HERE COME THE QUADRANTID METEORS

[Whitters]

HERE COME THE QUADRANTID METEORS

The New Year opens with very favourable conditions for the Quadrantids, one
of the three most active regular annual showers. Active from January 1-6,
the Quadrantids have been poorly observed in most recent years thanks to a
combination of factors - a very narrow period of high activity, poor January
weather, and moonlight interference in at least one year out of three!
However, when the shower was last well-covered by BAA observers, a peak ZHR
of 100-120 m/h was found. Unfortunately, activity is close to peak levels
for only about six hours: at other times, only a 'trickle' of a few meteor
per hour might be detected. The Quadrantid radiant (RA 15h 28m Dec +50o)
actually lies in northern Boötes (in a region occupied by the now defunct
constellation of Quadrans Muralis), and from the latitudes of the British
Isles it is circumpolar.

Timing of the Quadrantid peak in January 2011 is quite favourable from the
UK perspective, especially as the peak coincides with new Moon, so there
will a complete absence of interference from moonlight. The shower maximum
is expected around Jan 04d 00h UT, midnight at our longitudes. Although the
radiant is rather low in the northern sky during the evening hours, it will
be rising higher by midnight and it climbs to a very favourable elevation as
dawn approaches.  Observations in the hours after midnight on January 3/4
will be the most productive.


Local Time          Radiant Altitude             Local Time       Radiant
Altitude
                            (Lat. 53oN)
(Lat. 53oN)

17                                22.5o                             00
21.8o

18                                18.1o                             01
27.2o

19                                14.9o                             02
33.3o

20                                13.3o                             03
41.8o

21                                13.1o                             04
49.0o

22                                14.6o                             05
56.9o

23                                17.5o                             06
66.3o


Much of the high activity close to the peak is comprised of moderately
bright to faint meteors. As a result of particle-sorting, brighter
Quadrantids (produced by larger meteoroids) become more numerous following
the maximum, and this might be evident by dawn on January 4. Quadrantids
are, like the Geminids, relatively slow meteors, with an atmospheric entry
velocity of 42 km/sec. The brighter shower members are sometimes strongly
coloured (often blue or green).

The stream's dynamic orbital history - much perturbed by Jupiter's gravity -
has made identification of its parent body complicated. Recent studies have
suggested that the Quadrantids may be debris from asteroid 2003EH1 (another
similarity with the Geminids!), a possible break-up product of Comet 1490Y1
following the latter's close approach to Jupiter in 1650.

The Quadrantids can certainly be listed as a shower very much in need of
observation - so why not make it your New Year's Resolution to start 2011
with a few hours of meteor watching between midnight and dawn on January 4.
And, observers who have been out Quadrantid watching during the early
morning hours of January 4 can reward themselves with a most interesting
partial eclipse of the Sun at sunrise that morning.

Additional information about the Quadrantid meteor shower is given in the
'Notes and News' section of the December BAA Journal.


For further details, or copies of report forms, observing notes, and
details of how to carry out group meteor watches, please visit the BAA
Meteor Section website at http://britastro.org/meteor or contact the
undersigned:

John Mason
Acting Director, BAA Meteor Section