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Jupiter's red spot - time

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#1 clarnibass

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Posted 18 October 2020 - 07:04 AM

Hi

 

I looked into when I could see and the best I could find is this list https://www.projectp...om/jeve_grs.htm

 

First, does anyone have a better link to find that out?

 

Second, if I understand, that list of the starting times? i.e. today at 16:34 is appears, then remains for... how long?

 

Also, how does that relate to time zone? Since the rotation speed is different, I imagine it's not the same time everywhere?

Is there a way to check my time zone (I'm in Israel)?

 

Amazingly... in a couple of years of observing... I've only seen it once... a few weeks ago.

 

Thanks



#2 randcpoll

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Posted 18 October 2020 - 07:25 AM

Sky Safari has all of the planetary events for the next +/- 18 hours on it's details page for each planet.

Once you know the features transit time (for instance the red spot) you can see it for about an hour before and after.

Sky and Telescope magazine also has a chart in each issue that has the times for each month.



#3 BFaucett

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Posted 18 October 2020 - 08:05 AM

Is there a way to check my time zone (I'm in Israel)?

 

Time Zones in Israel

https://www.timeandd...ime/zone/israel

 

The local time in Israel and the UTC (Coordinated Universal Time) offsets are shown on that page. 

 

Bob F.


Edited by BFaucett, 18 October 2020 - 08:15 AM.

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#4 beggarly

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Posted 18 October 2020 - 08:56 AM

The predictions on the Project Pluto site aren't accurate. Better use https://skyandtelesc...great-red-spot/

These correspond to the predictions by SkyChart/Cartes du Ciel: https://www.ap-i.net...php?id=en/start

 

It's not 'starting' times, it's times when the GRS transits = crosses the central meridian.

Jupiter's sidereal rotation period is 9h 55m. The GRS is transits every ~10 hours.

 

Calculated in SkyChart with GRS longitude 340° and yearly drift 18.3°. Values from Jupos 01 September 2020.

Jupiter GRS.jpg

 

https://www.cloudyni...nsit-reference/

 

http://jupos.privat....ne.de/index.htm


Edited by beggarly, 18 October 2020 - 10:00 AM.


#5 GaryS

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Posted 18 October 2020 - 10:59 AM

Of course, you could take the easy route and just look in the current issue of S&T. We publish accurate Red Spot transit times as well as Jupiter satellite events tables in every issue.

 

The trouble with software-based GRS transit predictions is that the current longitude of the Spot has to be up to date -- the GRS drifts quite significantly -- on the order of around 2 degrees/month at present. For every degree your software is off by, the transit times will be wrong by about 1-2/3 minutes. Most programs have the capability to be updated, but some make it easier than others.


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#6 Davesterx

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Posted 18 October 2020 - 06:21 PM

I use the Sky and Telescope JupitersMoons App on my iPhone.



#7 chakel

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Posted 18 October 2020 - 08:46 PM

I use the Sky and Telescope JupitersMoons App on my iPhone.

 +1



#8 Jeff B1

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Posted 19 October 2020 - 05:19 PM

WinJUPOS 11.3.0 is about as accurate as I know and the GRS longitude is 344.6 degrees on October 19, 2020.  It's a huge storm within some clouds of H and He, so mathematical models are tenuis as best.


Edited by Jeff B1, 19 October 2020 - 05:22 PM.


#9 catalogman

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Posted 21 October 2020 - 10:51 PM

The GRS drift rate has been steadily increasing in recent years, but otherwise follows no definitive pattern
because nearby storms can change the longitude of the GRS and they are unpredictable:

 

https://iopscience.i...3881/aaae01/pdf

 

The best that software can do is model past measurements analytically and allow input for a current value.

 

-- catalogman


Edited by catalogman, 21 October 2020 - 11:10 PM.


#10 clarnibass

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Posted 22 October 2020 - 10:34 AM

Thank you. If I understand, times referring to "transit" are, to use layman 's terms, when the spot is in the middle? :)

 

So guesstimating... and drift, etc. aside... approx how long is it in reasonable view? I mean when the entire spot has not passed the edge. I'm going to guess, maybe three hours? Anyone knows (I realize this might be very approximate)?

 

I'm asking because I don't have much time this time of year to see Jupiter from my porch and I don't want to set up the telescope only to miss it by a little bit.

 

thanks again




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