Jump to content

Io Transit


Recommended Posts

Posted (edited)

MfZYXLh.png

 

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. 

 

CXmxJZF.jpg

 

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 by Nightspore
Forgot the interrogative ...
  • Like 1
Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Posted (edited)
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.

 

6yfPPQf.jpg

 

And a good Strehl number. 

 

n2tr05S.jpg

 

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

 

rfPGbPK.jpg

 

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

 

yvWVZKU.png

 

I had the impression of two sets of solar panels.

 

7pUcRZY.png

 

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

 

Zf6yyF4.jpg 

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 by Nightspore
Link to comment
Share on other sites

  • 1 month later...
Posted (edited)
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?

 

D1yzjw6.png

 

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.

 

dSx4iKul.jpg

 

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.

 

7rzcpmMl.jpg

 

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.

 

4TOCyXd.png

 

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.

 

Jr5oDFP.png

 

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 by Nightspore
  • Like 1
Link to comment
Share on other sites

Wednesday, July 21st, 01:00 BST. 

 

xYh88V3.jpg

 

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.

 

0cCK8Bb.jpg

 

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

Edited by Nightspore
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...