Sunburst Transparency Gradient

[Rails]

I'm trying to blend two photos I took of the solar eclipse, each taken with a different exposure. "Photo 1" with the shorter exposure is best for the regions around the perimeter of the sun (you can even see some solar flares), but the coronal streamers are rather short. "Photo 2" with the longer exposure is a bit blown out around the perimeter of the sun but has longer coronal streamers. So ideally, I would like to overlay the two images such that Photo 1 fades out just past the sun's perimeter while Photos 2 fades in over the same region.

I've been playing with this for days and cannot get it right. Part of my problem (I think) is that I cannot seem to get a handle on how the controls work in Paint Shop Pro 2018. I've applied a Sunburst transparency gradient in a mask layer. When I try to edit the start and stop positions in the Gradient page of the Materials Properties dialog box, nothing really changes in the final image. I'm not sure if I should be sliding the markers on the top, bottom, or both, but no matter what I do, the final image doesn't change. The only way I've been able to change the start and stop positions of the transparency gradient to to move the opacity stops which are displayed when the gradient fill tool is selected with the mask layer active (see image below). But when I position those markers to where I want the gradient to start and stop, the gradient isn't applied at those points - it gets applied at an offset, which makes it a trial and error process.

The other anomaly I'm seeing is a distinct bright ring at the edge of the transparency gradient. You can see it in the image above and when I blend the two images together it is also apparent (see image below). I don't understand how or why the application of a transparency gradient should result in a bright white ring at the trailing edge (where opacity reaches 100%).

So I'm looking for help. The user manual is unclear on how to use the tools to apply a transparency gradient without any color. So any advice would be greatly appreciated.

[flagpole]

I would try different blend modes. The drop down at the top of the layer palette

[Rails]

The problem isn't with blending to two images - it's with the fade-in of the corona in Photo 2. What I need to achieve with that photo is 100% transparency from the center of the sun's disk all the way out to the corona (and a little farther to eliminate the overexposed coronal rich just around the perimeter of the sun), then start to fade in linearly to 100% opacity over a relatively short distance. That should allow it to blend nicely with Photo 1.

Here is Photo 1 with the transparency gradient applied:

And a close-up view of the transparency fade, which looks pretty good:

Now here is Photo 2 with an inverse gradient applied so that the sun and inner ring of the corona is transparent with the corona fading in over a short distance:

You cannot see how the edge of the transparency gradient injects a bright white ring in the photo above, but if I turn on a black background, is it readily apparent as shown in the photo below:

I don't understand how or why that bright white ring is getting added to the image at the outer edge of the transparency gradient - it should be a very smooth transition. If I can fix that, then I'm confident the two photos will blend well and yield the results that I want. That's why I was asking for information on how to apply and make adjustments to the transparency gradient controls in my original post. I must be doing something wrong, but I don't know what.