon creates no additional difficulties for visual observers hoping to catch some Sextantids in late September, though radiant-rise is less than an hour before dawn in either hemisphere.

Piscis Austrinids (PAU)

Active: July 15 — August 10
Maximum: July 27 (λsol = 125°)
ZHR = 5
Radiant: α = 341° δ = -30°
Radiant drift: see Table 6
vinf = 35 km/s; r = 3.2
TFC: α = 255° to 000° δ = 00° to +15°
choose pairs separated by about 30° in α (β < 30° N)

Very little information has been collected on the Piscis Austrinids in recent decades, so the details on the shower are not well-confirmed, and it seems possible the ZHR may be a little optimistic. However, that impression may simply be due to the large amount of northern hemisphere summer data, and the almost complete lack of southern hemisphere winter results, on it. The stream seems to be rich in faint meteors, rather like the nearby ANT and SDA, so telescopic work is advisable to try to establish more about it. Along with all the late July shower peaks this year, the PAU benefits from a nearly-new Moon.

Southern δ-Aquarids (SDA)

Active: July 12 — August 19
Maximum: July 27 (λsol = 125°)
ZHR = 20
Radiant: α = 339° δ = -16°
Radiant drift: see Table 6
vinf = 41 km/s; r = 3.2
TFC: α = 255° to 000° δ = 00° to +15°
choose pairs separated by about 30° in α (β < 40° N)

One of the biggest changes brought about in the revamp of the Working List was the removal of the former streams of the Northern δ-Aquarids, and the Northern and Southern δ-Aquarids, all of which proved separately unidentifiable in a series of recent IMO and non-IMO analyses. This greatly simplifies matters for visual observers especially, who often struggled because of the confusion of minor radiants thought present in the Aquarius-Capricornus region during July-August. Like the PAU and ANT, the SDA meteors are often faint, thus are suitable targets for telescopic observing, although enough brighter members exist to make visual and imaging observations worth the effort too, primarily from more southerly sites. Radio work can pick up the SDA as well, and indeed the shower has sometimes given a surprisingly strong radio signature. Careful visual plotting is advised, to help with accurate shower association. The SDA/PAU/ANT/CAP radiants are well above the horizon for much of the night. The moonless maximum may not be quite so sharp as the single date suggested here might imply, perhaps lasting with similar activity from July 27 — 29. Its rates have been suspected of some variability at times too, though not in the more recent investigations.

α-Capricornids (CAP)

Active: July 3 — August 15
Maximum: July 29 (λsol = 127°)
ZHR = 4
Radiant: α = 307° δ = -10°
Radiant drift: see Table 6
vinf = 23 km/s; r = 2.5
TFC: α = 255° to 000° δ = 00° to +15°
choose pairs separated by about 30° in α (β < 40° N)
IFC: α = 300° δ = +10° (β > 45° N)
α = 320° δ = -05° (β 0° to 45° N)
α = 300° δ = -25° (β < 0°)

The α-Capricornids and SDA were both definitely detected visually in former years, standing out against the much weaker other radiants supposed active in Capricornus-Aquarius then. Whether the CAP can still be detected separately from the new ANT radiant area remains to be discovered, as its radiant now partly overlaps that of the large ANT oval region. In their favour, CAP meteors are noted for being bright, at times even of fireball-class, 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 minor enhancement of CAP ZHRs to ~ 10 was noted in 1995 by European IMO observers. More recent results sugges