(meteorobs) Meteor Activity Outlook for July 1-7, 2005

Peter Brunone peter at brunone.com
Thu Jun 30 20:43:13 EDT 2005


Hi Robert,

	I just wanted to say thanks again for the link to the HTML
version.  Also, the table at the bottom of the page... Is that new?
Either way, that distilled data is incredibly helpful.

Cheers,

Peter Brunone

-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Robert Lunsford
Sent: Thursday, June 30, 2005 7:33 PM
To: meteorobs at meteorobs.org
Subject: (meteorobs) Meteor Activity Outlook for July 1-7, 2005


This upcoming period will see the moon reaching its new phase on
Wednesday July 6. At this time the moon rises and sets with the sun and
will not interfere with observing. This weekend the waning crescent moon
will rise an hour or two before morning twilight. The moon's phase will
be so thin that it will not cause much interference to meteor observers.
The estimated total hourly rates for evening observers this week should
be near two for those in the Northern Hemisphere and three for those
observers south of the equator. For morning observers the estimated
total hourly rates should be near seven for those located in the
Northern Hemisphere and ten for those in the Southern Hemisphere. These
rates assume that you are watching from rural areas away from all
sources of light pollution. 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 listed below are exact for Saturday night/Sunday
morning July 2/3. 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. 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 are the showers that may be observed this week:

The Alpha Capricornids (CAP) are now producing a ZHR of one from a wide
radiant located at 18:52 (283) -17. This position lies in northern
Sagittarius, five degrees northwest of the third magnitude star Pi
Sagittarii. The radiant is best placed near 0100 local daylight time,
when it lies highest in the sky. With an entry velocity of 23 km/sec.,
most activity from this radiant would be slow. This radiant is well seen
except for far northern latitudes where it remains twilight all night
long and the radiant does not rise as high into their sky. This radiant
is located close to the anthelion radiant this time of year and it may
be difficult to separate the two.

The Anthelion radiant is now centered at 19:40 (295) -21. This area of
the sky is located in eastern Sagittarius, eight degrees east of the
third magnitude star Pi Sagittarii. Since this radiant is large and
diffuse, any slow to medium speed meteor from eastern Sagittarius,
southern Scutum or western Capricornus could be a candidate for this
shower. The center of this area is best placed near 0200 local daylight
time when it lies on the meridian and is highest in the sky. At this
time expect to see two shower members per hour from the Southern
Hemisphere and one from the Northern.

Unlike most of the annual showers the antihelion source is produced by
debris from unknown objects orbiting in a direct motion like the earth.
These objects are most likely asteroids, which produce stony and
metallic debris whose density is much greater than material produced by
comets. There is also the possibility that some of this activity may be
caused by the "Jupiter family of comets", comets which have been altered
by Jupiter's gravity into much shorter orbits. This material collides
with the earth on the inbound portion of its orbit, before its closest
approach to the sun. Therefore we best see them just after midnight when
we are facing the direction from which this activity appears. The
antihelion source is active all year from an area of the sky nearly
opposite that of the sun. The center of this source will move
approximately one degree eastward per day and travels through many
different constellations over the course of a year. It may make sense to
list these meteors as anthelions or "ANT" but a majority of meteor
organizations prefer that you list them from the constellation in which
the radiant is currently located or the constellation where the shower
reaches maximum activity. Observers who send their reports to the
International Meteor Organization (I.M.O.) should label these meteors as
Sagittarids (SAG).

The Sporadic rates for the Northern Hemisphere are now rising from their
low plateau for the year. Observers can expect around six random meteors
per hour during the morning hours as seen from locations in the Northern
hemisphere. During the dark evening hours perhaps two random meteors can
be seen per hour north of the equator. Sporadic rates seen from the
Southern Hemisphere are near a secondary annual maximum. From south of
the equator one would expect to see approximately eight random meteors
per hour during the late morning hours and three per hour during the
evening.

Alpha Capricornids (CAP)        18:52  (283)  -17
Hourly Rate =    <1  N.  Hemisphere,   <1  S. Hemisphere

Anthelion  (Sagittarids)    19:40 (295) -21
Hourly Rate =     1   N. Hemisphere,    2  S. Hemisphere

Clear Skies!
Robert Lunsford
American Meteor Society
http://www.amsmeteors.org/lunsford/





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