SOLAR NOTES by Ken Medway
Updated 26th November 2001
This page has been added to publicise some of the Solar observations made by Ken Medway, the
Society's Secretary. Although this page was generated by me, I am grateful for the input by Ken
who supplied material for inclusion on this page.
Derek Haselden - Webmaster
SOLAR NOTES
OTHER ASTRONOMY AND SPACE NEWS AND INFORMATION
WARNING
Never, ever look at the Sun directly through any optical instrument - instant blindness could be the result.
Even looking at the Sun with the naked eye can be harmful.
DO NOT look at the Sun with magnifying glasses, cameras, binoculars or telescopes, any optical instrument in fact, without the use of a properly designed, approved and tested filter or specialised instrument.
DO NOT use photographic film, smoked or tinted glass, plastic or metal film.
Use only materials and instruments designed for the specific purpose for viewing the Sun.
If in doubt, seek expert advice first!
Foreword by Ken Medway
Observations were made from 1966 to 1972 using a 60mm refractor, 1972 to 1976 with a 76mm
refractor and from 1976 April 29 to the present using my 102mm, f/15 Unitron refractor housed in a
sliding roof observatory. Solar observing is always a worthwhile activity and amateur observations
are always needed by professional astronomers.
I entered the Ha (Hydrogen Alpha) field in 1974 with a 0.5Å filter purchased from Carson
Astronomical Instruments in the United States. Later in 1977/78 I built a coronagraph-type
prominence telescope to take a new filter aquired on an eclipse trip in 1977. Much later in 1990 I
acquired my present Ha filter from the Daystar Filter Corporation which has a passband of O.6Å. It
still gives me excellent results.
Recent solar projects have been to video events on the Sun in white and Ha light, the results of
which have been shown at some of the monthly meetings of Solent Amateur Astronomers.
When making a white light sunspot drawing it is necessary to obtain the correct orientation of the
solar image to establish the N, S, E, and W points. If this is not done the drawing is uselsss and
inaccurate sunspot positions will result. The observer must bring the projected image of the Sun
on to a grid work of squares, then allow a spot to drift across a horizontal line - it must follow the line exactly, without deviation.
Once this procedure has been completed the process of obtaining the sunspot positions can
begin. I make sure the projected solar image fills a circle (15 cm or 6 inches diameter) drawn on a projection card. Then with reference to the grid work of squares transfer the spot positions from
there on to a solar blank on a recording board on which a similar gridwork of squares has been
drawn. This procedure, once mastered takes very little time to complete, even with at times,
heavily spotted disks.
Feedback about this page and requests for data are welcome, please send an e-mail to
Ken Medway.
MDF - Mean Daily Frequency
Mean Daily Frequency (MDF) is a measure of the average amount of active areas on the Sun over
a period of time, typically one month. So, if 51 active areas were noted on 18 days of solar
observation, then the MDF for that month is: 51 divided by 18, which equals 2.83.
Below are two graphs that plot the course and trend in solar activity. In the case of these graphs they show the levels of visual (white light) observations of active areas. The first is based on MDF data from January 1986 to December 2000; the second from January 1970 to December 2000. In each graph the trend towards increasing solar activty can be clearly seen. The Sun is thought to have reached peak activity in July of last year although this has yet to be confirmed. The Sun is expected to maintain these currently high levels of activity for a year or so before it starts to decline. The next solar minima can be expected sometime around 2006.
Previously, I had shown line type graphs which ploted three traces; Total MDF; North MDF and
South MDF. North was plotted as a positive value, South as negative.
The graphs plotted this time are area type graphs. This time round I have plotted the graphs by using the data to calculate a 6 month moving average. This results in a smoother, less spikey graph but the trend and pattern of solar activity is retained. These shown only the total MDF value but in all other respects they still show levels of solar activity over time.
The last solar minimum occured around the beginning of 1996 and this graph shows the steady
rise in activity since then. Although the length of the solar cycle does vary, the average cycle
length is 11.1 years, so the Sun should have reached a peak of activity sometime last year. It should continue to be more active for a couple of years yet before is starts to decline toward the next solar minima.
This graph shows the results of 30 years of observation. It contains the same data as the previous graph but instead goes back to 1970. A little under 3 complete solar cycles can be seen.
With 34 years worth of observation (and 3 complete solar cyles) the above graph demonstrates the results of Ken's dedicated observations. A few things are worth pointing out here. Note that the rise to solar maximum is sharper than the fall from maximum. Also, note that each successive minimum has been slightly deeper than the previous.
The above graphs show some of the merits of regular observation and data recording. The data itself, endless rows and columns of numbers, looks quite uninteresting - until presented in
graphic form!
OCTOBER 2001
Some large spots were seen, a large unipolar spot near the central meridian in the northern hemisphere on the 24th and a large spot group which appeared round the north east limb on October 12th at latitude +9°. This group was carried by the Sun's rotation and was seen near the central meridian on October 31st when it was easily seen with the naked eye and using a Mylar filter.
The numbers of solar prominences seen remains quite high. Observations in hydrogen alpha light were made on 7 days in October. Of particular note was a very high arch prominence seen on the north west limb on October 9th.
SEPTEMBER 2001
AUGUST 2001
The highlight of the month was the passage across the disk of a large sunspot group - first seen on the east limb on August 23rd at -19° latitude. In hydrogen alpha light the group was very flare-active and on Saturday August 25th a brilliant, large 3B flare was observed from 16:25 to 17:30 UT - an impressive sight! The group crossed the central meridian on August 28th by which time it was enveloped in a bright hydrogen plage. As was the case in July, the northern hemisphere was slightly more active that the southern.
JULY 2001
JUNE 2001
MAY 2001
APRIL 2001
Of all the prominences seen during April using my 0.6Å Hydrogen Alpha filter the splendid display of loop prominences seen on the south east limb on April 3rd were the most outstanding. Classic loop prominences which are often used to illustrate books and chapters about the Sun were visible.
MARCH 2001
On March 24th a large spot was seen near the north east limb at +15°. This turned out to be the largest sunspot recorded since the giant one of March 1989 and was visible with my naked eye using an aluminised solar filter every day for the rest of March except the 26th when it was cloudy. This spot, which had 5 large umbral centres, crossed the central meridian on March 28th. It was last seen near the west limb on April 3rd. It will be interesting to note what changes have taken place in this spot when it reappears on April 17th at the east limb.
Only 4 days observations were secured with the 0.6 Angstrom filter in Hydrogen alpha light. The level of high prominence activity remains the same compared with February.
FEBRUARY 2001
JANUARY 2001
Although spots seen were mostly small and the active area count rising to 11 on January 7th, there was an interesting bipolar group seen on January 14th at latitude +14/15° W and this was visible to the naked eye using an aluminised solar filter. Sunspots seen ranged in latitude from +28° to 0°. Observations of the Sun are made by projecting the Sun with my 102mm, f/15 refractor to a scale of 150mm to the solar diameter. Accurate sunspot positions are then read off the projection screen attached to the telescope and transferred to the drawing chart on my recording board. It sounds a lengthy process but the truth is it only takes me about 10 minutes to complete a solar disk drawing given that lately the solar disk has been heavily spotted.
Prominences were far more numerous around the solar limb in hydrogen alpha light using my 0.6 Angstrom filter. The MDF turned out at 9.66, North 4.83, South 4.83. Many prominences seen resembled tall spikes.
DECEMBER 2000
Sunspot activity was lower in December, the Mean Daily Frequency being 4.35
(North=2.43, South=1.92). Perhaps the most interesting sunspot group was the one observed on December 30th. Located at solar latitude -2 degrees, it consisted of one large leading spot, which
was visible to the naked eye, and several smaller spots preceding the large spot.
Hopefully we can look forward to the appearance of many more large spots like this. It is considered that solar maximum was reached in July 2000. Further confirmation of this date is awaited.
NOVEMBER 2000
The sunspot M. D. F. turned out at 5.64 (North=2.50, South=3.14). The general level of sunspot activity was disappointingly low considering the Sun is at or near the maximum of the current solar cycle. Prominence activity was very high. I only managed observations on 3 days in November and the prominence M. D. F. turned out at 9.00 (North=5.00, South=4.00) slightly down on activity observed in October.
Feedback about this site and suggestions for additional information and pages are welcome, please send an e-mail to The Webmaster.
© Derek Haselden, Ken Medway & Solent Amateur Astronomers 2004
The data presented here in graphical form is the result of 34 years of routine daily observation of the Sun by me. During this time I have always used the same, safe method for observing the Sun, i.e. the projection method. I have closely followed the solar observing guidelines laid down by the late Bill Baxter in his 1963 book, The Sun and the Amateur Astronomer.
Derek Haselden writes: There are a variety of ways of observing the Sun as well
as recording those observations. One of the most common methods used is that of recording the
amount of active areas on the solar surface. For example, by observing the Sun on a regular basis
and recording the sunspots and spot groups seen it is possible over a period of time to work out
how active the Sun is. However, with an activity cycle of on average 11.1 years it will take many
years of observation to establish a pattern.
The Sun was observed on 18 days in white light in October using my 102mm, f/15 refractor to project a 15 cm solar image. The northern hemisphere was slightly more active than the southern hemisphere as my M.D.F. statistics show as follows: Total - 5.72; N. - 2.94; S. - 2.78. The active area count during October fell during the first half of the month then rose peaking on the 20th.
Sunspot activity underwent an increase in September with a MDF of 7.74 (North - 3.69, South - 4.05). Large spots were seen on September 10th and 25th - both visible to the naked eye. Many fine prominences were seen. On September 23rd a tall spire prominence was seen on the North West limb.
The Sun was observed in white light on 26 days during August. There was a slight increase in sunspot activity during the month with the Mean Daily Frequency being 5.31 (N: 2.85, S: 2.46).
During July the Sun was observed on 29 days using my 102mm, f/15 refractor using the projection method. The general level of sunspot activity was down on that of June with the MDF being 4.37. One special point of interest was the observation of a high latitude spot during the first week of July. The latitude of the spot was -43° - unusual when the average latitude of spots recently observed has been +10°. The spot was short-lived and had disappeared by July 6th. Prominences seen were mostly small.
The Sun was observed on 21 days in June and a sunspot Mean Daily Frequency of 7.09 (North 4.86, South 2.23) was obtained, an increase in the number of spots observed in May. There were many small spots and groups in June, the active area count attaining 10 and 11 for the first part of the month and then falling off to 2 to 3 by the end of June. The numbers of prominences seen were also fewer during the month, the M.D F. being 7.55.
The month of May was completely covered, my sunspot Mean Daily Frequency being 5.77, (North 3.90, South 1.87). There were many small spots visible in May and the range of spot latitudes was quite varied extending from spots observed near the solar equator on May 23rd to a small spot mote on May 5th. The numbers of solar prominences showed an increase in May but many features were mostly small and took the form of spikes and mounds. A large hedgerow prominence was seen on May 25th.
Far better coverage of the Sun was attained in April with observations being made on 28 days. The MDF was 5.79 (North = 3.25, South = 2.54). The large sunspot observed in March appeared around the east limb again on April 18th. Although slightly reduced in area it was nonetheless quite an impressive spot. It was lying across the central meridian on April 24th and visible to the naked-eye (using a Orion Telescopes Solar Filter).
Solar Activity in 2001 March: First some statistical details... The Sun was observed on 16 days in March and the Mean Daily Frequency of Sunspots turned out at 6.06 (North 3.44, South 2.62) a slight increase on the level of sunspot activity observed in February. Up until March 24th the number of sunspots seen was similar to that of February with between four and six active sunspot areas being seen every day, weather permitting.
The Sun was observed by me on 17 days in February and a Mean Daily Frequency for sunspots of 4.35 obtained (North: 2.12, South: 2.23). This is a disappointing figure especially in view of the fact that the Sun is near the maximum stage of the solar cycle. No outstanding spots or groups were seen in the month, in fact on February 6th the southern hemisphere was spotless. Hopefully we can look forward to the appearance of some large sunspots and groups before too long.
The Sun was observed on 17 days in January. I read reports in the press that January was the sunniest since 1959. This is reflected in the number of days I managed to observe the Sun which was 17. The M.D.F. or Mean Daily Frequency, the index of sunspot activity adopted by the Solar Section of the British Astronomical Association amounted to 5.47 - a slight increase on that of December's activity. The North MDF was 3.23 and the South 2.24.
Despite the really awful weather in December the Sun was observed on 14 days using my observatory based 102mm, f/15 refractor and portable 60mm, f/13.3 refractor at work. With both scopes I projected the Sun to the standard 15cm to the solar diameter and spot positions were taken accordingly.
The Sun was observed on 14 days in November. Weather conditions were far from ideal and many weekday observations were conducted using my 60mm, f/13.3 refractor projecting a 15cm solar disk from the 9th floor landing of my place of work - in the lunch hour, of course. Many of my colleagues are now familar with the appearance of sunspots as a result.
