What are these nasties?

[codemonkey (Lee)]

I've been noticing these a lot lately. Does this look like something that would be caused by dust on filters?

Somehow the filters in my filter wheel keep getting very dusty, but since it's all precariously put together I'm hesitant to keep taking it apart to clean the filters.

Definitely need to start taking flats, which I'd never bothered with previously, but it'd be good if I could solve the underlying issue rather than fixing it with flats.

[h0ughy (David)]

no mater how clean you are you will need to take flats

[PeterEde (Peter)]

Dirty sensor
Usually become visible at smaller apertures

[multiweb (Marc)]

Flat and dithering will take care of most dust motes. I don't think it's on the sensor though. I reckon somewhere on a corrector/lens or filter.

[RB (Andrew)]

Originally Posted by h0ughy

no mater how clean you are you will need to take flats

+1, exactly what David said!
Taking and applying flats is essential, not only for removing dust bunnies but also to eliminate system vignetting caused by your system 's light path and
the uneven brightness around the center of the FOV of the system.

Very easy to take and apply.

[RickS (Rick)]

I also recommend that you take flats but it's also a good idea to get rid of the dust from time to time. Here's a calculator that will help you figure out where you need to clean: http://www.wilmslowastro.com/software/formulae.htm#Dust

Cheers,
Rick.

[LightningNZ (Cam)]

Flats are pretty easy to take. A lot of people think they are difficult to take but they aren't. Your pictures will always be better for them.

[codemonkey (Lee)]

Thanks everyone!

I tried to shoot some flats last night figuring the scope hadn't been moved so I might be ok, unfortunately I ended up with a big dark patch in the flats that wasn't in the lights so they were unusable (maybe condensation?).

Either way, what I did notice was how nasty it was... the lights don't come close to telling the full story. I'll definitely be taking flats in future!

Originally Posted by RickS

I also recommend that you take flats but it's also a good idea to get rid of the dust from time to time. Here's a calculator that will help you figure out where you need to clean: http://www.wilmslowastro.com/software/formulae.htm#Dust

Cheers,
Rick.

That's a really cool link, thanks Rick! According to that, the dust should be on the glass covering the CCD sensor, which is interesting because I was pretty confident that it was on the filters.