Antennae and Sombrero Galaxies - LRGB

[MarsG76]

Hello Fellow lovers of Astronomy,

As clouds have returned, I'm continuing in processing my captured data of the 6 DSO objects I imaged across the 8 clear and moonless nights I was lucky to have recently.

The images attached are of the Sombrero Galaxy (M104) and the Antennae Galaxies (NGC4038 & 4039) through LRGB filters... The Antenna galaxies were a last minute choice when I got ready to image the Sombrero and realised that my observatory hut still obscured it, so I though that I'll spend a couple of hours on the Antennae through the same filters before moving onto the Sombrero a bit later on in the night, and perhaps score a bonus image to add to my collection.

The Antennae Galaxies ( NGC 4038/NGC 4039) are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation.

The total exposure time of the Antennae Galaxies through all of the LRGB filters was 5 hours and 9 minutes.
Exposures: L:15x600s @ FW:31, R:17x120s G:15x180s B:16x300s @ HCG:62/OFS:25

And the total exposure time the Sombrero image for all of the LRGB filters was 6 hours and 14 minutes.
Exposures: L:17x600s & 15x300s @ FW:31, R:14x120s, G:12x180s, B:13x300s @ HCG:62/OFS:25

Both pictures were imaged using a 8" SCT (at the native 2032mm focal length), with a QHY268M camera.

Clear Skies,
Mariusz

Edited May 11, 2022 by MarsG76

[wimvb]

On 11/05/2022 at 17:36, MarsG76 said:

The Antennae Galaxies ( NGC 4038/NGC 4039) are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation.

Very nice images, both

Re star formation, do you plan to add Ha atg some point? This will very likely add another dimension to this fine image.

[Dan_Paris]

Two excellent captures of iconic galaxies, well done.

[MarsG76]

12 minutes ago, wimvb said:

Re star formation, do you plan to add Ha atg some point? This will very likely add another dimension to this fine image.

Hi Wim... I'd love to add Ha if weather would permit... 

[CCD Imager]

I agree, nice images, M104 is only just imageable from the UK! What was the cause of the green incursion on the Sombrero image?

Adrian

[wimvb]

4 hours ago, CCD Imager said:

What was the cause of the green incursion on the Sombrero image?

Reflected light from a bright star outside the fov. The reflection extends all the way to the galaxy.

[MarsG76]

8 hours ago, CCD Imager said:

I agree, nice images, M104 is only just imageable from the UK! What was the cause of the green incursion on the Sombrero image?

Adrian

 

3 hours ago, wimvb said:

Reflected light from a bright star outside the fov. The reflection extends all the way to the galaxy.

Possible that it's caused by a out of FOV bright star, but more likely it's from a street light. At one point during the tracking the scope was angled where a street light was in that direction and about half of the subs had this flare every night.

I had to remove the dew shield from my SCT because there were slight wind gusts which were caught by the shield and caused a bit of a vibration, ruining subs.. as you can imagine that at 2000mm FL it doesn't take much to render a sub unusable... I have dew heating which controlled the condensation on the corrector but external light flaring does (and did) occur frequently in the past when I removed the dew shield.

 

[wimvb]

Agreed, if it's not on all aubs, then it's most likely from a street light. Adam Block has a youtube video qhere he shows a way to remove the effect without having to toss the affected subs. The method assumes you use pixinsight. 

[CCD Imager]

The fact that it is not in your Antennae image suggests its not  a fixed light source on your imaging rig or related to the camera, so a source close to your camera that doesnt move could be the culprit or as Wim suggested  a star just outside the FOV. I looked at Stellarium and there arent really any bright stars close by that makes me wonder if this is the cause, but I think its still the most likely. A street light I think is unlikely as that would produce a much more diffuse gradient across the image. The fact that it is green suggests a "light pollution" source rather than a star. 

Thesee artefacts are a pain in the a**** and it is always best to find their source, but to edit, I would remove stars with Star Xterminator or Starnet then easily clone stamp or use the spot healing brush tool in Photoshop.

Adrian

[MarsG76]

4 minutes ago, CCD Imager said:

The fact that it is not in your Antennae image suggests its not  a fixed light source on your imaging rig or related to the camera, so a source close to your camera that doesnt move could be the culprit or as Wim suggested  a star just outside the FOV. I looked at Stellarium and there arent really any bright stars close by that makes me wonder if this is the cause, but I think its still the most likely. A street light I think is unlikely as that would produce a much more diffuse gradient across the image. The fact that it is green suggests a "light pollution" source rather than a star. 

Thesee artefacts are a pain in the a**** and it is always best to find their source, but to edit, I would remove stars with Star Xterminator or Starnet then easily clone stamp or use the spot healing brush tool in Photoshop.

Adrian

The antennate galaxies were imaged with a dew shield, wind gusts picked up during the luma exposure of the sombraro when I removed the shield.

 

[CCD Imager]

Maybe it is the street light then, would fit with the green colour of the light intrusion.

Adrian

[wimvb]

The pattern can be caused by reflections off chip edges, bonding wires or what have you not, within the camera and close to the sensor. Basically any light that can make its way into the sensor chamber.

This was suggested by Adam Blick in one of his youtube videos.

[CCD Imager]

Wim, 100% agree, any light incursion can be scattered within the optical path, probably close to the sensor, there are several potential reflective surfaces. The problem is identifying its source. Here is an image I had fun with! Work out the problems here

[wimvb]

@CCD Imager: ouch!

[MarsG76]

4 hours ago, CCD Imager said:

Wim, 100% agree, any light incursion can be scattered within the optical path, probably close to the sensor, there are several potential reflective surfaces. The problem is identifying its source. Here is an image I had fun with! Work out the problems here

Yawzah.... initially I'd guess stacked filters and internal reflection??

 

[MarsG76]

9 hours ago, wimvb said:

The pattern can be caused by reflections off chip edges, bonding wires or what have you not, within the camera and close to the sensor. Basically any light that can make its way into the sensor chamber.

This was suggested by Adam Blick in one of his youtube videos.

 

10 hours ago, CCD Imager said:

Maybe it is the street light then, would fit with the green colour of the light intrusion.

Adrian

I know it's easily removed but personally I like the flare in the image... I wouldn't want all of my astrophotos to have a flare but this one is OK. Something different from my past images of M104.

[CCD Imager]

2 hours ago, wimvb said:

@CCD Imager: ouch!

Ha, thought you would appreciate that one

[CCD Imager]

1 hour ago, MarsG76 said:

Yawzah.... initially I'd guess stacked filters and internal reflection??

 

To diagnose, I one by one removed optical components, filters, filter wheel, but the main culprit was the field flattener. The image contains different sources of reflections as you probably guessed!

[wimvb]

2 hours ago, CCD Imager said:

Ha, thought you would appreciate that one

I'd probably crop the image. ✂️

[CCD Imager]

8 hours ago, wimvb said:

I'd probably crop the image. ✂️

You would be left with just M81

[wimvb]

15 hours ago, CCD Imager said:

You would be left with just M81

I don't think you need to crop that much. There are other methods to remove or reduce the effect.

Do you see the reflections here?

https://www.astrobin.com/vouq78/

The image was cropped to remove the worst part. Then I used desaturation to hide the rest.

Btw, I noticed the same reflection effect while watching a netflix series tonight. There it was definitely a bright light near the camera that caused it.

[MarsG76]

21 hours ago, CCD Imager said:

You would be left with just M81

Wouldn't be that bad. Looking at the flares, you wouldn't need to crop out much more than when I do with almost every image on my cheap refractor to get rid of most of the edge star distortion.

In actual fact cropping out your flares would frame it quite nicely.

[CCD Imager]

14 hours ago, wimvb said:

I don't think you need to crop that much. There are other methods to remove or reduce the effect.

Do you see the reflections here?

https://www.astrobin.com/vouq78/

The image was cropped to remove the worst part. Then I used desaturation to hide the rest.

Btw, I noticed the same reflection effect while watching a netflix series tonight. There it was definitely a bright light near the camera that caused it.

My image looks far worse than it actually is because of the extreme stretch, in fact I couldnt see the arc reflections in a single sub. My procedure now is to remove the stars and either clone stamp or use the healing brush to remove those reflections.

I think my problem is that I now have a dome observatory and so light reflects every where! I need to examine every possible source, possibly even the dome shutter as the scope is quite near to it.

[CCD Imager]

9 hours ago, MarsG76 said:

Wouldn't be that bad. Looking at the flares, you wouldn't need to crop out much more than when I do with almost every image on my cheap refractor to get rid of most of the edge star distortion.

In actual fact cropping out your flares would frame it quite nicely.

Do notice that the flare from the bright lower left arc extends all the way to the middle of the image.

I dont have an issue processing this image and have maintained most of it, I just wanted to show the extent of problematic internal reflections that you encountered.