M42 - 10 minutes of data

[AstroViking (Steve)]

Evening all,

I had the scope out last night and managed to squeeze in a quick capture of the Orion Nebula.

Now, this is only 10 minutes of data, and I am very impressed with the amount of colour and detail that I got. (Why can't my other targets come out this well??)

I know there's a bit of noise in the dust / gas clouds if you go looking for it, and the core is blown-out a bit as well. But, hey, for such a short run, I'm not complaining.

I had a play with Ekos' flats-wizard but didn't have much luck with it. I set it to 32000 ADU but Ekos kept bouncing between 29k and 41k ADU and only captured a couple of frames. Based on these auto-captured ones, I guess-timated an exposure of 0.25 seconds would be enough, but it wasn't.

One thing that did surprise me was the lack of distortion in the stars. When using the 72ED at 420mm with the DSLR, I had stretched stars in the corners. I guess the much smaller sensor size of the '183 is the reason behind this.

As always, constructive feedback very much appreciated.

Cheers,
V

Details:
EvoStar 72ED @ 420mm / ASI183MC / HEQ5 / SV165+SZ305
Proc: Siril, Affinity Photo
Bortle: 5/6
Gain: 25
Offset: 10
Temp: 0 degrees C
Lights: 60 @ 10 seconds
Darks: 40
Flats: 40
Bias: 44

[xelasnave]

You can go shorter even as the core blows out very easy. Folk go for the nebulosity but nailing that core is the hard part. I don't know if my approach is correct but usually I have two images for this object ..one showing the nebulosity and one showing the core and then layering them to combine the best from each.
And any image you bag...is a good image...
Alex

[Stephane]

Nice one Steve, very promising indeed. I agree with Alex to take two sets of images if you can: short exposures for the core and longer ones for the rest. Trevor Jones made a good video on this.

[Crater101 (Warren)]

Well done again mate, you're getting the hang of this far quicker than I am.
How do you find setting the temperature to Zero on the camera? I've been hovering it around the 3 / 4 degree mark.

[oska (John)]

Good one Steve, keep 'em coming

[AstroViking (Steve)]

Thanks for the feedback and compliments, everyone. Much appreciated!

When I get serious about M42, I'll definitely be doing two sets of lights, as suggested. I just have to wait until it's above next door's roof long enough to capture it. (Which will be December / January, from memory.)

Originally Posted by Crater101

How do you find setting the temperature to Zero on the camera? I've been hovering it around the 3 / 4 degree mark.

It seems to work well for me. I chose 0C because it's about 10 degrees below ambient, so not too much strain on the cooler. All you really need is a stable temperature for the sensor. I might try a bit cooler, say about -5C, as I noticed a couple of 'hot' pixels in my last set of dark frames.

Cheers,
V

[Crater101 (Warren)]

Originally Posted by AstroViking

It seems to work well for me. I chose 0C because it's about 10 degrees below ambient, so not too much strain on the cooler. All you really need is a stable temperature for the sensor. I might try a bit cooler, say about -5C, as I noticed a couple of 'hot' pixels in my last set of dark frames.

Cheers,
V

Ah, I see. Thanks indeed!

[AstroViking (Steve)]

Actually, I'll correct myself here.

It's my understanding that the aim of cooling the sensor is to primarily reduce any heat-induced noise. A warmer sensor is more likely to convert thermal energy into a false signal within one of the sensor's electron wells.

The stable temperature means that your frames (light and calibration) are smoother (for lack of a better word) in terms of thermal noise.

Cheers,
V