How to automate opening of images as a layer, change blend, save as JPG, repeat?

I've been trying to figure out how to do something, and having poor luck searching for info on it as well, hoping this crowd can help.

I have a folder of 1,100+ RAW images (can batch convert to other format if needed). The images are of a landscape with stars to make a star trails image. I have loaded them all into PS and changed the blending mode to Lighten, and boom there are the star trails.

But I got the idea (my usual problem) to:

1. Open image 1
2. Open image 2 as a new layer 
3. Change blending mode to Lighten
4. Save the resulting combined image as a JPG or PNG
5. Add the next layer on top of the existing ones, repeat from step 3
6. Continue until I have a series of 1,100+ new images, each one has an additional frame added on to the timelapse.

My goal is to then turn those images into an animated GIF or short movie, showing the star trails building across the sky over time. I hope that explanation makes sense? Any ideas on how best to go about this? TIA!