Friday -- Yesterday and today were devoted to getting a 3.5-inch Questar to work as a portable solar prominence 'scope. On Thursday, I conducted "field trials" using the tiny off-axis aperture the OEM (white-light) filter holder provides. While I could see that there were clouds of crimson gas above the sun's limb and could make out the "burning prairie," I saw very little structure in the prominences. For the most part they seemed unconnected with the sun's limb, probably on account of glare as the low-contrast prominence filaments require all the contrast the optics can provide or else get lost adjacent the sun. Thursday evening, I cobbled up a new filter holder for the Questar using the lid of an "I Can't Believe It's Not Butter" margarine tub. Even with the sun low in a very hazy sky, prominences were much better and brighter. So I carried this to the University on Friday to try with the sun high in the sky.

Much better! In fact, I was very pleased during the day and showed some prominences to several people. (Three or four middle-aged men standing around a telescope in the parking lot adjacent the womens' dorm... would someone please explain what passersby found interesting about this?) The telescope is about F18.5 and contrast is further enhanced by masking the aperture down slightly from the full 77mm available; this is one easily adjustable factor that needs to rigorous trials. I put the Questar away until evening for side by side comparison with the 5-inch.



This is representative of the best views during the day using the Questar, the 77mm filter pack in the "I Can't Believe It's Not Butter" retaining bracket, and the 16mm Nagler eyepiece. I've flipped the image around to match up the orientation in the 5-inch refractor. Below is how the sun looked through the 5-inch with the same eyepiece, using the 63mm Maxwell House On-aXis Apparatus (MHOXA?):



As for the Questar view, "I Can't Believe It's Not Better." Something needs to be optimized if this is going to be my mid-day solar inspection instrument for short winter days when I can't count on getting home in time to bring the big guy to bear.

After retiring the Questar for further cogitation, I concentrated my eyepiece notes on the most vivid prominence patch on the sun's leading limb, preparing several diagrams and sketches to be used in getting the appearance right.



A curious "splash" well to the left of this elaborate prominence is shown in the wider view above -- no further detail turned up there, despite giving it lots of attention. [All: 1996 August 16, 18:10 - 18:40 EDT]

By Saturday morning, this feature had either developed or come into better view; a "fountain" structure with faint lobes graced this part of the limb, suggesting that the "splash" is just the top of a larger structure that is now visible over the limb. The large prominences from yesterday are still evident, but the northern (right) side has collapsed / flattened and the loops to the left seem less well defined. Seeing deteriorated very rapidly late Saturday morning and cloud cover increased before I could gather enough notes to do much with the limb detail. The seeing seemed much worse just downwind of clouds, particularly in the 30-45 seconds just before the sun was obscured. After 10:00 AM, the sky was too cloudy or hazy or turbulent (or all three at once) to see much.

During the clearest (but not very steady) moments, I saw what I took to be the last visible remnants of a departing prominence above the trailing limb -- just a faint sheen 5 - 7 minutes above the sun with one involved knot low in the structure (a down-pointing chevron). The whole, dim structure appeared much-elongated (radially, from the center of the sun) like a fun-house mirror distortion of something that might have once resembled the the portal- and canopy-rich prominence drawn above.

During the steadiest (but not very clear) moments, I concentrated on the structure of the "burning prairie" itself and could easily see individual spicules which comprise the brightest portions. Lots of variation in their individual height, brightness, and their "crowdedness" around the limb. Many are not radial to the sun. They seem transparent, as if the brightest clusters might be coincidental alignments of two or three spicules, though there is plenty of room for individual brightness variations as well. The distinction between the brightest clumps of spicules and the smallest prominences is not so much a matter of scale but of morphology: spicules seem to taper and to be very narrow indeed, like needles, while even the smallest prominences seem much broader and more varied in their shapes of their upper bounds.

Next Observations: Sunday
Previous: Wednesday

Take me home!