Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope

Details Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope

2009-05-27

arxiv.org/abs/0905.4501v1

Astronomy and Astrophysics

Astrophysics

Instrumentation and Methods for Astrophysics

Accepted for publication by The Astronomical Journal

Scientific paper

High resolution (~1 arcminute) astronomical imaging at low frequency (below 150 MHz) has only recently become practical with the development of new calibration algorithms for removing ionospheric distortions. In addition to opening a new window in observational astronomy, the process of calibrating the ionospheric distortions also probes ionospheric structure in an unprecedented way. Here we explore one aspect of this new type of ionospheric measurement, the differential refraction of celestial source pairs as a function of their angular separation. This measurement probes variations in the spatial gradient of the line-of-sight total electron content (TEC) to 0.001 TECU/km accuracy over spatial scales of under 10 km to over 100 km. We use data from the VLA Low-frequency Sky Survey (VLSS; Cohen et al. 2007, AJ 134, 1245), a nearly complete 74 MHz survey of the entire sky visible to the Very Large Array (VLA) telescope in Socorro, New Mexico. These data comprise over 500 hours of observations, all calibrated in a standard way. While ionospheric spatial structure varies greatly from one observation to the next, when analyzed over hundreds of hours, statistical patterns become apparent. We present a detailed characterization of how the median differential refraction depends on source pair separation, elevation and time of day. We find that elevation effects are large, but geometrically predictable and can be "removed" analytically using a "thin-shell" model of the ionosphere. We find significantly greater ionospheric spatial variations during the day than at night. These diurnal variations appear to affect the larger angular scales to a greater degree indicating that they come from disturbances on relatively larger spatial scales (100s of km, rather than 10s of km).

Affiliated with

Also associated with

No associations

Rating

Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Probing Fine-Scale Ionospheric Structure with the Very Large Array Radio Telescope will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-292922