The Sun

[Naemeth]

Just seen the Sun with my Solar Filter, and it looks amazing with the stock 25mm and 10mm, although I didn't get as many sunspots as I expected (only two, one on the west and one on the east). It's really good to know my solar filter is okay, even though it didn't look perfectly flat, it doesn't seem to effect the image.

I do have a question though, near the end of my observation, the image was fuzzy around the edge, when the Sun was clear and sharp, would that be from the scope getting hot (it took me a long time to find the Sun, so the scope was out for a while)?

[Bizibilder]

The filter sheet will work perfectly well with a few loose wrinkles in it - in fact it must not be "tight" to work properly.

The fuzzy edge you see round the Sun is due to the earth's atmosphere - often known as "boiling". It can cause really bad seeing especially later in the day when it has been sunny for a few hours. Not only is the atmosphere warmed up and turbulent but the ground is warm and that causes hot air to form and rise up, making matters worse!

I severe cases the Sun's disc can look like a circular saw blade!

[Naemeth]

The filter sheet will work perfectly well with a few loose wrinkles in it - in fact it must not be "tight" to work properly.

The fuzzy edge you see round the Sun is due to the earth's atmosphere - often known as "boiling". It can cause really bad seeing especially later in the day when it has been sunny for a few hours. Not only is the atmosphere warmed up and turbulent but the ground is warm and that causes hot air to form and rise up, making matters worse!

I severe cases the Sun's disc can look like a circular saw blade!

Would it make any difference only having the scope out for as little time as possible? I thought it would actually be better to view it later in the day as it might be easier to find with my Dob and not at Zenith.

Due to heat, is it better to view in Winter if you can?

[sanmatt]

The filter sheet will work perfectly well with a few loose wrinkles in it - in fact it must not be "tight" to work properly.

The fuzzy edge you see round the Sun is due to the earth's atmosphere - often known as "boiling". It can cause really bad seeing especially later in the day when it has been sunny for a few hours. Not only is the atmosphere warmed up and turbulent but the ground is warm and that causes hot air to form and rise up, making matters worse!

I severe cases the Sun's disc can look like a circular saw blade!

I made a 30s avi of the sun earlier, when i played it the whole outer area seemed to wobble in a haze

[iwatkins]

Best situation would be no atmosphere at all

But if you can, observe and image earlier in the day before ground heating really gets going. I cannot from home, most of my east side is blocked by trees.

So I tend to image as late in the day as I can. But of course, the closer to the horizon the sun gets, the more atmosphere you are looking through. It's a game of compromises

Cheers

Ian

[Naemeth]

East is out for me too, blocked for most stars below Saturn... I need to walk 1.7 miles carrying my scope for the transit. It's great to know that my filter works.

Just out of interest, what would covering some of my aperture do to my views of the Sun (ie Increasing the focal ratio)?

[SamAndrew]

I also saw the sun for the first time today, I made a filter using the Baader solar film, and saw the same two spots, altho one of them was a cluster of several small spots.

I also used the standard 10 and 25mm eyepieces that came with my ST80, plus a 3x barlow. It would be nice to have even more magnification but not sure I can achieve that with short focal length of the st80 or equinox 80. It's got me excited about the transit !

[estwing]

first timer today aswell and i thought those spots were dirt on my lense!!

[Ganymede12]

I see the fuzzy edges on the sun as well and I think that they're just small prominences.

[iwatkins]

The fuzzy edges is the heat in our atmosphere causing sudden changes in refraction of the air. For proms you'll need to be viewing in H alpha not white light.

Naemeth,

If you use a smaller aperture, this stops down the scope, as you say, increasing the f ratio. For solar this has the effect of making the focus point "longer" (hard to explain without a diagram). I.e. the image stays in focus longer as these bubbles of seeing pass in front of the sun. It also makes getting an initial focus easier.

Cheers

Ian

[Ganymede12]

On the topic of the sun, is granulation actually on the sun or is it an optical illusion?

[jason.p]

I've got one of those solar projection screens that fixes to the bottom of the counterweight shaft (TAL2). I presume you turn the tube round and project through the focusser (am I correct?)

I read in another thread that the heat could damage the secondary mirror and eyepiece. Would I be better off getting a sheet of that film and forget about the screen?

Thanks

Jason

[iwatkins]

GM,

No, granulation is a real feature. It's simply bubbles of hot plasma rising to the (visual) surface of the photosphere due to convection. Each granule lasts for about 20 minutes at most.

Jason,

I would go with solar film. Viewing is much better through an eyepiece than on a projection screen. And no heat build up on your secondary either

Cheers

Ian

[Naemeth]

Hmm... I think for the moment I'll keep my filter the way it is, on a 5.1" Aperture (which is nice actually, the 10mm makes the Sun almost as big as the FOV, but not quite.

It was strange that I seemed to get more sunspots in the 25mm than the 10mm, although they may have just been rotating with the Sun. Who knows?

[Bizibilder]

"More Sunspots with the 25" - if you rotate the eyepiece and the sunspots rotate with it then you have a dusty eyepiece!

[Naemeth]

I'll have to check that out, but I've viewed trees in the daytime and haven't seen black spots...