[Theme] Night sky shots

[Øivind Tøien]

The Orion constellation from a few nights ago with the 85mm f/1.8S @ f/2 on Z8, stacked 6 sec exposures at ISO 500. I usually do not do this wide captures, but Siril was able to handle the very strong light pollution gradient and the color calibration worked well this time. Due to some trees interfering with the view I only could use 11min total integration time although I captured much more. There was some haze that helped enhancing the major stars of the constellation a bit. Both Orion Nebula ( at the "knee") and the Flame Nebula (near Orion's Belt) is visible. (Open in new tab for larger view.) The warm red giant star of the left shoulder, Betelgeuse is a pulsating variable star, the periodic dimming probably caused by an unseen companion star orbiting Betelgeuse according to a new theory: https://www.simonsfoundation.org/2024/10/21/betelgeuse-betelgeuse-bright-star-betelgeuse-likely-has-a-betelbuddy-stellar-companion/

[Akira]

The Orion constellation from a few nights ago with the 85mm f/1.8S @ f/2 on Z8, stacked 6 sec exposures at ISO 500. I usually do not do this wide captures, but Siril was able to handle the very strong light pollution gradient and the color calibration worked well this time. Due to some trees interfering with the view I only could use 11min total integration time although I captured much more. There was some haze that helped enhancing the major stars of the constellation a bit. Both Orion Nebula ( at the "knee") and the Flame Nebula (near Orion's Belt) is visible. (Open in new tab for larger view.) The warm red giant star of the left shoulder, Betelgeuse is a pulsating variable star, the periodic dimming probably caused by an unseen companion star orbiting Betelgeuse according to a new theory: https://www.simonsfoundation.org/2024/10/21/betelgeuse-betelgeuse-bright-star-betelgeuse-likely-has-a-betelbuddy-stellar-companion/

Øivind, thank you for sharing this neat image of the Orion which is my go-to constellation for my night sky shots.

I'm also very much intrigued by the Betelgeuse.  Another interesting theory I've read about elsewhere is that the hectic and gigantic convection on the surface causes the red/blue shifts the star shows.

Ah, I wish I could eyewitness the supernova explosion of Betelgeuse!

[Øivind Tøien]

Thanks, Akira. If the latest theory is correct, the periodic dimming might not be a sign that Betelgeuse is about to go supernova, so one would have to wait for quite some time...

I thought I had seen a recent nice capture of the Orion constellation somewhere and found it now in the daily thread: https://nikongear.net/revival/index.php?topic=11088.msg203934#msg203934. At your latitude, Orion is running up a very steep hill.    . How did you deal with light pollution gradients over Tokyo skyes?

In the capture above I had messed with my initial flat exposure - it is very sensitive to a bumped focus, so I had to redo it on the first clear night that allowed new infinity focus to be achieved. But is was likely not perfect as there was some central shading after stacking that made me bring background levels down to hide it.

[Akira]

Thanks, Akira. If the latest theory is correct, the periodic dimming might not be a sign that Betelgeuse is about to go supernova, so one would have to wait for quite some time...

I thought I had seen a recent nice capture of the Orion constellation somewhere and found it now in the daily thread: https://nikongear.net/revival/index.php?topic=11088.msg203934#msg203934. At your latitude, Orion is running up a very steep hill.    . How did you deal with light pollution gradients over Tokyo skyes?

In the capture above I had messed with my initial flat exposure - it is very sensitive to a bumped focus, so I had to redo it on the first clear night that allowed new infinity focus to be achieved. But is was likely not perfect as there was some central shading after stacking that made me bring background levels down to hide it.

LOL!  My Orion image was taken in a hurry and I didn't pay attention to the orientation of the camera.  So, that was a pure night sky image and has no value as "astrophotography". 

I shot the image when the air was pretty dry, and the Orion was close to the zenith.  Also, the image was shot utilizing the central portion of a full-frame lens on an APS-C sensor, the lens was stopped down by one stop, and the image was cropped, which collectively help me avoid the affect of the vignetting.  As a result, I could raise the clarity and dehaze in ACR quite a bit without worrying about the unnatural image.  I also used a soft filter to render the stars bigger.

[Øivind Tøien]

Thanks for the explanation, Akira. Yes the lower latitude/ higher altitude helps with light pollution gradients, here the bottom left star (Saiph) is only at 15° altitude when due south, and in direction of the worst light pollution. Nice touch with the filter you used.

[Øivind Tøien]

A slightly better version, this time I used DSS to do the stacking of all of the captures, for a total of ca. 38 min integration time; the Sigma clipping in DSS seems to have taken care of the trees that got into the frame in combination with a slightly tighter crop and the background extraction during the following processing of the resulting 32 bit linear .fit file in Siril. There is even faint manifestation of the Horsehead Nebula below the Flame Nebula in this one when viewed at high resolution. I am happy that I was able to make the color calibration work in this one, as it means that my many previous targets stacked in DSS with additional 32 bit linear .fit files saved can likely be reprocessed in Siril without re-stacking.

[ColinM]

As someone who's ignorant about astrophotography,  can i ask a dumb question about Øivind's image?

I often see Orion at night and I've looked at it with binoculars.
I've never seen the nubula before

I now realise its faintly visible in Akiras image too.
Is this another example of the way cameras can pick up things our eyes just don't
(e.g. like aurora images)?

[Øivind Tøien]

Thanks for commenting, Colin. With respect to visibility of the Orion Nebula, our eyes can probably pick up the brightest part of it, looking mostly like an irregular diffuse star, but the weaker peripheral parts will need the longer exposure of a camera, in my image by stacking a number of shorter exposures. Also, as with the aurora, those red/purple hues are not easily picked up by our eyes at low light intensity.

[Nasos Kosmas]

Thanks for commenting, Colin. With respect to visibility of the Orion Nebula, our eyes can probably pick up the brightest part of it, looking mostly like an irregular diffuse star, but the weaker peripheral parts will need the longer exposure of a camera, in my image by stacking a number of shorter exposures. Also, as with the aurora, those red/purple hues are not easily picked up by our eyes at low light intensity.

Yes you may see it like a non clear star as Oivid explains above

Oivid excellent captures

[Øivind Tøien]

Thanks, Nasos.

[Akira]

As someone who's ignorant about astrophotography,  can i ask a dumb question about Øivind's image?

I often see Orion at night and I've looked at it with binoculars.
I've never seen the nubula before

I now realise its faintly visible in Akiras image too.
Is this another example of the way cameras can pick up things our eyes just don't
(e.g. like aurora images)?

Just to add Øivind's explanation, my image was shot in a pretty "normal way" (exposed according to the camera's meter indicated), and my image is much closer to the way we see the night sky with our naked eyes.   A soft filter will make the essentially punctual images of the star larger and more visible but reduce the fainter stars and nebulae as the side effect.

[Øivind Tøien]

I had a go at the Rosette Nebula (NGC 2238) last day of the year with the 500PF @f/5.6 on Z8 using 32-frame pixel-shift mode for a minimal amount of dithering. Cropped stack of 54 x 30second exposures in Siril. As as the output was not quite where I wanted, I continued to mistreat it in CNX2, pulling out more contrast and saturation. While I am pretty satisfied with the colors, please bear over with the resulting noise. It is possible this can be remedied down the road when I understand the tools in Siril to treat stars and nebulosity differently, but considering the strong light pollution in the capture direction, the non-astromodified body, and the weak H-alpha emission, I cannot complain too much.

[Bruno Schroder]

I would not complain either . Worth investigating further.

[Øivind Tøien]

I would not complain either . Worth investigating further.

Thanks, Bruno.

[Akira]

I would not complain either . Worth investigating further.

Very true!