EDP Sciences
Free Access
Volume 373, Number 2, July II 2001
Page(s) 746 - 756
Section Instruments, observational techniques and data processing
DOI https://doi.org/10.1051/0004-6361:20010611
Published online 15 July 2001

A&A 373, 746-756 (2001)
DOI: 10.1051/0004-6361:20010611

Optimization of heterodyne observations using Allan variance measurements

R. Schieder and C. Kramer

I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

(Received 11 January 2001 / Accepted 26 April 2001)

Stability tests based on the Allan variance method have become a standard procedure for the evaluation of the quality of radio-astronomical instrumentation. They are very simple and simulate the situation when detecting weak signals buried in large noise fluctuations. For the special conditions during observations an outline of the basic properties of the Allan variance is given, and some guidelines how to interpret the results of the measurements are presented. Based on a rather simple mathematical treatment clear rules for observations in "Position-Switch" , "Beam-" or "Frequency-Switch" , "On-The-Fly-" and "Raster-Mapping" mode are derived. Also, a simple "rule of the thumb" for an estimate of the optimum timing for the observations is found. The analysis leads to a conclusive strategy how to plan radio-astronomical observations. Particularly for air- and space-borne observatories it is very important to determine, how the extremely precious observing time can be used with maximum efficiency. The analysis should help to increase the scientific yield in such cases significantly.

Key words: instrumentation: miscellaneous -- methods: data analysis, observational -- space vehicles: instruments -- techniques: spectroscopic -- telescopes

Offprint request: R. Schieder, schieder@ph1.uni-koeln.de

© ESO 2001

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.