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Neptune, Possible Spot?

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#1 bunyon

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Posted 08 September 2013 - 01:16 AM

Please let me know if I'm crazy. Had good seeing tonight. Shot some planetaries with the dob and ASI120 while waiting for Neptune to get high enough (and clear a tree). Once that happened, I fired off two avis. It was two because clouds interrupted the first. So, there was a gap of about 5-10 minutes between them. I'd meant to rotate the camera during the break, figuring, why not? But I got distracted and didn't. So the orientation of both was the same.

In both, I clearly see a bright spot on the southern side of the disk. Obviously, if it is something in the imaging train, it would be there for both. But if it were an artifact of processing, I'd think only one would have it.

Anyway, the imaging details: 15" Newt at approx 3900mm EFL. Baader IR685 Pass filter. ASI120MM at 100% gain, 0.162s exposures. For the posted image, 2774 frames were collected and this is a stack of the best 80% using a single reference point and noise robust 6 in AS!2. The stack was sharpened with slider 6 in registax 6 and then final processing was carried out in photoshop.

Triton is clearly visible where it should be. The image was recorded for 525s starting at 0503UT. WinJupos puts the CM of Neptune for this capture at 346, although the spot is clearly not on the CM.

So, it looks to me like I captured a bright spot. However, after several years of doing this, I'm not expert enough to know if this could be some sort of artifact and, if it is, I'd very much appreciate being set straight before I get too excited.

Here is the stack from the first avi (at 0503), fully processed. I'll follow with a crop and enlargement. Then a shot from the second avi.

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#2 bunyon

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Posted 08 September 2013 - 01:16 AM

200% enlargement.

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#3 bunyon

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Posted 08 September 2013 - 01:23 AM

I went ahead and processed the second avi. It didn't look as good, on screen or stacked. After the first wave of clouds went through, it cleared but seeing degraded. The second avi was also cut short by clouds, which ended the session. It's still cloudy an hour later as I write this.

This is the best 2000 frames of 2994, starting at 0512 - so there was only about 2 minutes between the end of the first avi and the start of the second.

Processed identically.

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#4 bunyon

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Posted 08 September 2013 - 01:23 AM

200% enlargment of the second avi image.

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#5 bunyon

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Posted 08 September 2013 - 01:25 AM

Incidentally, I thought I could see the spot at times on the live feed throughout the session. Didn't believe it.

It seems to me there is clearly something there - what it is (artifact, anomaly or real spot), I've no idea.

I'm eager to hear thoughts and opinions. Cheers.

#6 bunyon

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Posted 08 September 2013 - 01:39 AM

Here's all of them together. Should have done that first.

I really need to go to bed.

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#7 sfugardi

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Posted 08 September 2013 - 09:01 AM

Paul, you're not crazy! The orientation seems correct. Congradulations on the white spot capture and thanks for posting it

Regards,
Steve

#8 bunyon

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Posted 08 September 2013 - 10:22 AM

Thanks, Steve.

I edited out some blank spots with traces of cloud and appended the two avis together. This is a 3000 frame stack. Enlarged 300%.

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#9 Sunspot

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Posted 08 September 2013 - 10:29 AM

Paul,

Very nicely done. IMHO I think you definitely got a spot. I wish there was a way to get this information to someone like Heidi Hammel for confirmation.

Paul

#10 John Boudreau

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Posted 08 September 2013 - 10:58 AM

Well you're probably only as crazy as the rest of us Paul! You've got a beautifully clean capture of what we've been calling the bright spot--- it's exactly in the same location as the other images. The Pic Du Midi image from July 1st shows that it may be an elongated feature--- perhaps part of a band, that we are probably not resolving with our smaller apertures. It could also be a series of spots. Whatever it is, it doesn't seem to be drifting much. Nicely done!
:waytogo:

#11 CPellier

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Posted 08 September 2013 - 12:53 PM

Very interesting, again !
The southern IR bright bands on Neptune might shows variations that would explain the spot aspect.
Here is another Pic image (rather old, but the time on Neptune is longer than here) that shows a similar aspect:

Posted Image

#12 stanislas-jean

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Posted 08 September 2013 - 01:23 PM

Try to image with 1-2hours time intervalle to see if thé spot is moving
Stanislas-Jean

#13 Marc Delcroix

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Posted 08 September 2013 - 05:07 PM

Hi Paul ;)

It's the same bright spot imaged by Pete and John - my measures show they all align nicely to form a constant drift rate at about -0.6°/day.

The predictions for CM transit of this spot are:
WinJUPOS 10.0.19 (Neptune), C.M. transit times, 2013/09/08 23:29
Object longitude: L = 21,7° - 0,5745°/d * (T - 2013 Aug 27,5)
Time interval: 2013 Sep 08,0 ... 2013 Oct 01,0
Output format: Date UT (C.M. of System 1)
------------------------------------------------------------------------------
2013 Sep 08 06:21 ( 15°) 22:27 ( 15°)
2013 Sep 09 14:32 ( 14°)
2013 Sep 10 06:38 ( 14°) 22:43 ( 13°)
2013 Sep 11 14:49 ( 13°)
2013 Sep 12 06:55 ( 13°) 23:00 ( 12°)
2013 Sep 13 15:06 ( 12°)
2013 Sep 14 07:11 ( 11°) 23:17 ( 11°)
2013 Sep 15 15:22 ( 11°)
2013 Sep 16 07:28 ( 10°) 23:33 ( 10°)
2013 Sep 17 15:39 ( 10°)
2013 Sep 18 07:44 ( 9°) 23:50 ( 9°)
2013 Sep 19 15:56 ( 9°)
2013 Sep 20 08:01 ( 8°)
2013 Sep 21 00:07 ( 8°) 16:12 ( 7°)
2013 Sep 22 08:18 ( 7°)
2013 Sep 23 00:23 ( 6°) 16:29 ( 6°)
2013 Sep 24 08:34 ( 6°)
2013 Sep 25 00:40 ( 5°) 16:46 ( 5°)
2013 Sep 26 08:51 ( 4°)
2013 Sep 27 00:57 ( 4°) 17:02 ( 4°)
2013 Sep 28 09:08 ( 3°)
2013 Sep 29 01:13 ( 3°) 17:19 ( 3°)
2013 Sep 30 09:25 ( 2°)
------------------------------------------------------------------------------

#14 bunyon

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Posted 08 September 2013 - 05:36 PM

Marc,
Thanks for that information! It looks like I have a chance at the next one, perhaps, and I'd like to try it again when it isn't visible.

#15 bunyon

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Posted 09 September 2013 - 09:02 AM

Thinking about the processing, it occurred to me that the spot is quite bright and that by properly stretching the disk, the spot becomes overexposed. So here is one with a much darker disk. Not really sure the best way to present the data.

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#16 J-Luc Dauvergne

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Posted 09 September 2013 - 10:42 AM

congratulation for this discovery !

#17 Mike Phillips

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Posted 09 September 2013 - 03:00 PM

Very nice Paul! How important is the orientation if you capture Triton and report the known time? I need to try again as my last set was poor seeing and the 5x PM instead of the 2.5x one.

Good job!

#18 Kokatha man

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Posted 09 September 2013 - 07:12 PM

Thinking about the processing, it occurred to me that the spot is quite bright and that by properly stretching the disk, the spot becomes overexposed. So here is one with a much darker disk. Not really sure the best way to present the data.


Congratulations Paul! :applause: :applause: :applause:

Tbh when I first looked at your thread I realised the bright spot was clearly a phenomenon but appeared so un-naturally bright that I refrained from being the first to reply to you.....feeling it best to wait for those experienced in Neptune imaging to do so! :)

With your new processing and multiple images it's patently clear to us "Neptune Newbies" :lol: that you have clearly caught that brightening..! :waytogo:

#19 bunyon

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Posted 09 September 2013 - 08:19 PM

Darryl, your phrase "unnaturally bright" is exactly how I felt about it. I knew it looked like Pete and John's images but it just popped out. I didn't do anything special. Seeing was good, but not great, didn't get as many frames as I wanted and, bam!, it was just there out of the stack and really pronounced upon sharpening. Thus, my worry it wasn't real.

As I say, imaging that spot didn't require anything extraordinary. If you can be out at the times Marc suggests, give it a try.

#20 Pete Gorczynski

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Posted 09 September 2013 - 11:02 PM

Darryl, your phrase "unnaturally bright" is exactly how I felt about it. I knew it looked like Pete and John's images but it just popped out. I didn't do anything special. Seeing was good, but not great, didn't get as many frames as I wanted and, bam!, it was just there out of the stack and really pronounced upon sharpening. Thus, my worry it wasn't real.

As I say, imaging that spot didn't require anything extraordinary. If you can be out at the times Marc suggests, give it a try.


I agree. That white spot stood out in the unsharpened raw stack.

Pete G.

#21 stanislas-jean

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Posted 10 September 2013 - 02:53 AM

Spot question is thé fact they are located at limbs of thé planet.
only Pète'image is shown near the méridien.
Is it the result of the feature location mainly?
Stanislas-jean

#22 Marc Delcroix

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Posted 10 September 2013 - 05:50 AM

Hi Stanislas,

I personnaly do not question the reality of that spot: I also observed it on July 1st at Pic du Midi :
Posted Image
It's the brightenning to the lower left of the globe.

Others observers have imaged it on Aug. 21st, and 25th, and all of the longitude measured of these spots nicely align on a constant drift rate line from July 1st to Sep. 8th.

#23 stanislas-jean

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Posted 10 September 2013 - 12:20 PM

Yes ok Marc my comment is to note the feature captured mainly at the planet edge, not at the CM location or the disk middle.
It should be interesting to do in addition on the same night.
Stanislas-Jean

#24 bunyon

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Posted 10 September 2013 - 12:54 PM

Indeed, Stanislas. I would dearly have loved to do this. But clouds cut me short. I went out hoping again to do this but was clouded out entirely. Frustrating.

#25 rolo

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Posted 10 September 2013 - 12:54 PM

Excellent work Paul!






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