Share Email Print
cover

Proceedings Paper

Spectroscopy with adaptive optics: spectral slope variations
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

We present a note on low to medium resolution spectroscopy using adaptive optics (AO) system. A special focus is put on the problem of spectral slope variations. In principle a stellar image compensated by AO has a varying point spread function (PSF) strongly dependent on the observing wavelength. Even when the AO is working perfectly, the fraction of the energy in a finite size slit will change with the wavelength. The performance of AO correction is very sensitive to the observing conditions. Spectral slope variations directly connected to the wavelength dependency of the enclosed energy in the slit. Those features common and relatively harmless in conventional spectroscopy such as temporal variation in the seeing, brightness of the targets, imperfect slit peaking, atmospheric differential refraction, and fixed aperture size at spectral extraction, all introduce artificial continuum slopes. The degree of uncertainty in the spectral slope could be serious enough to interfere the observing goals in AO spectroscopy. A case for a spectroscopic observation for low mass stars is presented to demonstrate the problem. We found a steep continuum slope that is unrealistic for a low mass star. We undertook laboratory experiments with a calibration source in the AO system to test if the unrealistic continuum slope could be accounted for by the varying AO performance. In the experiments the "bluing" of the continuum slopes have been confirmed when the light source is dropping off of the slit or the wavefront reference source is faint. The effects are also qualitatively reproduced with calculations done by an AO simulation code.

Paper Details

Date Published: 7 February 2003
PDF: 7 pages
Proc. SPIE 4839, Adaptive Optical System Technologies II, (7 February 2003); doi: 10.1117/12.459251
Show Author Affiliations
Miwa Goto, Subaru Telescope/National Astronomical Observatory of Japan (United States)
Yutaka Hayano, National Astronomical Observatory of Japan (Japan)
Naoto Kobayashi, National Astronomical Observatory of Japan (Japan)
Hiroshi Terada, National Astronomical Observatory of Japan (Japan)
Tae-Soo Pyo, Subaru Telescope/National Astronomical Observatory of Japan (United States)
Alan T. Tokunaga, Institute for Astronomy/Univ. of Hawaii (United States)
Hideki Takami, National Astronomical Observatory of Japan (Japan)
Naruhisa Takato, Subaru Telescope/National Astronomical Observatory of Japan (United States)
Yosuke Minowa, National Astronomical Observatory of Japan (Japan)
Wolfgang Gaessler, Max-Planck-Institut fur Astronomie (Germany)
Masanori Iye, National Astronomical Observatory of Japan (Japan)


Published in SPIE Proceedings Vol. 4839:
Adaptive Optical System Technologies II
Peter L. Wizinowich; Domenico Bonaccini, Editor(s)

© SPIE. Terms of Use
Back to Top