First attempt at M78

[Jonny_H]

Hi all,

I saw an opportunity to get a few minutes in before the clouds came over so thought I would give M78 a go.

This is my third DSO attempt.

Camera gain 150. 10 x 300s lights, 10 x 300s darks, 60 flats and 60 bias. Stacked in APP and a bit of fiddling in PS and PI (Albeit badly!).

I know 50 mins isn't much but I still don't understand why my images look so 'grainy/noisy?  Also my calibration frames don't seem to be removing the hot and cold pixels.....not sure what I am doing wrong as I had the same issue with my NGC2023 image!? 🤔

I welcome any feedback/pointers.

Clear skies,

Jonny

[PeterCPC]

If you want to reduce noise the best way is to dither.

[Jonny_H]

2 hours ago, PeterCPC said:

If you want to reduce noise the best way is to dither.

Thanks Peter,

I haven't plucked up the courage to dither yet but might give it a go in the next session.

I understand that more integration time will also help - but what exposure times are best (other than as long as possible). Are we talking 2+hours minimum ideally?

[PeterCPC]

Yes I would say 2 hrs min. If you use BYE or APT, dithering is very straightforward.

[Jonny_H]

26 minutes ago, PeterCPC said:

Yes I would say 2 hrs min. If you use BYE or APT, dithering is very straightforward.

Thanks Peter,

I am currently using a ZWO ASIair Pro connected to mount (HEQ5 Pro) using an EQDIR cable.

You can dither using the aisair but the instructions allude to not trying if you're a beginner.....which I am...so I haven't yet! ☺️

[AndysAstroPix]

Good start! M78 is a very dim target, so you're probably going to need at least 5-6 hours data to bring the noise down, and yes as mentioned above, dithering makes a huge difference. 😀

[Gerr]

M78 seems quite a difficult target to me and one I haven’t had a go at yet (watch this space)! You seem to have nice composition and the promise of nice detail with sharp stars too. Not bad for only your third DSO. As stated earlier noise can be reduced by taking lots of images (60 plus) whilst keeping your camera cool!! Then there is noise reduction techniques in your processing. An acquired skill dependent on your image processing application (I use photoshop plus plug ins for this). Do you tick the median noise filter box when you stack in DSS? 
Gerr.

[MartinB]

M78 has a lot of dark nebulosity which immediately makes noise a challenge.  Keep gathering the data, it is looking fine.