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Convert J2000 to "Jnow"


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To convert J2000 to "Jnow" ("Jdate-obs")


Any software to run in windows, windows cmd, or online?
(or, optimistically, in Javascript in an HTML page !)

I have googled and found (in another forum far far away :) ) ref to a python to run in astropi and other refs to telescope control progs that can run in J2000 or Jnow mode, and lots of refs on how to do it using Meus AA etc.

But nothing for a humble windows user !
 

Edited by MalcolmP
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5 hours ago, Waddensky said:

Thank you very much, nice find, that is exactly what I needed !


I have been puzzled for a long time by my plate solve in ASTAP not aligning exactly with my view in Stellarium.
I am using core.move in the script console which takes me to a position a little off from where I expect it to be. Not by much and all is good if I change the viewing date/time in Stell to Jan 2000 instead of the date of the obs  !!
That little calc. by Mel transfoms the J2000 o/p of ASTAP just about right so that the marked position in stell is in the right place when viewing at the right time !!!! 

I need to post some pictures and give a better explain to make sense of what I am up to later, at the mo. I have a good sky and a view of T CrB to attend to, ,, , 
more later and again, many thanks  👍 
 

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Posted (edited)

The offset I get when entering the RA/Dec from astap is corrected by first applying MelB precession from 2000 to 2024.6 , Using 9 Vul as an example :-

108.jpg.08ec1a520f86fe7d2710326e7d0d7e35.jpg

 

Edited by MalcolmP
corrected a 2014 typo
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1 hour ago, MalcolmP said:

The offset I get when entering the RA/Dec from astap is corrected by first applying MelB precession from 2000 to 2014.6 , Using 9 Vul as an example :-

108.jpg.08ec1a520f86fe7d2710326e7d0d7e35.jpg

 

Can Stellarium not be set for Jnow I know in carte du ciel you can , 

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6 hours ago, bottletopburly said:

Can Stellarium not be set for Jnow I know in carte du ciel you can , 

I must be missing something like that.
The precession test/confirmation indicates that I am not driving Stellarium correctly in the coordinate refs. it was expecting,  rather than me inputting a bad string with the wrong month or hour or something really very very silly !

I must now go in search of more info&learning on how to script, in particular the 'core.move' (etc) command(s) 
 

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