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10:00UT, projected image H25 eyepiece, 63mm Aperture OG, 840mm f/l.
The full version of the formula can be expressed as
R = k(10g + s)
Where R, g & s are as above. k is an observing constant based on personal experience and instrumentation.
Back in the 1990’s when I used to observe the Sun I found my k was 0.8.
Deciding what was one or two active areas is very much a matter of experience (feeling), but a Stonyhurst Disc could be used as a somewhat crude guide (if you observe by whole disc drawing).
Not as far as I am aware (Historical Section Deputy Director), but then again, the archive is a separate entity.
Thomas Frid Maunder was Assistant Secretary of our Association from its foundation in October 1890 until he retired age 87 on 30 September 1928 (JBAA 38, 9 (September 1928), p.282).
Available online here
Light radiating from the Sun follows the inverse square law (ie intensity = 1/d*d)
The benchmark value for the Earth at one Astronomical Unit (AU) from the Sun is thus 1/1*1 = 1.
For Mercury 1/0.3*0.3 = 11. The Sun is more than ten times brighter than on Earth.
For Venus 1/0.7*0.7 = 2. The Sun is around twice as bright as on Earth.
For Mars 1/1.5*1.5 = 0.44. The Sun is less than half as bright as it appears on Earth.
For Jupiter 1/5.2*5.2 = 0.036. The Sun is only around 4% as bright as it appears on Earth.
For Saturn, 1/9.5*9.5 = 0.01. The Sun is only around 1% as bright as it appears from the Earth.
For Neptune 1/30*30 = 0.001. The Sun is only 0.1% as bright as it appears from the Earth.
Solar filters typically reduce light levels by 99.999% (ie allow 0.00001 pu through).
We need to rearrange the inverse square law formula to make distance the object (ie d = sqrt (1/i))
sqrt (1/0.00001) = 316 AU or 29 374 000 000 miles.
At this distance the Sun would subtend an angle of arc tan 865 300/29 374 000 000 = 0.0017 deg. or 6 arc seconds (hopefully I haven’t made any mistakes in my maths).
For those not ‘in the know’ Star Men was a 2015 documentary film that followed four British astronomers:- Donald Lynden-Bell, Roger Griffin, Wallace Sargent & Neville Woolf as they took a road trip across the South West of the United States. Neville Woolf is the only one still alive. I think the film is available on YouTube.
If anyone who currently does not receive the Historical Section Newsletter, but would like to, then just private message me your email address to be added to the distribution list.
If anyone is looking for a copy of the Basil Brown biography, a limited stock has just gone on sale.
Here is Basil Brown’s Wikipedia recent pageview graph. It bumps along at less than one hundred hits on most days, then the film comes out and it spikes to 44½ thousand!
John,
From memory the 1968 edition is merely a reprint of the 1932 edition. The images are of a slightly lower quality though.
As you might guess I have one of each.
Daryl,
Yes, perhaps not unsurprisingly the astronomical side of Brown’s life there was uploaded by me.
A more detailed analysis is here.
A recording of this presentation is now available at:-
Previous webinars are available on the BAA’s YouTube channel
iPhone image (not sure why, but it’s been turned while uploading) from Slough caught at 20:00, didn’t think I was going to get it as it was cloudy at 18:58 when I went out.
Next (and last) opportunity, 28 April at 21:30BST.
A tribute to Heather is going to be on this afternoons BBC Radio 4 obituary programme ‘Last Word’ broadcast 16:00-16:30 Friday 21 February 2020 and available online afterwards.
My (very incomplete) knowledge of Elizabeth in the Liverpool Astronomical Society is that she joined on 1884 January 21 and that she published two papers in the LAS Journal:-
1, Solar Section Report, vol. 4, p. 2 (1885 October)
2, Auroræ and Sun-spots, vol. 7, p. 52 (1888 December)
She may well have made other contributions.
Elizabeth is noted as having a 6½ inch aperture Calver reflector, a 3½ inch aperture Wray refractor and a 3 inch aperture refractor by an unknown maker and various spectroscopes in vol. 2, no. 6 (1896 June) p. 97 of the Journal of the Astronomical Society of Wales. On page 120 of vol. 1, no. 4 (1898 November) of the Cambrian Natural Observer she is noted as an ‘Associate Member’ of the Astronomical Society of Wales.
Volume 5, p. 28 (1897) of our Memoirs lists her observations of variable stars during the summer and autumn of 1895, a field not usually associated with her name.
