I was very disappointed by last night session. I use the Seestar S50 in ÉQ mode and I repeated several times the polar alignment procedure until I reached (0°, 0.1°) of residual pointing error. Which 50 mm aperture, I am expecting foot Earth rotation compensation with such error. Also, last night, sky condition were very nice, no Sirius, no wind. Despite this, all my 20s and above exposure exhibited star trails of 10th of pixel long, rejection rate 100%. I did in the past manage to have 60s exposure.

What could have been wrong ?