(meteorobs) Question about Aurigids peak Sept 1

[Bruce McCurdy]

EarthSky.org has put out a bulletin about the tomorrow morning's Aurigids
peak. 

http://earthsky.org/astronomy-essentials/aurigid-meteor-shower-peaks-before-
dawn-september-1 

While their article cites both AMS and a rate of 14-20 meteors per hour, the
way I read it is they have taken Bob Lunsford's hourly rates for sporadics
(as per weekly outlook below) and applied it to this story about Aurigids. 

While I'm tempted to go out just to catch the Jupiter/Moon/Mars trio in the
pre-dawn sky, I'd appreciate any insights from the list: Is there anything
unusual about the 2013 Aurigids that would make them an especially
worthwhile target?  

Thanks!

Bruce
*****

-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Robert Lunsford
Sent: Thursday, August 29, 2013 5:10 PM
To: meteorobs at meteorobs.org
Subject: (meteorobs) Meteor Activity Outlook for August 31-September 6, 2013

September offers longer nights in the northern hemisphere that tend to be
less hazy than those experienced in mid-summer. In the sky, no major showers
are visible from either hemisphere but the northern hemisphere enjoys the
advantage of higher sporadic rates. Most of the shower activity this month
is produced from the Perseus-Aurigid complex active this time of year. These
showers rarely produce more than five meteors per hour but still manage to
produce most of the shower activity seen this month. Unfortunately the
Perseus-Aurigid complex lies too low in the northern sky for southern
hemisphere observers to view very well. Video studies have shown that the
Southern Taurids are visible as early as September 7th therefore after this
date the Antihelion radiant will no longer be listed until the Taurid
showers end in December. The Anthelion meteors are still active but their
radiant is superimposed upon that of the more numerous Taurids, therefore it
is impossible to properly  separate these meteors. Observers in the southern
hemisphere suffer from some of their lowest rates of the year this month.
The Southern Taurid radiant is not too badly placed so observers south can
expect to see a little of this activity this month. Lastly, recent video
data has shown that the Orionids are active all month long, even though
their maximum is not until October 22nd.

During this period the moon reaches its new phase on Thursday September 5th.
At this time the moon is located near the sun and will not be visible at
night. This weekend the waning crescent moon will not rise until the early
morning hours, leaving a majority of the night in total darkness. Even with
the moon above the horizon for an hour or two before dawn, it will be so
thin that it will not interfere much with observing. The estimated total
hourly meteor rates for evening observers this week is near five for
observers located in the northern hemisphere and three for those viewing
south of the equator. For morning observers the estimated total hourly rates
should be near twenty as seen from mid-northern latitudes and near eleven
for observers viewing from tropical 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.  Note that the hourly r  ates 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
August  31/September 1. 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 th  e 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 sources of meteoric activity are expected to be active this
week:

The center of the large Anthelion (ANT) radiant is currently located at
23:24 (351) -02. This position lies in western Pisces, just below the
"Circlet", a group of six faint stars forming a circle. Due to the large,
oval-shaped radiant, activity from this source may also be seen coming from
eastern Aquarius, northwestern Cetus, southern Pegasus as well as Pisces.
These meteors may be seen all night long but the radiant is best placed near
0200 local daylight time (LDT) when it lies on the meridian and is located
highest in the sky. Rates at this time should be near two per hour
regardless of your location. With an entry velocity of 30 km/sec., the
average Anthelion meteor would be of slow velocity.

There is an new unnamed source of meteors active this week from a radiant
located at 00:36 (009) +78. IMO shower #141 is active from August
26-September 3, with maximum activity occurring on August 29. The radiant is
located in northern Cepheus, a few degrees northeast of the third magnitude
star known as Errai (Gamma Cephei). This area of the sky is best placed in
the sky near 0300 LDT, when it lies highest above the horizon in a dark sky.
With an entry velocity of 59 km/sec., most activity from this radiant would
be of swift speed.

New data for the September Epsilon Perseids (SPE) shows that this radiant is
active from September 1st through the 28th with maximum activity occurring
on the 9th. The radiant position is currently located at 02:52 (043) +41.
This position lies in southwestern Perseus, only three degrees west of the
famous eclipsing variable star known as Algol (Beta Persei). The radiant is
best placed near 0500 LDT, when it lies highest above the horizon. Rates are
currently less than one per hour but will increase to near 3 per hour at
maximum. Commencing on September 5th, this radiant will become the strongest
source of activity in the sky and will remain so throughout most of the
month. This shower experienced an outburst in 2008 with ZHR's near 25 for a
short time. Many bright meteors were produced during this outburst with the
brightest estimated at magnitude -8. With an entry velocity of 66 km/sec.,
most activity from this radiant would be swift. This activity is visible
from the tropi  cal regions of the southern hemisphere, but further south
the radiant becomes too low in the sky to produce much activity.

You may be surprised to see the Orionids (ORI) as an active radiant this
time of year, but there is clear evidence from the IMO database that this
shower is active long before its October 22nd maximum. In fact it is in the
top four most active radiants throughout September. This radiant is
currently located at 04:04 (061) -01, which places it in northern Eridanus,
near the Taurus border. The closest star of note is third magnitude Zaurak
(Gamma Eridani), which lies ten degrees to the south. Perhaps an easier way
to find the radiant would be to draw a line between Zaurak and the bright
star Aldebaran (Alpha Tauri). The Orionid radiant lies approximately halfway
between the two stars. This area of the sky is best placed in the sky during
the last hour before dawn, when it lies highest above the horizon in a dark
sky. With an entry velocity of 67 km/sec., most activity from this radiant
would be of swift speed.

Another new, unnamed source of meteors active this week from a radiant
located at 04:20 (065) +43. IMO shower #149 is active from August
29-September 9, with maximum activity occurring on September 3rd. The
radiant is located in eastern Perseus, three degrees northeast of the third
magnitude star known as Epsilon Persei. This position was once given for the
September Perseids, now called the September Epsilon Perseids. The true
radiant position for the September Epsilon Perseids was not revealed until
an outburst of these meteors occurred in 2008,  displaying a radiant further
west toward Algol. This radiant is the strongest source of meteors in the
sky on the mornings of September 3rd and 4th. This area of the sky is best
placed in the sky during the last hour before dawn, when it lies highest
above the horizon in a dark sky. With an entry velocity of 70 km/sec., most
activity from this radiant would be of swift speed.

The Aurigids (AUR) are first seen on August 29th and peak on Sunday morning
September 1st. On the morning of maximum activity, the radiant will be
located at 06:02 (091) +39. This position lies in central Auriga, two
degrees north of the third magnitude Theta Aurigae. Hourly rates will range
from 3-5 in the northern hemisphere down to 0-2 in the southern hemisphere.
The radiant is well placed for northern observers high in the northeastern
sky during the last hour before the start of morning twilight. South of the
equator, this shower is not well seen as it lies low in the northern sky
during the morning hours. With an entry velocity of 67 km/sec., most
activity from this radiant would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see
approximately fourteen sporadic meteors per hour during the last hour before
dawn as seen from rural observing sites. Evening rates would be near four
per hour. As seen from the tropical southern latitudes (25S), morning rates
would also be near seven 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 list of radiants that are expected to be active
this week. Rates and positions are exact for Saturday night/Sunday morning
except where noted in the shower descriptions.

Anthelions (ANT) - 23:24 (351) -02   Velocity - 30km/sec. 
Northern Hemisphere - 1 per hr.   Southern Hemisphere - 1 per hr 
 
IMO #141 - 00:36 (009) +78   Velocity - 43km/sec. 
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr 

September Epsilon Perseids (SPE) - 02:52 (043) +41   Velocity - 66km/sec. 
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr 

Orionids (ORI) - 04:04 (061) -01   Velocity - 67km/sec. 
Northern Hemisphere - 1 per hr.  Southern Hemisphere - 1 per hr 
 
IMO #149 - 04:20 (065) +43   Velocity - 70km/sec. 
Northern Hemisphere - 2 per hr. Southern Hemisphere - 1 per hr 
 
Aurigids (AUR) 06:02 (091) +39   Velocity - 67km/sec. 
Northern Hemisphere - 3 per hr.  Southern Hemisphere - 1 per hr 
 
Clear Skies! 
Robert Lunsford 	 
American Meteor Society 	 	 	 	 	 	 

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