Perseid Meteor Shower

When is the peak of this meteor shower? Please provide the time in GMT.

Mij Adyaw wrote:

When is the peak of this meteor shower? Please provide the time in GMT.


1800 UT Aug 12.

http://www.skyinsight.net/wiki/index..._Meteor_Shower

..

Mij Adyaw wrote:
When is the peak of this meteor shower? Please provide the time in GMT.



2005 Aug. 12 @ 18:29 UT

Mij Adyaw wrote:
When is the peak of this meteor shower? Please provide the time in GMT.

There two predications -
Vaubaillon: 8/12/2005 at 3:54 UT
IMO: 8/12/2005 at 18:30 UT

Generally, see the International Meteor Organization calendar for
details.
http://www.imo.net/calendar/cal05.html#perseids
http://www.imo.net/calendar/per.gif (Position of Perseid radiant for
Jul 15 to Aug 25)

and -

NASA Headlines. The 2005 Perseid Meteor Shower (7/22/2005)
http://science.nasa.gov/headlines/y2...rseids2005.htm
http://science.nasa.gov/headlines/y2...ymap_north.gif

and -

Kronk's Meteor Shower Page -
http://comets.amsmeteors.org/meteors.../perseids.html

Jeremie Vaubaillon forecasts likely ZHR for many meteor showers. Here
is his June 15 forecast for the 2005 Perseids -
http://www.imcce.fr/page.php?nav=3De...eteor/PER/200=
5Perseids.php

"The expected ZHR is not expected to be higher than the annual activity
(recorded by IMO), i.e. ZHR=3D100 /hr. From the above figure, the maximum
is expected to occur on the 12/08/2005 at 3:54 UT (Solar
longitude=3D139.478=B0)."

The IMO predicts a different time for the peak - 18:30 UTC on
8/12/2005, or around noon MDT on 8/12/2005.

See discussion at the IMO calendar regarding uncertainty in the Perseid
peak time.

ZHR is based on the number of meteors seen when the radient is at the
zenith. The number of meteors you can expect to see are lower, where
the Perseid radiant is lower in altitude above your local horizon. See
the Appendix to this post for the computation converting ZHR to an
meteor hourly rate where the radiant is off-zenith.

My usual way of enjoying the Persieds is to sit either facing north
towards the radiant or with my back to the radiant facing south. When
facing south in previous years, many fainter widely dispersed meteors
were seen on a broad arc. The arc traces a cone back to the radiant.

I have prepared two alt-az charts, one north facing and one south
facing for my OP at 41deg N. I use these to pass the time by roughly
plotting meteors seen. These charts are for approximately 1am local
time on 8/12, North America.

http://members.csolutions.net/fisher...sChart2005081=
2_7UTCNF130FOV.gif
http://members.csolutions.net/fisher...sChart2005081=
2_7UTCSF270FOV.gif

(Right-click on the chart, save it to your desktop and then print to a
full landscape page.)

Enjoy - Canopus56(Kurt)

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D
Appendix - Conversion of ZHR to hourly rate off-zenith

The zenith hourly rate is the rate observed when the shower is at local
observer's zenith. The International Meteor Organization gives the
following information regarding when the meteor shower's radiant is not
on the
observer's local zenith:

"Table 1 gives the number of meteors an observer might expect to see at
different radiant elevations if the ZHR amounted to the
impressive value of 100. Now you can imagine what you will see with a
radiant elevation of 10=B0 if the ZHR is not as impressive as
100. Therefore, when planning your watch you should take care that the
radiant will have a reasonable elevation for the whole watch.
For several reasons the lower limit is about 20=B0.


Table 1: Numbers of meteors visible per hour for a ZHR=3D100 shower and
different radiant elevations h (limiting magnitude of 6.5m)
h in =B0 | 90 | 70 | 50 | 40 | 30 | 20 | 10
n | 100 | 94 | 77 | 64 | 50 | 34 | 17 "


Source: IMO. http://www.imo.net/visual/major01.html

IMO Table 1 appears to follow a simple sin function -
alpha =3D altitude of the radiant above the local horizon at a local
time * pi() / 180
hr_alpha =3D zhr * sin(alpha)

where hr_alpha is the predicated hourly rate at the selected altitude
of the radiant above the local observer's horizon.

"Mij Adyaw" wrote in message
news:gcyKe.131$Ji4.62@fed1read03...
When is the peak of this meteor shower? Please provide the time in GMT.


Thursday evening. Sorry, I don't live in Greenwich. :-)

Mij,

I have seen reports of two peaks ...

August 12 @ 18:29 GMT and
August 13 @ 00:12 GMT

Being at UT+3 (or GMT+3), I am shooting (excuse the pun) for the second
peak under mag 6.5+ skies tomorrow evening.

Good luck!

Anthony.

Mij Adyaw wrote:

When is the peak of this meteor shower? Please provide the time in GMT.

When is the peak of this meteor shower? Please provide the time in GMT.


Jim, why do you make simple-minded posts like this? I'm sure you're=20
quite capable of using a web browser to look up some info on the=20
shower.

-Florian