Over saturated stars LRGB

[Andywilliams]

Greetings all,

I am putting together data for Centaurus A, it’s my first LRGB image.

Anyhow, Impatient chap that I am, I couldn’t wait to have a little peek at the data.

n.b. This has NO calibration frames at all.

This is a sneaky peek at 3 hours L, 30 minutes RGB.

Sw 150pds, HEQ5 pro, asi1600mm and calibrated and stacked in Pixinsight.

There are no calibration frames in this at all at the moment.

I was surprised to see how over saturated some of the stars were with colour.

Is this due to the lack of calibration frames ? Something more obvious ?

If you have any ideas do give me a yell……and thanks heaps !

Andy 😊

[wimvb]

What  software do you use? In pixinsight you can simply apply a star mask and desaturate the stars. Also, have a look at how large the rgb stars are compared to the L stars.

[Adam1234]

What were your sub exposure times?

[Andywilliams]

On 06/05/2022 at 16:56, wimvb said:

What  software do you use? In pixinsight you can simply apply a star mask and desaturate the stars. Also, have a look at how large the rgb stars are compared to the L stars.

This is Pixinsight, wbpp, LRGB combination, ez processing deconvolution, de noise and soft stretch. Then I did a dbe and then a final histogram stretch. I have done an ez star reduction (Adam block) which has improved things somewhat but the colour on the stars still appears as a halo as in this picture.

[Andywilliams]

On 06/05/2022 at 21:07, Adam1234 said:

What were your sub exposure times?

Hi Adam,

These are 120 seconds, gain 50, offset 21 

[Adam1234]

15 hours ago, Andywilliams said:

Hi Adam,

These are 120 seconds, gain 50, offset 21 

I think you've probably over exposed your stars then. You could try taking a few shorter subs just for the stars 

[scotty38]

Are you sure it’s nothing to do with deconvolution? What does it look like if all you do is an STF and apply that to HT so we can see it?

[Andywilliams]

5 hours ago, scotty38 said:

Are you sure it’s nothing to do with deconvolution? What does it look like if all you do is an STF and apply that to HT so we can see it?

I’ll do that tonight and post the results 👍

[The Lazy Astronomer]

There seems to be ringing present in the image above, if you're using ezdecon, then you need to increase the size of your star mask until the dark ringing no longer appears around the stars after running deconvolution.

[Andywilliams]

On 10/05/2022 at 05:20, scotty38 said:

Are you sure it’s nothing to do with deconvolution? What does it look like if all you do is an STF and apply that to HT so we can see it?

Many thanks Scotty…..

I just did the stf  and then stretch with ht and all was well 👍👍

Ive since reprocessed with my go to, which is Harry’s astroshed routine and it’s looking rather nice 😊

Now I need to get some good Ha data and see if I can grab the elusive relativistic jet that hides in there somewhere ! 
 

Thanks again …. Onwards and upwards ! 

[Adam J]

On 05/05/2022 at 22:11, Andywilliams said:

Greetings all,

I am putting together data for Centaurus A, it’s my first LRGB image.

Anyhow, Impatient chap that I am, I couldn’t wait to have a little peek at the data.

n.b. This has NO calibration frames at all.

This is a sneaky peek at 3 hours L, 30 minutes RGB.

Sw 150pds, HEQ5 pro, asi1600mm and calibrated and stacked in Pixinsight.

There are no calibration frames in this at all at the moment.

I was surprised to see how over saturated some of the stars were with colour.

Is this due to the lack of calibration frames ? Something more obvious ?

If you have any ideas do give me a yell……and thanks heaps !

Andy 😊

looks like an issue with star masking at some point during the processing to me, you probably did it without realising.

Adam

[scotty38]

yes as mentioned by others too I think the deconvolution is probably the culprit and has introduced the ringing