#############################################################################
version1/	used until October 2013
		TNO ephemerides with old version of ephemeris computation.
		The weight of observations is given by:
			- Astdys (MPC):	given by Astdys
			- ESO:		weight =  90mas
			- OPD:		weight = 180mas
			- Pic du Midi:	weight = 180mas
			- Fraser:	weight = 300mas
			- Unknown:	weight = 300mas

version2/	used from 25 October 2013 to 18 September 2014
		TNO ephemerides with new version of ephemeris computation.
		weight is given by sqrt(bias^2+sigma^2/N) with N, the number
		of observations per night
		
		The bias is given by:
			- Astdys (MPC):	depending on the catalogue
			- WFI:	
				ESO	bias =  75mas
			 	OPD	bias = 150mas
			 	PdM	bias = 150mas
				other 	bias = 300mas
				
			- UCAC/other
				ESO	bias = 150mas
				OPD	bias = 225mas
				Other	bias = 300mas
				
			- Fraser:	bias = 300mas
			- Unknown:	bias = 300mas
			
		The sigma is given by:
			- Astdys (MPC):	weight given by Astdys
			- ESO:		sigma =  75mas
			- OPD:		sigma = 150mas
			- Pic du Midi:	sigma = 300mas
			- Fraser:	sigma = 300mas
			- Unknown:	sigma = 300mas
			
version3.1/	used from 19 September 2014 to 25 November 2014
		TNO observations are not merged into night anymore.
		Each observation now appears and the weight given to each
		observation is sqrt(bias^2*N+sigma^2) with N, the number
		of observations per night.
		
		The bias is given by:
			- Astdys (MPC):	depending on the catalogue
			- WFI:	
				ESO	bias =  75mas
			 	OPD	bias = 150mas
			 	PdM	bias = 150mas
				other 	bias = 300mas
				
			- UCAC/other
				ESO	bias = 150mas
				OPD	bias = 225mas
				Other	bias = 300mas
				
			- Fraser:	bias = 300mas
			- Unknown:	bias = 300mas
			
		The sigma is given by:
			- Astdys (MPC):	weight given by Astdys
			- ESO:		sigma =  75mas
			- OPD:		sigma = 150mas
			- Pic du Midi:	sigma = 300mas
			- Fraser:	sigma = 300mas
			- Unknown:	sigma = 300mas
			
version3.2/	used since 25 November 2014
		TNO observations are not merged into night anymore.
		Each observation now appears and the weight given to each
		observation is sqrt(bias^2*N+sigma^2) with N, the number
		of observations per night.
		
		The bias is given by:
			- Astdys (MPC):	bias = 300mas
			- WFI:	
				ESO (809)	bias =  75mas
			 	OPD (874)	bias = 150mas
			 	PdM (586)	bias = 150mas
			 	CA  (493)	bias = 150mas
			 	SN  (J86)	bias = 150mas
			 	LH  (I95)	bias = 150mas
			 	MLP (Z20)	bias = 150mas
			 	LLP (J13)	bias = 150mas
				other 		bias = 300mas
				
			- UCAC/other
				ESO (809)	bias = 150mas
			 	OPD (874)	bias = 225mas
			 	PdM (586)	bias = 225mas
			 	CA  (493)	bias = 225mas
			 	SN  (J86)	bias = 225mas
			 	LH  (I95)	bias = 225mas
			 	MLP (Z20)	bias = 225mas
			 	LLP (J13)	bias = 225mas
				other 		bias = 300mas
				
			- Fraser:		bias = 300mas
			- Occultation 		bias =   0mas
			- Unknown:		bias = 300mas
			
		The sigma is given by:
			- Astdys (MPC):	weight given by Astdys
			- ESO (809)	sigma = bias
			- OPD (874)	sigma = bias
			- PdM (586)	sigma = bias
			- CA  (493)	sigma = bias
			- SN  (J86)	sigma = bias
			- LH  (I95)	sigma = bias
			- MLP (Z20)	sigma = bias
			- LLP (J13)	sigma = bias
			- Fraser:	sigma = 300mas
			- Unknown:	sigma = 300mas
			- Occultation 	sigma =  40mas/75mas 
			
version4/ 	since 7 December 2016
		identical to version 3.2 with new exception for offset obs
		reduced with DR1  
			bias  = 40 + 20 * |yr-2015| (mas)
			sigma = 20 + 20 * |yr-2015| (mas)
			
			
Version2 from October 2013, 17 to 25, observations from Pic du Midi have bias 
and sigma of 150 mas. It only produces minor changes in orbit.			

############################ 2014.11.25 #####################################