relative sunspot number

relative sunspot number

Symbol: R . A somewhat arbitrary index of the level of sunspot activity, derived from the formula R = k (f + 10g ), where g represents the number of sunspot groups, f the total number of their component spots, and k is a constant dependent on the estimated efficiency of, and also the equipment used by, a particular observer. Though a more objective assessment of the level of sunspot activity relies on the measurement of sunspot areas, relative sunspot numbers provide an almost continuous record back to the mid-18th century and yield graphs similar (at least so far as the yearly means are concerned) to those based on other indices.

The relative sunspot number was originally called the Wolf number, after Rudolf Wolf who introduced it at Zürich in 1848 and extended it back using old observations. It later became known as the Zürich relative sunspot number and then, when the Zürich tradition came to an end with the transfer of responsibility to the Sunspot Index Data Center in Brussels in Jan. 1981, the International Sunspot Number (symbol: RI ). See also sunspot cycle.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

relative sunspot number

[′rel·əd·iv ′sən‚spät ‚nəm·bər]
(astronomy)
A measure of sunspot activity, computed from the formula R = k (10 g + f), where R is the relative sunspot number, f the number of individual spots, g the number of groups of spots, and k a factor that varies with the observer (his or her personal equation), the seeing, and the observatory (location and instrumentation). Also known as sunspot number; sunspot relative number; Wolf number; Wolf-Wolfer number; Zurich number.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Using his relative sunspot number R, Wolf also sought to reconstruct the variation in solar activity for the earlier period, prior to 1849.
There was a slight upturn in solar activity in both hemispheres during August with the relative sunspot number (R) around the average for the year so far.
The citation of the Sunspot award reads: "For a cumulative contribution since 1999 of 1 500 sunspot observations in support of the American Relative Sunspot Number program and service to the AAVSO Solar observing program."
Spotted Sun "Late 1957 saw the relative sunspot number climb to record heights.
BAA sunspot data, 2013 June-July Day June July g R g R 1 4 50 5 72 2 4 63 6 94 3 3 51 4 79 4 3 46 4 86 5 4 68 3 90 6 4 63 4 102 7 2 38 4 109 8 1 25 4 92 9 1 26 4 83 10 1 20 2 65 11 1 16 3 55 12 2 24 4 51 13 2 41 2 32 14 4 54 3 49 15 5 78 4 59 16 6 86 3 55 17 6 98 3 56 18 5 97 5 71 19 6 102 4 58 20 7 111 3 52 21 7 114 2 44 22 7 113 3 42 23 7 105 4 59 24 6 84 4 54 25 5 65 5 66 26 3 45 4 55 27 4 53 4 56 28 4 62 4 60 29 4 57 6 79 30 4 61 5 75 31 6 83 MDFg 4.10 (50) 3.88 (46) Mean R 63.80 (46) 67.25 (42) North & south MDF of active areas g MDFNg MDFSg June 1.38 (40) 2.76 (40) July 1.18 (36) 2.65 (36) g = active areas (AAs) MDF = mean daily frequency R = relative sunspot number The no.
BAA sunspot data, 2013 April-May Day April May g R g R 1 5 66 5 100 2 6 84 4 83 3 6 81 4 81 4 5 79 5 88 5 5 83 6 90 6 7 94 5 83 7 7 100 6 99 8 6 94 7 105 9 7 106 6 93 10 6 103 7 96 11 6 110 8 109 12 5 105 7 118 13 5 98 7 131 14 6 94 7 129 15 5 82 9 146 16 5 83 10 165 17 5 80 9 150 18 4 70 7 120 19 5 71 7 109 20 4 67 7 98 21 4 69 7 91 22 3 66 7 103 23 3 61 5 83 24 5 77 4 80 25 6 96 5 90 26 6 84 4 75 27 6 89 4 72 28 5 93 4 57 29 6 112 4 56 30 6 107 4 50 31 4 45 MDFg 5.31 (53) 6.01 (52) Mean R 86.71 (47) 96.58 (46) North & south MDF of active areas g MDFNg MDFSg April 2.84 (41) 2.56 (41) May 2.73 (43) 3.21 (43) g = active areas (AAs) MDF = mean daily frequency R = relative sunspot number The no.
BAA sunspot data, 2013 February-March February March Day g R g R 1 4 54 4 56 2 4 54 5 73 3 5 62 5 76 4 2 31 5 75 5 3 37 4 62 6 3 39 5 66 7 4 52 3 50 8 3 48 4 59 9 3 50 5 65 10 3 47 5 66 11 4 49 6 83 12 4 57 6 89 13 2 33 6 95 14 2 25 7 105 15 3 32 7 97 16 3 37 7 99 17 4 60 7 100 18 5 73 6 88 19 5 86 4 58 20 5 83 3 42 21 5 68 3 46 22 5 65 3 39 23 2 32 3 40 24 3 33 2 33 25 3 43 3 36 26 3 45 2 24 27 3 48 2 27 28 4 57 3 39 29 4 60 30 5 68 31 6 75 MDFg 3.55 (43) 4.50 (49) Mean R 49.92 (38) 64.19 (45) North & south MDF of active areas g MDFNg MDFSg February 2.42 (33) 1.27 (33) March 2.47 (37) 2.33 (37) g = active areas (AAs) MDF = mean daily frequency R = relative sunspot number The no.
Solar activity in January increased and the relative sunspot number recorded was the highest since 2011 December.
BAA sunspot data, 2012 October-November Day October November g R g R 1 5 64 4 41 2 5 62 3 34 3 4 55 3 33 4 4 52 3 41 5 3 46 3 39 6 3 37 3 32 7 3 36 4 53 8 3 35 5 56 9 4 51 5 65 10 4 51 5 72 11 4 60 6 82 12 5 70 6 93 13 5 71 6 102 14 5 84 7 109 15 6 97 8 121 16 6 98 8 117 17 6 81 8 117 18 7 87 7 99 19 5 79 6 87 20 4 63 5 95 21 5 67 5 100 22 4 72 4 74 23 5 91 4 68 24 5 76 4 69 25 4 72 4 73 26 4 61 4 69 27 4 51 4 74 28 3 46 4 63 29 5 59 4 62 30 4 46 4 53 31 3 40 MDFg 4.33 (47) 4.81 (42) Mean R 63.17 (42) 73.11 (39) North & south MDF of active areas g MDFNg MDFSg October 1.61 (35) 2.65 (35) November 2.84 (32) 2.04 (32) g = active areas (AAs) MDF = mean daily frequency R = relative sunspot number The no.
Overall solar activity remained similar to that recorded in May, June and July with the relative sunspot number (R) actually falling slightly.
Lyn Smith, Director BAA sunspot data, 2012 June-July Day June July g R g R 1 7 99 6 111 2 8 126 5 114 3 7 107 4 101 4 7 110 5 105 5 7 101 5 97 6 7 115 6 108 7 7 108 6 107 8 6 89 5 100 9 6 84 5 108 10 7 103 3 91 11 7 106 3 77 12 4 80 4 85 13 4 85 4 88 14 4 94 4 95 15 4 96 4 90 16 4 87 5 76 17 4 65 4 55 18 3 44 3 44 19 3 35 2 29 20 1 20 2 21 21 1 12 1 17 22 1 14 2 23 23 1 11 4 48 24 1 7 5 57 25 1 15 4 50 26 2 30 6 75 27 3 58 6 87 28 4 72 6 87 29 5 91 6 89 30 5 90 6 98 7 106 MDFg 4.29 (49) 4.45 (53) Mean R 71.79 (44)78.58 (47) North & south MDF of active areas g MDFNg MDFSg June 1.55 (39) 2.37 (39) July 1.41 (38) 3.16 (38) g = active areas (AAs) MDF = mean daily frequency R = relative sunspot number The no.
As solar cycle 24 progresses towards its predicted maximum in early 2013, the Relative Sunspot number (R) has gained momentum during the session.