12 replies to this topic

[Kiwi Paul]

Hi folks,

 

I had some good circumstances for very good seeing on the evening of May 23rd and the morning of May 24th. My plan was to image Mars on the 23rd and Saturn, Neptune, Venus and the Moon on the morning of the 24th. The seeing turned out to be 8/10 at times - better the higher the target was. So I have a lot of data to process. I have started this and am very pleased with my images. Will post a few soon.

 

I was quite excited when I saw my Neptune result. The disc is only 2.2" across and I wasn't expecting much. It was easy to find being very close to Saturn.

 

Here is an image timed at 202505231756Z:

 

 

It seems fairly clear that that one polar area is brighter than the other. As far as I can tell, the north pole is the darker one. Evidence for this comment comes from some images posted on ALPO - Japan, specifically by Andy Casely on 30/10/2024 where he (and others) comment that the south polar area is brighter. There are no current images posted there.

 

Here is a reference image for the same time from SkySafari:

 

 

It clearly shows one pole darker than the other (assuming its correct). I checked the orientation of the Neptune image with my ones of Saturn. With Saturn, the top was South in SkySafari and so without having changed the orientation of the camera or telescope slewing to Neptune I thought south would be in the upper part of the disc. But this seems to be at odds when comparing SkySafari representation of Saturn and then switching to Neptune as depicted. Maybe there is something quirky about the orientation of Neptune's poles (like Uranus?)

 

I will be interested to hear what you think.

 

The image was 3000 frames stacked out of 7500 using QHY 462C 40ms gain 402.

Telescope C9.25" edgeHD.

 

Cheers Paul

Edited by Kiwi Paul, 24 May 2025 - 10:42 PM.

[Kiwi Paul]

I did a bit of research and found that Neptune’s rotational axis is tilted to the plane of the solar system 28.8 degrees. Watching the way the planet rotates shows the spot near the limb in the reference image (a big spot) disappears off the limb. This implies the pole in the image on the RHS is the South Pole! So the SkySafari image is really of no help!
Cheers Paul

[KpS]

Every time I take a picture of Neptune I can always pull Triton out of the background. Then WinJupos will allow you to find out the orientation of the camera and Neptune's axis.

[Kiwi Paul]

Thanks for that.
Cheers Paul

[Mike Phillips]

Cloud activity not surface details have been observed on Neptune before.  Report it to PVOL http://pvol2.ehu.eus/pvol2/

 

Mike P in NC

[Kiwi Paul]

Hi Mike.
Thanks your comments. I was using the term surface features loosely. Yes, I thought they might be clouds. I will send my image in as you suggest.
Darryl, if you read this, what do you think?
Cheers Paul

[Kokatha man]

...not really enough to determine anything definite Paul, Neptune is such a challenge and animated frames are always the best method of determining variations in the disk's appearance. I did a quick Google as well as had a look at the ALPO-Japan site where I found R. Sedrani's images the most interesting...The only info I came up with on Google re "any recent Neptune images showing activity" was a link to our site's Neptune webpages!  

 

We haven't imaged this planet for quite some time but hope to spend a bit of time on it this apparition!

[Kiwi Paul]

Thanks Darryl. I can see that using animated frames would be an effective way of establishing elusive features.
But the disc does appear to brighter in one hemisphere. This might result from unresolved bright clouds?
I will keep a watch during this apparition too. I look forward to seeing what you might achieve.
Cheers Paul

[BGazing]

If I remember correctly, playing with Registax wavelets on Uranus got me to a similar effect, so could be a sharpening artefact.

But it could be the real deal, although, as I understand, it is easier to eke such detail in IR and bigger aperture.

[sfugardi]

Paul, Nice image. The best Neptune cloud capture images have come using an RG610 filter. While it will darken the data, it will increase the chances of capturing any contrast if you can keep the frame rate >20 and the histogram peaking <99. If Triton is not popping in and out of view on the capture screen, conditions or focus are not good enough to be successful. You've got me very interested in trying Neptune again but realistically it hard to pass on Saturn right next to it...

 

Regards,

Steve

[theaberrator]

If I remember correctly, playing with Registax wavelets on Uranus got me to a similar effect, so could be a sharpening artefact.

But it could be the real deal, although, as I understand, it is easier to eke such detail in IR and bigger aperture.

In waveSharp you can use the "drop background" feature, that will show the "data" as seen by the sharpening process that will be enhanced. If you see clear features in that, they are surely part of your dataset. To test this keep your sharpening-filters default (0.1). And its often wise/important to check two separately created datasets, you could try cutting the original-imagesequence into two sections and see what they bring.

Edited by theaberrator, 26 May 2025 - 08:40 AM.

[Kiwi Paul]

Paul, Nice image. The best Neptune cloud capture images have come using an RG610 filter. While it will darken the data, it will increase the chances of capturing any contrast if you can keep the frame rate >20 and the histogram peaking <99. If Triton is not popping in and out of view on the capture screen, conditions or focus are not good enough to be successful. You've got me very interested in trying Neptune again but realistically it hard to pass on Saturn right next to it...

 

Regards,

Steve

Thanks for your ideas Steve. I will keep your approach in mind.

 

Cheers Paul

[Kiwi Paul]

In waveSharp you can use the "drop background" feature, that will show the "data" as seen by the sharpening process that will be enhanced. If you see clear features in that, they are surely part of your dataset. To test this keep your sharpening-filters default (0.1). And its often wise/important to check two separately created datasets, you could try cutting the original-imagesequence into two sections and see what they bring.

Many thanks for your ideas. I will try them out.

Cheers Paul