Tuesday, August 31, 2010

Nightlog 2010-08-30

SA: Petri, Paul
SO: Patrick


- Clouded out, did not open.


Nightlog 2010-08-29

SA: Petri, Paul
SO: Patrick
Others: Janus


- Continued with IQ work after Darragh's and Lisa's successful
week (and year, or years) - which ended last night with Champagne
after seeing 1.1" stars over the full science field. DOD to
report elsewhere. Thank you!

- Star images are not round yet though, with various aberrations
visible, so work to chase remaining smaller issues continues.
Aberrations appear consistently the same though, over the field
and over several nights. Tonight, we saw ~1.2" stars over the whole
field, and stable auto/collimator performance.

- Night cut short with clouds.

Thursday, August 12, 2010

The SAC is back!

See Lisa's post on SALT IQ blog (I've even stolen the her post name) for all the details and lots of beautiful pictures. There is still plenty of work to do before Darragh and the IQ team start on-sky testing, but this is huge step forward in returning SALT back to full operations. Congratulations go out to Darragh, the IQ team, and the SALT operations team!

Wednesday, August 4, 2010

the plot thickens.....

since weather cut us a bit short on the previous try, i redid the test of leaving the telescope open, but parked in a fixed position while taking images of the sky to measure the actual pointing position. this time we pointed SALT to an azimuth of 180, locked the tracker at (0,0), and took data for about 8 hours. the air temperature was not changing quickly during this time, though the wind did kick up considerably after about midnight UT. the behavior in elevation is similar to the previous test. the azimuth behavior, however, is rather surprising and i'm not sure what to make of it.

what is clear is that there are significant drifts in pointing that occur without anything happening mechanically with the telescope. i suspect they're related to temperature changes and/or radiational cooling. i also suspect that they'll be difficult to model and predict accurately.