Another Sun Test

So, yesterday's test was a success, overall. Today I decided to try to address the banding and temperature issues.

The bands in the previous image are likely Newton's rings, based on what I have read. The Coronado PST reduces the light it receives down to a single wavelength (or pretty close to it). There is probably a misalignment somewhere in the optical train that is causing a reflection. The reflected light bounces around, and since light travels as a wave, the crests and troughs sometimes meet up--crest + crest, trough+trough, and crest+trough--amplifying or cancelling the light. The Wikipedia article probably explains it better.

Anyway...

I attempted to apply a flat field in the hope that it would reduce the effect. It did not work. I have run out of time, so the images tomorrow will just have to be wavy.

The temperature problem, however, may have been solved. I modified an old reflective windshield shade to fit over the scopes and cameras. The temperature inside the shield was almost 30 degrees less (96F) than direct sunlight (125F). The ambient temperature at the time was 96F.

I spend a great deal of time (and frustration) trying to mount the ST80 and PST together, like I did back during the Venus Transit. A problem that I had then, that I was attempting to solve this afternoon, was that the two scopes do not line up perfectly. The Sun will be visible in one, but either out of view or on the edge of view in the other. Unfortunately, despite a couple of frustrating hours working on it, I was unable to solve this problem.

My priority will be on the PST images, with a few white light images here and there.

Now, on to the pictures!

Here are the two scopes on the mount with their heat shield:

The Mallincam SkyRaider is on top, in its own custom heat shield sleeve.

It was getting late by the time I finished with everything else and started testing the rig. So, I only had time for a few shots before the Sun went behind a tree. Below is a composite image that combines the surface with some prominences that were visible on the solar limb. The original images were monochrome (black and white). I colorized them since, you know, the Sun is supposed to be yellow.

Sunspot region AR 2671, located near the center of the Sun's disc, looks a little like Santa's sleigh, doesn't it?

And, finally, here is a white light test image taken with the ST80:

Another sunspot group is coming around the limb on the left side of the image. I do not know what its number is at present.

Enjoy tomorrow's eclipse, and wish me luck!