JosÃ© J. ChambÃ³
GSO 8″ 760mm. f/3.8 & Atik 383L+
Comet C/2017 O1 ASASSN photographed on September 18th 2017. Comparing this image with I took a month ago is seen as have increased the apparent size of its greenish coma from 7′ to 10′, and the lenght of its ionic tail from 10′ to 20′. Its brightness has slightly increased on same time from magnitude 9 to 8.5 approximately. The brightest star in field is 37 Tauri with magnitude 4,4.