My First Jupiter

[Knight of Clear Skies]

Had my first try at imaging Jupiter last month, and I finally got around to processing it properly yesterday. I'm certainly not disappointed with it, I was pleased to get anything at all, but it hasn't come out nearly as well as the Mars I did the same night and I'd like to understand why for next time.

(12" newtonian, 4x barlow, Canon 1100D controlled by APT capturing at about 13fps. That's the best 15% of about 600 frames stacked in Registax, RGB align, linked wavelets applied and contrast/colour balance tweaked in PS CS2.)

Unlike Mars, it's not responding much to the wavelets so I think the data just isn't there in the stack. Focus could have been an issue but I had a few goes and they are all turning out about the same. I've heard people say Jupiter doesn't take high magnification as well as Mars, could this be because of the lower contrast? Would I have been better off using a 2x barlow perhaps?

600 frames isn't really enough, but I could only get 13fps and I've been told about 90 seconds is about the maximum on Jupiter before it starts to blur due to rotation. Is that accurate please? Next time I'll try making the image window smaller in APT, which I'm told should boost the frame rate.

According to Stellarium the great red spot should have been visible at lower right. Is this accurate? If I look hard I may have captured a hint of it but I'd expect it to be much more visible.

Finally, what is the dark feature bottom left please? There was an Io transit at the time it was taken (24th Apr, 22:08) but it was going the other way (in a later image it is further from the terminator when it should be closer) and I'd expect it to be much smaller. Could it be a storm, or is it a bit of grot in the image train?

Any thoughts, feedback or constructive criticism would be welcome.

[emadmoussa]

Fantastic! Good job!

[cockney]

amazing image well done. can i ask do you guys use a 2" barlow or just standard with adapter

[Doyley]

Great image.

[Pete Presland]

nice image! i think it is Io, its in exactly the right position.

[PeterCPC]

Very nice indeed. Is it oriented correctly? If you did a 180 would that explain about Io?

Peter

[Knight of Clear Skies]

Thanks everyone, I've looked again and I think I have captured an Io transit, which I'm delighted with. Looking on Celestia Io is on one side but it's shadow is on the other side and moving in the opposite direction due to the angle of the Sun. Celestia also disagrees with Stellarium on the location of the GRS so it probably isn't visible, which is a relief. As it's a storm system I guess predicting its position a long way in advance isn't possible?

Very nice indeed. Is it oriented correctly? If you did a 180 would that explain about Io?

Peter

I get terribly confused with this. I think it's the right way up but needs to be flipped left-right. That would mean Io is somewhere on the right hiding in the cloud band but its shadow is on the left.

[glowingturnip]

seems the GRS is shrinking rapidly    - http://www.space.com/25891-jupiter-great-red-spot-shrinking-video.html

[Gomtuu]

As [the GRS is] a storm system I guess predicting its position a long way in advance isn't possible?

It's very predictable - it's been there for centuries. Jupiter rotates once every (just under) 10 hours. The GRS appears for about half of that.

I use an iPhone app for determining when the GRS is likely to be visible. If Stellarium was not showing it and you expected to see it on the edge of the disc, make sure that Stellarium is working from the same time zone. An hour's difference could put it out of view.

Nice shots, btw!

[Knight of Clear Skies]

It's very predictable - it's been there for centuries. Jupiter rotates once every (just under) 10 hours. The GRS appears for about half of that.

I use an iPhone app for determining when the GRS is likely to be visible. If Stellarium was not showing it and you expected to see it on the edge of the disc, make sure that Stellarium is working from the same time zone. An hour's difference could put it out of view.

Thing is Jupiter rotates at different speeds at different latitudes. The GRS may be at least 300 years old, but is its position completely stable relative to the cloud belts? Stellarium and Celestia don't agree on the GRS position, so something isn't right there. Searching again I've found this handy table for 2013/2014. If I'm reading it right it wasn't visible when I took my image which is good news - when I saw the GRS in Stellarium I thought something was wrong with my image. According to this site it does wander around a bit, which causes the transit times to vary and explains why Stellarium & Celestia don't agree.

Thanks for the phone app tip, I'll see if I can find anything for Android.

[mitchelln]

Hi.

Great image

Stellarium has to be tweaked "out the box" as the GRS time wanders slightly. You can make a fix by tweaking rot_rotation_offset =

in the Jupiter section of ssystem.ini

I'm running Stellarium 0.12.4 and have rot_rotation_offset  set to 250. Seems to be about right.

[PeterCPC]

You might find this helpful.

http://www.projectpluto.com/jeve_grs.htm#mar

Gives GRS and moons info.

Peter

[Davey-T]

Nice first try , only got myself organised a couple of weeks ago so bit too late for Jupiter, I've found focusing the most difficult thing, having a bobbing fuzzy ball to focus on I run the motor focus back and forward then hope for the best. Will be having a go at Jupiter in daylight tomorrow around 19.00 BST, should be good for a laugh

Dave 

[Knight of Clear Skies]

Stellarium has to be tweaked "out the box" as the GRS time wanders slightly. You can make a fix by tweaking rot_rotation_offset =

in the Jupiter section of ssystem.ini

I'm running Stellarium 0.12.4 and have rot_rotation_offset  set to 250. Seems to be about right.

Good tip thanks.

Nice first try , only got myself organised a couple of weeks ago so bit too late for Jupiter, I've found focusing the most difficult thing, having a bobbing fuzzy ball to focus on I run the motor focus back and forward then hope for the best. Will be having a go at Jupiter in daylight tomorrow around 19.00 BST, should be good for a laugh

Dave 

Focussing was a complete nightmare. For Jupiter I tried focussing on a star first but at 5x zoom all I got was a multi-coloured swirl, which I tried to make as small as possible. When moving across to Mars the focuser couldn't take the weight of the upside down camera and extended with a bang, so I re-focussed on Mars itself. I could just see the occasional bit of detail, I was about to start messing with it again but had a crucial bit of help, being told that any surface detail was a good sign and it was worth doing an imaging run.

Next time I should look at the focussing aids in APT (FWHM).

Good luck on a daytime Jupiter, it is possible to get decent results. Got to give these things a try, and it's all practise.

seems the GRS is shrinking rapidly    - http://www.space.com/25891-jupiter-great-red-spot-shrinking-video.html

We had a thread about this a while back. It would be a real shame if it disappeared, but who knows what other features might appear over time? Also, although it may have shrunk over the last few decades could it rebound and grow? I don't think anyone really knows what to expect.

[mitchelln]

A good focusing aid is a Bahtinov mask on a bright star. You need to turn the ISO right up to get an image, but you can get the focus spot on after a few shots.

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