Nightlog 2011-02-27

SA: Paul
SO: Zolisa
Others: Johnathan

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Summary
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- It was cloudy at the beginning of the night but it cleared later.

- Did astrometric field observations.

- DIMMs ran for most of the night.

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Nightlog 2011-02-25

SA: Paul
SO: Zolisa
Others: Phil, Leslie Sage, Keith

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Summary
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- Continued with pointing observations at different altitudes covering a range
of Az.
- timdimm ran for a while tonight.
- had software issues which were sorted out by Keith at the beginning of the
night.

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NASSP Summer School 2011

Here is guest post by Gopolang Mohlabeng about the NASSP Summer School which is organized every year at SAAO for the incoming NASSP honours students. For many of the students, the NASSP program is their first exposure to astronomy. As they progress in their studies, many of the students will end up using SALT, and like a number of previous NASSP students, some of them will end up making key contributions to the development of SALT.

The National Astrophysics and Space Science Program summer school is a 4 week program that is aimed at the new Honours students. Most of the students who get accepted into NASSP honours have backgrounds in Physics, Mathematics or Engineering and no Astronomy. The summer school introduces these students to Astronomy through Introductory lectures, fun activities that are related to Astronomy and Space Science and excursions to national facilities.

The 2011 Summer School started on the 17th February 2011, there were 19 honours students. The first three weeks were hosted at the South African Astronomical observatory in Cape Town and a typical day at the SAAO consisted of the following: in the morning a lecture on introductory Astronomy by Dr Petri Vaisanen for two hours, there would then be tea and after tea there would be an invited speaker to address the students about his or her field of research. After the talk from the invited speaker, there would be lunch, after that there would be a talk from another invited speaker and then there would be an activity or an excursion. After this there would be dinner. The day would then end with a short activity. The excursions included: A trip to iThemba Laboratory for accelerator based science. A trip to the KAT(Karoo Array Telescope) offices in Pinelands, Cape Town. A trip to the Iziko Planetarium. The students also spent a week at the Hermanus Magnetic Observatory learning about Space physics and all its applications. After the week at the HMO, they spent a few days at the SAAO in Sutherland, where they took a tour of the Southern African Large Telescope and the other smaller telescopes. The last week was spent at the University of Cape Town where they were given an orientation and given an introduction on Latex and on the UNIX system.

The NASSP summer school is organized and coordinated by different people every year, preferably students who were honours the previous year. For 2011 it was organized and coordinated by Gopolang Mohlabeng and Rocco Coppejans.

Nightlog 2011-02-24

SA: Paul
SO: Zolisa
Others: Janus

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Summary
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- We confirmed that the rho rotation star tracks we observe for BCAM are the
same in VCAM. Janus was here and he checked the fold mirror which was a suspect
for the star tracks. It would seem that the fold mirror is not the cause.

- Got pointing data, but instead of using central tracks we chose different
altitudes for the objects.

- The pointing seems to be good to within 10''.

- The MASS and DIMM was running tonight.

- Closed 00:30 due to high humidity.

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Nightlog 2011-02-22

SA: Alexei
SO: Siphelo
Others: Zolisa, Paul

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Summary
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=> AC stray light tests:
Start to track with no baffle fitted over MOAB end. AC locked.
Put 10mm aperture and try to track.

The main conclusion of this test is: telescope is not able to track in this configuration -
the configuration is very unstable and AC continuously lost and find signal again.

But telescope is able to track with 15mm aperture and AC does not lose signal.

=> Some more data for open-loop rho test.

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Nightlog 2011-02-21

SA: Alexei
SO: Siphelo
Others: Charl

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Summary
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=> The test for AC leaks in case of 10mm MOAB aperture.

=> Some more data for open-loop rho test.

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Nightlog 2011-02-20

SA: Alexei
SO: Siphelo
Others: Johan

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Summary
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=> The test for SAC baffle position was redone with tracker "out in the middle".
We tried to check both baffles.
Hard to say about the result without proper data reduction.

=> Some more data for open-loop rho test.

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Nightlog 2011-02-19

SA: Alexei
SO: Siphelo
Others: Johan

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Summary
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=> The test for SAC baffle position was done.
AC leak really drop down.

=> Some more data for open-loop rho test.

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Nightlog 2011-02-18

SA: Alexei
SO: Siphelo
Others: Grant and Sharl by phone.

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Summary
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=> There was problem with SALTICAM fold mirror that can explain strange
results of our last night tests. Our tonight imaging shows
that we see the difference in signal levels when AC on/off.

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Nightlog 2011-02-17

SA: Alexei
SO: Siphelo
Others: Johan

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Summary
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=> Cloudy all night.

=> The general idea was to
test SAC baffle position (as was suggested by DOD).
Unfortunately, I do not see the difference in signal level
when AC on or off. For this reason the test was postponed.

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Nightlog 2011-02-14

SA: David
SO: Patrick
Others: Tim

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Summary
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Clouds and thunderstorms at sunset.
High hunidity all night, threatened to clear at 2:3o, but dew point
stopped us.

No data taken.

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Nightlog 2011-02-13

SA: David
SO: Patrick
Others: Tim, Jonathon, Charl

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Summary
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Initially clear, but increasing humidity killed us by 2:30

Continuation of stray light tests.

Pointing & tracking tests.

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Nightlog 2011-02-09

SA: David
SO: Patrick
Others: Chris & Keith for a spell

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Summary
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. Night lost to weather. Thunderstorms at sunset, then rain, high
humidity & cloud.

. Continuation of stray light tests with the autocollimator and track
tests.

. Could not get tracking with AC and needed to remove the
Mother-Of-All-Baffles in order to get closed loop control with the
throttled AC. Subsequent tracks all worked fine (tried all extreme
azimuths).

. Looks like the AC stray light has been beaten down to ~60 ADUs (~80e),
not quite the desired 50e, but maybe good enough? Ambient dome
straylight is at ~20 ADUs and there's clearly a few LEDs still (like
hexapods). Inside payload it looks like there only ~10 ADUs above dark.

. Cal Sys flat field pattern is still not centred on BCAM (x=422, y =
646). Might need to verify that the axis of illumination is
perpendicular to screen.

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Nightlog 2011-02-08

SA: Encarni
SO: Zolisa
Others: David, Martin, Eben

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Summary
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. Night lost to weather. We did not open.

. Stray light tests with the dimmed autocollimator and a couple of
track tests.

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Nightlog 2011-02-07

SA: Encarni
SO: Zolisa
Others: Eben, Martin. Hitesh and Charl on the phone early in the

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Summary
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. Beautiful night, but with several telescope problems.

. Took sky flats, more pointing and an open loop traking tests.
Established BCAM and VCAM's centre of rotation.

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Nightlog 2011-02-06

SA: Encarni
SO: Zolisa
Others: Eben and Abigail for a quick visit. Nimrod to help with TimDimm.

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Summary
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. Beautiful night, Moon-less, clear skies. TimDimm seeing around 1.5".

. Took sky flats with both instruments, modified pointing model and
did open loop tracking tests and pointing tests. Also found new values
for the autocollimator angles.

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Nightlog 2011-02-05

SA: Encarni
SO: Zolisa
Others:

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Summary
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. Cloudy and humid night again. Could not open.

. Repeated last night's calibration flats, adding also a Ne lamp. QTH1
seemed *much* dimmer for VCAM than last night. QTH2 much brighter. See
attached image (calsys.jpg): top row is for BCAM, bottom row VCAM.
From the left, the lamps used are: QTH1, QTH2 and Ne. The lamps now
give a consistent picture for each instrument, though VCAM still has
some sort of obscuration.

. Also checked stray light due to calsys lamp leaks with the cal
screen out (autocollimator also off). See attached image
(strayLight_calsys.jpg): Top left: all lamps off. Top right: QTH lamp
on. Bottom left: QTH1 on. Bottom right: Ne lamp on. Can clearly see
contamination from QTH2 (top right).

In terms of stats:

IMAGE MEAN MIDPT MODE STDDEV
MIN MAX
lamps_off.fits 270.6 279.2 288.3 64.78
9.667 531.
QTH2.fits 416.4 409.8 349. 93.09
64.5 787.5
QTH1.fits 274.5 283.5 292.6 64.21
16.5 532.
Ne.fits 271.1 279.8 285.9 64.93
9.5 532.

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Nightlog 2011-02-04

SA: Encarni
SO: Zolisa
Others: Charl and Eben

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Summary
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. Cloudy night with high humidity.

. Tested the new calsys - all working OK except for the CuAr lamp,
which has blown. Got some QTH flats both for VCAM and BCAM - the VCAM
ones look a bit peculiar (see attached images) - but it can be seen
that the centre of the illumination is not at the centre of either of
the cameras.

. Established that we cannot track with the autocollimator at its
current setting, it is too dim. No new baffling installed, so no more
stray light tests tonight.

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Nightlog 2011-02-03

SA: Encarni
SO: Zolisa
Others:

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Summary
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Glycol tests underway, so the tracker is not available. No work tonight.

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Wavefront testing the CCAS Instrument

As of the end of August last year, the SALT IQ saga was mostly resolved, but a small amount of astigmatism was still apparent in images obtained in good seeing.  With the SAC fixed & a bare CCD unable to contribute aberrations, the remaining problem had to lurk within the primary mirror system.  This has been investigated & during the past week, efforts centred on testing the Shack-Hartmann CCAS instrument that's used to align the primary's 91 segments.

The instrument has a light source that's fed, via a beam-splitter, to each of its 2 arms - 1 of which includes a small reference mirror. 

& another that incorporates the primary array.

After reflecting off either the reference mirror or the primary, the light passes back through the beam splitter & gets collimated by a camera lens before going through the lenslets.

There are both coarse & fine lenslets that can be placed in the beam to produce either 1 spot per mirror segment (for coarse alignment), or 7 spots per segment (for fine alignment).

The first priority was to test the optical quality of the reference mirror to ensure that it wasn't responsible for introducing astigmatism into the primary during the alignment process.  The CCAS instrument had to be dismantled to allow a wavefront camera to be placed at the focus (located down-stream from the beam-splitter).

The lenslets deserved a closer look under a microscope while they were out & about, niftily illuminated from below with a red LED.

In white light, the coarse lenslets appear slightly blue & a faint set of ghosts can be seen in the photo below.  The stray satellite spot to the lower right is associated with a damaged lenslet in the outermost ring (beyond the central 91 that matter).

The good news is that the reference mirror's in great shape & can not account for the astigmatism.  In fact, the wavefront measurements were in perfect agreement with Darragh's Zemax analysis, which showed that the only aberration that should be present is spherical aberration produced by the beam-splitter (& since both arms are subject to this, it makes no difference).

The next trick was to feed the spots from the perfect reference mirror into the alignment software & pretend that they came from the primary.  This ought to have led to a perfect alignment - but It Didn't!  So, that points to a software issue that will need to be traced...

Hitesh, Darragh & Francois will thus remains locked up in the CCAS tower until further notice while they figure it out.

In the meantime, Sutherland continues to provide spectacular sunsets to taunt the astronomers!

Technical Papers from 2010

With an SPIE Astronomical Instrumentation Conference in 2010, there was a large number of technical papers published about the developments at SALT. These offer insights into control systems, the primary mirror, software development, and some science highlights. Most of the papers can be found under our technical publications. I'll just mention the first author for each of the papers, but please check out the full author lists to see all of the contributors to these projects.

John Menzies and David Buckley present results for the teams working on developing and improving the sensors on the primary mirror. These include a paper on testing FOGALE's edge sensors and a paper on new sensor technologies.

Darragh O'Donoghue and Lisa Crause along with the IQ team report their exciting results in fixing the IQ problem and 'Saving SALT.' Beyond keeping us all updated throughout the project in addition to her work on the IQ fix, Lisa was very busy with two contributions including information about cleaning the M5 mirror and optical alignment using a Faro arm.

With the Robert Stobie Spectrograph ready to go back onto the telescope, Ken Nordsieck detailed the testing that was required to understand the UV throughput, Anthony Koeslag describes the control system for the instrument, and Janus Brink presented results from his Masters thesis on 'Spectropolarimetry with the SALT RSS' which details the polarimetric capabilities of RSS.

User software was detailed in papers by Christian Hettlage and Steve Crawford. Christian described the PIPT tool that will be used for preparing SALT proposals. I submitted a paper on the PySALT data reduction and analysis tools. David Buckley presented some highlights from the time-resolved observations being done with SALT.

Finally, highlights of two next generation instruments were also given at the meeting. David Bramall gave a review of the capabilities of the High Resolution Spectrograph and Marcia Wolf described the predicted performance capabilities for the near-infrared arm of RSS.

Nightlog 2011-01-31

SA: Tim
SO: Siphelo
Others:

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Summary
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got some more short exposure burst mirror data under mediocre to poor seeing conditions. we got closed up by humidity and clouds shortly before midnight, but still acquired 6000 images in total. too much data is only marginally sufficient....

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