Last Updated:
2012 Jan 11 23:00 UTC
Source file:
forthcoming_meteors.txt
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Meteor Activity 2011 February to 2012 JanuaryEdited by Tony MarkhamWith most of the major meteor shower maxima occurring mid month, an inconveniently timed Full Moon can adversely affect all of them in certain years. In practice, this occurs one year out of every three. Unfortunately, 2011 is such a year, with moonlight being a problem for the maxima of the Lyrids, Perseids, Giacobinids, Taurids, Leonids and Geminids. Conditions will be favourable for the maxima of the Eta Aquarids, Delta Aquarids-S, Alpha Capricornids and Ursids. The Orionids and 2012 Quadrantids will also suffer from some moonlight interference. Despite the moonlight interference, October's Giacobinids may well be the highlight of the year - provided that the predicted enhanced activity does occur. Virginids / Spring Antihelion SourceAfter the Quadrantids of January, night time meteor rates are rather low for northern hemisphere observers. However, from mid February to early May there are a number of minor showers with radiants close to the ecliptic. Older sources collectively refer to these as the Virginids, whilst more recently lists treat them (and later showers such as the Capricornids and Piscids) as being part of an "Antihelion source" that is assumed to be active throughout the year from an area of sky located about 180 degrees from the Sun. Minor showers historically grouped together as the "Virginids" have included the Delta Leonids (max Feb 26), the Alpha Virginids (max Apr 11-12) and the Gamma Virginids (max Apr 14). Peak rates from this collection of minor showers generally occurs in early April.New Moon in 2011 occurs on Mar 4, Apr 3 and May 3. Lyrids max Apr 22d23h UTChart. Lyrid activity can be seen from Apr 18-25 each year. For observers at northern latitudes, the Lyrid radiant is above the horizon all night. As for many of the major meteor showers, observed rates pick up as the radiant altitude increases during the night, so meteor watches after midnight are the most productive. The Lyrids are the main night time meteor shower of the spring months for northern hemisphere observers. Although they don't usually produce observed rates comparable with major showers that occur later in the year, the Lyrids do stand out relative to the low background activity of the spring months. Some intense but brief Lyrid outbursts have occasionally been seen, such as in 1982.Full Moon in 2011 occurs on Apr 18. For observers at the latitude of the UK, moonrise will be after midnight on maximum night, resulting in dark skies early in the night but hindering observations in the second half of the night when the radiant is highest Eta Aquarids max May 4This shower, resulting from the Earth's post-perihelion with the meteoroid stream of comet Halley, is active from late April to mid May and produces higher peak ZHR values than do the Lyrids. However, while easy to observe from the southern hemisphere and from the tropics, for observers in northern Europe dawn is approaching before the radiant reaches a reasonable altitude. Thus observers at northern latitudes can only expect to see low observed rates.In 2011, the Eta Aquarid peak occurs only a day after New Moon and so moonlight will not be a problem. The radiant is in northern Aquarius, at RA 22h20m, Dec -01. Daytime showersFor observers at northern latitudes the Eta Aquarids are almost a daytime-only shower. However, active throughout May and June are several showers whose radiants are only above the horizon during daylight hours (although in a few cases, some activity may be detectable late in the night by observers in tropical latitudes). Consequently observation of these showers is limited to radio methods. ZHR and radiant information is generally poorly known. The most active of these showers appear to be the May Arietids (max May 16), the Omicron Cetids (max May 20), the Arietids (max Jun 7), The Zeta Perseids (max Jun 9) and the Beta Taurids (max Jun 28).June Bootids max Jun 23-24?This shower produced an unexpected outburst in 1998, with a broad peak during June 27-28. Another outburst was seen on 2004 June 23. Although several outbursts from this shower were seen in the early 20th century, these latest outbursts were unexpected as the Earth now passes some distance from the orbit of the particles which produced the earlier outbursts. The parent comet 7P/Pons-Winnecke was at perihelion on 2008 Sep 26, but there is no evidence that recent outbursts have been related to the position of the comet. It is worthwhile monitoring this shower's activity however in case further outbursts occur. There is some uncertainty as to the current location of the shower radiant, with recent reports merely describing the activity as originating from "northern Bootes".In 2011, Last Quarter Moon occurs on June 23 and so the Moon should not be a major problem for observers (although all-night twilight may well be a problem for observers at more northerly latitudes!) July Minor ShowersNight-time sporadic activity picks up in July. Among the minor showers sometimes listed are the Alpha Cygnids, which are active throughout the month and into early August (radiant 21h00m, +48) and the Lacertids, which are active later in the month (radiant 22h05m, +37). Neither shower seems to have any clearly defined maxima and it is possible that many of the meteors assigned to the showers have merely been chance lining-ups of sporadic meteors.Full Moon in 2011 occurs on July 15, with New Moon occurring on July 30. Aquarid-Capricornid complex / Summer Antihelion SourceChart. This Aquarid-Capricornid group of showers includes the Delta Aquarids-S (max July 28-29), the Piscis Australids (max July 31), the Alpha Capricornids (max Aug 2), the Delta Aquarids-N (max Aug 5-9) and the Iota Aquarids-S (max Aug 6-7). Other than for the Delta Aquarids-S, the peak ZHRs are all below 10 per hour. The Alpha Capricornids have been noted for producing a number of slow moving flaring fireballs. Rather confusingly some sources refer to the Alpha Capricornids as the Capricornids, whilst others use the term Capricornids to describe a minor shower peaking around July 25 !The proximity of the radiants to each other, together with their motion from night to night means that visual observers must take great care to distinguish between the individual showers. For this reason, the above showers, with the exception of the Delta Aquarid-S are often now merely grouped together as part of the "Summer Antihelion Source". With New Moon in 2011 occurring on July 30, observations of these shower maxima will suffer little interference from moonlight. Perseids max Aug 13d03h UTChart. Despite not producing peak rates as high as those of the Geminids, the Perseid meteor shower remains the favourite for most observers. This is because, in addition to being rich in bright and trained meteors, it also occurs during summer in the northern hemisphere as opposed to the cold nights of December for the Geminids. Perseid activity can be seen from the last week of July through to the third week of August. The highest observed rates on any given night are likely to be seen when the radiant is highest in the sky late in the night. The more detailed analyses of recent decades have also shown that there is often more than one Perseid peak, the supplementary peaks being shifted several hours away from the main peak and probably associated with dust trails left behind by specific perihelion passages of the parent comet.Moonlight conditions in 2011 will be rather unfavourable, with Full Moon occurring on Aug 13. However, for observers at the latitude of the UK, the Full Moon will be fairly low in the sky and so not as much a hinderance as it would be for showers later in the year. Observations on maximum night with the observer facing away from the Moon should therefore still be quite productive. Oberavtions of the early Perseids made up to and including the first week of August should not be affected significantly by moonlight. August Minor ShowersSporadic activity is quite high in August and numerous minor showers have been reported as being active. Many of them are probably spurious, with some of their supposed members being misidentified Perseids and late members of the Aquarid/Capricornid complex.The more reliable showers include the Alpha Aurigids, which reach maximum late in the month (radiant RA 04h56m , Dec +43), and the Kappa Cygnids which reach maximum on Aug 20 (radiant 19h20m, +55) and often produce fireballs. Some sources also list an Iota Aquarid-N maximum on Aug 20 and a second Kappa Cygnid maximum on Aug 26. Full Moon in 2011 occurs on Aug 13, with New Moon occurring on Aug 29. Minor Showers in September / early Autumn Antihelion SourceSporadic activity is also high in September and, again, numerous minor showers have been reported, although not as many as for August, probably because less observers are usually active. Be aware that in many cases the names allocated to these minor showers varies from one source to the next ! The more reliable minor showers include the Alpha Aurigids (continuing from August), the Beta Cassiopeids (max Sep 1-6, radiant 00h05m, +63), the Epsilon Perseids (max Sep 3-7, radiant 04h10m, +37), the Delta Aurigids (max Sep 8, radiant 04h00h, Dec +47) and the Piscids (max Sep 8-9, radiant 00h36m, +07 ; max Sep 21, radiant 00h24m, +00).More recent sources usually include the Piscids as part of the "Antihelion Source" (whereas later autumn ecliptic based radiants are allocated to the Taurid complex) Full Moon in 2011 occurs on Sep 12, with New Moon occurring on Sep 27. October Camelopardalids max Oct 5-6 ?In 2005 and 2006, enhanced meteor activity from Camelopardus was recorded on video around this date. On neither occasion were there visual records of high activity, although the bright nearly Full Moon would have made observation very difficult in 2006. If this is an annual shower and it occurs at the same solar longitude each year, then it might be seen again around 07h-09h30m UT on 2011 Oct 6. This, together with the gibbous Moon hindering observations early in the night, would make observers at Pacific longitudes best placed to observe activity, but it would be also be worthwhile observers at other longitudes monitoring for activity given the vagueness of the details reported to date.Giacobinids (Draconids) max Oct 8d 19-21h ??21P/Giacobini-Zinner, the parent comet of this shower, passed through perihelion in July 2005, with some enhanced activity been reported when the Earth passed close to the comet's orbit at around 17h UT on Oct 8 2005.With the next perihelion passage due to occur on Feb 11 2012, there is a good chance of seeing enhanced Giacobind activity in 2011. Despite the 2011 Giacobinid shower occuring around 4 months ahead of this, calculations have indicated that the Earth is likely to encounter a series of dust trails left by the comet in the late 19th century. Storm level activity is very unlikely, but ZHRs of several hundred are a possibility. The radiant, at RA 17h23m, Dec +57, lies near the head of Draco and is quite high in the sky for observers at northern latitudes at the start of the night. Giacobinid meteors are relatively slow moving. Unfortunately, in 2011, with Full Moon occurring during the night of Oct 11-12, it will only be about 3 days from Full at the time of the hoped for Giacobinid activity. Orionids Max Oct 20-23Chart. Orionid activity lasts from Oct 14-31, with a broad maximum occurring between Oct 20 and Oct 23 - however, even within this period there will be several peaks and troughs in the activity levels. The Orionids, which are the result of the Earth's per-perihelion encounter with the meteoroid stream of comet Halley, sometimes brings surprises such as the unusually high rates seen during the night of 2006 Oct 21-22. There were also indications of enhanced rates in 2008 and 2009 andThe radiant position at maximum is RA 06h24m , Dec +15 (on the border of Gemini and Orion) but actually appears quite diffuse since it consists of a number of sub-centres, as shown by the chart, whose combined activity can give the impression of the radiant remaining almost stationary for several days. The Orionid radiant does not rise until mid evening and is highest in the sky late in the night. In 2011, Last Quarter occurs on Oct 20 and so the Moon will only be a problem in the later part of the night. Taurids Max Nov 7Chart. Activity lasts throughout October and November, with a broad maximum in early November. Observed rates are far from spectacular, but some observers report that the shower produces a good percentage of fireballs. Indeed a good number of bright Taurids were reported in 2005. Some Taurid activity will also be visible during the Orionid watches of October and the Leonid watches of November. The Taurid radiants are highest at around the middle of the night.The 2011 maximum is unfavourably timed, with First Quarter occurring on Nov 2 and Full Moon occurring on Nov 10. Leonids max Nov 18Chart. Leonid activity last from Nov 14-20 each year. The Leonid radiant rises in the late evening and is highest in the sky around dawn. The Leonids produced storm level activity for observers at favoured locations in 1999, 2001 and 2002. It had been assumed that we had encountered all of the significant Leonid filaments. However, in 2008 the Earth passed close to a filament of material ejected at the 1466 return of the parent comet, resulting in rates being enhanced to around normal Perseid levels. A further close approach to this filament in 2009 resulted in similar rates during 20h-21h UT on Nov 17. Observing conditions were fairly unfavourable in 2010, but data reported did indicate a ZHR over 20 - and so well above the rates usually quoted for years between perihelion returns of the parent comet. In 2011, Last Quarter occurs on Nov 18 and so the Moon will rise soon after the Leonid radiant on the night of maximum. Geminids max Dec 14d13h UTChart. Although the Geminids were overshadowed by the enhanced Perseid activity of the early 1990s and the enhanced Leonid activity of 1998-2002, the Geminids are the shower that produce the highest reliable rates year on year and only lose out in popularity to the Perseids due to the colder December nights.Geminid activity can be seen from Dec 7-16. Results from recent years have shown the peak ZHR to be over 100 and to remain above 70 per hour for about 24 hours - and the shower's profile is evolving from year to year. The Geminids are typically rich in bright meteors, but produce few trained meteors. The radiant is highest at about 02h local time and for observers at northern temperate latitudes is above the horizon all night. Moonlight conditions are rather unfavourable for the Geminids in 2011 with Full Moon occurring on Dec 10. The Moon will rise by mid evening on the night of maximum, with the radiant still fairly low in the sky. Ursids max Dec 22-23Ursid activity lasts from approx Dec 17-25, with the radiant, at RA 14h28m, Dec +78, being highest late in the night and circumpolar for most northern hemisphere observers. High rates were recorded from this shower in 1945, 1982 ,1986, 2000, 2004 and 2006. It is suspected that other such peaks may have been missed due to lack of observations.With New Moon occurring on Dec 24, Ursid observations in 2011 will not be hindered by moonlight. Quadrantids 2012 max Jan 04d06h UTChart. The Quadrantid radiant, lying at Dec +50, in a rather bland area od the sky between Draco, Bootes and Ursa Major, is circumpolar for observers north of latitude 40 N. The radiant is at its lowest altitude at around 20h local time and is highest at the end of the night. The maximum is usually rather narrow, with the predicted time for 2012 favouring observers at west European longitudes. However it should be noted that the 2009 peak was broader than usual with the ZHR being above 100 for nearly 12 hours.The 2012 peak occurs with the Moon between First Quarter and Full Moon, and so moonlight will be a problem until late in the night.
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