solar

[mattifor]

Great sky to day, first for weeks bet it does not last

Fisrt time tested new Ha filter on WO with B1200. great view of the solar disc,

saw my 1st I think they are called flares (dont shoot me if I am describing them wrongly) coming from the edge of the disc a double at the top about 12oclock position and a single at the bottom about 5oclock.

I was amazed as a twin engine passenger plane passed over the image clear shape and the vapour from the engines.

back to have another look now.

[brianb]

saw my 1st I think they are called flares (dont shoot me if I am describing them wrongly) coming from the edge of the disc

Those things projecting outside the disk are called prominences. Flares are exceptionally bright patches on the Sun's surface ... when there are active areas on the Sun you will see bright areas associated with them, called plages, flares are even brighter than these.

[mattifor]

Thanks still learning

[daveg]

Glad youre enjoying the Sun. Watch out for prominences on the disc too - they will appear as long black "snakes" called filaments.

Thanx for keeping us up to date still clouded out here in Ireland

David Gradwell

[george7378]

Can prominences be seen during projection viewing? Is there anything else of interest visible on projections?

[brianb]

Can prominences be seen during projection viewing? Is there anything else of interest visible on projections?

No, projection shows only the photosphere. You will see sunspots if there are any. Sometimes you may see faculae, especially near the limb, these are the white light "ghost" of the bright plages associated with active areas but are best viewed in Calcium K emission. Exceptionally bright solar flares may just be visible by white light projection but this will be a very rare event.

When using a high magnification, if the seeing is steady, you may be able to make out the fine "rice grain" granulation of the photosphere in a projected imge. The rather coarser "mottling" is very low contrast & shows up better by direct viewing (WITH A PROPER OBJECTIVE END SOLAR FILTER!!!!!) than it does by projection.

Projection is relatively safe but should not be attempted except with a small refractor - the concentrated heat on the secondary mirror of a reflector or compound scope can melt or crack it, or at least the glue that hold it in place, and sunlight striking the inside of the baffle tube can ignite it if, as is common, it is manufactured from plastic. Remove or cap the finder unless it is provided with its own safe solar filter ... the finder can concentrate sunlight enough to burn clothing which strays into its beam. When using the projection method, the Sun is best "found" by moving the tube until the size of its shadow is minimised. Do not use your "best" eyepiece for projection - it's not unknown for the cement used to connect "contacting" optical surfaces to be affected by the heat concentration even with a small refractor. Old fashioned Huyghenian or Ramsden eyepieces do not have cemented components and are recommended. Tolles or Coddington eyepieces made from a single thick glass element should also work well though I haven't tried this.

[kev]

FWIW Theres a couple of nice prominences on the sun at the moment, one reasonably large on the NNW of the disk.

Kev (sat 12.00)