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seven_legs

Mercury transit in May

35 posts in this topic

What time Mercury transit start and how long does it last for?

plus that would make a good day out if all the boys and girls with solar scopes where to go to one of the dark (or bright):Dsite so everyone else could view it.

 

thanks

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I have had the day booked off for months, cant wait for this!!

 

Starts approximately 12:10 (depending on location) and completes the transit at 19:30 but by that time the sun has all but set.

Edited by Daz Type-R

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Thanks Daz, off that day as well, just need to get solar filter when I get paid

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12:07 til 19:32 BST from around the East Midlands. If clear I will be streaming as much as possible until we loose sight of the Sun below the local horizon.

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Day booked off for me too.

I'll be using my refractor & Herschel wedge. (with binoviewer of course)

 

26407096296_69510f04c6.jpg

Edited by Bino-viewer

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I'm away in Mallorca while that's happening but will pack my solar eclipse plastic glasses I bought for the solar eclipse.

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1 hour ago, BAZ said:

:ph34r: Yay, that day is booked off for me now.

 

Pop round if you want Martyn, plenty of room at mine.

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3 hours ago, Doc said:

I'm away in Mallorca while that's happening but will pack my solar eclipse plastic glasses I bought for the solar eclipse.

I know you have very keen eyesight Mick, but I'm not sure that even you could see Mercury through your eclipse glasses :)

 

It will be about 12 arcseconds across! Venus is just doable at a transit as it is 4 or 5 times the angular size of Mercury.

 

Binoculars with filters would definitely show it.

Edited by Tweedledee

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2 hours ago, Tweedledee said:

I know you have very keen eyesight Mick, but I'm not sure that even you could see Mercury through your eclipse glasses :)

 

It will be about 12 arcseconds across! Venus is just doable at a transit as it is 4 or 5 times the angular size of Mercury.

 

Binoculars with filters would definitely show it.

 

You have passed Pete. It was a little test I just threw into the thread ;)

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Put your eclipse glasses on your binocular's Mick??

 

Edited by Perkil8r
Potentialy Dangerous Advice

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I'm retired, but won't go fishing or golfing that day, unless it's cloudy... ;)

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6 hours ago, Ron Clarke said:

Put your eclipse glasses on your binocular's Mick??

 

No no no and a thousand no's!!! Do not ever try this if you want to see again!!!!!! Solar glasses are a much weaker filter than solar film and should never be used with any optical device. Not EVER!

Edited by Perkil8r
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1 hour ago, Doc said:

 

You have passed Pete. It was a little test I just threw into the thread ;)

Brilliant, what's the prize then Mick? Surplus Delos or 31Nag?? :D

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As Mike as pointed out, DON'T put eclipse glass filters on any optical equipment. They are rated for zero magnification use. If you stick them on any optical gear like bino's, the magnification amplifies the energy as well as the image size. If you have 10X binoculars, the magnification makes the object appear 10X closer, not 10X bigger, therefore the energy which goes through the object lens say 50mm is then squeezed out the eyepiece end to what ever the exit size the eyepiece provides and is increased by the same magnification factor.

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10 minutes ago, Perkil8r said:

No no no and a thousand no's!!! Do not ever try this if you want to see again!!!!!! Solar glasses are a much weaker filter than solar film and should never be used with any optical device. Not EVER!

Yes - use only a proper filter between the sun and objective. NOT between eyepiece and eye. Dim the light before it enters any optics.

 

I think the film used in the glasses gives the same attenuation as the Baader type film ( about 10000 times, equivalent to 10 magnitudes ), but may be of cheaper and inferior quality. Even the Baader film would just melt straight through if subjected to the magnified and concentrated solar light from the eyepiece. Some kids incinerate ants with a magnifying glass, don't do the same to your eyes.

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I watched the May 2003 Mercury transit early in the morning from the sea front at Portsmouth using my old 4" Meade SCT on a camera tripod. I had a 4" Thousand Oaks glass filter that was specified for that particular scope, they are much safer than the Baader film but a lot more expensive. It was quite a blast to watch in the little SCT especially at higher powers, and I got a real buzz from the view, as did a few passers by :). I could have watched it for the full duration, but had to pack away for a morning meeting as I was working away.

 

Several years after that, I used the same scope on the Venus transit, which was even more of a spectacle as Venus was so much bigger.

 

Wish I still had that 4" SCT and filter, it was a very handy, longish focal length scope in a tiny package.

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I guess the Herschel wedge is the exception here, as it sits BEHIND the objective.

 

Solar viewing is a serious matter. 

For example, the focal point of an unfiltered telescope pointing at the sun measures in at around 600 deg C.

 

The Herschel wedge is a very cleverly designed bit of kit, in that it removes around 96% of the suns energy.

Even so the 4% remaining is still 1000 times too bright to be viewed without additional filtration.

 

I always carefully explain this when at a solar viewing session.

On May 9 DDAS may be attending a public viewing session.

I will be repeating myself alot.

 

 

 

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Been thinking of getting a Lunt White Light Herschel wedge for my st120, I already have a polarising filter, do I need anything else?

 

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Just now, seven_legs said:

Been thinking of getting a Lunt White Light Herschel wedge for my st120, I already have a polarising filter, do I need anything else?

 

Nope, should be fine at that. You will need that polarising filter though, with the ED80 it's still pretty darned bright but safe.

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I was thinking the same thing Rob, but only rich, solar fanatics can afford such advanced tackle :P.

 

Very responsible that you highlight the dangers at solar sessions, as inexperience people can have very silly ideas about how they can look at the sun.

 

There are also some older wedges that may be dangerous.

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Don't forget to cover or better still take the finders off

20 quid for a sheet of very safe baader solar film is not expensive.

always check filters before use

if in any doubt at all do not do it

if you are worried watch it online or go to an outreach event

 

if i'm not working I will also be streaming it

 

 

 

Edited by Ibbo
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Or even leave the finder on, with Baader film securely over the objective for finding the sun.

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10 minutes ago, Ibbo said:

ps I'm not rich

I spent it all on telescopes and beer

 

A beer keg telescope...

beercan.jpg  beercan1.jpg

Edited by Tweedledee
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