Share:
Notifications
Clear all

2022-05-29: APP 2.0.0-beta2 has been released !

Release notes

Download links per platform:

windows 2.0.0-beta2

macOS x86_64 2.0.0-beta2

macOS arm64 M1 2.0.0-beta2

Linux DEB 2.0.0-beta2

Linux RPM 2.0.0-beta2

Artifacts


(@centaurus)
Molecular Cloud Customer
Joined: 4 years ago
Posts: 6
Topic starter  

Please help! The integration frame shows artifacts, like shadows of the brighter stars of  M 45. The shadows don't show on the individual frames, I checked and rechecked them. I used the default settings of APP, light frames, master flat, dark and bias. MDark and MBias have been used in the past for processing with the same ISO/exposure time without any problem. To nail it down I noticed the first appearance of the shadows after normalisation, and clear shadows after integration. I have no idea what goes wrong. Can anyone help me please?  


ReplyQuote
Topic Tags
(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

Could you maybe pinpoint as to what you mean with the shadows? I can't see anything really strange, apart from the gradient in the image.


ReplyQuote
(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 1723
 

When you click on the image you'll see reflections of the bright stars just above and slightly to the right of the stars.


ReplyQuote
(@centaurus)
Molecular Cloud Customer
Joined: 4 years ago
Posts: 6
Topic starter  

Thank you, wvreeven, reflections are the right word, and for helping to point at the positions.


ReplyQuote
(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

Ah right, I was looking for darker artefacts. 😉 Thanks Wouter. So are you sure they are not visible in your single frames? They will show up very faintly probably and when stacked pop out more. It seems extremely likely these are actual reflections in the data, stars look like they have been registered properly and they show up for the brightest of stars, which makes sense as well.


ReplyQuote
(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 1723
 

I agree with Vincent. Probably stretching the original light subs VERY much will make them visible there as well. It looks like reflections in the optical train to me.

 

Wouter


ReplyQuote
(@centaurus)
Molecular Cloud Customer
Joined: 4 years ago
Posts: 6
Topic starter  

Thank you for dealing with my issue. I went through all my subs again and didn't find anything strange in the original data. I took subs of a different target with the same configuration the same night, and the integration went well as usual. I have no idea what haunts me with M 45. I'd probably better discard the subs and try again.


ReplyQuote
(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 1723
 

Do the subs of the other target also contain magnitude 5 and brighter stars? Could you perhaps share one of the raw M 45 subs with us?

 

Wouter


ReplyQuote
(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

Yes it would be great if you could upload a single frame for us to have a look at. Nothing really haunts you I'm sure, the stars in this target are extremely bright so that would make sense.


ReplyQuote
(@centaurus)
Molecular Cloud Customer
Joined: 4 years ago
Posts: 6
Topic starter  

Wvreeven, the subs of the other target don't contain such bright stars. The M45 sub is larger than 30 MB - would resizing affect the 'screening' ? Sorry I'm a newbie - is there any way of preprocessing with APP or taking subs  I could 'tame' bright stars against faint nebulosities? The same problem appears e.g.with Flame and Horsehead nebulae and Alnitak.


ReplyQuote
(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 1723
 

Perhaps you could use a system like WeTransfer to make a sub available?


ReplyQuote
(@centaurus)
Molecular Cloud Customer
Joined: 4 years ago
Posts: 6
Topic starter  
SM 45 LIGHT 20s 800iso 20191205 19h23m51s322ms

I attached the cropped but otherwise unchanged file that contains the bright stars that trouble me. I hope this works.


ReplyQuote
(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4830
 

Thank you! So I marked the position of the reflection in this light, it's faint, but it is there. So the problem is that you have a reflection going on in the image-train.

Screenshot 2019 12 12 at 21.23.28

ReplyQuote
(@centaurus)
Molecular Cloud Customer
Joined: 4 years ago
Posts: 6
Topic starter  

I can see the reflection on your stretched image  but not on my own ones. I think it's best deleting my M 45 subs and try again another night. Thank you Vincent!


ReplyQuote
Share: