From: http://www.minorplanetcenter.net/mpec/K13/K13V48.html
From scully.cfa.harvard.edu/cgi-bin/returnprepeph.cgi?d=c&o=CK12S010


    C/2012 S1 (ISON)
Epoch 2013 Nov. 4.0 TT = JDT 2456600.5
T 2013 Nov. 28.77568 TT                                 MPC
q   0.0124464            (2000.0)            P               Q
z  -0.0001612      Peri.  345.56358     +0.31512418     +0.51244303
 +/-0.0000005      Node   295.65358     -0.75893711     -0.36930781
e   1.0000020      Incl.   62.39481     -0.56983438     +0.77525085
From 5363 observations 2011 Sept. 30-2013 Nov. 8, mean residual 0".5.

    C/2012 S1 (ISON)
Epoch 2013 Dec. 14.0 TT = JDT 2456640.5
T 2013 Nov. 28.77569 TT                                 MPC
q   0.0124464            (2000.0)            P               Q
z  -0.0001541      Peri.  345.56381     +0.31512377     +0.51243580
 +/-0.0000005      Node   295.65334     -0.75893882     -0.36931071
e   1.0000019      Incl.   62.39524     -0.56983233     +0.77525425
From 5363 observations 2011 Sept. 30-2013 Nov. 8, mean residual 0".5.




;;IDL
tperi=anytim('2013/11/28')+86400.*.77568 - 67.183 & q=0.0124464 & O=295.65358 & i=62.39481 & w=345.56358 & e=1
;;OR:
;elements={tperi_ET_ccsds:anytim(anytim('2013/11/28')+86400.*.77568,/CCSDS),q:0.0124464,e:1.0000020,O:295.65358,i:62.39481,w:345.56358}