J2000 and Jnow with SLT mount

[Cosmic Geoff]

I have been scratching my head trying to figure out why I was having so much trouble trying to make a 'discovery' image of Pluto. I would use the SLT GoTo and plate-solve to find the area, and then on analysing the images find out that where it was pointing did not match the "TheSKyLive" finder chart at all.  Only one image, with a radical offset to the west, got the planet (confirmed by plate-solving the processed image with Platesolver2.)

I noticed that "TheSkyLive" is using J2000 co-ordinates. It occurred to me to check the Jnow co-ordinates for Pluto, which is easily done.  Running the cursor across the "TheSkyLive" finder chart, one can see that it makes a BIG difference, and puts the minor planet much further west (in terms of the 30x20 minute of arc field of the camera chip).

So why doesn't the platesolve sort it?  Maybe because I am using an old Nexstar* handset (the Nexstar+ one failed).  I suspect the old handset uses J2000, even if the up-to-date ones don't.

If you are wondering why I am using the SLT mount and an old handset, it's because it's the only mount to hand that will lift the 102mm scope high enough to clear a fence and building.

[Cosmic Geoff]

I had another go at Pluto on the 21st, this time entering the Jnow co-ordinates into 'GoTo RA/Dec'.  I had only used a 1-star align, but this got it in  field (I could recognise the star pattern now), and the 'Platesolve & re-sync' from Sharpcap4 was only a minor adjustment.

Platesolving the images next morning confirmed that I had 'found' the minor planet. 

[Mandy D]

Yay! Well done! I still have Neptune to image to complete my collection of the major planets. I am certainly not at a level where I would consider attempting Pluto. Are you posting your images?