Perseids Meteor Watch in Cudham

Another ROG astronomer quoted on the Perseids

Gosh... I hope she was misquoted... cause it's complete nonsense...  100 meteors per hour with an almost full Moon?... no way.

As ever, Pete Lawrence has got it spot on. See here for his latest infographic. Pete calculates something between 3 and 7 meteors per hour, which sounds about right to me.

Interesting that the RAS haven't publicised the Perseids this year as they believe that a low activity shower isn't something to promote to the general public.

Should still be a good show, but nonsense like a hundred meteors per hour will only serve to heighten expectations amongst the general public, who will then be severely disappointed when they don't see anything.

Sorry about my kit attack, Andy! Perhaps we could have an ongoing thread for "What astronomical item have you burnt your wallet with recently?"...or maybe not...

Thanks for the Pete Lawrence guide but I am stuck on the LM value.  Although he gives examples, he does specify how dark the skies are.  What are the ranges for this value from darkest sky to most light polluted skies.  I can work out that Pete adds 2 to 2.5 for a full moon...but this bit is vague.  What value would you plug in for tomorrow skies...in London and then for Cudham?

Oh crap, I'm so damn slow to clicked on.  I just realised why Andy's is sounding an alert...I'm bringing bad luck arent I?  New kit...bad weather, bad luck!   If Mike was giving me a lift, I'm pretty sure he would have dumped me somewhere on the motorway.

Tej, I've quickly learned about the Flamsteed 'curse of new kit'. (Whenever there's a Blackheath viewing or some such and the weather turns foul, the cry goes out: "Okay, who's bought new kit recently???") So I was worried that the Perseids viewing would be a washout because of your wallet-burning exercise!

I provoked a mini 'new kit' curse all by myself up in Scotland when I made a sun filter using a sheet of white light filter foil and some lumps of cardboard. As soon as I completed the effort, all the sunspots disappeared.

EDIT: Ah - you got my drift as I was typing my explanation 😉

Aye, got your drift finally and I recall Mike blaming me at the last Blackheath solar viewing event when his telescope focussing was playing up...naturally caused by the fact I had purchased a new astro camera, lol.

I think the New kit issue should be a reason for being barred from events.

🙁

... I am stuck on the LM value... What are the ranges for this value from darkest sky to most light polluted skies... What value would you plug in for tomorrow skies…in London and then for Cudham?

Good questions, Tej.

So, the limiting magnitude is the faintest object that you can see with a particular instrument... in this case, the eye!

There is a good website here which gives you estimates of the limiting visual magnitude for the whole of the UK.

So, the limiting magnitude for London is around +4. With a full Moon, I'd take this back a couple to around +2.

For Cudham, I'd estimate around +5 normally, so around +3 or so with a full Moon. Plugging that into the formula gives 1 meteor per hour. Crikey! Not good.

However, if we can limit the effects of the Moon, by keeping it at our backs (perhaps behind the tree line), we could bring the limiting magnitude up to nearer 4 or 4.5, increasing the number of meteors to around 5 or 6 an hour. At least in theory!

I was going to challenge your +4 for London, thinking back to when I was looking at the sky over Canary Wharf from ROG. I think +2 would have been a challenge then!

Then I remembered having to do some naked-eye constellation drawings. In London I did Auriga (dimmest of the main constellation stars is about +3.65) and Cassiopeia (+3.45). In Scotland I did Ursa Minor and so I was able to get down to +4.95 without any trouble.

BTW, you may or may not know that a magnitude difference of 1 equates to a relative brightness of around 2.5 times. So a star of mag +3 is 2.5 times as bright as one of mag +4, and 6.25 times as bright as one of mag +5.

What would be fun to find is some sort of app or website that either ranks stars by their magnitude or which gives the number of stars that ought to be visible given the limiting magnitude. Anyone know of such a thing?

What would be fun to find is some sort of app or website that either ranks stars by their magnitude or which gives the number of stars that ought to be visible given the limiting magnitude.

Sky Safari allows you to set the limiting magnitude and then depicts the night sky with that magnitude. You can also search for star within magnitude limits... I've just done it now for all objects of magnitude +4 or brighter, and have come up with 832 objects (including stars, double stars, clusters, nebulae, planets and moons)!

{EDIT: that, of course, is for the whole sky - northern and southern hemispheres! For the northern hemisphere, it will be around half that number}

Thanks Mike, that really clarifies it for me.

Andy, although it doesnt do exactly what you are asking for but I posted a link in another thread that you created (the Guardian dark sky locations article) to a quick internet simulator tool which allows you to click on any point of a map and it will simulate the night sky view, calculating the limiting value.  Its a quick goto tool on the internet if you dont have Sky Safari and I think its smart.  It describes what factors are taken into consideration and what is not.  It doesnt take the moon light into consideration as far as I can tell.

http://www.need-less.org.uk/    (scroll down a few pages to get to the tool)

How well do you guys think it performs?  Are the results to expectations?

EDIT:  I just realise Mike, the link you gave is the same I posted yesterday in the darks sky locations thread!

Hi all,

Anyone need a lift tongiht?  Looking forward to it!

Already saw about 10 over an hour last night from the roof (in Nunhead)!

See you all there,

Fuzz

See you all there, Fuzz

Welcome to the Flamsteed forum!

I think most people have sorted out their travel arrangements for tonight, but thanks for the offer.

It seems likely that we will go ahead, though I think we will be battling with the clouds for at least part of the evening.

I should be getting to the pub at about 9.30pm, before heading out to the recreation ground after a swift pint or two!

Hope to see you there.

Sadly due to this damn chest infection I am unable to go to Cudham so I will try to see the meteors from my back garden.

Ok, Brian. Take care and I hope you get better soon.