The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
Meteor activity picks up a bit during April as two major showers are active during the month. The first of these, the Lyrids, are active from the 16th through the 25th, with a pronounced maximum on the 22nd. The Eta Aquariids start appearing near the 28th and reach maximum activity during the first week in May. Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) rise this month toward a maximum in July.
During this period the moon reaches its new phase on Wednesday April 14th. At this time the moon lies near the sun and cannot be seen at night. This weekend the waning crescent moon will not cause any interference to meteor observers. The estimated total hourly rates for evening observers this week is ~3 for those in the northern hemisphere and ~4 for those south of the equator. For morning observers the estimated total hourly rates should be ~10 from the northern hemisphere and ~16 as seen from the southern hemisphere. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity.
The radiant positions and rates listed below are exact for Saturday night/Sunday morning April 10/11. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.
The following showers are expected to be active this week:
The wide Antihelion (ANT) radiant is now centered at 14:16 (214) -13. This area of the sky lies on the Virgo/Libra border, ten degrees west of the second magnitude star Zubenelgenubi (Alpha Librae). This radiant is best placed near 0200 local daylight time (LDT) when it lies on the meridian and is located highest in the sky. Due to the large size of this radiant, any meteor radiating from eastern Hydra, Libra, or Virgo could be a candidate for this shower. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.
Zeta Cygnids (ZCG)
The team of Sirko Molau and Juergen Rendtel have discovered a weak radiant active at this time in the constellation of Cygnus. Video data shows that the Zeta Cygnids (ZCY) are active from March 27th through April 18th. Maximum activity occurs on the morning of April 6th. The radiant is currently located at 20:08 (302) +42. This position lies in central Cygnus, six degrees west of the second magnitude star Sadr (Gamma Cygni). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 44km/sec. the Zeta Cygnids would produce meteors of medium velocity. Expected rates are near one per hour during the last dark hour before dawn. Due to the northerly declination, these meteors are not well seen from south of the equator.
The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.
Shower Name RA DEC Vel Rates km/s NH SH ANT Antihelions 14h 16m -13 30 1 2 ZCY Zeta Cygnids 20h 08m +42 44 1 <1 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere