The MagAO team (or at least part of it) has returned to Florence for another round of integration and testing. I (Jared) have been here for 2 weeks, and Laird and Derek just arrived. As soon as I arrived we successfully closed the loop again, with only minimal adjustments of the alignment using the X-Y-Z stages. The system came right back up, with less than 5 minutes of work, after 3 months of down time.
The last two weeks have been mostly uneventful, consisting of a lot of software development and debugging. In preparation for the next 2 weeks of work on the ASM and the CRO tests we removed the NAS from the tower on Friday. The two videos below show the process of lowering, and then tilting the NAS upright on its handling cart.
While the NAS is off the tower we will be fine tuning the WFS and VisAO camera alignment, as well as testing the AO to Magellan software interface. In about two weeks we’ll reverse the process, and mount everything back in the tower for some more exciting closed loop action.
I have updated our VisAO filter curves to now include the effects of 3 reflections from Aluminum mirrors (important because Al has a feature at 0.8 microns), the Clio dichroic, the AR coated surfaces of the VisAO Optics, and the protected silver gimbal mirror in the VisAO camera. Most of these are small losses, but 3 Al reflections are fairly costly at only ~90% reflectance each. I have also convolved the resultant curves with the HST/STIS Vega spectrum to give the approximate photon flux in each filter from a 0 magnitude star. The only major thing not included in these calculations is the reflectance of the beam splitter, since it will vary depending on AO system setup.
Last week Laird and I had the pleasure of attending the Arizona Board of Regents meeting in Phoenix, and presenting a poster about the Magellan AO system and the VisAO camera. The session we were invited to was on the impact of scientific research on student’s education at Arizona’s universities. Click the image below to download the poster as a pdf. It contains an introduction to AO in general and visible AO in particular, as well as an overview of the MagAO project. We also took the opportunity to show off some of our exciting results from the test tower in Florence.
We are about to start posting some very exciting results, so I thought we should provide some information about our filter system. We are using Sloan Digital Sky Survey (SDSS) standard r’, i’, and z’ filters as our main bandpasses. These filters were provided by Asahi Spectra. Our CCD47 has a near-IR coating to maximize its long wavelength quantum efficiency (QE). The below plot shows the combined QE of our system (taking into account only the CCD and filters), as well as the mean wavelengths of the filters.
Update 22 July 2011: added the transmission of our 950 Long Pass (950 LP) filter. This should be treated with a little caution, as it is from a catalog page, and not a measurement of our actual filter. Also note that these calculations were done assuming our CCD47 QE goes to 0 at 1.1 microns, since the manufacturer’s curve stops at 1.05.