HISTORICAL LIGHT CURVE FROM 1959-2018 COMET 21P / GIACOBINNI-ZINNER

I analyzed a total of 2725 visual observations of comet 21P / Giacobinni-Zinner, from 1959 to 2018, with a total of 10 steps perihelion, analyzing their photometry the general equation shows the following result, my personal equation is as follows: m1 = +11.5 + 5 log (d) + 11.2 log (R) Photometricals Parameters General of 10 Perihelion Magnitude Absolute m0 = 11.5 Activity Index n = 11.2 (4,5) ICQ Formula m1 = 9.0 + 5 log (d) +15.0 log (R) This is the largest historical series obtained from this comet based on the data offered by MPC / IAU and COBS database International. The residual data obtained by J.P. Navarro Pina, offer greater statistical confidence: +/- 1.70 + 0.000 ---- 2725 Visuals Observations (Navarro Pina 2018) +/- 2.54 +1.82 ------ 2725 ICQ / IAU Navarro Pina has also updated the following physical quantities of the comet 21P / GZ data 2018, Diameter of the core log D (kms) = 0.42 ( 2,0 kms ) , Estimated mass log M (kg) = 11.9, Water rate production max log Q (H2O) ~ 28.5 mol / s-1, in the perihelion . The last updated indicated active are of FA ~ 80 km2 ( based in Ye et al. 2018 ) The photometric-visual parameters obtained for 2018 are m0 = 8.6, n = 8.3, the latter indicates a high rate of volatile chemical components of the nucleus.