+++++++++++++++++++++++++++++++++++++++++++++++++++ Ron OF SHORT PERIOD COMETS. Version 050627. +++++++++++++++++++++++++++++++++++++++++++++++++++ When planning observations of the nucleus of a comet, it is useful to know the turn on point of the coma (Ron, Ton) or the turn off point (Roff, Toff), to be sure that the coma does not contaminate the measurements. The preliminary Table presented below provides this information for 49 comets. The turn off point is also given when known. Some times the information is given in days pre or post perihelion. It must be emphasized that this information is preliminary and subject to change. That is why the version date is given above. In Paper 1 we have shown that the mean value of Roff/Ron= 1.44±0.29 . For the comets in the present data base, Roff/Ron spans a range of 1.1 < Roff/Ron < 2.02 . Thus if Roff is not known it can be calculated approximately from the above ratio and the above range. Notice that 107P and 133P are the only cases in which the comets turns on ** after ** perihelion. To use this information we only request that proper credit be given to this web page. Thanks. +++++++++++++++++++++++++++++++++++++++++++++++++++ TABLE 4. Ron of Short Period Comets (-) pre, (+) post perihelion. +++++++++++++++++++++++++++++++++++++++++++++++++++ COMET q[AU] Ron[AU] Roff[AU] Ton[day] Toff[day] +++++++++++++++++++++++++++++++++++++++++++++++++++ 1P/Halley 0.59 -6.15 +12.56 2P/Encke 0.33 -1.82 > 1.2 4P/Faye 1.59 -3.2 ----- 6P/D'Arrest 1.29 -2.1 + 3.3 - 74 d + 250 d 9P/Tempel 1 1.50 -2.4 + 3.6 10P/Tempel 2 1.38 -1.99 ----- 11P/Swift-Tutt 1.58 -125 d + 70 d 12P/Pons-Winne 1.26 -1.95 ----- 15P/Finlay 1.09 -1.65 ----- 17P/Holmes 2.17 -2.2 ----- 19P/Borrelly 1.37 -2.90 > 5.0 21P/Giacob-Zinn 1.03 -3.6 + 5.4 22P/Koppf 1.59 -2.51 ----- 23P/Brorson-Met 0.45 -1.51 ----- 24P/Schaumasse 1.21 -2.19 ----- 26P/Grigg-Skejl 0.99 -1.4 + 1.8 28P/Neujmin 1 1.53 -2.1 + 2.4 30/Reinmuth 1 1.88 -3.5 + 2.1 32P/Comas-Sola 1.83 -3.16 ----- 37P/Forbes 1.48 -1.74 ----- 38P/Stephan-Ot 1.57 -1.99 ----- 39P/Oterma 5.47 -7.1 + 6.6 40P/Vaisala 1 1.80 -2.32 ----- 43P/Wolf-Harri 1.61 -2.82 ----- 45P/Honda-M-P 0.53 -1.9 + 2.0 46P/Wirtanen 1.06 -2.1 + 2.3 47P/Asbrook-Ja 2.31 -3.71 ----- 48P/Johnson 2.31 -2.6 + 4.0 49P/Arend-Riga 1.44 -1.95 + 2.0 50P/Arend 1.85 -1.88 ----- 52P/Harri-Abell 1.77 -2.24 ----- 53P/Van Briesb 2.40 -3.35 ----- 56P/Slaught-Bur 2.54 -2.69 ----- 62P/Tsuchin 1 1.50 -1.51 ----- 64P/Swift-Gehr 1.36 -1.62 ----- 65P/Gunn 2.47 -3.24 ----- 67P/Chury-Geras 1.30 -2.8 + 4.0 70P/Kojima 2.00 ---- + 170 d 73P/SW3 0.93 -1.11 ----- 76P/West-K-Ik 1.58 -2.2 + 3.9 78P/Gehrels 2 2.00 -200 d > 300 d 81P/Wild 2 1.58 -4.4 + 5.8 88P/Howell 1.41 -290 d > 350 d 93P/Lovas 1.67 -1.92 ----- 103P/Hartley 2 1.03 -4.1 >+5.9 104P/Kowal 2 1.40 >-250 d >+100 d 107P/Wilson-Ha 0.98 +1.14 +1.40 + 41 d + 70 d 109P/Swift-Tut 0.96 -2.6 + 3.2 133P/Elst-Piza 2.63 +2.64 + 2.79 + 42 d + 223 d +++++++++++++++++++++++++++++++++++++++++++++++