Coma Berenicids (COM) - Μεγιστο 29 Δεκεμβριου '08

[Bi2L]

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Coma Berenicids (COM)

 

Active: December 12 — January 23

Maximum: December 29 (λsol = 278°)

ZHR = 5

Radiant: α = 185° δ = +21°

Radiant drift: see Table 6

vinf = 65 km/s; r = 3.0

TFC: α = 180° δ = +50° and α = 165° δ = +20° before 3h local time

α = 195° δ = +10° and α = 200° δ = +45° after 3h local time (β > 20° N)

 

 

One of the significant bonuses of the new Working List upgrade has been to define a rather better visual activity profile for the Coma Berenicids than had been possible previously. The shower was confirmed as quite weak, but apparently long-lasting, though coverage after the Quadrantid epoch in January still left many gaps, a period which needs more observations. The maximum was found to be about ten days later in December than previously thought too, hence the amended parameters above.

 

The radiant ephemeris of the shower is severely questioned after the scrutinization of single-station video data showing a clear radiant drift with an offset of about 15° to the Working List positions. The result is given as 'possible COM' in the figure below. We recommend to use the old positions in 2008, while meteors from the 'possible COM' position should be noted separately.

 

 

In 2006, Spanish video observers reported an unexpected COM outburst on December 24/25, with EZHRs suggested as perhaps ~ 60, but this was not apparent in any of the radio observations then, nor in another detailed set of video observations made in Italy at the same time, so it remains uncertain. Since the possible outburst came from the 'old' COM position, the new ephemeris from video data may actually indicate a separate source rather than an erroneous COM drift.

 

There is much we still do not know about this shower, and as it is almost unobservable from the southern hemisphere, northern watchers must brave the winter cold to improve matters. The radiant is at a useful elevation from local midnight onwards, and new Moon near the probable peak makes this a particularly good year to make observations.

[Bi2L]

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αναφερει οτι το μεγιστο ειναι στις 20 Δεκεμβριου

http://www.imo.net/calendar/2008#table5

 

Shower: Coma Berenicids (COM)

Activity: Dec 12 - Jan 23

Max Date: Dec 20

λsol: 268°

α: 177°

δ: +25°

vinf: 65

r: 3.0

ZHR: 5