Click image to enlarge. Fig.1 Comparison of Ri (provisional) and Ra estimates for October. (Ri Source: http://sidc..oma.be/index.php3)

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Smoothed Mean Sunspot Number (Rsm) for April 2001: 116.5

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Sudden Ionospheric Disturbance Report

Sudden Ionospheric Disturbances (SID) Recorded During October 2001

The events listed above meet at least one of the following criteria

Reported in at least two observer reports Visually analyzed with definiteness rating = 5 Reported by overseas observers with high definiteness rating

I had the pleasure of attending the AAVSO Meeting this past month and it was a very enjoyable time. I only have one regret. I was meaning to get together with Art Stokes but when I got a chance to do so he had gone up to his room because he was not feeling very well. I didn't see him again till later at the evening banquet. I did not talk to him right away because I figured I'd see him after we had all eaten. By then he had once again retired to his room, again not feeling well. Unfortunately I never did get to chat with him that day. Art died four days later. We have all lost a most active and important member of the SID program and the AAVSO. Art will be missed but will live on among us as we all use our Stokes Gyrator receivers which he designed and perfected, thereby making SID monitoring so approachable. I learned from this how important it is to seize each moment; to not let things wait if possible. I wish I had talked to Art that day. I will forever miss that final chat we would have had. God Bless you Art - Rest in Peace. There were 257 flares detected by the Goes-8 Satellite. Most of them were C-Class flares with 32 rated as M-Class events and 4 as X-Class events. These X -Class events caused a lot of activity here, including some wonderful auroras. There were only 87 SID Events detected. The most active days occurred on or around the 2nd, 14th, and 18th. The X-Class events resulted in some very strong SID events, especially on the 19th and 25th.

Casper H. Hossfield, SID Sup. Editor PO Box 23 New Milford, NY 10959, USA

SUDDEN IONOSPHERIC DISTURBANCES RECORDED DURING October, 2001

capaavso@aol.com Fax 973 853 2588

The Magnetogram above shows the great magnetic storm on 6-7 November. This storm, starting near 0200 UT (9PM EST Monday evening, 5 November), produced an aurora that was seen as far south as Georgia in the Eastern United States. I had received an email from AAVSO sunspot observer, Jim Carlson, saying there had been a major X flare that produced a coronal mass ejection so the great magnetic storm and aurora were not unexpected. This storm recording was made by Jim Mandaville, A-90, in Tucson, AZ, USA. Jim recorded the magnetogram with his homemade McWilliams torsion balance magnetometer. Here is how Jim describes it: "The vertical scale is in nanoTeslas relative to the baseline before the storm onset. Total amplitude of the storm variation was 450nT. This is truly a classic magstorm, starting with the sharp positive spike of the ‘sudden commencement' near 02 hrs UTC. Then comes the ‘main phase,' characterized by a rapid plunge in field strength. After bottoming out it begins the ‘recovery phase' working its way gradually back toward the original station baseline." Jim has calibrated his magnetometer with a Helmholtz coil so the 450 nT range of the storm is accurate. A McWilliams magnetometer that was built from a Solar Division kit as a science fair project is described below. This is taken from a paper I presented at the recent AAVSO meeting in Somerville, Massachusetts, USA.

REBECCA'S MAGNETOMETER

I helped Rebecca Ragar, a high school senior, in Arkansas, USA, build a McWilliams torsion-balance magnetometer as a science fair project. Rebecca's magnetometer was one of the winners at the regional fair which qualified her to enter it in the Arkansas State Science Fair. At the state fair Rebecca won two awards. One was from The United States Geological Survey and the other from the United States Navy. I believe these awards probably played a significant part in Rebecca's being accepted by the college of her choice. Helping students build science fair projects is a good way for scientists, whether amateur or professional, to help students learn about science through hands-on experience. I am a judge each year at the regional science fair in Orlando, Florida and know from experience that a student who actually builds something stands a much better chance of being a winner than those who simply download stuff from the Internet for their project. This is probably the reason Rebecca's homemade magnetometer was a winner that made it into the state fair to win additional awards.

For me, helping Rebecca build her science fair project was a very rewarding experience. I hope my experience might inspire other scientists to get involved with helping students build science fair projects. A good way to get started is to offer to be a judge at your regional science fair. Judges are also always needed so get in touch with a science teacher at your local high school. As an amateur scientist you will be most welcome as a volunteer judge. With that in mind I have built a homemade magnetometer similar to the one Rebecca built from a Solar Division kit and brought it to the fall meeting of the AAVSO so others can see what it looks like. If you are interested in building a magnetometer for yourself or know a student you might want to help build one, please contact me at my address above. For $5.00 you can have a Solar Division minimum kit which consists of drawings and detailed instructions how to build the magnetometer. Also included is the hard-to-find .006 inch diameter torsion wire. Software on floppies to record the magnetometer's output on a computer comes with the minimum kit. A list of suppliers and what to buy is also included. Plans for building an A/D converter for the software can be found on the AAVSO web site at << WWW.aavso.org >>. By the time you buy all the stuff you need you will have spent about $100.00 and you will need some home workshop tools to build it. A complete kit with the more difficult work already done is available for $120.00 and you can probably put it together on the kitchen table if you don't have a home workshop. The complete kit is the minimum kit above plus everything you will need to build the magnetometer and set it up and record magnetic storms. The larger parts for the base and the torsion wire suspension post are already cut to size from wood from Home Depot. All you will have to do is drill some holes for wood screws with a hand drill and glue the torsion wire suspension post assembly together with five minute epoxy which is supplied. The shadow vane and magnet assembly that are suspended on the torsion wire are made from model airplane wood that you would have to find at a hobby shop. A tiny model maker's miter box and saw to cut this small wood to size are included with the kit as is the Cyanoacrylate glue to fasten it all together (the glue hardens in 30 seconds). The Plexiglass for the wind screen is also cut to size and all you have to do is put it together with cyanoacrylate. The photocells, light source, power supply and associated electronics to make the motion sensor are all included. The kit also includes a 4-inch long Alnico 8 magnet, all the brass screws, brass tubing, miscellaneous hardware and small round files needed to make clearance holes in the wind screen for the torsion wire and electrical connections.

The McWilliams torsion balance magnetometer was designed by Al McWilliams, A-94, about twenty years ago when he was a physics professor at the University of St. Cloud in Minnesota. It is a very simple instrument but nevertheless will produce magnetograms that look exactly like those made by a nearby United States Geological Survey magnetic observatory using professional flux-gate magnetometers. Basically it is a magnetic compass needle suspended on a length very thin music wire. The needle would normally point north and south but the torsion wire is twisted enough to produce enough torque to make the needle point east and west. The needle is therefore balanced against the Earth's magnetic field by the torsion wire. This accounts for the name, torsion balance magnetometer. Magnetic storms are produced by the Sun when solar flares or coronal holes radiate charged particles that become trapped in the Earth's magnetosphere. They produce a magnetic field that adds to or subtracts from the Earth's normal magnetic field thus changing the balance on the torsion wire and therefore the direction the needle points from the direction it normally points when there is no storm. A shadow vane on one end of the needle shades two Cadmium Sulfide photocells from a light source to act as a motion detector. The torsion wire is adjusted so the shadow vane shades the photocells equally, half of each cell being exposed to the light source. Cadmium Sulfide photocells are variable resistors. Their resistance varies with the amount of light they are exposed to. They are connected in series as two elements of a four element Wheatstone bridge in which no current flows when each pair of elements have equal resistance. A meter connected across the bridge will therefore read zero. When a magnetic storm disturbs the balance of the torsion wire the needle moves and the shadow vane attached to it moves to cover the photocells unequally thus unbalancing the Wheatstone bridge and causing current to flow in the meter. The changing value of the current and its polarity is recorded on a strip chart recorder or computer , preferably at a chart speed of ¼ inch/hour to make the magnetogram. Storms can last from a few hours to more than a day. Having your own magnetogram allows one to predict the possibility of an aurora which often occur in response to magnetic storms. Rebecca built her magnetometer as an experiment to see if she could predict an aurora. Science fair projects are more apt to be winners if the student performs an experiment and then writes a scientific paper to report the results of the experiment. Chances of winning are enhanced by building your own homemade scientific instrument to perform the experiment. The homemade McWilliams magnetometer apparently makes a very favorable impression on science fair judges and therefore stands a good chance of being a winner. It is also interesting just to build a magnetometer for your own use to keep track of magnetic storms, predict auroras and follow what the Sun is doing to the Earth's magnetosphere. If you are an amateur radio operator you can make your own K index.   CHH

Jim Ellerbe, A-63, in Spain sent the chart below that shows four SESs he recorded on 22 October. This is a nice clean recording with no interference that shows a typical sunrise pattern starting just before 0600 UT. It was made with one of Art Stokes's gyrator receivers and recorded on a Rustrak strip chart recorder running at 1-inch/hr chart speed.

There is sad news to report. We have lost Art Stokes, A-62, who died unexpectedly of a heart attack Monday, 6 November after returning home from the AAVSO meeting (3-4 November) in Somerville, Massachusetts. It is good that we all had a chance to see Art one more time at the meeting. Art and I are the two oldest SID observers (both of us 83) who regularly attend the meetings. We remarked about how lucky we were to still make it to the meetings both of us have been attending for over 35 years. That was Saturday. By Monday Art was gone. It shows how vulnerable we are when we reach 80. About the only thing that can be predicted with reasonable certainty is we are not apt to have many more years left. We can hope to make it to 90 but most of us won't. We can also hope to go suddenly like Art without pain and suffering but that too, is just a matter of luck.

October was a month of high solar activity that produced many SIDs. Below are SIDs Roberto Battaiola, A-96, recorded as SESs on 30 and 31 October. Roberto lives in Italy and records VLF station HWU in Le Blanc, France transmitting on 20.9 kHz.

Below is an interesting SES recording of the VLF station in La Mourie. North Dakota, USA transmitting on 25.2 kHz. Jerry Winkler, A-50, in Houston Texas, USA made this one with its multiple inversions in its rise to maximum. There is a normal sunrise pattern at the left end of the chart followed by an SES that starts out as a sudden short rise followed by an inversion that brings the traceto the bottom of its travel and then suddenly back up again where it reverses again and drops more slowly to the bottom. Then it returns to normal near the middle of the chart. The second time it reaches the bottom is actually the maximum of the SES and everything before that is its "rise" to maximum. The chart was made with a Dataq A/D converter and plotting software that is sold by Radio Shack.

An SES chart below made by Jim Mandaville, A-90, shows ten SESs recorded on 25 October. The station recorded is NPM in Hawaii transmitting on 21.4 kHz.

Most AAVSO observers who record solar flares by their effect on the Earth's ionosphere use the Gyrator VLF receiver which is Art Stokes's Legacy. Over the years Art has helped many of them get their receivers working properly when they were not quite able to adjust it for optimum performance themselves. Jim Ellerbe's chart above is a good example. Now that Art is gone there will be no one to help observers put the finishing touches on their receivers or help them get their receivers going in the first place if they run into trouble. Sometimes Art built a gyrator receiver for overseas observers who might find it difficult to find the parts to build the receiver. At the recent meeting Art promised to build a receiver for Jaime Garcia who lives in Mendoza, Argentina. Jaime is an AAVSO variable star observer who attended the meeting and we saw this as opportunity to add a South American observer to our group. Jaime lives on a four-hectare farm and would be able to place the receiver's antenna far enough away from household interference to produce nice clean interference-free recordings. Art was going to tune his receiver to NAA in Cutler, Maine, USA so he would have a long north-south propagation path which usually is very sensitive to ionospheric disturbances produced by solar flares. It would be nice if someone would carry out these plans for him now that Art is gone. If you would be interested in doing this please get in touch with Solar Division Chairman Carl Feehrer or me for Jaime's address and other information.

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