You are here: Foswiki>AdaptiveOptics Web>Logs>Log_20110608 (09 Jun 2011, GBrusa)Edit Attach
Observer(s): L Busoni, A. Puglisi, S. Esposito, E. Pinna (Arcetri), G. Brusa (LBTO)

Telescope Operator:

SW Support:

Telescope Support: J. Little, M. Midkiff

Instrument Support:

The activity started around 7:45am.

Following Dave T. suggestion we decided to test the H-band AO corrected image on PISCES but reducing significantly the reference star flux from 8 to 9.5 magR equivalent (or more? check notes) this required going to BIN2 with the AO system. We eventually obtained an AO corrected image in H-band that did not have the central 'dip'. This proves that the problem of the central 'dip' was due to the saturation of the first read of PISCES, which caused the image (difference between second and first read) to have that behavior.

We, however, found that the maximum Strehl ratio in this configuration was 60% in H-band vs. 76% in FeII, given the fact that the two bands have the same central wavelength we have to possible explanations: a) the H-band has some intrinsic problems and b) the width of the filter is the cause. Since images in H-band gave good Strehls in the lab we guess there should be a problem with the width (see Simone's report for a discussion of the issue).

We measured he NCPA for one more angle of the instrument rotator: 43 degress in FeII

Comparison between SR measurements in Ks and H2 show similar (although not as dramatic) difference between the wide and narrow band filters... We think that there is some optical component that has a significant chromatic aberration that is eliminated by the use of a narrow band filter. One possible culprit is the ND used in forn of PISCES in order to reduce the flux into PISCES.

We measured Strehl in J-band and found similar behavior as yesterday, i.e. a SR somewhat lower than expected, again this could be due to some chromaticity in the optical path.

We removed the ND and measured the best focus without ND with BIN2 and low light in Ks, H2, FeII, the focus shift is consistent with what expected from the ND thickness.

We verified the slope offsets for one rotator angle (which one? check notes) without ND and found them to be same as with ND. This confirms what expected, i.e. the ND does not introduce any significant NCPA.

The retro-reflecto was removed for the night. This ends our daytime activity.

-- Main.GBrusa - 09 Jun 2011
Topic revision: r1 - 09 Jun 2011, GBrusa
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