During this period the moon reaches its first quarter phase on Monday the 28th.
At this time the moon will be located ninety degrees east of the sun and will
set near 0100 local daylight time as seen from mid-northern latitudes. As the
week progresses the waxing gibbous moon will set later and later, narrowing the
window of opportunity to view in dark conditions. The estimated total hourly
meteor rates for evening observers this week is near two for observers in the
northern hemisphere and three for those south of the equator. For morning
observers the estimated total hourly rates should be near seven as seen from
mid-northern latitudes and thirteen from mid-southern latitudes. 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.
Evening rates during this period are reduced due to moonlight.
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 May 26/27. 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.
The following shower is expected to be active this week:
The large Antihelion (ANT) radiant is currently located at 17:12 (258) -23. This
position lies in extreme southeastern Ophiuchus, ten degrees northeast of the
bright first magnitude orange star Antares (Alpha Scorpii). Due to the large
size of this radiant, Antihelion activity may also appear from Scorpius ,
western Sagittarius, southwestern Serpens Cauda, as well as southern Ophiuchus .
This radiant is best placed near 0200 LDT, when it lies on the meridian and is
located highest in the sky. Rates at this time should be near two per hour as
seen from the northern hemisphere and three as seen from south of the equator.
With an entry velocity of 30 km/sec., the average Antihelion meteor would be of
slow velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see
approximately five sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near one per hour. As
seen from the mid-southern hemisphere (45S), morning rates would be near ten per
hour as seen from rural observing sites and two per hour during the evening
hours. Locations between these two extremes would see activity between the
listed figures.
The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.
SHOWER | DATE OF MAXIMUM ACTIVITY | CELESTIAL POSITION | ENTRY VELOCITY | CULMINATION | HOURLY RATE | CLASS |
RA (RA in Deg.) DEC | Km/Sec | Local Standard Time | North-South | |||
Antihelions (ANT) | – | 17:12 (258) -23 | 30 | 02:00 | 2 – 3 | II |