Night report 2025-07-23

Night report 2025/07/23

Observers: Gonçalo Martins and Rita Santos

Support:  Santiago González-Gaitán and João Duarte

TAT: Claudia Gutiérrez, Priscila J. Pessi and Timo Kravtsov

Start (23:18 UT): humidity 15%, temperature 11.3º C, wind speed 5.8 m/s, seeing 0.7'', airmass 1.09

Middle (04:23 UT): humidity 5%, temperature 12.0º C, wind speed 7. 0m/s, seeing 1.3', airmass 1.37 

End (10:05 UT): humidity 9%, temperature 9.5º C, wind speed 8.1 m/s, seeing 1..42'', airmass 1.26 

Comments: When seeing > 1.5, the exposure times were set to be 30% longer.

Calibrations: Afternoon calibrations: bias, arcs in gr11, g13, gr16. In evening twilight: photometry flats in grz and i bands, UBV aborted (lack of time, done in the morning twilight) Morning calibrations: twilight photometric flats in UBVRi, arcs in gr11, g13, gr16.