Star artefacts LRGB

[bri]

Hi all,

After stacking an image of the iris, I noticed this flaring on some of the larger stars. I have a feeling that I have the lum filter in the wrong way round causing some weird reflection. Its only showing in the lum channel. Is this the case or is it something else?

They are 36mm unmounted and I remember that the L was difficult to tell which way round it was supposed to go using the pen method

I thought I would ask on here before I open up the filter wheel so I can carry on with tonights session

Ta very much

[ollypenrice]

Could we see your RGB-only result without the added lum?

If you are processing stars separately, as is the modern way, RGB-only is likely to be better than LRGB for stars anyway.

Olly

[bri]

Sure thing Olly. Here are a couple of screen grabs. Auto stretch in PI.

All these were 2 min subs. About 1 hour of L and RGB were 20mins each (more to come eventually). L is the only filter to show these flares

 

So what you are saying with regards to LRGB imaging is:

I should combine RGB only, stretch and process the image with the stars

L to stretch and process seperately, remove the stars, add L to the rgb image afterwards. Is that correct? Is the order in which I do it important? 

Thanks

Bri

[wimvb]

That actually looks more like a diffraction. Do you have power lines or maybe even your own washing line between you and where you're pointing at? It may have been in the fov when you took the L, but not when you took the RGB.

Edited August 15 by wimvb

[inFINNity Deck]

Hi Wim,

This is indeed typical for overhanging wire(s), but could also be caused by the edge of a dome's shutter (or another edge). Is your equipment in a domed observatory?

See my white-paper on this for more info: https://www.dehilster.info/astronomy/imaging_artefacts.php

Nicolàs

[bri]

Im not in an observatory but my scope was pointing close to the roof of my house. Perhaps a little too close as may be the case. Later tonight, I will check my lum subs further into that session to see if the diffraction spikes have gone as the object has moved across the sky and cleared the roof. If so, then it looks like operator error 🫢

I will post my findings

thanks

Bri

[bri]

I've checked all of my L subs. They all have the same artefact and the 1st sub looks like the last one. About an hours worth.

7 minutes later, the R filter was in action. No artefact to be seen. Coincidence that the target had cleared my roof in those 7 minutes? maybe, but cant be sure either way.

I will use the next imaging session to test it again