Nightlog 2010-08-30

SA: Petri, Paul
SO: Patrick
Others:

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Summary
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- Clouded out, did not open.

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Nightlog 2010-08-29

SA: Petri, Paul
SO: Patrick
Others: Janus

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Summary
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- 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.

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!

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.

tim

Night report 20100725

Nightlog 2010-07-25

SA: Tim
SO: None
Others: Hitesh, Jonathan, Ted

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Summary
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ted worked on FP stuff most of the day and through the evening until about 2300. tim assisted in the afternoon and evening. details to follow in separate note. jonathan and hitesh performed a mirror align test and then tim opened up, pointed at az=180, and let the starcam take images every 3 minutes from 1930 until 0325. analysis and results to follow later. tim also ran the seeing monitors (mass-dimm + timDIMM) from 0000 until 0315 when high winds kicked up and started blowing scopes around too much.

Night report 20100723 & 20100724

Nightlog 2010-07-23

SA: Tim
SO: None
Others: Hitesh, Charl, Ockert, Chris, Martin, Ted

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Summary
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no SALT operations other than hitesh doing a quick mirror alignment to test something. tim and ted worked on FP stuff until 2330 and then tim worked on mass-dimm/timdimm stuff until 0330.

Nightlog 2010-07-24

SA: Tim
SO: None
Others: Hitesh, Charl, Ockert, Ted

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Summary
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ted worked on FP stuff most of the day and through the evening. tim assisted in the afternoon and evening. charl gave a tour to the group from university of central lancashire and exercised the structure as part of the exercise. with an assist from hitesh tim opened up and did some starcam observations with the structure and tracker both fixed in position. got just under two hours of data before being forced to close due to humidity at 2040 SAST.

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Results
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the behavior of the previous starcam results led me to believe that the non-repeatability probably has something to do with temperature effects. namely, the clear, dry conditions we were experiencing means the sky is very cold and different parts of the structure will couple to that differently depending on how they're shielded by the dome. to test this, we took some data tonight with the structure fixed at an azimuth of 150 degrees and the tracker locked down at (0,0). in this configuration with the dome open we ran a script to take a starcam image once a minute. we were only able to get just shy of 2 hours of data due to high humidity, but even this was enough to show significant drifts in both elevation and azimuth (see attached plots). the drifts amount to 1.1' in elevation and 2.7' in azimuth. we didn't open the louvers or condition the chamber well so this probably exaggerates the effects of temperature variations, but it does show how significant they can be and the results are consistent with what we observed in our previous tests.

Night Report 2010-07-22

SA: Amanda
SO: Fred, Zolisa, Siphelo
Others: Tim, Charl, Ockert, Deon, Chris, Morgan, Laure

Summary
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*Took more StarCam data to characterize polar misalignment.
This went mostly smoothly, with two structure position losses.

*Winds were too high to take SAMS data.

*Fred's last official night as an SO! Thanks for all of your hard
work and best of luck.

Conditions
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evening midnight morning
Weather: clear clear clear
Wind Dir 10m (speed; km/h): 327(50.9) 303(57.8) 285(53.5)
Seeing(FWHM SALT images): -
Photometric: no no no
RH(%): 22.7 38.6 40.7
Temp (2m): 12.1 8.4 8.2
T-Dp (ext.): 20.7 13.3 12.6

Sunset-rise (SAST): 17:57-07:21
Moon rise-set (SAST; phase): 14:33-05:37 (92%)