October to December 2005

Potential Draconid hunting should be practical this year in early October. Unfortunately, things are less helpful for the very weak ε-Geminids (maximum due on October 18) and the major Orionids (main peak expected on October 21), which are both lost to waning gibbous moonlight. As the Moon rolls on, Taurid-watching from late October to almost mid-November is chiefly Moon- free. Later, the Leonids must endure full Moon near their probable maximum, towards 14h30m UT on November 17. Although the α-Monocerotid peak is also badly moonlit, the shower is highlighted here on the tenth anniversary of its latest outburst. The early December mostly minor shower maxima are acceptably free from moonlight through to the sigma-Hydrids, but this means both the major Geminids (maximum within 2 h 20 m of 4h30m UT on December 14) and the minor Coma Berenicids (peak around December 19) are both swamped by full moonlight. Something of the Ursids at least should still be seen without the Moon.

Draconids

Active      : October 6-10;
Maximum     : October 8, 16h UT (sol = 195.195°, but see below);
ZHR         : periodic, up to storm levels;
Radiant     : alpha = 262°, delta = +54°; Radiant drift: negligible;
V           : 20 km/s
r           : 2.6;
TFC         : alpha = 290°, delta = +65° and alpha = 288°, delta = +39° (beta > 30° N).
Figure 11 - Radiant position of the Draconids.

The Draconids are primarily a periodic shower which produced spectacular, brief, meteor storms twice last century, in 1933 and 1946, and lower rates in several other years (ZHRs ~ 20-500+), most recently in 1998 (when EZHRs briefly reached 700). Most detected showers were in years when the stream's parent comet, 21P/Giacobini-Zinner, returned to perihelion, as it did in 1998 November. The comet returns to perihelion again in July this year, but whether it will have any effect on the Draconids we see in 2005 is not clear. Earlier theoretical discussions suggested an outburst was unlikely, but theory is not always the perfect guide to reality! The 1998 outburst happened at sol = 195°075, equivalent to 2005 October 8, 8h15m UT, although the nodal crossing time used above may be more generally applicable. In 1999 an unexpected minor visual-radio outburst (ZHRs ~ 10-20) occurred over the Far East between sol = 195°63-195°76. A repeat at this time would fall between 2005 October 8, 21h40m to October 9, 0h50m UT. The radiant is circumpolar from many northern hemisphere locations, but is higher in the pre-midnight and near-dawn hours of early October. The waxing crescent Moon sets by mid-evening on October 8 and 9 at such places, so much of the night will be available for dark-sky observing, whatever the shower may yield - even if that is nothing detectable. Draconid meteors are exceptionally slow-moving, a characteristic which helps separate genuine shower meteors from sporadics accidentally lining up with the radiant.

Taurids

Southern Taurids

Active      : October 1-November 25;
Maximum     : November 5 (sol = 223°);
ZHR         : 5;
Radiant     : alpha = 052°, delta = +13°; Radiant drift: see Table 6;
V           : 27 km/s
r           : 2.3;
TFC         : Choose fields on the ecliptic and ~ 10° E or W of the radiants (beta > 40° S).

Northern Taurids

Active      : October 1-November 25;
Maximum     : November 12 (sol = 230°);
ZHR         : 5;
Radiant     : alpha = 058°, delta = +22°; Radiant drift: see Table 6;
V           : 29 km/s
r           : 2.3;
TFC         : as Southern Taurids.

These two streams form part of the complex associated with Comet 2P/Encke. Defining their radiants is best achieved by careful visual or telescopic plotting, photography or video work, since they are large and diffuse. They are currently being studied using IMO data by Mihaela Triglav. The brightness and relative slowness of many shower meteors makes them ideal targets for photography, while these factors coupled with low, steady, combined Taurid rates makes them excellent targets for newcomers to practice their plotting techniques on. The activity of both streams produces an apparently plateau-like maximum for about ten days in early November, and the showers have a reputation for producing some excellently bright fireballs at times, although seemingly not in every year.

David Asher has indicated that increased Taurid fireball rates may result from a "swarm" of larger particles within the Taurid stream complex, and he suggested such "swarm" returns might happen in 1995 and 1998 most recently. In 1995, an impressive crop of bright Taurids occurred between late October to mid November, while in 1998, Taurid ZHRs reached levels comparable to the usual maximum rates in late October, together with an increased flux of brighter Taurids generally. This year brings the next potential October-November "swarm" return. Thus, observing what happens with the Taurids between last quarter Moon in October through to the Northern Taurid maximum in November is most important, especially as early November's new Moon makes almost the whole of this spell very favourable.

The near-ecliptic radiants for both shower branches mean all meteoricists can observe the streams. Northern hemisphere observers are somewhat better-placed, as here suitable radiant zenith distances persist for much of the late autumnal nights. Even in the southern hemisphere, a good 3-5 hours' watching around local midnight is possible with Taurus well above the horizon, however.

Figure 12 - Radiant position of the Northern and Southern Taurids.

α-Monocerotids

Active      : November 15-25;
Maximum     : November 21, 15h00m UT (sol = 239.239°);
ZHR         : variable, usually ~ 5, but may produce outbursts to ~ 400+;
Radiant     : alpha = 117°, delta = +01°; Radiant drift: see Table 6;
V           : 65 km/s
r           : 2.4;
TFC         : alpha = 115°, delta = +23° and alpha = 129°, delta = +20° (beta > 20° N); or
              alpha = 110°, delta = -27° and alpha = 098°, delta = +06° (beta < 20° N).

Another late-year shower capable of producing surprises, the α- Monocerotids gave their most recent brief outburst in 1995 (the top EZHR, ~ 420, lasted just five minutes; the entire outburst 30 minutes). Many observers across Europe witnessed it, and we were able to completely update the known shower parameters as a result. Whether this indicates the proposed ten-year periodicity - with heightened rates in 1925, 1935, 1985 and 1995 - is real or not, only this year (or other future decadal returns) may tell, so all observers should continue to monitor this source closely.

The waning gibbous Moon on November 21 is very bad news however, as it will rise between mid to late evening across much of the world, ruining any chance of dark skies for watchers, because the radiant is well on view from either hemisphere only after about 23h local time. The expected peak time falls especially well for sites around and in the western Pacific Ocean, including eastern China, far eastern Russia, Japan, Oceania, and Alaska in North America. With the Moon so problematic, visual observing will be extremely difficult, but highly important, along with all other techniques, especially radio, which should readily detect any strong outburst from this source.

χ-Orionids

Active      : November 26-December 15;
Maximum     : December 2 (sol = 250°);
ZHR         : 3;
Radiant     : alpha = 082°, delta = +23°; Radiant drift: see Table 6;
V           : 28 km/s
r           : 3.0;
TFC         : alpha = 083°, delta = +09° and 
              alpha = 080°, delta = +24° (beta > 30° S).
Figure 13 - Radiant position of the Geminids, χ-Orionids, Monocerotids, and sigma-Hydrids.

A weak visual stream, but one moderately active telescopically. Some brighter meteors have been photographed from it too. The shower has at least a double radiant, but the southern branch has been rarely detected. The χ- Orionids may be a continuation of the ecliptic complex after the Taurids cease to be active in late November.

The radiant used here is a combined one, suitable for visual work, although telescopic or video observations should be better-able to determine the exact radiant structure. It is well on display in both hemispheres throughout the night, and new Moon on December 1 makes this a perfect year for watching it.

Phoenicids

Active      : November 28-December 9;
Maximum     : December 6, 8h45m UT (sol = 254.254°);
ZHR         : variable, usually 3 or less, may reach 100;
Radiant     : alpha = 018°, delta = -53°; Radiant drift: see Table 6;
V           : 18 km/s
r           : 2.8;
TFC         : alpha = 040°, delta = -39° and alpha = 065°, delta = -62° (beta < 10° N).

Only one impressive Phoenicid return has so far been reported, that of its discovery in 1956, when the EZHR was probably ~ 100, possibly with several peaks spread over a few hours. Three other potential bursts of lower activity have been reported, but never by more than one observer, under uncertain circumstances. Reliable IMO data shows recent activity to be virtually nonexistent. This may be a periodic shower however, and more observations of it are needed by all methods. Lunar circumstances for southern hemisphere watchers are quite good, with a waxing crescent Moon setting half an hour either side of local midnight in most mid-southern locations on December 6, while the radiant culminates at dusk, remaining well on view for most of the night.

Puppid-Velids

Active      : December 1-15;
Maximum     : December ~ 7 (sol ~ 255°); ZHR ~ 10;
Radiant     : alpha = 123°, delta = -45°; Radiant drift: see Table 6;
V           : 40 km/s
r           : 2.9;
TFC         : alpha = 090° to 150g, delta = -20° to -60°; choose pairs of fields separated
              by about 30° in α, moving eastwards as the shower progresses (beta < 10° N).

This is a very complex system of poorly studied showers, visible chiefly to those south of the equator. Up to ten sub-streams have been identified, with radiants so tightly clustered, visual observing cannot readily separate them. Photographic, video or telescopic work would thus be sensible, or very careful visual plotting.

The activity is so badly known, we can only be reasonably sure that the highest rates occur in early to mid December, coincident with a waxing Moon this year. Some of these showers may be visible from late October to late January. Most Puppid-Velid meteors are quite faint, but occasional bright fireballs, notably around the suggested maximum here, have been reported previously. The radiant area is on-view all night, but is highest towards dawn, so the better radiant elevations will happen after moonset.

Monocerotids

Active      : November 27-December 17;
Maximum     : December 9 (sol = 257°);
ZHR         : 3;
Radiant     : alpha = 100°, delta = +08°; Radiant drift: see Table 6;
V           : 42 km/s
r           : 3.0;
TFC         : alpha = 088°, delta = +20° and alpha = 135°, delta = +48° (beta > 40° N);
              or alpha = 120°, delta = -03° and alpha = 084°, delta = +10° (beta < 40° N).

Only low rates are likely from this minor source, making accurate visual plotting, telescopic or video work essential, particularly because the meteors are normally faint. The shower's details, even including its radiant position, are rather uncertain. Recent IMO data showed only weak signs of a maximum as indicated above. Telescopic results suggest a later maximum, around December 15- 16 (sol ~ 264°) from a radiant at alpha = 117°, delta = +20°. This is quite a good year for making observations, as the waxing gibbous Moon sets between local midnight and 1h across the world on December 9, while the radiant is on-show virtually all night, culminating about 1h30m local time.

σ-Hydrids

Active      : December 3-15;
Maximum     : December 12 (sol = 260°);
ZHR         : 2;
Radiant     : alpha = 127°, delta = +02°; Radiant drift: see Table 6;
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 are generally very low, close to the visual detection threshold. Since their radiant, a little over 10° east of the star Procyon (α Canis Minoris), is near the equator, all observers can cover this shower. The radiant rises in the late evening hours, but is best viewed after local midnight. Although the Moon is only three days before full for their predicted peak, there remains a short dark-sky observing window after moonset and before dawn, particularly north of the equator, for observers to take advantage of. Recent data indicates the maximum may happen up to six days earlier than this theoretical maximum, which would be very much more favourable for Moon-free watching. The shower would benefit from visual plotting, telescopic or video work to pin it down more accurately.

Ursids

Active      : December 17-26;
Maximum     : December 22, 13h UT (sol = 270.7°);
ZHR         : 10 (occasionally variable up to 50);
Radiant     : alpha = 217°, delta = +76°; Radiant drift: see Table 6;
V           : 33 km/s
r           : 3.0;
TFC         : alpha = 348°, delta = +75° and alpha = 131°, delta = +66° (beta > 40° N);
              alpha = 063°, delta = +84° and alpha = 156°, delta = +64° (β 30° to 40° N).

A very poorly observed northern-hemisphere shower, but one which has produced at least two major outbursts in the past 60 years, in 1945 and 1986. Several other rate enhancements, recently in 1988, 1994 and 2000, have been reported too. Other similar events could easily have been missed due to poor weather or too few observers active. All forms of observation can be used for the shower, since many of its meteors are faint, but with so little work carried out on the stream, it is impossible to be precise in making statements about it.

The radio maximum in 1996 occurred around sol = 270°8, for instance, which might suggest a slightly later maximum time in 2005 of December 22, 15h20m UT, while the 2000 enhancement was seen surprisingly strongly (rm EZHR ~ 90) by video at sol = 270°78 (equivalent to 2005 December 22, 15h UT), although the visual enhancement was much less, rm ZHR ~ 30. The Ursid radiant is circumpolar from most northern sites (thus fails to rise for most southern ones), though it culminates after daybreak, and is highest in the sky later in the night. The waning gibbous Moon will rise around 23h local time on December 22, so conditions will not be perfect for seeing whatever happens this time. The expected peaks favour northerly sites between central Asia eastwards across the Pacific Ocean to western North America.

Figure 15 - Radiant position of the Ursids.