Small worlds: Mars, Uranus & Neptune in 1 night...

[Kokatha man]

Please excuse the almost 100% "cut & paste" from the thread I posted earlier today on Cloudy Nights - it was far too much to rewrite it separately for SGL.

Hi all - Pat & I will now take a rest from imaging & indulge in our new addiction of small vintage Japanese refractors...retiring to the "Classic Scopes" forum on CN until those planets we'll image rise to an acceptable elevation down here!

"Small worlds" refers to the apparent diameter of these 3 planets atm - Mars at 4.4" being the largest, followed by Uranus at 3.7" & Neptune at 2.3".

We went to Palmer where we were the first AA'ers to image Saturn's North Polar hexagon quite a few years ago now...haven't been there too often these last couple of years but decided it was the best place for last Saturday night. (9th December)

After our recent problems being ready etc for Neptune imaging we were well-prepared for the earliest possible start this night - greeted with good seeing even though Neptune was pretty low by the time we could see & target Lambda Aquarii: no sign of the (hoped for) Equatoria activity but even my sceptical appraisal "thinks" a Southern Latitude spot can be seen in 2 of the images measured at about -30°S in one of the images posted below.

Moving to Uranus for only about the 3rd time this year when it had dropped to around 42° we were surprised to see a rather steady feed: both iR610nm images yielded good outcomes & the NP collar was evinced along with the darker N. Temperate Belt & the thin, brighter Equatorial band, about as good as one can hope for unless there is a storm - & one of these hasn't been seen for several years...only very recently I said to someone here on CN that I didn't think we'd get anything on Uranus this year because of elevation & seeing - but it just goes to show that I spoke too soon..!

The iR610 is a WinJupos integration of the 2 captures (each 9 minutes at 100fps) we took with that filter.

Encouraged by the steady seeing we decided to attempt an r-g-b capture, 5 minutes each for the red & green & a bit longer for the blue to ensure that this channel yielded something worthwhile even with drastic frame culling in AS3.

Of note was that like the iR610nm captures where we know we can see the brighter NP region in the live onscreen feed, we could also see it in the red channel display onscreen!

The r-g-b image outcome does show this brighter NP region contrasted against the darker NT area to the left of it in the image: this rgb Uranus showing albedo variations (all from the r-channel) was a bit of a bonus particularly in light of what I had recently said about our opportunities with this planet in 2017..!

Have posted a small snippet of the livefeed onscreen display of Uranus to show the type of seeing we were lucky enough to encounter - we did not re-collimate as we normally would between Neptune & Uranus because the planet was dropping rapidly.

Hit the sack about 12:30am & decided to be silly with an attempt on Mars in the morning...

Got up about 3/4 hour before sunrise & after setting up had lost Mars to our eyesight but could still see Jove & the Moon, knowing Spica's rough position apropos these 2 objects...

By a lot of luck I got Spica rather quickly in the finder & we enabled a quick but decent collimation - we'd had the foresight to at least find rough focus earlier that night after finishing Uranus imaging - we had swapped the train to the ASI224MC (wasn't silly enough to attempt without an ADC or use the mono camera...employing a train that utilised the 2" Antares 1.6X barlow, a good unit under-utilised these days for us.)

I'd decided that Mars was not worth trying to find & swung the scope back towards a pathetically low Jupiter...& again by sheer chance caught Mars in the finder as we slewed towards Jove low on the eastern horizon..!

Focusing was about as demanding as we could possibly imagine & with no time to spare as the Sun was rising - ran a 2 minute 8 second avi followed by a 6 minute 20 second one.....plus a couple of others well after the Sun had risen: sun-light was shining on the end of the dew-shield as we went through the 2nd capture & fully on the scope for the last 2. (it rises earlier on the Murray Mallee plains due to the flat horizon)

Nothing at all to get excited about but it at least displayed some detail on the Acidalium & Sinus Meridiani - Oxia Palus - Aurorae Sinus & associated Mare Erythreum etc regions...a tiny 4-frame animation as well btw! 

We'll leave imaging the planets of the 2018 apparition to braver souls than us as we wait & do other things until the New Year!

 

 

[knobby]

Great stuff and very informative.

[Pete Presland]

A terrific set of images. Always good to see the live feed capture view posted as well, it indicates the seeing and how much work is left after capturing. 

Considering the current size of Mars that is a very respectable capture with some nice detail. Its still amazes me that such detailed images of Uranus and Neptune can be produced rom ground based telescopes.

I notice you use a 224mc on Mars and the 290mm+610 filter on the ice planets. Why do you choose the 290mm over the 224mc, is it purely because its mono? I have an older 120mm-s still, but seem to get better results with my 224mc.

[Kokatha man]

Hi Pete - we use the ASI290MM (mono) almost exclusively...but with Mars at 30° & the Sun already up there was no way I was going to try r-g-b capture runs, plus we thought that the ADC might assist,although it really did not tbh.

Fortunately,before we hit the sack after Uranus imaging I'd set up the ASI224MC with the Antares 1.6X barlow & ADC & adjusted the primary mirror focus for that imaging train...although we still had to collimate on Spica in the morning...

Here's the live feed of Mars btw - & remember this is AFTER I focused..!

Also, instead of the 2 Uranus captures integrated in WinJupos, this is the 2nd capture by itself where I think some of the more subtle features are better seen tbh. (eg, in the LHS inset, the red lines pointing to the North Polar "collar" of darker shading surrounding the NP & some darker shading above the North Temperate Belt (ie, to the right in the image) in an area normally depicted as just a bright NP zone...just as the NP "collar" is rarely evinced also...  -

[Pete Presland]

Looking at the respective QE charts for the 120mm-s and the 290mm, am correct in thinking the 290 is quite a bit sensitive. Especially from around the wavelength 600nm and up.

[Kokatha man]

...I think so Pete, although I haven't looked at those graphs for quite some time...remembering that you have to factor in that until you go longer/deeper into iR, the G & B's response isn't as good as the R...& with a mono all the pixels are exposed to R...

[sloz1664]

Great set of images and very informative. Thanks for posting.

Steve

[Mr niall]

Amazing images, not seen any ones of Ariel for ages.

[mystyco]

Love the Mars shot, very impressive. A lot of details.

[Owmuchonomy]

On 13/12/2017 at 09:03, Kokatha man said:

Hi Pete - we use the ASI290MM (mono) almost exclusively...but with Mars at 30° & the Sun already up there was no way I was going to try r-g-b capture runs, plus we thought that the ADC might assist,although it really did not tbh.

Fortunately,before we hit the sack after Uranus imaging I'd set up the ASI224MC with the Antares 1.6X barlow & ADC & adjusted the primary mirror focus for that imaging train...although we still had to collimate on Spica in the morning...

Here's the live feed of Mars btw - & remember this is AFTER I focused..!

Also, instead of the 2 Uranus captures integrated in WinJupos, this is the 2nd capture by itself where I think some of the more subtle features are better seen tbh. (eg, in the LHS inset, the red lines pointing to the North Polar "collar" of darker shading surrounding the NP & some darker shading above the North Temperate Belt (ie, to the right in the image) in an area normally depicted as just a bright NP zone...just as the NP "collar" is rarely evinced also...  -

Very interesting thread.  I'm interested to know if you run the C14 at native f/11 with the 290MM or do you Barlow to 1.5x or 2x?

[Kokatha man]

Good grief..!  

I must admit I haven't posted on SGL for quite some time, but seeing a response to this old thread from last year was quite a surprise!

Chris, we never image at native scale for any planet...& for this mono camera we barlow at about 1.8x...this is achieved by using just the lens element of a Televue 2x barlow & setting the camera sensor at the relevant back-spacing distance (which incorporates the EFW) to achieve said amplification.

My conscience has been pricked.....so I'll try & put together a compendium of our 2018 Mars captures when I am able. (the 2018 Mars imaging opportunities have almost finished btw)