* * * * * C/2017 E1 (Borisov) * * * * *

Year Mn Day    MM  Mag Ref Scope Pwr coma  DC tail p.a. Obs  Site
2017  4 30.35   S 10.9 AU  22.0L 160   2   4            GOI  Araçatuba
2017  4 28.79   M 11.0 AQ  25.0L  83  1.3  4            WYA  Walcha, NSW
(Close to bright star, slight interference. Outer coma diffuse with a brighter moderately condensed inner coma.
Zodiacal light interference. Low altitude 17.0°.)
2017  4  7.19   S  7.9 TK  20.3T  77   6   2            GON  Puerto de Aralla, León
(Altitude 6°. A hint of tail was observable. Astronomical twilight.)
2017  4  5.77   M 10.9 AQ  25.0L  39   3   5/           WYA  Walcha, NSW
(Coma diffuse, faint stellar central condensation in good seeing. Slight zodiacal light interference. Altitude 18.1°.)
2017  4  4.19   S  8.5 TK  20.3T 100   5   2            GON  Puerto de Aralla, León
(Altitude 6°. Astronomical twilight.)
2017  4  1.19   S  8.8 TK  10.0B  25   4   2/           GON  Candanedo de Fenar, León
(Altitude 6°.)
2017  3 29.35   S 11.4 AU  22.0L 160  2.5  4            GOI  Araçatuba
(Nautical twilight.)
2017  3 28.20   S  9.2 TK  20.3T 100   5   2            GON  Collado del Fresno, Asturias
(Altitude 9°. Beginning of astronomical twilight.)
2017  3 27.74   M 11.0 AQ  25.0L  83  1.5  3/           WYA  Walcha, NSW
(Coma enhances in Swan Band filter. Slight zodiacal light interference. Low altitude 13.5°.)
2017  3 20.20   S  9.7 TK  20.3T 100   3   2            GON  Puerto de Aralla, León
(Altitude 10°. Field stars checked in DSS. Background star of mag 12.4 [GSC] in coma. Some moonlight interference [phase 0.54].)
2017  3  9.20   S 11.2 TK  20.3T 100  2.5  2            GON  Cea, León
(Faint and diffuse outer coma. Altitude 12°. Field stars checked in DSS.)
2017  3  3.81   S 12.2 AU  40.0L 144  1.4  1/           YOS  Mt. Hanadate, Ibaraki
(Diffuse and near limit. It was located low in the sky and in a dense field of faint stars. So maybe I overestimated the brightness.)