Open AccessA site‐testing campaign at the Calar Alto Observatory with GSM and DIMM instruments
Author(s) -
Ziad A.,
Gredel R.,
Aceituno J.,
Borgnino J.,
Hoyo F.,
Irbah A.,
Martin F.,
Thiele U.,
Pedraz S.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09299.x
Subject(s) - physics , observatory , standard deviation , remote sensing , astrophysics , coherence (philosophical gambling strategy) , optics , astronomy , geology , statistics , mathematics , quantum mechanics
The main atmospheric optical parameters have been measured at the Calar Alto Observatory simultaneously using the Generalized Seeing Monitor (GSM) and a Differential Image Motion Monitor (DIMM) during several nights in 2002 May. The temporal evolution of the seeing, the outer scale, the isoplanatic angle and the coherence time have been analysed. There is excellent agreement between the seeing measurements provided by the two instruments, particularly when the turbulence is slow. Indeed, the GSM measurements are corrected from the exposure time when the DIMM data were recorded for at least 5 ms. From almost three years of DIMM (at 5 m height above ground) data, a seeing of 0.92 arcsec with a standard deviation of 0.31 arcsec has been obtained for this site. The outer scale , the isoplanatic angle θ 0 and the coherence time τ 0 measured with the GSM are well fitted with log‐normal distributions with median values of 22.9 m, 2.27 arcsec and 3.7 ms, respectively.