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%)

More pointing data

We took more pointing data later on during the night of 20100720, but this time in a more careful manner. We performed large moves back to Az = 0 several times during the course of taking the previous data which we think probably created the large amount of scatter. This data was taken by making small 10 degree moves in Azimuth in the same direction between each observation. We took one set moving in a clockwise direction from Az=0 and another set moving counter-clockwise from Az=360. As we hoped, taking data in this way shows the systematic cyclical signature much more clearly. Recall that for our experiment the elevation is fixed by leaving the tracker locked at (0,0) and thus should remain constant.

Summary Night Report 20100721

Nightlog 2010-07-21

SA: Amanda
SO: Fred
Others: Tim, Siphelo, Zolisa, Deon, Morgan, Chris, IQ team, Nic, Ted,
Hitesh

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Summary
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* Took more StarCam data to investigate polar misalignment. A new
plot is posted on the blog that shows the results from last night.

* Ran six tracks as though we were undertaking normal
observing. Three tracks ended abnormally, all with fatal following
errors.

* Hitesh ran SAMS tests. Conditions were beautiful, so hopefully he
got alot of good data!

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Conditions evening midnight morning
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Weather: clear clear clear
Wind Dir 10m (speed; km/h): 0 (20.5) 338(30.7) 329(36.2)
Seeing(FWHM SALT images): -
Photometric: yes yes yes
RH(%): 19.0 23.1 27.5
T-Dp (ext.): 22.9 20.0 17.6

Sunset-rise (SAST): 17:56 - 07:22
Moon rise-set (SAST; phase): 13:42-04:44 (85%)

Summary Night Report 20100720

Nightlog 2010-07-20

SA: Amanda
SO: Fred
Others: Siphelo, Zolisa, Deon, Morgan, Ockert, Charl, Chris, Laure,
IQ team, Nic, Ted, Hitesh

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Summary
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* Took some data on mirror alignment degradation at beginning of night
(with goal of investigating how much alignment degrades as
environmental conditions change). Hitesh took SAMS data later.

* Got alot of data with the StarCam to characterize polar
misalignment. Tim's initial results show a strong sinusoidal
variation in the azimuth and elevation of the actual pointings with
respect to the telescope positions. (see plot in blog)

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Conditions evening midnight morning
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Weather: clear clear clear
Wind Dir 10m (speed; km/h): 102(14.9) 81(11.9) 26(20.9)
Seeing(MASS/DIMM): -
Photometric: yes yes yes
RH(%): 24.3 26.6 27.4
T-Dp (ext.): 19.5 18.0 17.6

Sun set-rise (SAST): 17:56 - 07:22
Moon rise-set (SAST; phase): 12:51-03:46 (68%)

20100720 Pointing residual plot

20100720. First plot of the differences between the azimuths and
elevations derived from astrometric fits to StarCam data and those
based on the telescope location (tracker at 0, structure told to go to
various azimuths). These data should help us characterize any
polar misalignment of the pier. The data were taken
in steps of 30 degrees, with 10 degree offsets between three different
sets, all in a counterclockwise direction. (plot courtesy of Tim!)