April 18th 2019 Focuser motor & AR2738

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I turned a brass V-pulley for the "Skywatcher" DC focuser motor. The motor can easily cope with lifting the weight of the big solar prism and binoviewer but does so rather slowly even on fastest speed. It does just the same when lowering all that weight.

I don't like the curly "telephone" cable and will be looking for a much longer straight one. Just found a 2m long white one in my vast cable collection. Being able to fine focus without touching the telescope is a revelation in fine detail. Which you would [probably] never achieve without considerable luck.

Thursday: 57/55F, clear and sunny.

10.20: AR2738 is heading for the limb at 3.00. Two small spots inboard of AR2738.

The large spot is getting very close to the limb and will soon be invisible as it travels onwards out of sight.

We must hope another spot arrives on the opposite limb. To replace it and hold interest for all the solar observers and imagers around the globe. A spot a day keeps the Minimum at bay.

I am very pleased with the surface detail I am capturing at the moment. The solar cells of granulation are just on the verge of individual clarity in the small spots image. Though I have to be careful not to overdo Wavelets in Registax. I have watched lots of YT tutorials but struggle to remember a lot of the detailed advice. Nor do I have access to Photoshop which many imagers use for its sophisticated "powers" to enhance the final images.

In H-alpha a patch of plage is visible where the smaller spots show in WL.

The seeing conditions deteriorated badly in the afternoon as the sun heated the house roof to my south. There may have been some thermal effects from the dome surface as well. Heat rising out of the observation slit disturbs the view. Rather like the background wavers when seen over a garden bonfire. Telescopes magnify so much that they are far more sensitive to variations of refractive index with the changing temperature of the air.

The 2" Lacerta Herschel prism's heatsink became too hot to touch today after hours of tracking the sun. Instrumental, internal thermal effects should not be ignored in image quality. I withdrew an H-alpha fitting one day to see swirling heat effects in the bright red beam. Should I consider a vent or a small fan to draw warm air out of my telescope tubes? I do have the option of painting the dome white to reflect more heat. Today the plywood panel were radiating heat inside the dome like a domestic heater. That can't be good for seeing conditions! Do I want to draw more attention to the dome? White will certainly make it far more visible. Though it is a race against time with the neighbour's rapid tree growth. Distant views of the dome will shortly become impossible as the trees come into leaf.

Even a modified [secondhand] PST etalon/filter system is not the world leader in H-alpha image quality. There are larger filters in increasingly expensive, solar "elbows." Then there is the Quark device which is popular in bringing out amazing surface texture at considerable cost. Not to mention the increasing use of full aperture, external, rejection filters on SCTs. These can bring much larger apertures into play with amazing image resolution but at ever increasing cost. The external filter has the advantage of removing a lot of heat before it enters the instrument. While I am using a smaller, internal D-ERF inside my battered, old, secondhand, 6" f/8 refractor on the grounds of cost.

 Click on any image for an enlargement.

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