In this thread no-one seemed to know the characteristics of your Regular 1x filter either, or of the UV 1x filter for that matter. But they do confirm it is probably 34mm in size. I did manage to find one 34mm UV(0) filter on Amazon and even after the $35 shipping on a $5 item (!) it's not overly expensive. Not all UV(0) filters have the same steep cutoff as the recent Hoya ones so it's hard to know if it would do the job but at least it's multicoated.
Speaking of multicoated, the Tiffen Haze 2A is NOT. In fact, as far as I can tell it has no anti-reflection coatings at all. This means brighter stars will create flares and it creates strange artifacts even on dimmer ones. I say this confidently because I bought a 52mm one and tried it for a night's imaging. I won't say I wasted the night but nearly so. I won't be using it again. (Thankfully, I only paid about $10 for it on Amazon.)
Btw, your photo is definitely better but as it is now in color, I think you need a little more of that (color). Of course, increasing the color saturation will make the CA more evident, so you could always mask the stars and increase the color only on the "nebulae." (Nebulae in quotes because there are of course actually three prominent galaxies in your image, each of which are largely composed of stars but unresolved so we treat them as extended objects.)
Edited by Alen K, 30 August 2019 - 01:00 PM.