Jupiter, filters and patience

[Size9Hex]

Slim pickings right now with the late summer nights and the planets low. I can’t see Jupiter or Saturn from home, but was keen to try to get at least one decent session on Jupiter this season so headed out to a site with a low southern horizon and reasonable seeing across the grassy fields.

Nice views in twilight, including the Great Red Spot and Io approaching/merging into the disk. The seeing was bad initially (and I almost packed up), but improved fairly quickly as the evening cooled, becoming ok but not brilliant.

With a few seasons under my belt now, it’s nice to see the evolution of the features on Jupiter. Not to claim any real level of expertise mind; A few seasons more needed to learn the names too! The equatorial zone is darker/yellower and seems wider than I recall from previous years. The northern and southern belts seemed thinner. The southern belt has previously had a broad swathe of turbulence in the wake of the GRS, whereas last night it was squeezed very thin by the bright zone to the south. The GRS had a notably dark southern boundary. I don’t know if these are fleeting or long term changes but still nice to notice things evolve.

In terms of the filters, these were a recent edition to the kit. I was in two minds, given that they seem to divide opinion, but in the end I took a punt. A blue filter brought out knotted texture in the north equatorial belt more prominently. An orange filter confirmed three large festoons and made the bright southern zone particularly obvious. Equally, some features were lost with the filters, so quite feature/filter specific rather than overall better/worse. I felt these effects were noticeable within a few seconds at the eyepieces and didn’t require scrutiny or a drawn out game of Spot-the-Difference. Not to say the effect was dramatic though. With the filters removed, the improved features were still there, but less often and less easily - but then the worsened features got better, so take your pick! 😛 Overall, I’m content with their first light and feel that they contributed towards a good session.

But, with little surprise, by far the most important aspect was patience - filters or otherwise - especially with the wobbly seeing.

Saturn was terrible, but the scope was practically horizontal peering through the soup. Better views to come though!👍

[MKHACHFE]

Interesting. Thanks for the info. I have been observing J with my XT8 and 25mm and cheap 10mm all last week and found that a standard moon filter (the only one i have) helped a tad with seeing detail. I'm shopping for some other filters, so your post is appreciated. 

 

Cheers

[dweller25]

I have found the Baader Neodymium filter to work very well on the planets.

[Grotemobile]

https://www.firstlightoptics.com/moon-neutral-density-filters/astro-essentials-variable-polarising-moon-filter.html

I have found this one can help as well especially on Jupiter.

[geoflewis]

Until this year I've never viewed Jupiter with any filters, however, after reading some reports here on SGL that even a Moon filter helps, I tried a couple of the old (and cheap) visual filters that I have, which are a 25% ND 'Moon' filter and a general LP filter. They both improved the views, mainly because the darkened the sky and removed the throbing haze around the planet and to a less extent it's moons, making it easier to dial in tight focus. The LP filter seemed to work best, though I wouldn't say that it brought out any features on Jupiter any better than the naked eye views. With Jupiter so low I do use my ADC which removes most of the blue/red dispersion fringes, which is pretty much essential with the C14.  I've had a few pretty decent sessions on Jupiter at the eyepiece using the LP filter over the past couple of weeks, so will continue to use that for visual observations. I tried the same with saturn, but the improvement was less apparent.

Cheers, Geof

[Stu]

Nice report. I've had some of my best viewing (for this apparition) of Jupiter in the last couple of weeks. Similar experience that as the night wears on the seeing improves substantially, presumably as everything cools off. It does seem to change subtly every opposition which is interesting to track. One thing I'm not seeing as much as I have done in the past is barges. I recall seeing them quite frequently a few years ago, but have not really noticed any recently. Am I just not picking them up?

[John]

2 hours ago, Stu said:

Nice report. I've had some of my best viewing (for this apparition) of Jupiter in the last couple of weeks. Similar experience that as the night wears on the seeing improves substantially, presumably as everything cools off. It does seem to change subtly every opposition which is interesting to track. One thing I'm not seeing as much as I have done in the past is barges. I recall seeing them quite frequently a few years ago, but have not really noticed any recently. Am I just not picking them up?

I agree re: the lack of barges Stu. I didn't see many last opposition either but before that they were relatively common features.

This years opposition, although very low, has not been without it's interests though. It's always worth getting a scope onto Jupiter if possible - you never quite know whats going to be happening there

 

[Stu]

Thanks John, glad I'm not just imagining it! I recall one time probably 7 or 8 years ago, confidently telling someone that they were seeing the GRS, only to find out it was a large barge and GRS appeared round the limb a little while later. Fortunately I did not have to face the embarrassment of correcting my error!

[AdeKing]

1 hour ago, Stu said:

Thanks John, glad I'm not just imagining it! I recall one time probably 7 or 8 years ago, confidently telling someone that they were seeing the GRS, only to find out it was a large barge and GRS appeared round the limb a little while later. Fortunately I did not have to face the embarrassment of correcting my error!

I had a large embarrassment, but involving a different planet.

I had an outreach session and told the public they were viewing Mars only to find out that I was actually showing them Mercury with Mars passing through the FOV  much later in the evening. Oops.

Likewise I didn't need to suffer the embarrassment of needing to explain my mistake.

 

[Size9Hex]

18 hours ago, MKHACHFE said:

Interesting. Thanks for the info. I have been observing J with my XT8 and 25mm and cheap 10mm all last week and found that a standard moon filter (the only one i have) helped a tad with seeing detail. I'm shopping for some other filters, so your post is appreciated. 

 

Cheers

Lots of factors involved when you’re trying to see things at the limits of your physiology, your kit and the conditions. Glad you had some success with the moon filter. Twilight viewing can show some surprising detail that seems to get tougher as the sky darkens - and is free! 😀. Of all the variables, I think the filters are not near to the top of the list though, so I’d recommend don’t be in too much of a rush to buy (nebula filters are a different story... 👍). A good quality high power eyepiece would be on my shopping list before coloured filters for sure. Plus collimation, seeing, patience, etc 🙂

[Size9Hex]

9 hours ago, geoflewis said:

... With Jupiter so low I do use my ADC which removes most of the blue/red dispersion fringes, which is pretty much essential with the C14.  I've had a few pretty decent sessions on Jupiter at the eyepiece using the LP filter over the past couple of weeks, so will continue to use that for visual observations. I tried the same with saturn, but the improvement was less apparent.

Cheers, Geof

Thanks Geof. Good feedback on the ADC especially with Saturn. Those red/blue fringes are partly what made me take a punt on a coloured filter this year with the planets so low. I haven’t noticed the fringe before, but it’s quite obvious now even when the planet is "high" directly in the south. The filters do tighten the view in suppressing the colour, but I wonder if the impact would be different when the planets are higher.

[John]

On the subject of using filters on Jupiter, one thing I'd suggest from my experience of using quite a few different types over the years (including Tele Vue's rather expensive Bandmate Planetary filter) is to use them by all means but also take time to observe the planet without a filter.

What I've found is that some filters (including the Tele Vue one) can make the main features stand out a little more but this can be at the expense of making more subtle features such as festoons, white spots, vortex structure, ovals etc, harder to detect.

As experience increases in observing Jupiter and you spend more time at the eyepiece, seeing the Great Red spot, the main cloud belts and the more prominent festoons becomes easier and of course you want to delve into the more subtle features that the Jovian surface has to offer and IMHO this is the time to observe without a filter.

I find the same when observing the Moon as well. A filter can actually obscure the finest detail that is available under good seeing conditions.

So it's worth allowing time in your sessions for both filtered and filterless observation  

Also dark adaptation is not really an asset when trying to tease out more subtle planetary detail. I've often seen the best planetary details on Mars, Jupiter and Saturn with there is plenty of twighlight left in the sky. Experienced planetary observers sometimes illuminate a white card with white light before observing. Quite the opposite of what a deep sky observer would do !

 

[Geoff Barnes]

9 hours ago, Stu said:

One thing I'm not seeing as much as I have done in the past is barges.

Strange, there were two quite distinct barges on view a few nights ago when I was comparing the 4mm SLV and SW Planetary. I wonder if the poor seeing you currently have is limiting the finer details of such things?

[John]

13 minutes ago, Geoff Barnes said:

Strange, there were two quite distinct barges on view a few nights ago when I was comparing the 4mm SLV and SW Planetary. I wonder if the poor seeing you currently have is limiting the finer details of such things?

If the seeing is not that good, it is possible to mistake barges in the S part of the NEB for festoons and vice versa

Your seeing will be better than ours Geoff so your views will be more reliable I would think.

Chris caught Jupiter on 1st July and got a nice image. I don't see obvious barges there on that face of the planet at least:

Aussie Dave got the big planet from Oz on 2 July. I guess that small dark feature between the 2 white spots in the belt S of the GRS could be termed a barge of sorts. Or a darkening in the S temperate belt perhaps ?:

 

[Geoff Barnes]

I would say the barges I saw were as evident as the ones in this image, so maybe wouldn't be visible to you up there.....

 

[John]

Not sure about barges in those pics - I see small darkened patches, some spots and contrast darkenings but not what I term barges ?

This is what I refer to as barges:

We could just be getting a bit mixed over nomenclature ?

 

[Geoff Barnes]

Probably not the best example I could've shown, these images by Damian Peach are much more akin to what I saw, are these dark ovals not barges?.....

[John]

It's difficult to be precise about when an oval becomes a barge and the other way around. Personally I'd probably refer to the 2 features in the NEB as dark ovals and the more elongated feature in the N temp belt (to the left of the white oval) as a barge.

But thats just my interpretation !

Either way I've not seen such features at this opposition as yet or the last one as I recall but they have been there before that. Maybe it's the seeing or maybe the barges have become scarcer ?

I'm glad you are getting some great views of Jupiter Geoff - it keeps us up here keen for the next opposition and to make what we can of this one

[Geoff Barnes]

I don't want to drag this out any longer, but this post of yours John does illustrate how confusing some of Jupiter's features can be where barges do look like ovals.

( click on John's name at top)...

Satis dictum! 🙂

Edited July 9, 2019 by Geoff Barnes

[John]

I guess thats the joy of Jupiter - always something going on and not always the expected stuff !