Solar Bulletin, October 2003

• Sudden Ionospheric Disturbance Report

Click image to enlarge. Fig. 1. 10 cm Solar Flux and American Relative Sunspot Numbers (Ra) for October 2003 (10cm Source: http://www.drao.nrc.ca/icarus)

Click image to enlarge. Fig.2 Maximum, Mean, and Minimum Ra Values for Each Month from January 2001 to Present.

Chair and Sunspot Observing Group Leader: Carl E. Feehrer
Solar Flare/SID Observing Group Leader: William Michael Hill

The Division continues to attract new contributors to both of its observation activities. During the period, 95 observers have filed sunspot reports, a gain of five over the previous year, and 24 observers have filed SID reports, a gain of four. We hope that these gains and the high levels of interest demonstrated by both sunspot and SID observers can be maintained as solar activity levels now trend toward the minimum part of the sunspot cycle.

Sunspot Reports

During the period, 887sunspot reports containing a total of 13,645 observations were received and processed. A larger number of reports has been received in this period than in the previous periods as a result of growth in the size of the observer group. On average, reports have been received from an average of 75 observers during each month of the period.

SID Reports

Despite the loss of the NAA transmitter in Cutler, ME due to an extended period of maintenance, 158 reports based on the monitoring of seven different VLF stations were received and processed. The average number of SID observers reporting each month was 13.

Website Activity

The number of contributions of solar images continues to increase to the extent that it is now possible to become somewhat selective concerning the images chosen to appear on the site. The numbers of downloads from the AAVSO/Solar website also remain high and the ability to obtain the Bulletin in this way has reduced the need for hardcopy mailings.

Reorganization of the Sudden Ionospheric Disturbances Supplement

In December 2002, AAVSO member Doug Welch (A-104), who earlier had set up the AAVSO's GRB and SID discussion groups, assumed the responsibility for editing a stand-alone version of the Sudden Ionospheric Disturbances Supplement that had accompanied the Solar Bullletin until the death of its author, Casper Hossfield, the month before. This document is now published in electronic form on an irregular basis and is available for downloading via a link on the AAVSO website. The Solar Bulletin continues as before with analyses and commentary related to sunspots and solar flares.

New Software in Development

Software required for the analysis of sunspot reports in a modern (e.g., Windows XP) environment is now being written by AAVSO member Lenny Abbey. This software will replace programs written some years ago for an MS-DOS environment and will provide new tools for identification of non-conforming data formats and other report deficiences that greatly complicate the monthly task of preparing observations for analysis.

Acknowledgements

The successful performance of the Solar Division during the period was due, as usual, to the dedication and hard work of our network of observers, the AAVSO's staff, and Arthur Ritchie, a volunteer who assists in the preparation of the monthly sunspot data.

Thank you all.

Michael Hill, SID Analyst 114 Prospect St Marlborough, MA 01752 USA noatak@aol.com

Observer Code Station(s) monitored J Winkler A50 NPM XXX D Toldo A52 nwc xx22 xx41 J Ellerbe A63 ICV P King A80 HWU W Moos A84 FTA ICV G DiFillipo A93 DHO HWU M King A99 HWU F Steyn A102 NWC B Bose A103 FTX L Observatory A107 DHO P Mortfield A108 NLK Truman State U. A110 XXX

The events listed above meet at least one of the following criteria Event reported by two or more observers within +/- 5 minutes Event matched to GOES-8 XRA event to within +/- 15 minutes and event time < 1000 UT Reported by observer with a high quality rating > 8 (scale 1-10)

Solar Events