Strange dots on flats

[Saturn488]

When capturing my flats at 0.099 secs in SGP I am getting strange dots on my images. This is seen on all LRGB and H-alpha filters.

Once I have my gear connected and if I wait around 20 minutes - 30 minutes the dots slowly vanish as seen in the images below. It's making me think it might be condensation built up on my camera sensor but my scope has been inside for a few days now.

Anyone seen this before?

[multiweb]

Droplets on the sensor?

[The_bluester]

Cooled camera? If so it might be a sniff of moisture in the sensor chamber, I was getting something a little like that with my ASI294, only it was in the middle of the sensor, and it faded away like that over time too.

[Saturn488]

Yep cooled camera.

I might need to change the desiccant if the camera takes it.

[multiweb]

Get a canister of Argon from gasweld for $26 and purge it.

[Saturn488]

Can you send me a link please?

[multiweb]

Total tools in Campbeltown used to have them (02)6413 5905 otherwise try Bromic (https://www.bromic.com/plumbing/products/soldering-brazing/gas-cylinders-disposable/2-2-argon-gas-disposable-cylinder.html)

Last one I got was from a camping place in lithgow.

[Atmos]

That looks like frost / condensation. I’m guessing that the camera has a heated window and it just takes some time for it to kick in. I have the same issue with my ASI094 so I’ll either slowly cool it down or just start the cooler on a lower level while I’m doing all of my setup so it’s ready to go.

Doesn’t happen every night but on the humid ones it can be pretty nasty.

[LewisM]

Bunnings sell Argon for around $26 too.