MDM Trouble Report for 2003 Apr 2

Telescope: 1.3m
Observer(s): Martin Bureau, Davor Krajnovic (Columbia, Leiden)
Instrument: Echelle f/7.5 direct imaging

Problem(s) Encountered:
As in earlier days, the telescope would move suddenly and increasingly frequently in the Nort-South direction when pointing at an object between roughly 0 and 15 degrees in DEC, and from a bit East to essentially all the way to the West. This is in contrast to previous days when the range of hour angle concerned was much smaller (just a bit West). However, the telescope has been rebalanced since then.

The movements are less extended (i.e. they do not reach 70-80 arcseconds as before) and they are slower. However, the guiding stars do not necessarily come back to their original positions right away. They can stay at large excursions distances for a long time. In other word, it seems that the re-balancing of the telescope has decreased the violence of the problem but not its frequency. Now, guiding stars wonder around slowly in the North-South direction (sometimes almost non-stop)!

Beside pointing elsewhere in the sky, we have not found any cure to the problem. And as we have now exhausted all our targets outside of this DEC (and RA) range, we have no choice but to acquire a target and attempt integrations. Tonight, with exposures of 100s only, we found that typically only 3 out of 4 exposures could not go for the whole 100s without any anomalous North-South mouvement... we thus abort and restart most exposures, thereby waisting valuable time.

Perhaps related to a balancing problem, we experienced significant wind shakes in the East-West direction even at wind speeds of about 10 mph (pointing against the wind). Is this normal?

Unrelated to this issue, we are still unable to back-up our data efficiently since all drive systematically rewind the tape no matter what device name or command is sent.

------------------------------

Submitted on 2003 Apr 3 [6:25:22]