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Aktywność meteorowa 25 II - 3 III 2017
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Autor:  Ireneusz Włodarczyk [ 25 lutego 2017, 09:31 ]
Tytuł:  Aktywność meteorowa 25 II - 3 III 2017

As seen from the northern hemisphere, March is the slowest month for meteor
activity. No major annual showers are active and only a few very weak minor
showers produce activity this month. The sporadic rates are also near their
annual minimum so there is not much to look forward to this month except for the
evening fireballs that seem to peak this time of year as seen from the northern
hemisphere. This could be due to the fact the Antapex radiant lies highest above
the horizon this time of year during the evening hours. From the southern
hemisphere, activity from the Centaurid complex begins to wane with only the
weak activity visible from Norma and perhaps others nearby areas. At least
southern sporadic rates are still strong to make the late summer viewing a bit
more pleasurable.

During this period the moon reaches its new phase on Sunday February 26. At this
time the moon is located near the sun and is invisible at night. As the week
progresses the waxing crescent moon will enter the evening sky but will not
interfere with meteor observing. The estimated total hourly meteor rates for
evening observers this week is near 3 for those viewing from the northern
hemisphere and 5 for those located south of the equator. For morning observers
the estimated total hourly rates should be near 7 as seen from mid-northern
latitudes (45N) and 16 as seen from tropical southern locations (25S). 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. Note that the hourly rates listed below are estimates as viewed
from dark sky sites away from urban light sources. Observers viewing from urban
areas will see less activity as only the brightest meteors will be visible from
such locations.

The radiant (the area of the sky where meteors appear to shoot from) positions
and rates listed below are exact for Saturday night/Sunday morning February
25/26. These positions do not change greatly day to day so the listed
coordinates may be used during this entire period. Most star atlases (available
at science stores and planetariums) will provide maps with grid lines of the
celestial coordinates so that you may find out exactly where these positions are
located in the sky. A planisphere or computer planetarium program is also useful
in showing the sky at any time of night on any date of the year. Activity from
each radiant is best seen when it is positioned highest in the sky, either due
north or south along the meridian, depending on your latitude. It must be
remembered that meteor activity is rarely seen at the radiant position. Rather
they shoot outwards from the radiant so it is best to center your field of view
so that the radiant lies at the edge and not the center. Viewing there will
allow you to easily trace the path of each meteor back to the radiant (if it is
a shower member) or in another direction if it is a sporadic. Meteor activity is
not seen from radiants that are located below the horizon. The positions below
are listed in a west to east manner in order of right ascension (celestial
longitude). The positions listed first are located further west therefore are
accessible earlier in the night while those listed further down the list rise
later in the night.

These sources of meteoric activity are expected to be active this week.

The center of the large Anthelion (ANT) radiant is currently located at 11:20
(170) +04. This position lies in southeastern Leo, 2 degrees south of the 4th
magnitude star known as sigma Leonis. Due to the large size of this radiant,
Anthelion activity may also appear from Sextans and western Virgo as well as
southern Leo. This radiant is best placed near 0100 local standard time (LST),
when it lies on the meridian and is located highest in the sky. Rates at this
time should be near 2 per hour no matter your location. With an entry velocity
of 30 km/sec., the average Anthelion meteor would be of slow velocity.

The February Mu Virginids (FMV) were discovered by Damir Šegon and colleagues
from the Croatian Meteor Network using their data and that of SonotaCo. These
meteors are active from February 15 through March 4 with maximum activity
occurring on February 26. The current radiant position lies near 16:24 (246)
-02, which actually places it western Ophiuchus, 3 degrees northeast of the pair
of 3rd magnitude stars known as "Yeds" (delta and epsilon Ophiuchi). Rates, even
at maximum, are expected to be less than 1 per hour no matter your location.
These meteors are best seen near 0500 LST when the radiant lies highest above
the horizon. At 62 km/sec. the February Mu Virginids would produce mostly swift
meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately 5 sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near 2 per hour. As seen
from the tropical southern latitudes (25S), morning rates would be near 14 per
hour as seen from rural observing sites and 4 per hour during the evening hours.
Locations between these two extremes would see activity between the listed
figures.

Anthelion (ANT) - 11:20 (170) +04 30 Velocity - 30km/sec.
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr

February mu Virginids (FMV) - 16:24 (246) -02 Velocity - 64km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Zgodnie z:

Robert Lunsford
International Meteor Organization

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