M33 Triangulum unguided. First time effort.

[bomberbaz]

Had a little bash at M33 tonight. A little low in the sky which didn't help.

Anyway it's 15 x 23 seconds at 225 gain using a ZWO 183 colour camera on a SW EQM 35 pro goto. 

The image is unguided and I reckon it is close to it's maximum period before it will hit problems with the image drift.

There are a couple of image issues, from the left there is glow which I think is because it isn't a cooled camera and the donut aberration at the bottom. No idea what that is.  

I am still quite pleased with this and next time I will try tweaking gain higher and shortening exposure to see if that works better.

All good fun.

 

[Luke Newbould]

Hi mate,

Not a bad effort for a first go! - it's a difficult target because of it's deceptively low surface brightness

as you mention, there are issues with it, but all are fixable I should think!

if i may, a few things I see quickly are -

 

darkened corners, this is called vignette and is corrected out with flat frames

the ring at the bottom is a dust mote, also corrected out by flat frames

the glow to the right is amp glow, - this is usually calibrated out by dark frames which match in every way your light frames, just with the light removed! (e.g, same temperature, exposure, gain, offset, usb speed etc)

there's slight trailing to your stars, as you say - shorter exposures could help here but the ideal solution is autoguiding

and finally a bit of coma, inherent to Newtonian telescopes, sorted out by a correctly configured and spaced coma corrector!

 

I hope some of that helps you a bit with the physical issues with the image, after that's all sorted you can open the can of worms that is processing!!

 

Please note by the way, this is all just advice in the spirit of being friendly and helpful! - if you are enjoying yourself then you are already doing everything right anyway  

 

all the best,

Luke

 

[bomberbaz]

On 17/03/2021 at 03:02, Luke Newbould said:

Hi mate,

Not a bad effort for a first go! - it's a difficult target because of it's deceptively low surface brightness

as you mention, there are issues with it, but all are fixable I should think!

if i may, a few things I see quickly are -

 

darkened corners, this is called vignette and is corrected out with flat frames

the ring at the bottom is a dust mote, also corrected out by flat frames

the glow to the right is amp glow, - this is usually calibrated out by dark frames which match in every way your light frames, just with the light removed! (e.g, same temperature, exposure, gain, offset, usb speed etc)

there's slight trailing to your stars, as you say - shorter exposures could help here but the ideal solution is autoguiding

and finally a bit of coma, inherent to Newtonian telescopes, sorted out by a correctly configured and spaced coma corrector!

 

I hope some of that helps you a bit with the physical issues with the image, after that's all sorted you can open the can of worms that is processing!!

 

Please note by the way, this is all just advice in the spirit of being friendly and helpful! - if you are enjoying yourself then you are already doing everything right anyway  

 

all the best,

Luke

 

Thanks for the advice Luke, I am very new to this and just like to have a play around but if I can improve things with easy steps then worth a go.

I will make some flats and darks next time and see if it works out any better. Laziness stops me bothering but on longer exposure it is needed for sure.

I might try with my coma corrector next time, again laziness.

Guiding, tin of worms I am told so not sure I want to open it 😅

cheers

Steve