[APBeta] epoch 2000.0

[Paul Rodman]

On Feb 25, 2011, at 7:02 AM, Paul Rodman wrote:

> On Feb 25, 2011, at 5:07 AM, Dieter Welnowski wrote:
> 
>> I have changed all my objects (1690) from epoch 1950.0 to epoch 2000.0. And now I miss all my images. They are visible in image manager, but not in the objects-tab. The coordinates in the image-manager are now incompatible with the coordinates of the objects.  Is it possible, to go back with the objects to epoch 1950.0 ore what can I do?
> 
> Ouch! That's a good point. There isn't a way to return the objects from 2000.0 back to 1950.0, but I can add it pretty easily (or create a script to do so). Also, I should have the option of changing the epoch of associated images (although while this will associate the images with the objects, they will be out by 5' - 10' or more, since all images are epoch J2000.0).

You'll note that in the latest version (2.0b101) I added two enhancements to help with this:

a. The Object > Change Epoch... dialog now allows you to change an object's epoch to one other than 2000.0, with a suitable warning (since this is not something many will want to do on purpose).

b. Export to text/XML/Excel/JSON now allows you to specify the target epoch. Useful if you're exporting for an application that expects, say, JNow (the current epoch).

I decided not to fool around with changing the epoch of coordinates of images in the database, since that would, effectively, give them bad coordinates (all images are downloaded using J2000.0 coordinates). If you are in the position that you downloaded images for objects in another epoch and subsequently change the objects' epoch, then you'll need to re-download images, and probably delete the old ones.

If this is something that you feel strongly about, please file an enhancement request, and I'll consider it for a future release.

Paul R.

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