First Light Adaptive Optics System for Large Binocular Telescope
The paper describes the design of the single conjugate Adaptive Optics system to be installed on the LBT telescope. This system will be located in the Acquisition, Guiding and Wavefront sensor unit (AGW) mounted at the front bent Gregorian focus of LBT. Two innovative key features of this system are the Adaptive Secondary Mirror and the Pyramid Wavefront Sensor. The secondary provides 672 actuators wavefront correction available at the various foci of LBT. Due to the adaptive secondary mirror there is no need to optically conjugate the pupil on the deformable mirror. This allows having a very short sensor optical path made up using small dimension refractive optics. The overall AO system has a transmission of 70 % and fits in a rectangle of about 400x320mm. The pyramid sensor allows having different pupil sampling using on-chip binning of the detector. Main pupil samplings for the LBT system are 30x30, 15x15 and 10x10. Reference star acquisition is obtained moving the wavefront sensor unit in a field of view of 3x2 arcmin. Computer simulations of the overall system performance show the good correction achievable in J, H, and K. In particular, in our configuration, the limiting magnitude of pyramid sensor results more than one magnitude fainter with respect to ShackHartmann sensor. This feature directly translates in an increased sky coverage that is, in K band, about doubled with respect to the same AO system using a Shack-Hartmann sensor.
LUCIFER: a NIR spectrograph and imager for the LBT
LUCIFER is a full cryogenic NIR spectrograph and imager to be built by a consortium of fiber institutes, Max Planck Institut fuer Astronomie in Heidelberg, Max Planck Institut fuer Extraterrestrische Physik in Garching, Astronomisches Institut der Ruhr Universitaet Bochum and Fachhochschule fuer Technik und Gestaltung in Mannheim. The instrument has been selected as one of three first-light instruments for the Large Binocular Telescope on Mt. Graham, Arizona which first mirror becomes available to the community in early 2003. The second mirror and a second more or less identical spectrograph/imager follows 18 months later. Both LUCIFER instruments will be mounted dat the bent Gregorian foci of the two individual LBT-mirrors and include six observing six observing modes: seeing and diffraction limited imaging, seeing and diffraction limited longslit spectroscopy, seeing limited multi-object spectroscopy and integral-field spectroscopy. The detector will be a Rockwell HAWAII-2 HgCdTe-array with a pixel-size of 18(mu) .
Pedagogy of the “Not”: Negation, Exodus, and Postdigital Temporal Regimes
Postdigital capitalist time is an incessant acceleration that acts to homogenize time and wed us to the present, to which we have to constantly catch up. While the impulse of this is no doubt economic (the realization of value), it is crucially undergirded by a pedagogical logic wherein we have to perpetually learn and re-learn the latest apps, social media configurations, operating systems, and so on. Political strategies of resistance thus need to be bolstered by an alternative mode of educational life, and I propose a pedagogy of the “not” as one possibility. Such a pedagogy is an act of suspension that sustains a detachment from the present, clearing out oppositions and thereby exposing us to a radical indeterminacy and potentiality that is always untimely. Suspension is the praxis of negation, which means that negation operates by keeping sense indeterminate to meaning and signification. Rather than suppressing, disavowing, or annihilating the stated content, negation retains even that which is negated. While this would appear as a form of exopedagogy, which withdraws from the dialectic of the private/public, I instead argue that it redefines the terms of any dialectic, redefining the very categories exopedagogy withdraws from. Before concluding, I spend some time with Sandy Grande’s important critiques of Eurocentrism and progress in Western critical education, demonstrating how negation as suspension circumvents these errors through its accommodation of—or, better, insistence on—variegated temporalities and forms of life.