Seeing statistics at the upgraded 3.8m UK Infrared Telescope (UKIRT)

Marc S. Seigar; Andrew J. Adamson; Nicholas P. Rees; Timothy G. Hawarden; Malcolm J. Currie; Timothy C. Chuter

doi:10.1117/12.460604

2 January 2002 Seeing statistics at the upgraded 3.8m UK Infrared Telescope (UKIRT)

Marc S. Seigar, Andrew J. Adamson, Nicholas P. Rees, Timothy G. Hawarden, Malcolm J. Currie, Timothy C. Chuter

Proceedings Volume 4844, Observatory Operations to Optimize Scientific Return III; (2002) https://doi.org/10.1117/12.460604
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

From 1991 until 1997, the 3.8m UK Infrared Telescope (UKIRT) underwent a programme of upgrades aimed at improving its intrinsic optical performance. This resulted in images with a FWHM of 0."17 at 2.2 μm in September 1998. To understand and maintain the improvements to the delivered image quality since the completion of the upgrades programme, we have regularly monitored the overall atmospheric seeing, as measured by radial displacements of supaperture images (i.e. seeing-generated focus fluctuations), and the delivered image diameters. The latter have been measured and recorded automatically since the beginning of 2001 whenever the facility imager UFTI (UKIRT Fast Track Imager) has been in use. In this paper we report the results of these measurements. We investigate the relation between the delivered image diameter and the RMS atmospheric seeing (as measured by focus fluctuations, mentioned above). We find that the best seeing occurs in the second half of the night, generally after 2am HST and that the best seeing occurs in the summer between the months of July and September. We also find tha the relationship between Z_rms and delivered image diameter is uncertain. As a result Z_rms frequently predicts a larger FWHM than that measured in the images. Finally, we show that there is no correlation between near-infrared seeing measured at UKIRT and sub-mm seeing measured at the Caltech Submillimetre Observatory (CSO).

Citation Download Citation

Marc S. Seigar, Andrew J. Adamson, Nicholas P. Rees, Timothy G. Hawarden, Malcolm J. Currie, and Timothy C. Chuter "Seeing statistics at the upgraded 3.8m UK Infrared Telescope (UKIRT)", Proc. SPIE 4844, Observatory Operations to Optimize Scientific Return III, (2 January 2002); https://doi.org/10.1117/12.460604

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