Sol today

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SkyBrowser
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Sol today

Post by SkyBrowser »

A nice bright morning here, inbetween snow showers!

Observing, via projection, with my 60mm refractor, I can see just two spots on the sun, one quite hard to spot. The online images show some other smaller ones, but I can't see those with my current set up. What do others see?
nigeljoslin
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Re: Sol today

Post by nigeljoslin »

On Space Weather website, just the two spots are shown. This with the prediction of another weaker than normal solar maximum in 2025.

That said, NASA are saying that 2025 should see the end of a longer trend of decline that has taken place over the past four decades, the result of the magnetic field at the Sun’s poles weakening.
Skywatcher 350P f4.65, Skywatcher StarTravel 102 f5, Adler Optik 9x63 binoculars
RMSteele
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Re: Sol today

Post by RMSteele »

Hello Skybrowser, with 60mm at F15, 15mm plossl eyepiece with a diagonal by projection I counted 5 spots in 2 groups: group 1, single large spot closest to limb; group 2, 4 spots in two clusters of 2 spots each. Conditions: slightly unsteady seeing with reasonably good transparency. Bob
PS whereabouts are you, Skybrowser?
SkyBrowser
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Re: Sol today

Post by SkyBrowser »

Bob - yup, that's what the spacecraft images show. I only saw the big spot (12794) and, faintly, one of the spots in the other group (12795). Sounds like your 60mm refractor (make?) is better than mine. What diameter was your projected disk? I'm in the UK, so, yes, the sun is a bit low in the sky at the moment! Where are you? And I was observing through trees :) On the 29th I could see 3 spots, 1 big one and two in that second group.
brian livesey
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Re: Sol today

Post by brian livesey »

Projecting the Sun with cemented eyepieces, such as Plossls, runs the risk of the cement melting with the heat. A set of uncemented Hygenians or Ramsdens are better, although they work best with longer focus refractors.
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RMSteele
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Re: Sol today

Post by RMSteele »

First, Brian makes a good point, but 60mm is small enough to avoid heating probs with the mass of glass in a "cheap" 1.25 15mm plossl (Celestron Omni).
I am in Leeds. I project sideways via a 90 degree mirror diagonal onto a card screen shielded in a cardboard hand-held box so I can vary the image size at will. Normally 150mm is large enough to see what's there. On dim days with mist or haze 100mm is necessary to give a bright enough image. Regards, Bob. PS It's a 90mm f10 Skywatcher refractor stopped down to 60mm, using the lens cap's 60mm concentric aperture hatch.
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Re: Sol today

Post by brian livesey »

Quality Hygenians give better on-axis,colour free, images than any other eyepieces, including orthoscopics. I have two for solar projection at 20mm and 9mm focal length. The barrels are Continental 24.5mm in diameter and came with a small Prinz refractor.
The lens rings have been slackened to allow for expansion of the lenses to avoid possible cracking due to the heat.
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Re: Sol today

Post by SkyBrowser »

The difficulty with Huygenians (capital H?) is finding one! Especially a good one.

Lee Macdonald, in his book How to observe the sun safely, says that orthoscopics work well. And he was using an 80mm 'scope, though he claims not to observe when the sun is higher than 30 degrees in altitude. This, presumably, takes a little of the sting out of the sun.
RMSteele
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Re: Sol today

Post by RMSteele »

The only heat problems that I have had with apertures between 80 and 100mm have been the plastics comprising field stops melting in eyepiece barrels. It hasn't happened yet with the 60mm aperture and my 15mm plossl (which has quite a wide field stop). Bob
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Re: Sol today

Post by brian livesey »

Another way to deal with heat in the 'scope is to have an ERF ( Energy Rejection Filter ) over the front of the objective.
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Re: Sol today

Post by SkyBrowser »

Is projection still possible using one of those? I'd be loth to put my eye to glass, just in case the filter had pinholes or it fell off (as happened to somebody I once knew).
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