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All observing logs tagged with Jovian Event

2006-06-28


Location: Billingborough (South Lincolnshire, UK)
From: 2006-06-28 14:55 UT
To: 2006-06-28 15:00 UT
Equipment: Solarscope
Temperature: 22.9C ...
Dew Point: 10.5C ...
Humidity: 47% ...
Wind Speed: Calm ...
Pressure: 1018.7hPa ...
Notes:

Today has been similar to yesterday in that the day has mostly been overcast except for a brief spell of broken cloud in the afternoon. During this brief spell of sunshine I took the Solarscope out to do a sunspot count.

Sun

From: 2006-06-28 14:55 UT
To: 2006-06-28 15:00 UT

Area 897 was more spread out when compared to yesterday (hardly surprising given that it has rotated further into view) and I could count 5 spots in the region. The darkening I noted yesterday wasn't evident today.

New area 898 has come over the limb and comprises of a single, large, circular spot with quite a pronounced penumbra.

Location: Billingborough (South Lincolnshire, UK)
From: 2006-06-28 21:35 UT
To: 2006-06-28 23:34 UT
Equipment: Antares 905
Sky-Watcher Explorer 130M
Temperature: 16.8C ...
Dew Point: 9.0C ...
Humidity: 60% ...
Wind Speed: Calm ...
Pressure: 1019.1hPa ...
Notes:

Calm, clear evening with some thin cloud about. The sky wasn't very dark yet but given that I could see Jupiter from my usual observing spot I decided to get the 905 out and have a look.

Jupiter, including a transit event

From: 2006-06-28 21:35 UT
To: 2006-06-28 22:59 UT

Started out with the 905 and 6mm eyepiece. The image was awful. I could only just see the two main bands. The reason for this was probably down to the quality of the sky and also down to the fact that the 'scope hadn't had much time to cool down yet.

I could see all 4 Jovian moons (one of them was very close to the planet) and I could also see a reasonably bright background star that could have been mistaken for a 5th moon (later checking with Starry Night showed that it was HIP70714 ).

I then added the #80A Medium Blue filter to the 'scope and had another look. While this dulled the image a little it did also appear to improve the contrast. The two main bands stood out a little better, darkening towards the poles became obvious and in moments when the image was steady there was obvious mottling in the bands.

I'd say that tonight's view of Jupiter is the worst one I've had this apparition.

I've never compared the view of Jupiter in the 130M with that in the 905 so, at around 21:53 UT, I brought the 130M out and left it to cool off. A short while later (probably with too little cooling-off time) I lined Jupiter up in the 130M and used the 6mm eyepiece to have a look. The imagine was really terrible — much worse then the image in the 905. While the view was much brighter there was hardly any detail to speak of, almost as if it was impossible to get sharp focus.

I switched from the 6mm to the 10mm eyepiece and things looked a little better. This time the quality compared more favourably with that as seen in the 905+6mm but, even then, I'd say that the 905 won out in terms of detail that could be seen. It would appear that I need to give the 130M a good check-up at some point. While I did give the collimation a quick check when I brought the 130M out I guess I need to have it a really fine tweak some time soon.

I'm also seeing why planetary observers tend to prefer a refractor rather than a reflecting telescope.

Back at the 905 (with the 6mm), at around 22:19 UT, I noticed that the moon closest to Jupiter had apparently got even closer. Compared to when I started observing this evening it was harder to see it, the gap between it and the planet being obviously narrower. I stepped into the office to check what was going on and I confirmed that the moon was Europa and that it was due to start a transit of the planet at around 22:38 UT. My first ever transit of a Jovian moon! Annoyingly, when I came back out of the office, I noticed that some thin cloud had moved in the way and was dulling the view of Jupiter.

By 22:31 UT the image had improved again. I could just see Europa but it was impossible to see a gap between it and the planet — it looked more like a bump on the limb.

By 22:36 UT I had lost sight of Europa. From then until 22:59 UT I kept observing to see if I could detect Europa in front of the planet but I never got a hint of it. This was made harder by the fact that more thin cloud was moving in the way and significantly dulling the view.

Random sweeping of the Milky Way

From: 2006-06-28 23:00 UT
To: 2006-06-28 23:34 UT

To finish off the session I decided to use the 905 for one of the main purposes I intended: just sweeping around the sky and seeing what I can find. Using the 32mm eyepiece I started to have a random sweep and, almost right away, stumbled on The Coathanger (an asterism I first observed almost a year ago).

After spending some more time just sweeping around (mostly around The Milky Way in and around Cygnus) I decided to call it a night at 23:34 UT.


2006-06-08


Location: Billingborough (South Lincolnshire, UK)
From: 2006-06-08 14:05 UT
To: 2006-06-08 14:13 UT
Equipment: Solarscope
Temperature: 23.2C ...
Dew Point: 14.1C ...
Humidity: 57% ...
Wind Speed: Calm ...
Pressure: 1024.4hPa ...
Notes:

Very clear and calm day. Just the odd bit of very high-level cloud around, also a slight haze in the sky.Took the Solarscope out to do a quick sunspot count.

Sun

From: 2006-06-08 14:05 UT
To: 2006-06-08 14:13 UT

Area 892 looked a little less detailed when compared to yesterday with only 8 spots visible.

Area 893 also looked a little less complex too with just 2 spots visible (compared to yesterday's 3).

Location: Billingborough (South Lincolnshire, UK)
From: 2006-06-08 21:45 UT
To: 2006-06-08 22:55 UT
Equipment: Antares 905
Temperature: 16.5C ...
Dew Point: 11.2C ...
Humidity: 71% ...
Wind Speed: Calm ...
Pressure: 1024.1hPa ...
Notes:

Mostly clear night with some thin cloud around (I could, for example, see a pretty nice halo around the Moon). The sky was still very light but given that Jupiter was in a position where I could see it from my back garden I decided to have a quick session looking at it with the 905.

Jupiter, including a shadow transit

From: 2006-06-08 21:45 UT
To: 2006-06-08 22:55 UT

I got Jupiter lined up in the 905 using a low-power eyepiece and then I dropped in the 6mm eyepiece. Initially the image was pretty poor, moving around quite a bit and the visible detail was much less than previous views of the planet with the same equipment. That said, the 'scope hadn't had any chance to cool down.

As usual the two main bands were easily visible and there was obvious variation on the rest of the disc. I could only make out three moons (later checking showed them to be Europa, Ganymede and Callisto). Europa and Callisto were some distance out, either side of the planet while Ganymede was quite close to the planet.

Around 21:58 UT, in very steady moments (the image was rapidly getting better), I started to notice a very clear, sharp, dark spot near the north pole of Jupiter. My initial impression was that I was seeing a shadow of one of the moons (presumably the Ganymede). To be sure that this wasn't just an artifact I tried changing eyes, rotating the eyepiece and shifting the 'scope about to place the planet in a different part of the field of view. Nothing I did changed the image.

After watching this a bit more I grabbed my sketching box and, between 22:10 UT and 22:15 UT, I made the following rough sketch so that I could compare the view I had with some other source later.

Rough sketch of my view of Jupiter

After doing the sketch I popped into the office and fired up Starry Night to check what I was seeing. It confirmed that I was seeing a shadow and that it was the shadow of Ganymede. My first ever Jovian shadow transit!

Around 22:30 UT some thin cloud moved in such that my view of Jupiter got a lot worse. The amount of visible detail was reduced and I could no longer see the shadow. By 22:39 UT the cloud was still hanging around and the image had deteriorated even more. I also noticed that the air suddenly felt quite damp and that a thin layer of dew was forming on everything.

By 22:50 UT the cloud had finally cleared and the view of Jupiter had improved again (although it didn't seem to be as crisp as it had earlier on) but I still couldn't make out the shadow any more. At 22:55 UT, given that I still couldn't make out the shadow and that I needed to get to bed soon, I called it a night on the session.

Checking the following day, using the "Jupiter's Moons" tool on the Sky & Telescope website, I've now further confirmed that it was Ganymede's shadow. The times given for the event are:

  • 21:18 UT Ganymede's shadow begins to cross Jupiter.
  • 23:08 UT Ganymede's shadow leaves Jupiter's disk.

This would explain why I was unable to see the shadow towards the end of the session: it would have been very close to the edge of the planet's disc and I would probably have been unable to resolve it that close with the equipment I was using.


Page last modified: 2013-04-09 09:19:19 UT
Dave Pearson <davep@davep.org>
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