Monday, January 31, 2011

More than just raft races

To all those wondering how there can possibly be time for fun stuff like raft races when there's a big telescope to get going - fear not!  The team's slaving away, as always, & much progress is being made...


Shortly before Xmas, Phil was up at SALT & got to try out his fantastic new 10-24 mm lens while Jonathan was up on the cherry-picker to remove the central segment for re-coating.


This was historic stuff as it's the first time that Segment 1, the critical mirror upon which the procedure for aligning the primary hinges, was re-aluminised. 


With that, Hitesh can at last sleep peacefully again, knowing that the nasty little circle hand-drawn on the centre of the segment 3.5 years ago is Gone!


In the time since, much more rain has produced a greener Sutherland than most of us have ever seen before.


& if that wasn't exciting enough, there was the man-hunt for the French couple at large in the Sutherland area after an altercation that left one policeman dead & another injured :(  So much for peaceful, boring old Sutherland!


That story ended badly for the fugitives a few days later.  For the record, we'd like to confirm that the controversially named "gun turret" on RSS (which houses the grating rotation mechanism) played no part in the shoot-out - it really was in the spectrometer room the whole time...


In fact - were we not still waiting on SALTICAM (which too is progressing well down in Cape Town), RSS might soon have been allowed back up on the tracker after its excellent behaviour during exhaustive repetitive testing of the various mechanisms.


The other critical instrument that needs to go into the payload before RSS can go back on top is the Atmospheric Dispersion Compensator (ADC).  It will be inserted into the non-rotating structure (just above the SAC) using a custom-built installation jig that seems destined to spend at least part of its time closely associated with potjiekos events.


All the while, primary mirror segments continue to be cleaned & re-aluminised in the IQ Team's old haunt.


One of the ongoing night-time challenges is to sort out stray light issues due to the auto-collimator, as well as other spurious light sources like LEDs on the payload & within the telescope enclosure.  A large baffle that surrounds the SAC has been installed & aligned, the auto-collimator had its baffle (affectionately known as "the mother of all tubes") replaced & all the LEDs will ultimately need to be hunted down & blacked out.

Nightlog 2011-01-29

SA: Tim
SO: Siphelo
Others:

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Summary
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another smooth night with good, photometric weather and decent seeing for the most part. got lots of thruput data and a couple data sets with 0.03 sec exposures to do some turbulence analysis. had some tracker issues with motor H5 overheating which slowed us down a little bit, but we were able to work through it. the mass-dimm even worked flawlessly all night. MASS free seeing when i shut down at dawn was 0.12"....

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Nightlog 2011-01-30

SA: Tim
SO: Siphelo
Others: Charl

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Summary
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got a little bit more thruput data and one round of short exposure burst mirror data. struggled most of the rest of the night trying to get the mirror to behave. several segments were way out of whack from all of our bursting and anti-bursting. one was focusing almost an arcminute away from where it was supposed to. when we finally got all of that sorted out, the humidity came in and closed us up.

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Nightlog 2011-01-28

SA: Tim
SO: Siphelo
Others: Charl

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Summary
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night didn't look promising at the start, but turned out to be beautiful. warm, clear, light winds, and half-decent seeing for a stretch. got some good practice setting up burst mirror modes and recovering from them as well as recovering from other mirror issues. thanks to charl for coming up to help and to hitesh for putting up with us calling. got some data in burst mode with short exposure times to try and measure seeing/turbulence. got some thruput data at the end with the VI-apogee and its V filter

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Nightlog 2011-01-24

SA: Paul
SO: Patrick
Others: Siphelo, Zolisa, Darragh, Lisa, Charl, Hitesh

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Summary
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- The SAC baffle was reinstalled today. From the out of focus images we seemed
to see multiple spider components which we thought was due to the SAC baffle.
Took the SAC baffle off, but the multiple component remained. This cannot be
explained. The SAC baffled seemed well enough aligned in the way it was
installed. Multi component spider needs thinking about. The SAC baffle will be
re-installed tomorrow during the day.

- timdimm ran for a while but it was plagued by tracking issues.

- we continued the training and focused on getting the mirror alignment times
down to around 15min.

- some pointing offset observations were done and the results from that looks
good.

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Nightlog 2011-01-27

SA: Tim
SO: Siphelo
Others: Charl, Zolisa, Martin

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Summary
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smooth, productive night with good weather and mediocre seeing. spent the first half of the night doing stray light tests with a closed dome. spent the second half doing another track following out-of-focus images and got some open-loop tracking data at the end. the mass-dimm ran flawlessly until almost 0400. it somehow quit tracking and lost the stars. updated the commissioning wiki with some of the results from tonight.

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Nightlog 2011-01-26

SA: Tim
SO: Siphelo
Others: Charl, Zolisa

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Summary
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used BCAM to take some time-lapse data of out-of-focus images to watch the evolution of the mirror alignment over time. the stars used for this came up at the very edge of the BCAM field when slewed to so there's something screwy with the pointing. will need to follow up on that.

made movies out of the time-lapse data and wrote up a blog post on them at http://saltastro.blogspot.com/2011/01/salt-pupil-time-lapse.html.

got closed by humidity right after midnight and ridge cloud by 3 AM.

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