Meteor Activity Outlook for July 21-27, 2012

During this period the moon reaches its first quarter phase on Wednesday the
25th. At this time the moon will be located ninety degrees east of the sun and
set near midnight local daylight time (LDT). This weekend the waxing crescent
moon will set during the late evening hours and will not hamper observing
efforts during the more active morning hours. The estimated total hourly meteor
rates for evening observers this week is near four no matter your location. For
morning observers the estimated total hourly rates should be near sixteen from
the mid-northern hemisphere and fourteen from the mid-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 (the area of the sky where meteors appear
to shoot from) positions and rates listed below are exact for Saturday night/Sunday
morning July 21/22. 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 radiants are expected to be active this week:

A new source found by the IMO video cameras to be active this time of year are
the July Zeta Draconids (ZED). This radiant has been found to be active from
July 19-29. Maximum activity activity occurs on the 19th from a position of
17:23 (263) +61, which is situated in southern Draco, five degrees southeast of
the third magnitude star Al dhibain (Zeta Draconis). Due to a low amount of data
the mean position of activity shifts quite a bit night to night so consider this
a wide radiant until better parameters can be obtained. Current rates would most
likely be less than one per hour no matter your location. The radiant is best
placed near 2200 (10pm) LDT when it lie highest above the horizon. With an entry
velocity of 23 km/sec., the average July Zeta Draconid meteor would be slow.

The Alpha Capricornids (CAP) are active from a wide radiant located at 20:04
(301) -12. This position lies near the Sagittarius, Aquila, Capricornus border,
three degrees west of the third magnitude double star Alpha Capricornii. The
radiant is best placed near 0100 local daylight time (LDT), when it lies on the
meridian and is highest in the sky. Current rates should be near one per hour no
matter your location. Don’t confuse these meteors with the antihelion meteors,
which have a radiant just to the east. Both radiants need to be in your field of
view to properly sort these meteors. With an entry velocity of 25 km/sec., most
activity from this radiant would be slow, a bit slower than the antihelions.
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.

The large Antihelion (ANT) radiant is currently located at 20:48 (312) -17. This
position lies in central Capricornus, four degrees west of the fourth magnitude
star Dorsum (Theta Capricorni). Due to the large size of this radiant,
Antihelion activity may also appear from southern Aquila, Microscopium, eastern
Sagittarius, northwestern Aquarius, and western Piscis Austrinus as well as
Capricornus. 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 are near their
lowest of the year with one per hour no matter your location . With an entry
velocity of 30 km/sec., the average Antihelion meteor would be of slow velocity.

Activity from the Delta Aquariids (SDA) will begin this weekend from a radiant
located at 22:18 (334) -18. This position is located in southwestern Aquarius,
eight degrees southwest of the third magnitude Delta Aquarii. Maximum activity
is expected on July 29th. Hourly rates will depend on your latitude. Those
viewing from the southern tropics will see the best rates of near 1-2 per hour.
Rates seen from mid-northern latitudes will range from 0-1 per hour, depending
on the haziness of your skies. The radiant rises near 2200 (10pm) LDT for
observers located in the mid northern latitudes, but is best placed near 0300
LDT, when it lies highest in the sky. With an entry velocity of 42 km/sec., most
activity from this radiant would be of average velocities.

The Piscids Austrinids (PAU) are a minor shower not well seen from the northern
hemisphere. This radiant is active from July 15 through August 10. Maximum
activity occurs on July 28 when the zenith hourly rate (ZHR) may reach five.
These rates are only seen from the southern hemisphere where the radiant passes
overhead. From mid-northern latitudes, rates of one per hour at maximum are
usually seen. The radiant is currently located at 22:23 (336) -32. This position
lies in central Piscis Austrinus, eight degrees southwest of the bright first
magnitude star Fomalhaut (Alpha Piscis Austrinus). The radiant is best placed
near 0300 LDT, when it lies highest in the sky. With an entry velocity of
35km/sec., most activity from this radiant would be of average velocities.

The July Pegasids (JPE) are active with low rates during most of July with
maximum activity occurring on the 10th. The radiant is currently located at
23:52 (358) +14. This area of the sky lies in southeastern Pegasus, four degrees
west of the third magnitude star Algenib (Gamma Pegasi). This radiant is best
placed during the last dark hour before dawn, when it lies highest above the
horizon in a dark sky. Rates at this time should be less than one per hour no
matter your location. With an entry velocity of 68 km/sec., the average July
Pegasid meteor would be of swift speed.

The Perseids (PER) are active from a radiant located at 01:04 (016) +52. This
position lies in southern Cassiopeia, six degrees southeast of the second
magnitude star Shedar (Alpha Cassiopeiae). The radiant is best placed during the
last hour before the start of morning twilight when it lies highest in a dark
sky. Since the maximum is not until August 12th, current rates would be only two
to three per hour at best, as seen from the northern hemisphere. Activity from
this source is not visible south of 40 degrees south latitude. With an entry
velocity of 61 km/sec., most activity from this radiant would be swift.

Another new source found by the IMO video cameras to be active this time of year
is the Phi Piscids (PPS). This radiant has been found to be active from June 14
through July 30 with maximum activity occurring on July 1st. Current rates would
most likely be less than one per hour no matter your location. The radiant is
currently located at 01:56 (029) +36, which is situated on the
Andromeda/Triangulum border, three degrees northwest of the third magnitude star
Beta Triangulum. The radiant rises near midnight LDT but does not reach a
sufficient altitude above the horizon until three hours later. Activity would
best seen during the last dark hour of the morning when the radiant is located
highest in a dark sky. With an entry velocity of 71 km/sec., the average Pi
Piscid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately ten sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near three per hour. As
seen from the mid-southern hemisphere (45S), morning rates would be near eight
per hour as seen from rural observing sites and three 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.