[X] My Assistant

[elakdawalla]

Hi everybody,

I was talking with Amanda Hendrix at JPL today about the upcoming icy satellite encounters, and she asked me if I had any way of getting in touch with amateur observers. They are looking for people to do photometric observations of Hyperion for several days on either side of the flyby. She said: "Ground-based observing will help to constrain the current state of rotation of Hyperion, whose spin axis changes. The visual magnitude of Hyperion is 16.5, so serious photometry would require at least a 24-inch telescope."

Gulp. That's a big telescope, and short notice, with the encounter only 6 days away. I'm not an observer so I don't know how to get in touch with lots of amateurs with big scopes except for the couple of people I know personally. Can anybody on this board help get the word out?

--Emily

[elakdawalla]

It turns out there's hope for people with smaller telescopes after all. I got this in an email from Anne Verbiscer yesterday (she's the U. of Virginia planetary astronomer who did those Earth based opposition effect studies of Saturn during Earth's central transit across the Sun as seen from Saturn in January):

I took a look at your online entry calling for observations of Hyperion and found that you might be discouraging some potential observers by saying that they need to have a telescope 24-inches or larger.  One may need a substantial telescope in order to see Hyperion through an eyepiece with your own eye, but a CCD on even a modest (~ 8") telescope can make a long exposure and observe Hyperion quite easily.

Also, not to nitpick about numbers, but a quick check (i.e. Google) on the V magnitude of Hyperion comes up 14.2, not 16.5. That is an estimate of its magnitude at opposition (which we are nowhere near... the phase angle now is more than 6 deg.), so it will be dimmer than 14.2, but not by more than 2 magnitudes.

--Emily

[odave]

That's true, but I wondered if the eposure length would impact the data, and if having something bright like Saturn nearby would saturate the camera. I've never tried to image any of the moons by themselves - anyone else?

I may give it a shot, though my camera dates from those ancient days when a 640x480 CCD was considered "good" amateur equipment (1998).

[tedstryk]

That's true, but I wondered if the eposure length would impact the data, and if having something bright like Saturn nearby would saturate the camera.  I've never tried to image any of the moons by themselves - anyone else?

I may give it a shot, though my camera dates from those ancient days when a 640x480 CCD was considered "good" amateur equipment (1998). 

Other than being hard to aim, 640x480 really isn't a problem, since Hyperion will be a point source anyway! In fact, in planetary imagery, it is best to not magnify the image beyond the point that maximizes your telescope's resolution in the seeing conditions, because any enlargement beyond this simply spreads the light over more pixels, leading to a fainter image, and hence requiring a longer exposure time, allowing more impact from atmospheric seeing conditions.

[malgar]

Paolo Tanga
post-doc at Observatoire de la Côte d'Azur, France
Laboratoire Cassiopee, CNRS
Equipe Planétologie et systèmes dynamiques (Planetology and Dynamical Systems) reports this:

"Saturn is not very far from conjunction, at 50 degrees from Sun, that seems a lot but they are quite littles to observe it in the sky.
Hyperion, in these geometrical conditions, doesn't reach 2' of elongation from Saturn. They are very littles to don't be disturbed by the planet's light.
Photometric precision required is high and not easy with little diameters.
BTW, those with a really good equipment (cooled CCD, big and good telescope) could try."

Sorry for my very bad translation...
Bye,
Ale.

[odave]

I finally got some decent sky conditions this morning to try imaging Hyperion. I haven't done any CCD work in about 5 years, so I was a bit rusty, but all the equipment still seemed to work.

Anyway, here's what I got using my 8" SCT and SBIG ST-237 CCD camera (which is a bit of a dinosaur by today's standards) working at f/10, 10 second exposure.



Saturn is the saturated blob, Tethys and a background star are visible to the right, Titan, Dione, Rhea are pretty obvious on the left, and far to the left, waaaaay down there, just barely above the noise, is Hyperion. You may need to adjust your monitor's brightness/contrast to see it.

So it is feasable to get some photometry data with smaller equipment. A longer exposure with Saturn out of the frame will help bring it out more. The weather looks good for tomorrow AM as well - I'll give it another shot.

I may not be able to generate useful data for Cassini, but I think I'll go through the exercise anyway to get some experience for next time

[elakdawalla]

I may not be able to generate useful data for Cassini, but I think I'll go through the exercise anyway to get some experience for next time

Cool, O'Dave! Thanks for posting. I think it's cool that this challenge got you to dust off your equipment.

I'd like to collect anybody else's attempts to do this Hyperion viewing -- please share!

--Emily