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Solar Bulletin, April 2006

Solar Bulletin

THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS - SOLAR COMMITTEE
Carl E. Feehrer, Editor
9 Gleason Rd.
Bedford, MA 01730
Email: cfeehrer@hotmail.com

ISSN 0271-8480

Volume 62 Number 4April 2006

Table I. Mean Sunspot Numbers for April 2006
[boldface = maximum, minimum]
Table II. April Observers
Day N Raw Mean Ra
1 28 51 38
2 32 58 43
3 24 68 49
4 28 81 56
5 20 79 56
6 27 76 58
7 32 67 50
8 35 57 41
9 31 48 35
10 25 54 42
11 29 60 43
12 29 61 44
13 32 58 43
14 34 43 32
15 34 29 21
16 25 17 13
17 33 13 10
18 33 11 8
19 32 3 2
20 29 17 12
21 20 13 9
22 28 3 2
23 26 11 8
24 31 21 15
25 26 41 30
26 35 54 40
27 31 64 46
28 31 58 42
29 23 49 37
30 31 59 42
31 --- --- ---
Means:29.144.132.2
No. of Observers: 55
No. of Observations: 874

Reporting Addresses

Sunspot Reports -- email: solar@aavso.org

postal mail: AAVSO, 25 Birch St. Cambridge, MA 02138
FAX (AAVSO): (617) 354-0665

SID Solar Flare Reports -- email: noatak@aol.com

postal mail: Mike Hill 114 Prospect St. Marlboro, MA 01752
19 AAP P.Abbott
15 AJV J.Alonso
28 ARAG G.Araujo
12 BARH H.Barnes
11 BATR R.Battaiola
12 BEB R.Berg
17 BERJ J.Berdejo
10 BLAJ J.Blackwell
13 BMF M.Boschat
1 BRAM M.Bradbury
19 BRAR R.Branch
12 BROB R.Brown
24 CHAG G.Morales
29 CKB B.Cudnik
11 CLZ L.Corp
16 COMT T.Compton
27 CR T.Cragg
16 DEJV J.van Delft
10 DEMF F.Dempsey
17 DGP G.Dyck
20 FERJ J.Fernandez
21 FLET T.Fleming
20 FUJK K.Fujimori
6 GOEM M.Goetz
6 HALB B.Halls
9 HAYK K.Hay
17 JAMD D.James
6 JENS S.Jenner
23 KAPJ J.Kaplan
26 KNJS J.Knight
1 KROL L.Krozel
11 LARJ J.Larriba
21 MCE E.Mochizuki
16 MENM M.Menegotto
2 MEU E.Mason
9 MMI M.Moeller
25 OATS S.Oatney
21 PEKT R.Pektas
18 RICE E.Richardson
24 RITA A.Ritchie
27 SCGL G.Schott
12 SCHG G.Scholl
3 SDP D.Sharples
13 SIMC C.Simpson
17 STEM G.Stemmler
21 STQ N.Stoikidis
20 SUZM M.Suzuki
24 SZUM M.Szulc
26 TESD D.Teske
14 TJV J.Temprano
20 URBP P.Urbanski
19 VARG A.Vargas
6 WILD D.Williams
26 WILW W.Wilson
5 WRP R.Wheeler

Figure 1
Click image to enlarge.
Fig. 1. 10 cm Solar Flux and American Relative Sunspot Numbers (Ra) for April 2006
(10cm Source: http://www.drao.nrc.ca/icarus)

Figure 2
Click image to enlarge.
Fig.2 Smoothed Mean Sunspot Numbers (Rsm) from January 2000 to October 2005 (Waldmeier method).


Presented at the Spring Meeting of the AAVSO, Rockland, IL May 5-7, 2006

Committee Chair and Sunspot Observing Group Leader: Carl E. Feehrer
Solar Flare/SID Observing Group Leader: Mike Hill

Observer Reporting
The progressive diminution in the sun's activity as solar minimum approaches has resulted in a reduced amount of reporting by the corps of sunspot and SID observers. During the period covered by this summary, a total of 333 sunspot reports containing 4611 observations were received, while a total of 102 SID reports were received. The sunspot and SID reports were contributed by 82 and 20 observers, respectively. As always, the contributions were made by an active, widely distributed group of observers from the United States, Canada, Europe, South America, South Africa, India and Australia.

Observer Awards
Three new observers have now met the criteria established for awarding of certificates that recognize significant contributions. SID observer Paul Campbell from Canada and sunspot observers Gerd-Lutz Schott from Germany and James Knight from South Africa have now joined the earlier group of 26 that have achieved this distinction. In accord with tradition, these new observers will be recognized and receive their certificates at the AAVSO's Fall meeting.

Website Activity
Contributions of photos continue to be received and posted to the AAVSO website, though at a much reduced level. Presumably this outcome, like the reduction in reports, is due to the relatively small amount of solar activity.

Reorganization of Solar Committee
Carl Feehrer, chair of the Solar Committee and Sunspot Group Leader since 2000 will step down from his responsibilities in May. Taking his place as chair of the Committee will be Paul Mortfield, a SID observer who lives in Canada. Paul participates in the SOHO program and is active in solar outreach efforts. Daniel Williams, a new volunteer interested in H-alpha and white-light sunspot observing lives in Nebraska and will take over as Sunspot Group Leader. Mike Hill, SID/Solar Flare Group Leader and SID analyst will continue in his present position.

The current chair wishes to thank observers and AAVSO staff all of those for their unstinting support during his tenure and expresses the hope that they will welcome the new team and help to make their service as interesting and enjoyable as they made his.

Acknowledgements
As always, the successful performance of the Solar Committee's work during the reporting period was due to the dedication and activities of our solar observers, AAVSO staff, and headquarters' volunteer Arthur Ritchie. We are grateful to this group for their extensive support.

-------------------------

NOTE: As of May 15, I will no longer be able to guarantee that reports received by postal mail at my local address will be able to be forwarded to AAVSO headquarters in time for processing. Therefore, please be sure to send all regular mail reports and other communiques to the AAVSO headquarters address shown at the bottom of page 1.

Thank you.

-CEF


Michael Hill, SID Analyst
114 Prospect St
Marlborough, MA 01752 USA
noatak@aol.com

Sudden Ionospheric Disturbances (SID) Recorded During April 2006

(Analysis performed by Michael Hill, SID Analyst)
Date Max Imp
060405 1310 1+
060405 1522 1+
060406 0535 1+
060406 2042 2
060407 0804 1+
060411 1828 2
060422 0843 1+
060422 1640 1
060426 0650 1+
060426 0833 2
060426 1227 1
060426 1357 1+
060426 1453 1+
060426 1702 1+
060426 1828 1
060427 1552 2
060428 0828 2+
060429 1630 1+
060430 0931 1+

Importance rating: Duration -1: <191: 19-251+: 26-322: 33-452+: 46-853: 86-1253+: >125

Observer Code Station(s) monitored
A Clerkin A29 NAA
J Winkler A50 NAA NML
P King A80 HWU
M Hill A87 NAA
J Mandaville A90 NPM
G Di Filippo A93 HWU
R Battaiola A96 HWU
J Wallace A97 NAA
M King A99 HWU
F Steyn A102 NAA NWC
L Observatory A107 DHO
P Mortfield A108 NAA
M Suhovecky A115 NAA
K Hubal A117 NAA
The events listed above meet at least one of the following criteria
  1. Event reported by two or more observers within +/- 5 minutes
  2. Event matched to GOES-8 XRA event to within +/- 15 minutes and event time < 1000 UT
  3. Reported by observer with a high quality rating > 8 (scale 1-10)

SID ratings

Solar Events

April was a slow month but activity did pick up a bit from what we have had in the past few months. There were 19 correlated SID events reported by observers, most of them of low to medium importance rating. There were 132 X-Ray flares recorded by the GOES-12 satellite and of these only four were M-Class, 24 were C-Class and the rest were B-Class. Thanks to all of you for reporting in. I didn't get as many NO SID reports which was nice to see.

Solar Flare Summary Based on GOES-12 Data

SID ratings

 
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