Planets Tonight

[JohnSadlerAstro]

Hi,

I've got everything set up and ready for a night of planets. There's a bit of a breeze blowing but its looking very promising. The seeing was appalling earlier, I think it may have been warmth from the camera going up the tube though. Everything's calming down now anyway .

OpticStar 90S Gold
EQ5
ASI120MC

Still quite a bit of work to get the results looking better, but they are improving gradually.

Anyone else out looking at planets?  

John

 

[David Smith]

Nice. Some half decent seeing here today for a change

[JohnSadlerAstro]

It's a really weird looking view right now, with the GRS and another stormy area on the northern band right above each other.

[Sunshine]

Have fun touring the solar system!

[Stu]

7 hours ago, JohnSadlerAstro said:

It's a really weird looking view right now, with the GRS and another stormy area on the northern band right above each other.

Yes, that feature has been aligned with GRS for some time now I think. It is changing a little but seems to remain in the same position. Have a look back at past images for the last month or more and you should see what I mean.

Just been observing this myself, nice festoons dropping down from the NEB and GRS looking nicely orange.

[geoflewis]

2 hours ago, JohnSadlerAstro said:

Anyone else out looking at planets?

Nice Jupiter capture John,

I've just come in from a good session with both Jupiter and Saturn. Seeing was fair to good in patches with lovely views of the GRS, but views of Saturn were constantly interupted by passing cloud and eventually the sky lost out. Six of Saturn's moons were visible through the C14 at x200 magnification, though Mimas at ~mag 13 was tricky being close to the bright ring system. I managed to collect 2 runs of data on each planet, so that's more backlog for me to process in the coming days.

Cheers, Geof

 

[JohnSadlerAstro]

I wanted to get a picture of Saturn, but for some reason the transparency seemed dreadful to the east. I couldn't see the Cassini Division or any surface markings. Which was odd, because looking at Jupiter just a minute before, I could see more detail than I ever have seen before! Sometime I'm going to have to see what the planets look like through a big cat!  

John

[Stu]

26 minutes ago, JohnSadlerAstro said:

I wanted to get a picture of Saturn, but for some reason the transparency seemed dreadful to the east. I couldn't see the Cassini Division or any surface markings. Which was odd, because looking at Jupiter just a minute before, I could see more detail than I ever have seen before! Sometime I'm going to have to see what the planets look like through a big cat!  

John

Same for me John. Jupiter looked better than average, but Saturn was pretty bad. Some detail on the surface and A and B rings showing a difference but no Cassini really, perhaps hints that’s all.

I did notice a drop off in Jupiter between at its highest altitude and when it had dropped a few degrees. This has happened for a few sessions consistently so it is either the altitude or there may be some seeing disturbance in that direction, not obvious what it is though. Directly to the South I am observing over fields which is good.

[JohnSadlerAstro]

41 minutes ago, Stu said:

Same for me John. Jupiter looked better than average, but Saturn was pretty bad. Some detail on the surface and A and B rings showing a difference but no Cassini really, perhaps hints that’s all. 

I did notice a drop off in Jupiter between at its highest altitude and when it had dropped a few degrees. This has happened for a few sessions consistently so it is either the altitude or there may be some seeing disturbance in that direction, not obvious what it is though. Directly to the South I am observing over fields which is good. 

That's interesting--to the west-south-west of us are fields, but in the slightly-east-of-south where Saturn was there are houses, so it may be something to do with that. Something I've noticed a bit when it's getting dark is that there's what appears to be a dark band of haze up to about 15 degrees above the horizon. I'm not sure if this is an optical illusion, as it's easy to see all kinds of things in the sky an hour after sunset when it's white. It's irritating that Saturn should be like that, though, as it was at 14 degrees above the horizon and it's max is 16. Next time I'm out I will try again and see if its a regular thing. ?

If it is the houses, then I can just wait for Saturn and Mars to go round past them.

John

[Davey-T]

A good example of Saturn though the atmosphere last night, DSLR in crop mode 640X480 video, 10" SCT + 2X Powermate, single frame.

Dave

[JohnSadlerAstro]

Yup, that's just the kind of thing I was seeing, compared to Monday morning, when I could see colour bands and Cassini as clear as day. ?

John

[Davey-T]

Annoying isn't it, I had some good views a couple of nights ago but didn't bother imaging, sorry now 

Dave

[Stu]

1 hour ago, Davey-T said:

A good example of Saturn though the atmosphere last night, DSLR in crop mode 640X480 video, 10" SCT + 2X Powermate, single frame.

Dave

Yep, that looks like a bigger version of what I was seeing , except mine was wobbling  

[geoflewis]

2 hours ago, JohnSadlerAstro said:

I wanted to get a picture of Saturn, but for some reason the transparency seemed dreadful to the east. I couldn't see the Cassini Division or any surface markings. Which was odd, because looking at Jupiter just a minute before, I could see more detail than I ever have seen before! Sometime I'm going to have to see what the planets look like through a big cat!  

John

 

2 hours ago, Stu said:

Same for me John. Jupiter looked better than average, but Saturn was pretty bad. Some detail on the surface and A and B rings showing a difference but no Cassini really, perhaps hints that’s all.

I did notice a drop off in Jupiter between at its highest altitude and when it had dropped a few degrees. This has happened for a few sessions consistently so it is either the altitude or there may be some seeing disturbance in that direction, not obvious what it is though. Directly to the South I am observing over fields which is good.

A lot of the difference will be due to the much lower altitude of Saturn compared to Jupiter, Saturn really is down in the murk....

1 hour ago, Davey-T said:

A good example of Saturn though the atmosphere last night, DSLR in crop mode 640X480 video, 10" SCT + 2X Powermate, single frame.

Dave

Dave's image really shows how bad the atmospheric dispersion is at 15 degrees, something that using an ADC can really help correct, but even with mine there is still some dispersion remaining.

FWIW here is the final image from one of the 2 images runs of Saturn that I captured last night using my C14 with mono ASI120MM-s, x2 TV Powermate and ADC in train. I was fighting cloud illuminated by the nearby Full Moon throught both runs on Saturn; I haven't processed the other set yet (nor either of my 2 Jupiter runs), but this should be the better of the 2 as Saturn was almost at it's peak altitufde and there was less cloud than during the earlier session.

Cheers, Geof

[Davey-T]

6 minutes ago, geoflewis said:

FWIW here is the final image from one of the 2 images runs of Saturn that I captured last night using my C14 with mono ASI120MM-s, x2 TV Powermate and ADC in train. I was fighting cloud illuminated by the nearby Full Moon throught both runs on Saturn; I haven't processed the other set yet (nor either of my 2 Jupiter runs), but this should be the better of the 2 as Saturn was almost at it's peak altitufde and there was less cloud than during the earlier session.

Looks pretty good Geof, I'm not even going to try processing mine 

Dave

[JohnSadlerAstro]

13 minutes ago, geoflewis said:

How much difference does an ADC really make? What exactly does it correct?

Does it just make the image sharper? Can it be used for visual?  

John

[geoflewis]

4 minutes ago, Davey-T said:

Looks pretty good Geof, I'm not even going to try processing mine 

Dave

Thanks Dave,

Yes, I ditch a lot of mine and sometimes I abandon even capturing anything as the seeing clearly makes it a waste of time; that's what happened to my intended sessions on 26th and 27th, typical thta 27th was opposition of course

Geof

[Davey-T]

2 minutes ago, JohnSadlerAstro said:

How much difference does an ADC really make? What exactly does it correct?

Hopefully it helps cope with the red / blue colour separation as seen in my image.

Dave

[geoflewis]

1 minute ago, JohnSadlerAstro said:

How much difference does an ADC really make? What exactly does it correct?

Does it just make the image sharper? Can it be used for visual?  

John

Hi John,

It makes a huge difference the lower the altitude of the target (and depending on the aperture of your scope, where bigger is definitely not better) and yes, I'm using mine for visual observing where the colour fringing on the planet and rings is particularly distracting at high magnifications with my C14.

Martin Lewis (no relation as far as I know ) from St Albans wrote a great article on his website which I'm sure he won't mind me referencing. http://skyinspector.co.uk/atm-dispersion-corrector--adc

Martin explains the effect very well and there are some great diagrams, especially the chart that shows just how bad atmosheric dispersion gets down at 15 degrees, indeed anything below, say 40 degrees benefits from using an ADC; it's definitely a good reference site.

Cheers, Geof

[geoflewis]

11 minutes ago, Davey-T said:

Hopefully it helps cope with the red / blue colour separation as seen in my image.

Dave

Exactly Dave...!! It is it's sole purpose, but needs to be correctly tuned and adjusted over an imaging session, as both the altitude and angle of the target changes over time. I wouldn't be without mine and consider one of the best investments I ever made (astronomy wise that is) ?. Jupiter and Saturn will be low altitude targets from the UK for several years to come and even the next (2020) opposition of Mars sees it at only ~40 degrees, so if anyone in the UK wants to get the best from imaging the planets for the next few years I can't recommend using an ADC highly enough.

Geof

[JohnSadlerAstro]

Oh WOW! The before and after pictures are amazing! Does the ZWO one work ok? It sounds a bit complicated to get set up correctly though. ?

https://www.firstlightoptics.com/zwo-accessories/zwo-125-atmospheric-dispersion-corrector-adc.html

Jonh

[geoflewis]

21 minutes ago, JohnSadlerAstro said:

Oh WOW! The before and after pictures are amazing! Does the ZWO one work ok? It sounds a bit complicated to get set up correctly though. ?

https://www.firstlightoptics.com/zwo-accessories/zwo-125-atmospheric-dispersion-corrector-adc.html

Jonh

John,

I haven't used the ZWO ADC, but I've seen lots of excellent images from folks that do use it, so I have no reason to doubt it. I got mine from Astro Electronics in Germany (http://www.astro-electronic.de/) several years ago, long before ZWO brought their's out.

They can seem a little tricky to use when you start out, but after a bit of practice it fairly quickly becomes second nature. There are essentialy 2 factors to consider:

1. Dispersion effects vary with altitude parallel to the horizon, so at the zenith there is none and really very lttle of concern above 70 degrees. You set the prism angles to correct for changes in altitude.
2. As your mount tracks the sky the angle of your scope and hence the ADC changes relative to the horizon, i.e. it will tilt so that the prisms are no longer set parallel to the horizon which means that the correction is uneven. You therefore need to rotate the ADC periodically to reset the angle relative to the horizon.

The need to adjust the ADC is not important during short sessions (say 20 mins or less), or when the target is close to the southern meridian (from the UK anyway) as the change in altitude varies much less than when the target is rising or setting.

Hope that makes sense....

Geof