Great video of Titan occulting a double star

[SkyViking (Rolf)]

One of the coolest videos I have seen:
http://www.universetoday.com/72273/w...y-star-system/

[bird (Anthony Wesley)]

That is possibly the coolest thing I've ever seen... I want one :-)

Bird

[John Hothersall]

Love the way it flickers as it goes behind through atmosphere.

John.

[SkyViking (Rolf)]

I noticed there is now a youtube video of the event on that page, but the original video referenced in the article shows quite a bit more detail I think - best video is here: http://web.gps.caltech.edu/~mbrown/t...ccultation.mpg

[multiweb (Marc)]

Originally Posted by John Hothersall

Love the way it flickers as it goes behind through atmosphere.

John.

Yeah, that was weird hey? You can see the occulted star disc popping up briefly on the periphery of the satellite like flashes. Very cool.

[CraigS]

That was truly outstanding !!! Clever optics and an unusual event from which so much can be discovered !

The paper is interesting, also.

Mike Brown, eh ? .. "The man who killed Pluto" !

Thanks kindly for the 'heads-up', Rolf ... much appreciated !

Cheers

[SkyViking (Rolf)]

Originally Posted by multiweb

Yeah, that was weird hey? You can see the occulted star disc popping up briefly on the periphery of the satellite like flashes. Very cool.

It's awesome, and notice how each occulted star image appears on both sides of Titan at the same time! There is a great diagram of this in the mentioned paper, the stellar images seems to follow a line around Titan at 200-300km altitude.

[Matt Wastell (Matt)]

Excellent - thanks for taking the time to share!

[batema (Mark)]

Yes thats amazing.

[troypiggo (Troy)]

That's a ripper.

[Liz]

That was great!! Thankyou.

[DavidU (Dave)]

Very cool. Is it that the star refraction is quite large due to a hydrocarbon atmosphere on Titan?

[troypiggo (Troy)]

Originally Posted by DavidU

Very cool. Is it that the star refraction is quite large due to a hydrocarbon atmosphere on Titan?

I assumed it was due to the extremely high magnification/f-ratio that would be required to see this event.

[CraigS]

Some interesting info from the paper they wrote may provide some answers to the observations raised in the posts below. Here goes:

"Upon ingress and egress, both stars underwent large fluctuations in brightness on a timescale shorter than our sampling rate of 880 ms, though this effect was much more pronounced in the occultation of the western star, which passed south of Titan’s center. This well-known phenomenon is caused by local density variations, which in the case of Titan probably arises from upward-propagating gravity waves in the stratosphere."

(That one has me interested. More reading to do to work out the whats & whys).
...
"A more detailed analysis of the positions of both the near- and far-limb refracted stellar images of each occultation may allow us to map Titan’s stratospheric zonal wind velocities at two altitudes in each hemisphere".
(Interesting).
...
"The gradual drop of a star’s lightcurve at the point of immersion into the body’s atmosphere, and the subsequent rise at emersion, can be inverted to derive the local temperature and density profiles in the microbar pressure range. The primary cause of the dimming is differential refraction, effectively defocusing light rays in the plane of the local density gradient along the ray’s trajectory."
They're even reading the local temperatures & pressures from the light!
...
"For observers whose path lies near enough to the shadow’s geometric center, a “central flash” may be observed due to the coherent focusing of the starlight by multiple points on the planet’s limb. Imagine the ideal case of a perfectly spherical atmosphere, observed from the midpoint of its shadow. Every point on the limb is then capable of refracting starlight to the observer, leading to a sudden increase in the total stellar intensity recorded. The central flash was first recorded in unresolved photometry of the occultation of ε Gem by Mars on 8 April 1976, where it was used to derived the mean opacity of the lower Martian atmosphere near the south pole (the region inferred to have been sampled by the magnified rays)."

There's heaps of other interesting info they've learned from the observations discussed in the paper.

Hope the above helps & is interesting. (Even if this post has ended up a bit long).

Cheers & Rgds.