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Large partial solar eclipse March 20 (1 Viewer)

. This morning there was about 4/8 cloud, but the wind was gusting up to 40 kn, so there was a mixture of sunshine and cloud. Indoors, of course, the wind does not affect the stability of binoculars.

Normally, I use a 10×25 binocular for projection for my own use. Usually at about 40 cm projection distance.
I wondered if I could increase the projection distance substantially by using a low magnification binocular.

I used the 5×25 Foton and was surprised how good it turned out to be. This is a high resolution binocular, at least the one I used.
I thought I would be able to double the projection distance to get the same size image, but I found that as I was projecting further into the room I was projecting into a much darker part of the room. Normally, when near the window the projection surface is in a bright part of the room, but here it was in a dark part of the room.
I could easily increase the projection distance to 2 m, 2.5 m, and even 3 m and still see a good image, although it was far from me while handholding the 5×25 binocular.

. What this does mean is that a whole group of people, say 10 persons, could view the partially eclipsed Crescent Sun at the same time. Whereas at 40 cm perhaps two people could see it.

I suppose that a six times binocular might also manage something similar.
 
Some images of viewing methods from eclipses past :

ss_060322_eclipse_19.grid-8x2.jpg


ss_060322_eclipse_14.grid-9x2.jpg


ss_060322_eclipse_09.grid-7x2.jpg


ss_060322_eclipse_11.grid-8x2.jpg


ss_060322_eclipse_15.grid-9x2.jpg


ss_060329_worldeclipse_16.grid-8x2.jpg


ss_060322_eclipse_18.grid-9x2.jpg


Have fun, and view safely.
 
.. Hi Samandag,
. Thank you for posting the photographs, I don't know how to do this.

The first photograph, in black-and-white, shows some dangerous viewing.
The man on the right has no protection at all. The two girls have one welders glass, which may or may not be dark enough. It is impossible for two viewers to protect themselves at the same time, as one would be seeing the sun without protection.
The woman on the left may be using a black-and-white fully exposed negative, which contains silver and does give some protection. Colour film does not.

There's a nice photograph of the boy and his dog wearing goggles, but where are the goggles for the livestock? :)

The cardboard box on top of somebody's head has to contain a carefully attached welders glass 14 or at a pinch welders glass 13. People should not think that just having a hole in the cardboard box works, as then you are viewing the sun completely unprotected.

The photograph with the herring gull? Shows the person using a smaller welders glass, hopefully shade 14.
If, as in Britain, it is difficult to get shade 14, a welders glass 13 is okay for short periods, but you should try to get the welders glass that is longer vertically, so that you can tilt it to increase the density to the correct shade. Of course you should not tilt it in the direction to reduce the sideways size, i.e. it should fully cover both your eyes.

Still almost no sunspots today. A few minutes ago in white light I saw one small sunspot lower right with a properly filtered small instrument.

At 0932 UTC this morning in the H Alpha telescope, there was a beautiful double prominence. A large bright mushroom prominence connected to a large bright arch prominence at the 3.30 position inverted altazimuth view.
There was quite a lot of activity on the sun's disc, filaments and bright areas.
 
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Eye Safety During Solar Eclipses

This from NASA, by Fred Espenak :

"The Sun can be viewed safely with the naked eye only during the few brief seconds or minutes of a total solar eclipse. Partial eclipses, annular eclipses, and the partial phases of total eclipses are never safe to watch without taking special precautions. Even when 99% of the Sun's surface is obscured during the partial phases of a total eclipse, the remaining photospheric crescent is intensely bright and cannot be viewed safely without eye protection [Chou, 1981; Marsh, 1982]. Do not attempt to observe the partial or annular phases of any eclipse with the naked eye. Failure to use appropriate filtration may result in permanent eye damage or blindness!

Generally, the same equipment, techniques and precautions used to observe the Sun outside of eclipse are required for annular eclipses and the partial phases of total eclipses [Reynolds & Sweetsir, 1995; Pasachoff & Covington, 1993; Pasachoff & Menzel, 1992; Sherrod, 1981]. The safest and most inexpensive of these methods is by projection, in which a pinhole or small opening is used to cast the image of the Sun on a screen placed a half-meter or more beyond the opening. Projected images of the Sun may even be seen on the ground in the small openings created by interlacing fingers, or in the dappled sunlight beneath a leafy tree. Binoculars can also be used to project a magnified image of the Sun on a white card, but you must avoid the temptation of using these instruments for direct viewing.

The Sun can be viewed directly only when using filters specifically designed for this purpose. Such filters usually have a thin layer of aluminum, chromium or silver deposited on their surfaces that attenuates ultraviolet, visible, and infrared energy. One of the most widely available filters for safe solar viewing is a number 14 welder's glass, available through welding supply outlets. More recently, aluminized mylar has become a popular, inexpensive alternative. Mylar can easily be cut with scissors and adapted to any kind of box or viewing device. A number of sources for solar filters are listed below. No filter is safe to use with any optical device (i.e. - telescope, binoculars, etc.) unless it has been specifically designed for that purpose. Experienced amateur and professional astronomers may also use one or two layers of completely exposed and fully developed black-and-white film, provided the film contains a silver emulsion. Since all developed color films lack silver, they are always unsafe for use in solar viewing.

Unsafe filters include color film, some non-silver black and white film, medical x-ray films with images on them, smoked glass, photographic neutral density filters and polarizing filters. Solar filters designed to thread into eyepieces which are often sold with inexpensive telescopes are also dangerous. They should not be used for viewing the Sun at any time since they often crack from overheating. Do not experiment with other filters unless you are certain that they are safe. Damage to the eyes comes predominantly from invisible infrared wavelengths. The fact that the Sun appears dark in a filter or that you feel no discomfort does not guarantee that your eyes are safe. Avoid all unnecessary risks. Your local planetarium or amateur astronomy club is a good source for additional information.

In spite of these precautions, the total phase of an eclipse can and should be viewed without any filters whatsoever. The naked eye view of totality is completely safe and is overwhelmingly awe-inspiring!

References

Chou, B. R., "Safe Solar Filters," Sky and Telescope, August 1981, p. 119.

Marsh, J. C. D., "Observing the Sun in Safety," J. Brit. Ast. Assoc., 1982, 92, 6.

Pasachoff, J. M., and Covington, M., Cambridge Guide to Eclipse Photography, Cambridge University Press, Cambridge and New York, 1993.

Pasachoff, J. M. Field Guide to the Stars and Planets, 4th edition, Houghton Mifflin, Boston, 2000.

Golub, L. and Pasachoff, J. M. Nearest Star: The Exciting Science of Our Sun, Harvard University Press, 2001.

Reynolds, M. D. and Sweetsir, R. A., Observe Eclipses, Astronomical League, Washington, DC, 1995.

Sherrod, P. C., A Complete Manual of Amateur Astronomy, Prentice-Hall, 1981."

http://eclipse.gsfc.nasa.gov/SEhelp/safety.html
 
. At about 1330 UTC today I saw a sunspot with protected unaided eyes. There was quite extensive Cirrus cloud at 25,000 feet, some of it was quite thick and other parts very tenuous. There was high pressure and it was about 12°C and a nice sunny day.
I estimated the size of this sunspot as 40 arc seconds penumbral size. It was at the 10 o'clock position one third of the way from the limb to the centre disc.
At 1024 UTC this morning it was at the 8.30 position. As the Sun moves across the sky it seems to rotate depending on the latitude of the Observer.

I had no luck trying to project the Sun on the kitchen wall with either a 10×25 binocular or a 20×50 spotting scope handheld. The image was too unsteady and maybe not in focus. I think tripod mounted I would have seen the sunspot in the image projected on the wall.

There have been almost no sunspots in the last 10 days although there was quite a bit of cloud so I couldn't observe the Sun every day.

In a properly protected small instrument the sunspot is actually a large black sunspot with a small sunspot to its right and possibly other unresolved smaller sunspots.

By March 20 this sunspot will be either on the other limb or just rotated past it. However, there maybe new sunspots visible on the date.

This present sunspot may possibly become a bit larger as it moves towards the centre disc over the next few days, or possibly not.
 
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1452 UTC today. Much better conditions and the sun is at a much better angle for me.

The sunspot was easily seen by projection using handheld 10×25 binocular. It was at the 8 o'clock position on the image on the wall. Also I was not using my reading glasses earlier, so maybe that is why I didn't see the sunspot earlier

With protected unaided eyes the sunspot was just seen, but my eyes are tired now. It is at the 10 o'clock position, compared to the 8 o'clock position with the inverted projected view using the binocular.
 
1310 UTC today. Beautiful day but with extensive Cirrus cloud. 14°C.

With the free Sky at Night magazine Eclipse glasses, which are approximately shade 14, I saw reasonably easily, and using my distance glasses behind the eclipse glasses, a sunspot left of centre disc. Today these glasses were somewhat dark, compared with the optimum for resolution of sunspots. However, for the partial eclipse of the Sun these will be very good indeed. The Sun looks orange.

With a free astronomical Society flat eclipse shade, containing perhaps black polymer?, The sunspot was difficult to see. This shade is very dark about shade 15, possibly even shade 15.2 or thereabouts. The Sun looks a dim orange in this shade.

With the welders glass 13, large size, the sunspot was easily seen as a dark black spot.
I estimated the penumbral size as 50 arc seconds.

In fact, with a small properly protected instrument, this sunspot has now become quite large. It composes of a large black sunspot, with two equally large, small to medium sunspots to its right. With protected unaided eyes this sunspot group is seen as one sunspot.

I think that projection using binoculars will pretty easily show this sunspot today.

At 0924 UTC this morning, using the H Alpha telescope, this sunspot look smaller but was in the middle of of a bright white swirling area. I think that there was a flare taking place at this time, which possibly may give rise to Northern lights in perhaps two days time. Although one has to look at predictions or just look at the sky in a dark place.
 
. Regarding the last post, my neighbour was outside in the Street and I showed him the sunspot using the welders glass 13 large size. I don't think that his eyes are that great, but he did see the sunspot.
He is a keen photographer, and when I mentioned the eclipse on March 20, he says he had neutral density filters.
I explained that a neutral density filter is totally inadequate, maybe reducing the sun's light 10 times. You need an approved filter that cuts down the light about 100,000 times, maybe more.

For others, with similar ideas of using anything dark, please read the safety tips in the thread above.
You really do have to be careful if you want to observe the partial Eclipse on March 20 or the Sun at any time.
 
He is a keen photographer, and when I mentioned the eclipse on March 20, he says he had neutral density filters.

I explained that a neutral density filter is totally inadequate, maybe reducing the sun's light 10 times.

If he is a keen user of neutral-density filters, Binastro, he may have better filters than you realize.

Many landscape photographers nowadays use Black Glass filters, which allow only one-thousandth of the light to pass. In photography-speak, these are known as 10-stop filters (log to base 2) of optical density 3.0 (log to base 10).

Passing only one-hundred-thousandth of the light (am I right in thinking that is the opacity of welder's glass 13?) requires an optical density of 5.0, which could be achieved by stacking Black Glass with routine 6-stop (density 1.8) and 1-stop (density 0.3) filters.

Wouldn't that be enough to protect his film/sensor?

Later,

Dr Owl

----------------------------------
John Owlett, Southampton, UK
 
.Dear Dr Owl,
I am well aware of the 10 stop modern neutral density filters, some which you can vary in density.
And one might think that stacking two and a bit of these would equal a welders glass 13.

Unfortunately, I very much doubt whether these neutral density filters are approved or have been tested for ultraviolet and infrared radiation. This also applies to any other neutral density filters or polarising filters.

The fellow who was selling the plastic filters refused to believe that his filters were unsafe, even though laboratory tests at a top university showed that they were transmitting up to 28% in the infrared. People using these awful things were reporting their eyes were getting hot, even though I don't know if we have pain receptors in our eyes. Maybe we do in the front part of the eye? Although not in the retina.

If you could get one of these 10 stop neutral density filters tested throughout the wavelength from far ultraviolet to far infrared I would be interested. But this test would only apply to one particular filter or type and name of filter.

When I was talking to my neighbour, and I said the neutral density filter may reduce the light intensity 10 times he didn't comment. He is a very bright fellow, but I think he has somewhat fixed ideas. And in his innocence is quite unfamiliar with direct solar observation.
My neighbour was talking of using the neutral density filter for visual use when I gave him the welders glass 13 to see the sunspot. With the Cirrus clouds this was about the correct density.

For photographic use, there are special filters, which are less dense than for visual use. These filters should definitely not be used visually.
Also, digital cameras are sensitive in the infrared, and the special photographic filters take into account the sensitivity.
Unfortunately, very few people understand direct observation of the Sun. Every report that I have read in the media has glaring mistakes, except for the ones in the astronomical press, or from astronomical societies.

In a way I would be quite happy if next week's eclipse had never been publicised, but it has been and will be, and unfortunately there are going to be many cases of permanent eye damage where the weather is clear.
We just try to give safety advice for those who want to observe the Eclipse and are prepared to listen.

In a way we are lucky in Britain, as the timing is such that schoolchildren will be in their classrooms and can be controlled somewhat by adults.
This is not the case in Europe, either with their time one hour ahead or two hours ahead, where they will have real problems keeping the kids safe.

And for those not wishing to watch the eclipse, that is absolutely fine by me.
 
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Looking at the dates of the UK eclipses I think the one I most remember most must have been when I was 11. The teacher broke up a pane of window glass and put a lighted candles on a couple of tables so we could smoke the shards ourselves then we were let loose in the playground to watch the event. Apart from the cuts and burns and school nurse bathing some sore eyes I don't think anyone died or anything.

Health and safety gone mad!!" 8-P
 
. Dear David,
Luckily, may be you observed the eclipse in the time of coal fires, with vast amounts of pollution in the air.
I remember smog so thick that I could not see my feet. Smog like that probably makes a good solar filter.
:)
 
Press Association

The Press Association released this for the UK today :

"A near-total solar eclipse is expected to bring thousands of astro-tourists to the north of Scotland this week.

The dark skies of remoter parts of the country are said to offer the perfect environment to view the rare phenomenon on Friday morning.

The eclipse is predicted to be approximately 98% on the Isle of Lewis and 97% in Shetland, making the islands some of the darkest places in the UK.

Steve Mathieson, VisitScotland's island manager on Shetland, said: "The solar eclipse is a hugely exciting and rare phenomenon, and Shetland in particular is in the right place at the right time.

"We will have 97% darkness on Shetland during the eclipse so this will be one of the best places in the whole of the UK to witness the phenomenon."

Cruise and Maritime Voyages are running three solar eclipse cruises, with more than 2,500 passengers heading north to destinations including Lerwick in Shetland and Kirkwall on Orkney.

Mr Mathieson said: "We're delighted that nearly 2,000 extra visitors will spend a day exploring Shetland on their way up north to watch the eclipse, but it's also not too late for others to get involved with this special astro-tourism experience and book their trip here to watch the eclipse and then enjoy the stunning scenery of Shetland."

A viewing event will be held at Sumburgh Head lighthouse visitor centre and nature reserve on Shetland on Friday morning, while Frankie's in Brae, recently named the number one fish and chip shop in the UK, is offering a special "eclipse platter".

The cosmic event is happening at 8.25am on Friday with another near-total eclipse not expected in the UK until 2026
."
 
.The only problem with a 97% eclipse is that it is definitely not a total eclipse.
I saw something similar in 1999, but not the total eclipse.
It was interesting in that the light became strange and shadows maybe sharper.

However, the percentage of clear days in the Shetland Islands may be better than the Faroe Islands or Spitsbergen. The last two are where the Eclipse chasers are travelling. Or they are on ships travelling along the path of totality.

I want to clarify something about welders glasses.
I have just seen it claimed that welders goggles are unsafe because of ultraviolet leakage. However, I think that the main point of welders glasses is to prevent eye damage, particularly from the ultraviolet.
It is true that the lighter shades are dangerous when it comes to viewing the Sun.

However, I just looked at a Royal astronomical Society diagram and graph showing the transmittance of a welders glass 14, and they suggest that it is safe for direct viewing of the Sun. This is a view held by several astronomical sources.

The reason why I suggested that a welders glass 13 might be reasonable is that, in the past I have found it difficult to buy welders glasses shade 14 in England. I had to pre-order five glasses and this is too late for the eclipse.
But welders glasses shade 13 were often in stock, although they might be difficult to find if there has been a rush on these items because of the Eclipse.

I would much prefer somebody uses a welders glass 13 larger size tilted, when it is probably about shade 13.5, than somebody risk looking at the Sun with no protection at all.
Also for Britain the elevation of the Sun at the time of the eclipse is around 25° or maybe 30° at the end.
Generally, I found that at this elevation a tilted welders glass 13 larger size seems to give adequate protection and a good image.

But I do not use the welders glass 13, even tilted, when the sun's elevation is above 45°. This is especially if the sky is transparent and the sun bright. Then I use a welders glass 14.
But often in England at lower Sun elevation a welders glass 14 is a bit dark if there is a small amount of cloud, such as Cirrus cloud.

In any event, the total exposure time I use in any one day is one minute. And I rarely exceed 10 seconds maximum at one time.

If you do not have a welders glass 14 and only have a welders glass 13, preferably the larger size, if the Sun seems a bit bright it should be tilted. And I would keep to a maximum exposure time of 5 to 10 seconds and limit carefully the total exposure time.

For countries where the sun exceeds 60° elevation I would always use a welders glass 14 or perhaps even shade 15 if they are available. This is particularly if the sky is very transparent or one is viewing from a high mountain or anywhere that is high above sea level. Here the atmosphere gives lesss protection.

The free Eclipse glasses given with the Sky at night magazine seem to be shade 14.

For the eclipse, the safest procedure is to project an image as discussed in the above thread.

This eclipse event can be safe if you stick to the safety tips listed above.
The Royal Astronomical Society also has good information on their website.

For those who don't wish to watch the eclipse that is fine and safe. But for those who do wish to follow it please take care. And for heaven's sake don't use any unsafe homebrewed or home-made dark filters. Stick to the advice that has been built up over the last 50 years to try and make eclipses safer.
 
Stick to the advice that has been built up over the last 50 years to try and make eclipses safer.

The Royal Astronomical Society have produced a free booklet 'How to Observe an Eclipse Safely'.

What is a solar eclipse, and how is it caused ?

What can members of the public expect to see, and how can they observe an eclipse safely ?

The booklet, published January 2015, explains the answers to these questions and more.

**It also includes links to resources for teachers.

The booklet was created specifically for the solar eclipse of 20 March 2015, but the advice and explanations apply to all other solar eclipses too.

The Royal Astronomical Society booklet is attached below in pdf for free download.

Please take a moment to read it and recommend it to your colleagues and friends.


Please note that the Society's supply of free eclipse viewers has run out.

This thread is receiving a lot of traffic, thanks to Binastro for posting it and to the moderators of this forum for pinning it as a sticky for the benefit of everyone.
 
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Media - Scotland / Eclipse Video from Lucie Green

If you live in Scotland, tomorrow, Thursday 19th March the Daily Record is giving away a pair of ESSILOR eclipse safety glasses with copies of their newspaper at Morrisons supermarkets :

http://www.dailyrecord.co.uk/special-features/promotions/free-eclipse-safety-glasses-thursdays-5350951

And check out the video : “How to observe the partial eclipse on 20 March 2015”, Dr Lucie Green for the Society for Popular Astronomy, it runs to 8 minutes.

The video is available on vimeo, click the arrow pointer at the bottom left hand side of the video screen to start the video :

https://vimeo.com/119636834

:t:
 
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