Help! Nereid's position?

On Fri, 19 Sep 2003 12:21:54 GMT, (Maurice Gavin)
wrote:

Can someone accurately compute the position of Nereid for 2003 Sept 17
@ 22.00UT [J2000]. TIA.

Nereid was at PA 67 degrees, DIST 4' 24" (~mag. +19)
Triton was at PA 210 degrees, DIST 0' 14" (~mag. +13.5)

If you need a schematic for overlay purposes shout...

--
Pete
Homepage at http://www.pbl33.co.uk
CCD/digicam astronomy

Maurice Gavin wrote:
: On Fri, 19 Sep 2003 14:01:50 +0100, Pete Lawrence
: wrote:

:On Fri, 19 Sep 2003 12:21:54 GMT, (Maurice Gavin)
:wrote:
:
:Can someone accurately compute the position of Nereid for 2003 Sept 17
:@ 22.00UT [J2000]. TIA.
:
:Nereid was at PA 67 degrees, DIST 4' 24" (~mag. +19)
:Triton was at PA 210 degrees, DIST 0' 14" (~mag. +13.5)
:
:If you need a schematic for overlay purposes shout...
:
:--
:Pete
:Homepage at http://www.pbl33.co.uk
:CCD/digicam astronomy

: Sorry Pete - I need RA:h m s; Dec: o ' " for J2000 !

You can get that information for yourself using the MPC MPChecker
(http://scully.harvard.edu/~cgi/CheckMP). Simply enter the desired
date into the box, click the button that says "Include ONLY planets and
irregular outer satellites", then "Produce list".

For 2003 Sept. 17.92 UT this returns:

Neptune II 20 52 55.8 -17 31 36 19.1


--
------------------------------------------------------------------------
Gareth V. Williams, MS 18, 60 Garden Street, Cambridge, MA 02138, U.S.A.
Associate Director, IAU Minor Planet Center
http://cfa-www.harvard.edu/iau/mpc.html
OpenVMS & RISC OS: refined choices in operating systems

On Fri, 19 Sep 2003 15:14:11 GMT, (Maurice Gavin)
wrote:

On Fri, 19 Sep 2003 14:01:50 +0100, Pete Lawrence
wrote:

On Fri, 19 Sep 2003 12:21:54 GMT, (Maurice Gavin)
wrote:

Can someone accurately compute the position of Nereid for 2003 Sept 17
@ 22.00UT [J2000]. TIA.

Nereid was at PA 67 degrees, DIST 4' 24" (~mag. +19)
Triton was at PA 210 degrees, DIST 0' 14" (~mag. +13.5)

If you need a schematic for overlay purposes shout...

--
Pete
Homepage at http://www.pbl33.co.uk
CCD/digicam astronomy

Sorry Pete - I need RA:h m s; Dec: o ' " for J2000 !

Oh Maurice - that's easy enough to do in your head! Given that
Neptune is at 20h 52.704m -17d 33.236', you should be able to work out
that Nereid is at 20h 52.988m -17d 31.516' and Triton is at 20h
52.695m, -17d 33.449'. (d = degrees).

Unfortunately, in all seriousness, I have no idea what Epoch Starry
Night uses for it's co-ordinates or just how accurate the program is
to this sort of level. I did try though.

--
Pete
Homepage at http://www.pbl33.co.uk
CCD/digicam astronomy

Pete Lawrence wrote:
snip
: Oh Maurice - that's easy enough to do in your head! Given that
: Neptune is at 20h 52.704m -17d 33.236', you should be able to work out
: that Nereid is at 20h 52.988m -17d 31.516' and Triton is at 20h
: 52.695m, -17d 33.449'. (d = degrees).

: Unfortunately, in all seriousness, I have no idea what Epoch Starry
: Night uses for it's co-ordinates or just how accurate the program is
: to this sort of level. I did try though.

The position of Neptune above looks as if it is an apparent position.

The offset of Nereid is +6' 5" (= +25s) of R.A. and +141" of Decl.
(agreement between the MPC MPChecker and the AA): these values do
not seem to agree with your offset of 264" in P.A. 67 deg.

--
------------------------------------------------------------------------
Gareth V. Williams, MS 18, 60 Garden Street, Cambridge, MA 02138, U.S.A.
Associate Director, IAU Minor Planet Center
http://cfa-www.harvard.edu/iau/mpc.html
OpenVMS & RISC OS: refined choices in operating systems

In message , Pete Lawrence
writes
On 19 Sep 2003 14:46:22 -0400, "Gareth V. Williams"
wrote:
The position of Neptune above looks as if it is an apparent position.

The offset of Nereid is +6' 5" (= +25s) of R.A. and +141" of Decl.
(agreement between the MPC MPChecker and the AA): these values do
not seem to agree with your offset of 264" in P.A. 67 deg.

Not my positions Gareth - Starry Night's positions. I have this
program installed at work to allow me to rough plan a nights
observations. I must say that I've never really used it for high
accuracy stuff.

It would be interesting to check these figures against other
planetaria software.


Guide 8.0 reports

Right ascension: 20h52m55.871s
Declination: -17 31' 35.83"
Mean position at current epoch:
Right ascension: 20h53m08.422s
Declination: -17 30' 44.86"
Apparent position at current epoch:
Right ascension: 20h53m08.563s
Declination: -17 30' 49.01"

Hello Northern Sky doesn't list Nereid.

Pause

Nor does Cartes du Ciel.

Pause

Nor does Skymap. Shame on you, Chris!
BTW, Turnpike's spell checker wants to turn Nereid into nerd.
--
"Forty millions of miles it was from us, more than forty millions of miles of
void"

"Maurice Gavin" wrote in message
...
On Fri, 19 Sep 2003 14:01:50 +0100, Pete Lawrence
wrote:

On Fri, 19 Sep 2003 12:21:54 GMT, (Maurice Gavin)
wrote:

Can someone accurately compute the position of Nereid for 2003 Sept 17
@ 22.00UT [J2000]. TIA.

Nereid was at PA 67 degrees, DIST 4' 24" (~mag. +19)
Triton was at PA 210 degrees, DIST 0' 14" (~mag. +13.5)

If you need a schematic for overlay purposes shout...

--
Pete
Homepage at http://www.pbl33.co.uk
CCD/digicam astronomy

Sorry Pete - I need RA:h m s; Dec: o ' " for J2000 !


Hi Maurice,

Redshift 3 gives it as 20h 53min -17deg 31min J2000 so it probably will not
be anywhere near there ;-)

Robin

"Robin Leadbeater" wrote in message
...
Hi Maurice,

Redshift 3 gives it as 20h 53min -17deg 31min J2000 so it probably will
not
be anywhere near there ;-)


Correction 20h 53min -17deg 33min (forgot I had it set to BST) not that it
matters it's probably wrong anyway

Robin

"Jonathan Silverlight" wrote in message
...

Nor does Skymap. Shame on you, Chris!

.... for the simple reason that Neptune's satellites have no "satellite
theory", and SkyMap doesn't (currently) do numerical integration, which is
the only way to compute the positions of these satellites.

Regards,

Chris

In message , Chris Marriott
writes

"Jonathan Silverlight" wrote in message
...

Nor does Skymap. Shame on you, Chris!

... for the simple reason that Neptune's satellites have no "satellite
theory", and SkyMap doesn't (currently) do numerical integration, which is
the only way to compute the positions of these satellites.

Fair enough! Is it planned for a future release? IRC, you and Bill Gray
have exchanged ideas in the past. I notice that Guide also does a lot of
the faint moons of Jupiter and Saturn that are doubtless being sought by
the real deep-sky hunters.
--
"Forty millions of miles it was from us, more than forty millions of miles of
void"
Remove spam and invalid from address to reply.

On Sat, 20 Sep 2003 01:14:43 +0100, "Robin Leadbeater"
wrote:


"Maurice Gavin" wrote in message
...
On Fri, 19 Sep 2003 14:01:50 +0100, Pete Lawrence
wrote:

On Fri, 19 Sep 2003 12:21:54 GMT, (Maurice Gavin)
wrote:

Can someone accurately compute the position of Nereid for 2003 Sept 17
@ 22.00UT [J2000]. TIA.

Nereid was at PA 67 degrees, DIST 4' 24" (~mag. +19)
Triton was at PA 210 degrees, DIST 0' 14" (~mag. +13.5)

If you need a schematic for overlay purposes shout...

--
Pete
Homepage at http://www.pbl33.co.uk
CCD/digicam astronomy

Sorry Pete - I need RA:h m s; Dec: o ' " for J2000 !


Hi Maurice,

Redshift 3 gives it as 20h 53min -17deg 31min J2000 so it probably will not
be anywhere near there ;-)

Robin
Quite so but Megastar did ok eg correct to my actual Neptune images
hence the need for Nereid's precise position.