אטא-אקוורידים השנה

[Ella Ratz]

שבוע טוב לחטיבת המטאורים!

להלן המידע על המטר השנה כפי שמופיע באתר ארגון המטאורים הבינלאומי (IMO):

η-Aquariids (031 ETA) Active: April 19–May 28; Maximum: May 5, 20h UT (λ⊙ = 45 . ◦5); ZHR = 40 (periodically variable, ≈ 40–85); Radiant: α = 338◦ , δ = −1 ◦ ; Radiant drift: see Table 6; V∞ = 66 km/s; r = 2.4.

This stream is associated with Comet 1P/Halley, like the Orionids of October. Shower meteors are only visible for a few hours before dawn essentially from tropical and southern hemisphere sites. Some useful results have come even from places around 40◦ N latitude at times however, 8 IMO INFO(2-15) and occasional meteors have been reported from further north. The shower is one of the best for southern observers and 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. While the radiant is still low, η-Aquariids 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, occurs around May 5. IMO analyses based on data collected between 1984–2001, have shown that ZHRs are generally above 30 in the period May 3–10. The peak rates appear to be variable on a roughly 12-year timescale. Assuming this Jupiter-influenced cycle is real, the next trough is due around 2014–2016, so ZHRs should be close to their relative poorest this year. Activity around the most recent ZHR peak period in circa 2008 and 2009 seemed to have been ≈ 85 and 65 respectively. In 2013, ZHRs up to ≈ 70 have been recorded (WB, p. 24). New Moon on May 6 creates ideal viewing conditions for whatever the shower provides this year. All forms of observing can be used to study it, with radio work allowing activity to be followed even from many northern latitude sites throughout the daylight morning hours. The radiant culminates at about 08h local time.

רוצים לעשות תצפית? ישנה תצפית של האגודה יום אחרי, אבל השיא הוא רחב, כך שניתן לראות מטאורים גם לילה לפני ואחרי.

שבוע טוב,

אלה.