Io Transit

[Nightspore]

 

I could see this with my Altair 60mm EDF this morning. I hadn't intended to stay out this late/early but the seeing and transparency were really good. At first I thought it was the GRS, but it was more brown than red. 

 

 

I hadn't taken my ortho's out so resorted to an SvBony zoom and an Altair 3x Tele Extender. I figured it was a transit but it wasn't until I checked SkySafari that I knew it was Io. Pretty good for a 60mm ED doublet! Did anyone else see the transit?

 

 

Edited June 5, 2021 by Nightspore
Forgot the interrogative ...

[FracTak]

Did you spot the shadow transit as well? They are jet black and much easier to see.

[Nightspore]

2 hours ago, FracTak said:

Did you spot the shadow transit as well? They are jet black and much easier to see.

 

Yeah they're usually easier. I can't recall seeing it though as I was a bit distracted by the moon itself. I was surprised I'd witness this with a 60mm doublet.

[FracTak]

1 hour ago, Nightspore said:

 

Yeah they're usually easier. I can't recall seeing it though as I was a bit distracted by the moon itself. I was surprised I'd witness this with a 60mm doublet.

I’m very surprised to be honest, I’ve not been able to easily see Io transits even in larger scopes. They are generally very tricky unless near the limb and definitely would not appear brown. I know there are a few dark barges around at the moment so wonder if it was one of these, rather than Io. What time was it exactly? If the shadow was visible I’m sure that would have stuck out as much more obvious than Io.

[Nightspore]

6 hours ago, FracTak said:

I’m very surprised to be honest, I’ve not been able to easily see Io transits even in larger scopes. They are generally very tricky unless near the limb and definitely would not appear brown. I know there are a few dark barges around at the moment so wonder if it was one of these, rather than Io. What time was it exactly? If the shadow was visible I’m sure that would have stuck out as much more obvious than Io.

 

It was Io. It was perfectly round and contrasted against the EZ. It wasn't a barge. I first observed it at about 02:00. Then had to move the scope as there was an obstacle. Then again from around 02:15 to about 02:50. The 60 EDF has FPL53 glass.

 

 

And a good Strehl number. 

 

 

I was observing the Moon once with a 90mm Mak at 89x.

 

 

I saw a satellite move very quickly in front of it.

 

 

I had the impression of two sets of solar panels.

 

 

All the 'experts' told me that a 90mm Mak doesn't have the resolution to see that kind of detail. I'd argue this.

 

 

I found out what it was after a while using Stellarium and some sites online. It was an old Soviet era satellite; Intercosmos 24. I found this mock-up of it. Note the solar panel array. 

Edited June 10, 2021 by Nightspore

[Nightspore]

Found it on the Shed!

[Nightspore]

On 6/9/2021 at 11:35 PM, FracTak said:

I’m very surprised to be honest, I’ve not been able to easily see Io transits even in larger scopes. They are generally very tricky unless near the limb and definitely would not appear brown. 

 

How about Ganymede transits?

 

 

On Sunday, July 18th at around 01:38 BST I could plainly see Ganymede off the Jovian western limb. Its shadow was well defined more or less in the centre of the equatorial belt. Although there were transparency issues the seeing was exceptional, at least Antoniadi I. I was using a Sky-Watcher Evostar 72ED DS Pro.

 

 

I was initially observing with a TV Everbrite diagonal and a 4mm Takahashi orthoscopic for 105x. There was a Baader Neodymium filter in the diagonal nosepiece. The diagonal was rotated to the right of the fully extended AZ5 mount/tripod and I was seated comfortably looking up into the eyepiece. After only a few minutes I upped the magnification to 120x with a combination of a TV 2x Barlow and a 7mm KK Fujiyama orthoscopic. A few minutes after that I replaced the 7mm KK with a 6mm Tak' ortho for 140x. About an 0.5mm exit pupil. The detail was incredibly sharp and well defined with very rich colours and good colour separation. The GRS was a not easy to discern though as it was near the limb.

 

 

The 72ED DS Pro unsurprisingly has an aperture of 72mm. The doublet 'flint' is an unknown extra-low dispersion glass, but very well colour corrected almost certainly has a good Abbe number. The 'crown' is Schott. The visual back is aftermarket with a compression ring. I had a Baader 2" - 1.25" adapter in it.

 

 

All four Galilean moons were resolved into discs and I could perceive colour in some of them.  I watched Ganymede approach the limb and eventually transit the planetary surface during a period of over an hour. I also witnessed its shadow approach the opposite limb and eventually disappear.

 

 

When the shadow had completely gone I could still distinctly see Ganymede against the planetary surface. It appeared a grey - brown colour. The Evostar has only 12mm larger aperture than the Altair 60 EDF.

Edited July 18, 2021 by Nightspore

[Nightspore]

Wednesday, July 21st, 01:00 BST. 

 

 

I could see Io and its shadow near the western limb at 01:00 BST. I was using the 72ED and 140x magnification (6mm Tak' ortho' plus TV 2x Barlow). Seeing was well above average although the low, bright, Moon caused some transparency issues. I observed for about 75 minutes and watched Io and its shadow slowly track across the surface.

 

 

At 02:15 I could still see both Io and its shadow. Io was a light brown-yellow colour. 

Edited July 21, 2021 by Nightspore

[Nightspore]

 

I caught the tail end of the Europa transit at around 01:40. Seeing was below average and the best magnification I got with the 72ED was 105x (4mm TS Optics Planetary HR). Later I got better magnifications (131.25x, 157.5x) for a short while. I couldn't see the moon against the surface of the planet. I did witness it slowly appear as a spot then separate from the limb.

 

 

I couldn't see any colour in Europa with or without a Baader Neodymium filter. 

 

 

Although that's hardly surprising as it is mostly white. I can often detect a hint of colour in some of the other moons. Whether this is a form of CA or atmospheric in origin is difficult to ascertain. The moons can give a similar hue with different combinations of eyepieces or telescopes. 

 

 

Images by courtesy of SkySafari 6 Pro.

[FracTak]

Nice observations @Nightspore. I believe Ganymede and Callisto are darker so are much easier to see when they transit. In fact Callisto I have mistaken for a shadow in the past. It’s a shame they don’t transit as often as the other two.

 

I will have another try for Io next time, my seeing is often poor around here which obviously doesn’t help. Being able to watch it all the way helps maintain knowledge of where it is so it is easier to pick up. The brighter moons get easier against the limb darkening too.

Edited August 3, 2021 by FracTak

[Nightspore]

45 minutes ago, FracTak said:

Nice observations @Nightspore. I believe Ganymede and Callisto are darker so are much easier to see when they transit. In fact Callisto I have mistaken for a shadow in the past. It’s a shame they don’t transit as often as the other two.

 

I will have another try for Io next time, my seeing is often poor around here which obviously doesn’t help. Being able to watch it all the way helps maintain knowledge of where it is so it is easier to pick up. The brighter moons get easier against the limb darkening too.

 

Thanks. Ganymede and Callisto are darker. Pictures of Io always reminds me of a rotten tomato or something. lol

 

 

Often I'm sure I can see colour in it through a telescope. It definitely isn't grey or brown. Probably just atmospherics. Conditions are important. Jupiter's a bit higher this year and it can often look good on or near transit. It's always been a difficult target though. I could just see the GRS last night at 105x.

[Nightspore]

 

I had an unexpected and impromptu session this morning with the 72ED. Seeing was a good Antoniadi II and I got magnifications of 105x, 120x & 131x on Jupiter (mostly 120x). No clouds (!) although the transparency wasn't as good as I'd have liked. Right at the end of the session I was convinced I could see the GRS and a dark round transit shadow. I could see two moons either side of Jupiter earlier but didn't know which they were. Later after checking SkySafari I discovered that it was Europa's transit shadow. I couldn't see Europa.

 

[MarkAR]

Keep going with the reports, all I've had are some hazy views through 7x50 bono's. Poor skies and clouds mean it hasn't been worth setting up a scope.

 

[Nightspore]

1 hour ago, MarkAR said:

Keep going with the reports, all I've had are some hazy views through 7x50 bono's. Poor skies and clouds mean it hasn't been worth setting up a scope.

 

 

I'll try but it's getting a bit cloudy here. I'm not too optimistic for the Jupiter opposition. But you never know! Of the 82 sessions I've had this year the vast majority of them have been with a grab and go scope 80mm or under. My 60mm Altair EDF doublet has been out the most at 31 sessions, closely followed by the 72ED at 26. The ST80 has been out 17.  I can get any of these scopes out in one journey (there and back). Within a few minutes they can be set-up, cooled down, and deployed.

Edited August 14, 2021 by Nightspore

[Nightspore]

The opposition was almost a disaster but the clouds actually parted twice for a couple of minutes and I got a glimpse of Jupiter with my 127mm SkyMax. Last night (two days after opposition) was a different story.

 

 

I got nearly two hours with the SkyMax. Conditions were generally good although humid. Transparency was well above average and the seeing was a good Antoniadi II~I.

 

 

I watched Ganymede slowly move away from the limb. For a brief moment I could just about see the shadow. I had magnifications of 103x, 128x, 154x, 171x, 205x and 257x. The magnifications with the most acuity and which revealed the most detail were 154x and 171x. Jupiter was so bright at 154x I used a Baader Single Polarising Filter. The GRS was very prominent and considerable detail could be perceived in the NEB.

 

 

 

SkySafari 6 Pro planetary images are mirror reversed 

[Nightspore]

Of the eighteen sessions I've had so far this month, seven have been with my 127mm SkyMax. It's not a scope that gets out much. The conditions seemed good for a 5" Mak though as the bright moon was hindering any rich field observing.

 

 

I started observing the Io transit at around 23:16 BST until 01:23 BST. The seeing was around Antoniadi II~I although the transparency was below average with a high humidity. I'd missed Io approching the limb but the shadow was easily seen at 123x, 154x and 171x using a Takahashi 12.5mm orthoscopic, a 10mm LE and a 9mm orthoscopic. I mainly used the 10mm LE although at one stage I even used a 7.5mm LE (205x). I used five filters: a Baader Contrast Booster,  Baader Light Blue (470nm bandpass), Baader Neodymium, Lumicon #82A (light blue) and a Lumicon #11 (yellow green). I couldn't see Io until it was right near the limb and about to re-appear. I changed filters regularly. I thought the Contrast Booster and the Lumicon #82A revealed the shadow well. Overall detail was good. I definitely think yellow and light blue filters work well on Jupiter.