Does Callisto have any satellites ?

Hi,

I did my first decent spot of observing last night around midnight till 2am ish
and I noticed something in the region of Callisto :

There seemed to be two small points near it, one northish and the other
southish of it at a distance of around 1/4 or 1/8th of Callistos' aparent
distance from Jupiter.

Wikipedia doesn't say anything about Callisto having a natural moon and I
wondered if there is anything man made orbiting Callisto a.t.m. ? The objects I
saw are not shown by my copy of Stellarium and they were definitely not
HP71189/71240 which are much further away and were a long way out of the f.o.v.

Scope was a Revelation 12 and the items were clearly visible at magnifications
of 250 and 125.

Cheers,

--
Boo

On Tue, 30 May 2006 14:35:29 +0100, Boo
wrote:

Hi,

I did my first decent spot of observing last night around midnight till 2am ish
and I noticed something in the region of Callisto :

There seemed to be two small points near it, one northish and the other
southish of it at a distance of around 1/4 or 1/8th of Callistos' aparent
distance from Jupiter.

Wikipedia doesn't say anything about Callisto having a natural moon and I
wondered if there is anything man made orbiting Callisto a.t.m. ? The objects I
saw are not shown by my copy of Stellarium and they were definitely not
HP71189/71240 which are much further away and were a long way out of the f.o.v.

Scope was a Revelation 12 and the items were clearly visible at magnifications
of 250 and 125.

Most likely stars. TYC5576-364-1 (mag. +10.0) was 26" south of
Callisto at 23h00m last night.
--
Pete
http://www.digitalsky.org.uk

Most likely stars. TYC5576-364-1 (mag. +10.0) was 26" south of
Callisto at 23h00m last night.

Can't have been that one : the entire f.o.v. would have been only around 15"
and the two points I saw were much closer to Callisto than the edge of the f.o.v.

--
Boo

On Tue, 30 May 2006 15:28:20 +0100, Boo
wrote:

Most likely stars. TYC5576-364-1 (mag. +10.0) was 26" south of
Callisto at 23h00m last night.

Can't have been that one : the entire f.o.v. would have been only around 15"
and the two points I saw were much closer to Callisto than the edge of the f.o.v.

Well this is what it looked like...

http://www.digitalsky.org.uk/temp/2006-05-29_test.jpg

--
Pete
http://www.digitalsky.org.uk

Pete Lawrence wrote:
On Tue, 30 May 2006 15:28:20 +0100, Boo
wrote:

Most likely stars. TYC5576-364-1 (mag. +10.0) was 26" south of
Callisto at 23h00m last night.
Can't have been that one : the entire f.o.v. would have been only around 15"
and the two points I saw were much closer to Callisto than the edge of the f.o.v.

Well this is what it looked like...

http://www.digitalsky.org.uk/temp/2006-05-29_test.jpg

That's them ! That can't be a half an arc minute though surely ?

--
Boo

On Tue, 30 May 2006 18:59:39 +0100, Boo
wrote:

Pete Lawrence wrote:
On Tue, 30 May 2006 15:28:20 +0100, Boo
wrote:

Most likely stars. TYC5576-364-1 (mag. +10.0) was 26" south of
Callisto at 23h00m last night.
Can't have been that one : the entire f.o.v. would have been only around 15"
and the two points I saw were much closer to Callisto than the edge of the f.o.v.

Well this is what it looked like...

http://www.digitalsky.org.uk/temp/2006-05-29_test.jpg

That's them ! That can't be a half an arc minute though surely ?

Jupiter itself is currently 43" across you know ;-)
--
Pete
http://www.digitalsky.org.uk

JRS: In article , dated Tue, 30 May
2006 14:35:29 remote, seen in news:uk.sci.astronomy, Boo reply_to_group
posted :

I did my first decent spot of observing last night around midnight till 2am ish
and I noticed something in the region of Callisto :

There seemed to be two small points near it, one northish and the other
southish of it at a distance of around 1/4 or 1/8th of Callistos' aparent
distance from Jupiter.

Alas, the chances of a newish amateur seeing any permanent member of the
Solar System before it is seen by professionals or observed by
spacecraft must be pretty well negligible. Possible exceptions - very
small objects that come very close, and so shift from visible-to-nobody
to fairly-readily-visible in a short time - such as little comets, and
atmosphere-grazing meteors.

Wikipedia doesn't say anything about Callisto having a natural moon and I
wondered if there is anything man made orbiting Callisto a.t.m. ?

Callisto is some 3000 miles across; ISS, which is the largest man-made
object in space, is under 150 feet across on average. Therefore, the
ratio of brightness between Callisto and an ISS magically moved there,
given that the reflectivity is unlikely to differ by much more than a
factor of 10, must exceed about 100000^2 = 1E10. That's 25 magnitudes.


Iridium flares, at a distance of under 500 miles, go up to mag -8.
Callisto's distance is about 500 million miles, so we have a factor of
(1e6)^2 for that, and another of 25 for distance from Sol. That's about
33 magnitudes reduction, giving +25.

That suggests that flares from a satellite in the Jupiter system, **if**
it had very large and flat solar panels, **might** just about be
detectable with the best equipment in or around Earth - someone else can
probably give a better estimate.



Stephen - FAQ W.2 - how about adding, after Pluto, the magnitude limit
of the best telescopes? ((( BTW - apart from the entries for Mags +2 +4
+6.5, none of those are strictly "common objects", since each is unique
G ))) Or maybe in O.7 ??

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

Anyone have any luck seeing the smaller moons of Jupiter or Saturn?

Thanks,
Greg

On 30 May 2006 14:25:00 -0700, "Don't Be Evil"
wrote:

Anyone have any luck seeing the smaller moons of Jupiter or Saturn?

Seeing directly no, but here's Himalia from tonight...

http://www.digitalsky.org.uk/jupiter/himalia.html
--
Pete
http://www.digitalsky.org.uk

Dr John Stockton wrote in
:

JRS: In article , dated Tue, 30 May
2006 14:35:29 remote, seen in news:uk.sci.astronomy, Boo reply_to_group
posted :

I did my first decent spot of observing last night around midnight till
2am ish and I noticed something in the region of Callisto :

There seemed to be two small points near it, one northish and the other
southish of it at a distance of around 1/4 or 1/8th of Callistos'
aparent distance from Jupiter.

Alas, the chances of a newish amateur seeing any permanent member of the
Solar System before it is seen by professionals or observed by
spacecraft must be pretty well negligible. Possible exceptions - very
small objects that come very close, and so shift from visible-to-nobody
to fairly-readily-visible in a short time - such as little comets, and
atmosphere-grazing meteors.

The chances of such are going to get even less in the future when systems
like the LSST are up and running. A shame in some ways but that's progress.

Klazmon.


SNIP