Daytime AO work on 2 June 2011

Observer(s): D. Miller, L Busoni, A. Puglisi, L. Fini, S. Esposito (LBTO)

Telescope Operator: DHuerta (LBTO)

SW Support: (Tucson)

Telescope Support: J. Little, J. Urban (LBTO)

Instrument Support: (LBTO)

Summary

Doug, Luca and Alfio stayed at the LBT

Simone and Lorenzo stayed in Safford

Doug woke up at 6 am (yes, am) and helped John fill the PISCES dewar and install the retroreflector. This was completed at 9:15.

Simone and Lorenzo arrived from Safford at 9:10.

Retroreflector work went on all day

Doug and Luca reviewed the Action Item list from the AO Software Acceptance Test Document. More than half of the Arcetri AI's are done (possibly more once I have talked to Alfio) and a third of the LBTO AI's.

Alfio tested his PISCES image acquisition routines and they work well.

It is found that there is about a 7 second overhead (reading CCD and writing fits files) to collect a PISCES image. This is more than the 4 second overhead that was expected.

We called Craig to clarify the wrapping of image values (signed -vs- unsigned values). This point is somewhat moot because the counts are non-linear above about 15000 counts. They are using the narrow band filter 8 (FeII 1.64 um) and getting about 15000 counts for 0.8 second integrations (the minimum int time). They have optimized the loop a bit and it is easy to see 4 airy rings. The core of the PSF looks a bit square rather than round. This could be a bit of non-common path astigmatism.

Simone, Lorenzo and Alfio collected data at several binning levels. The light required for binning 1 on the pyramid was too much for the minimum exposure time of PISCES (0.8 sec) and so no full speed strehl measurements were made. Instead, bin 3 was used with only 66 modes. In this case strehls between 60 and 70% were measured in the FeII narrow band filter. Even on the best images there was a "bar" of light (very dim) across the core and several of the diffraction rings. They still have some optimization of the loop to do which may improve the image.

The Arcetri guys are becoming familiar with PISCES by taking some data to measure the linearity of the detector. They measured the response of the camera to be within 2% of linear up to 25000 counts.

-- DougMiller - 02 Jun 2011
Topic revision: r3 - 03 Jun 2011, DougMiller
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