Our Mailing Address:
BARCPO Box 17362
Boulder, CO
80308-0362
Email: BARC70@arrl.net
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BARC received this certificate recognizing it as an ARRL Special Services Club. BARC is one of only two such clubs in Colorado with this status. Thanks to the BARC members who make this SSC recognition possible by all you do! |
Crystal Sets to Sideband, A Guide to Building an Amateur Radio Station (PDF)
An eBook, in PDF format, written by Frank Harris, KØIYE, one of our long-time BARC members. This book is a great guide to learn how to homebrew your ham radio station, and to help learn the many facets of old and new ham radio technologies.
Revision 12, Copyright Frank W. Harris, 2002, 2010
Edge of Space Sciences (EOSS)
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Boulder A-Index
Space Weather Alerts, Watches, & Warnings (NOAA)
Boulder Magnetometer Monitor (NOAA)
Station K and A Indices (NOAA)The geomagnetic A-index is derived from the K-index, which quantifies disturbances in the horizontal component of earth's magnetic field using a 0-9 integer scale. K and A indices are indicators of ionospheric radio propagation conditions.
A K-index value of 1 indicates calm and 5 or more indicates a geomagnetic storm. The K-index is derived from the maximum fluctuations of horizontal components observed on a magnetometer over a three-hour interval.
The A-index provides an average level for geomagnetic activity. Because K scale magnetometer fluctuations are non-linear, quasi-logarithmic, it is not meaningful to take averages for a set of K-indices. Instead, each K is converted back into a linear scale called the equivalent three hourly range "a"-index (lower case "a"). The daily A-index is an average of eight "a" indices.
For many years, local hams had access to an A-index published for Boulder, Colorado. Although the formal "Boulder A-Index" is no longer officially publicized, the magnetometer used to provide it is still operational.