ENR CTIO Blanco 4-m 2013-04-16

HEXAPOD PROBLEMS:

Everything went smooth until around 3:30: we started getting the Alarm:

WARNING: FOCUS DONUT: AOS maybe hung.

Following what we remembered from D. James last night, we started in the HEXAPOD panel by clicking on the "Init. z trim"

, them try a test 30 sec exp, the hexapod values moved again, basically to where they were.

After several tries, we noticed that the z trim value goes to ~590 when Init z. trim was clicked twice, then realizing that's what needs to move to get to a decent position.

We noticed that the ellipticity went higher than ever before in the night. Stopped, and tried playing zeroing the values with "tweak" and "trim",  sending the values to zero  them by entering the opossite of their current ones (basically what "Init z Trim" does) to see if in that way we could get anything different, but it was giving us the same result: slightly elliptical images and an alarm. We decided to keep going and ignore it since the images were looking fine and the seeing/ellipticity was not affected noticeably. Still, several images were way out of focus in this process.

Curiously enough, even though the hexapod values were around the same all the time, the same alarm mentioned above was going on every 8 images precisely, or every 9 mins.