AAVSO: Solar Bulletin April, 2001

Solar Bulletin
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS - SOLAR DIVISION
Carl E. Feehrer, Editor 9 Gleason Rd. Bedford, MA 01730	Email: cfeehrer@hotmail.com ISSN 0271-8480

Volume 57 Number 4	April 2001

Table I. Mean Sunspot Numbers for April

Table II. April Observers

Day	N	Raw	s.d.	K-corrected	s.d.	s.e.
1	37	226	12.0	189	7.9	1.30
2	41	206	9.7	185	8.0	1.25
3	41	209	8.6	182	7.1	1.11
4	47	174	6.6	154	5.3	0.77
5	47	164	5.8	136	4.7	0.69
6	27	153	8.9	131	7.3	1.40
7	32	136	7.6	118	4.8	0.85
8	48	149	6.3	124	4.6	0.66
9	37	141	6.9	125	4.5	0.74
10	29	150	8.9	130	6.5	1.21
11	35	153	8.0	127	5.6	0.95
12	36	132	4.7	115	3.1	0.52
13	50	135	4.4	116	3.7	0.52
14	44	118	3.0	100	2.9	0.44
15	40	97	4.4	79	3.9	0.62
16	36	66	5.1	59	4.4	0.73
17	43	42	2.1	36	1.5	0.23
18	43	54	2.6	47	2.1	0.32
19	50	85	2.9	73	2.7	0.38
20	30	123	5.3	105	3.7	0.68
21	28	153	9.0	131	6.2	1.17
22	40	149	6.0	126	4.1	0.65
23	41	149	7.5	126	5.5	0.86
24	41	153	6.7	136	4.8	0.75
25	45	162	8.0	139	5.1	0.76
26	53	161	6.8	138	5.0	0.69
27	47	160	7.0	133	5.1	0.74
28	50	143	6.2	120	4.2	0.59
29	42	158	6.2	132	3.8	0.59
30	34	131	5.0	108	3.5	0.60
31	---	---	---	---	---	---
Means:	40.5	141.1		120.6
No. of Observations: 1214 No. of Observers: 71

Reporting Addresses

Sunspot Reports -- email: solar@aavso.org: postal mail: AAVSO, 25 Birch St. Cambridge, MA 02138; FAX (AAVSO): (617) 354-0665
SES Reports -- email: noatak@aol.com: postal mail: Mike Hill 114 Prospect St. Marlboro, MA 01752
Magnetometer Reports -- email: capaavso@aol.com: postal mail: Casper Hossfield PO Box 23, New Milford, NY 10959; FAX: (973) 853-2588 or (407) 482-3963

23	AAP	P.Abbott
4	ANDE	E.Anderson
11	ATON	A.Attanasio
12	BARH	H.Barnes
14	BATR	R.Battaiola
20	BEB	R.Berg
6	BEDJ	J.Bedient
16	BEGM	M.Begbie
10	BERJ	J.Berdejo
17	BLAJ	J.Blackwell
15	BMF	M.Boschat
27	BOSB	B.Bose
26	BRAB	B.Branchett
16	BRAR	R.Branch
25	BROB	R.Brown
11	CAMP	P.Campbell
20	CARJ	J.Carlson
23	CKB	B.Cudnik
8	CLZ	L.Corp
22	COLJ	J.Collins
16	COMT	T.Compton
30	CORA	A.Coroas
26	CR	T.Cragg
7	DEMF	F.Dempsey
21	DRAJ	J.Dragesco
18	DUBF	F.Dubois
26	ELR	E.Reed
15	FEEC	C.Feehrer
21	FLET	T.Fleming
22	FUJK	K.Fujimori
22	GIOR	R.Giovanoni
16	GOTS	S.Gottschalk
7	HAYK	K.Hay
14	HRUT	T.Hrutkay
11	IMPR	R.Imperi
24	JAMD	D.James
10	JEFT	T.Jeffrey
16	JENJ	J.Jenkins
4	JENS	S.Jenner
18	KAPJ	J.Kaplan
28	KHAR	R.Khan
18	KNJS	J&S Knight
13	LARJ	J.Larriba
19	LERM	M.Lerman
21	LEVM	M.Leventhal
18	LIZT	T.Lizak
19	MALK	K.Malde
11	MARE	E.Mariani
29	MARJ	J.Maranon
25	MCE	E.Mochizuki
9	MILJ	J.Miller
20	MMI	M.Moeller
14	MUDG	G.Mudry
14	OBSO	IPS Obs.
18	RICE	E.Richardson
21	RITA	A.Ritchie
6	SCHG	G.Scholl
16	SIMC	C.Simpson
3	STEF	G.Stefanopoulis
21	STEM	G.Stemmler
23	STQ	N.Stoikidis
21	SUZM	M.Suzuki
13	SZUM	M.Szulc
24	TESD	D.Teske
17	THR	R.Thompson
20	URBP	P.Urbanksi
15	VALD	D.del Valle
14	VARG	A.Vargas
16	WILW	W.Wilson
17	WITL	L.Witkowski
21	YESH	H.Yesilyaprak

Table III. Means of Raw Group Counts (RG) and Ratios of Spots to Groups (S:G) in April 2001
Day	RG	S:G	Day	RG	S:G	Day	RG	S:G	Day	RG	S:G
1	11.6	9.5	9	8.1	7.4	17	3.5	2.0	25	8.4	9.3
2	11.9	7.3	10	8.6	7.4	18	4.1	3.2	26	8.7	8.5
3	13.0	6.1	11	8.8	7.4	19	5.5	5.5	27	8.8	8.2
4	12.0	4.5	12	7.8	6.9	20	6.8	8.1	28	8.1	7.7
5	10.9	5.0	13	8.7	5.5	21	7.6	10.1	29	8.2	9.3
6	9.6	5.9	14	8.5	3.9	22	7.3	10.4	30	6.9	9.0
7	7.8	7.4	15	7.3	3.3	23	7.5	9.9	31	---	---
8	8.7	7.1	16	5.3	2.5	24	7.5	10.4	Mn.	8.3	7.0

Fig.1 Comparison of Ri (provisional) and Ra estimates for April.
(Ri Source: http://sidc..oma.be/index.php3)

Smoothed Mean Sunspot Number (Rsm) for October 2000: 119.4

Fig.2 Monthly Ra and Smoothed Mean Sunspot Numbers (Waldmeier method).

Editor's Note

This month I would like to welcome two new contributors and one former contributor to the group: Jon Wallace (A97) from Torrington, CT and Michael King (A99) from England, both of whom are SID observers, and Mike Begbie (BEGM) from Zimbabwe, who is a sunspot observer. During the mid-1980s, Mike filed reports as part of the Solar Section of the Astronomical Society of South Africa, which at the time was under the directorship of Jim Knight (KNJS), one of our regular contributors. Thank you all for your work and for sending your reports to AAVSO‘s Solar Division.

Clear Skies
CEF

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