Mitigation of Pulsed Interference to Redshifted HI and OH Observations between 960 and 1215 MHz

Abstract

The neutral hydrogen 21-cm spectral line (1420.4 MHz) and the four 18-cm lines of the hydroxyl molecule (1612-1720 MHz) are observable at redshifts which put their measured line frequencies well below their protected frequency bands. Part of the redshift ranges (z = 0.171-0.477 for HI and z = 0.37-0.73 for OH) fall in the 960 to 1215 MHz band that is allocated to aircraft navigation. Most of the signals in this band are pulsed emissions of low duty cycle so much of the time between pulses is interference free. This paper outlines the structure and measured properties of signals in this band and demonstrates a signal processing strategy that is effective at removing the pulsed signals from spectra at sensitivities produced by several hours of integration.

Astronomical Journal, May 2005, in press

References in corpus (8)

• The Lyman Alpha Forest in the Spectra of QSOs
• A Search for OH Megamasers at z > 0.1. III. The Complete Survey
• Methods for Constraining Fine Structure Constant Evolution with OH Microwave Transitions
• HI 21cm absorption in low z damped lyman-alpha systems
• HI 21cm absoprtion in two low redshift damped Ly-alpha systems
• The OH Megamaser Luminosity Function
• Variable 21cm absorption at z=0.3127
• Two New Low Redshift 21cm Absorbers

Cited by in corpus (5)

• Phased Array Feed Calibration, Beamforming and Imaging
• Statistically Stable Estimates of Variance in Radioastronomical Observations as Tools for RFI Mitigation
• The Search for HI Emission at z $\approx 0.4$ in Gravitationally Lensed Galaxies with the Green Bank Telescope
• Simulating Spectral Kurtosis Mitigation Against Realistic RFI Signals
• An Experimental setup to develop RFI mitigation techniques for radio astronomy