Perseids - ZHR Data request

11 years 3 months ago #72087 by dmcdona
Perseids - ZHR Data request was created by dmcdona
Folks, for those who expressed an interest in gathering meteor shower data and anyone else willing to help gather scientific data, here's your chance - weather permitting of course...

You can find detailed instructions of how to conduct a meteor observing session and a report sheet on which to log your data here

I've brazenly copied Terry Moseley's details of the forthcoming shower below.

Dave

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PERSEID METEORS. The 'Old Faithful' of meteor showers is with us once again, now building up to the maximum rate expected on August 12. Some Perseid meteors are already appearing, but the rate does not reach a really noticeable level until about August 7/8.

The peak is forecast for about 09h on the 12th, so best rates will be seen on the night of 11/12, just before dawn starts to lighten the sky. The waxing gibbous Moon will interfere somewhat on the night of maximum, with First Quarter being on the evening of the 8th, and Full Moon on the evening of the 16th. But the Moon will set by about 00.30 that night, giving a reasonable dark-sky window before dawn for keen observers.

The radiant, from where the meteors appear to originate, is in NE Perseus, not far from the famous Double Cluster. It is above the horizon all night from Irish/British latitudes, so some meteors can be seen as soon as the sky gets dark enough - say by about 11.30 p.m.

The maximum ZHR is forecast to be about 80, but please note that you won't actually see that rate! Why? The ZHR, or Zenithal Hourly Rate, is defined as the rate that would be seen by an experienced observer, in a very dark sky, with the radiant in the zenith. Even though the Moon will set well before dawn, and even if you observe from a very dark location, there's one insuperable problem - the radiant does not reach the zenith before dawn! From Belfast, for example, it only reaches an altitude of about 65 degrees before the sky starts to brighten. So don't believe so-called experts and commentators who just blindly quote the official ZHR as the rate that the average person will see, ignoring all the other factors! I even heard one professional astronomer say that the ZHR rate could be seen by anybody, not just on the night of maximum, but during the whole 2 weeks or so that the shower is officially 'active'!

However, 65 degrees is still quite good, so if all other conditions are favourable, you might see 60 to 70 Perseids per hour during that moonless window from a very dark site. Add in about another 10 sporadic meteors per hour, and it starts to become quite a respectable show.

Rates drop off during the few days after maximum, and with the Moon brightening to Full on the 16th, you won't see so many on the nights after maximum.

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