AAS 198th Meeting, June 2001
Session 75. Observing with the Upgraded Arecibo Telescope
Display, Thursday, June 7, 2001, 9:20am-4:00pm, Exhibit Hall

[Previous] | [Session 75] | [Next]

[75.02] Arecibo Spectral Baselines in the Presence of Continuum Emission

C.J. Salter, T. Ghosh (NAIC, Arecibo Observatory)

When a radio position-switched spectrum is taken in which there is a continuum imbalance between the relevant ON and OFF positions, the resultant (ON-OFF)/OFF spectrum frequently shows a significant standing-wave ripple. This has been found to be the case with Arecibo searches for HI emission and absorption lines against radio-loud AGNs. This effect can be dramatically reduced with a "double-switched" observing mode, using a continuum passband calibrator. Examples are presented, the improvement quantified, and the effect on the signal-to-noise ratios considered.

"The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation".

[Previous] | [Session 75] | [Next]