J/A+A/628/A103 Mt Wilson sunspot magnetic field measurements (Pevtsov+, 2019)
Reconstructing solar magnetic fields from historical observations.
V. Sunspot magnetic field measurements at Mount Wilson Observatory.
Pevtsov A.A., Tlatova K.A., Pevtsov A.A., Heikkinen E., Virtanen I.,
Karachik N.V., Bertello L., Tlatov A.G., Ulrich R., Mursula K.
<Astron. Astrophys. 628, A103 (2019)>
=2019A&A...628A.103P 2019A&A...628A.103P (SIMBAD/NED BibCode)
ADC_Keywords: Sun ; Magnetic fields
Keywords: Sun: magnetic fields - sunspots -
history and philosophy of astronomy -
astronomical databases: miscellaneous
Abstract:
Systematic observations of magnetic field strength and polarity in
sunspots began at Mount Wilson Observatory (MWO), USA in early 1917.
Except for a few brief interruptions, this historical dataset
continues till present. Here file Figs3_5.txt contains data shown in
Figures 3-5; files Fig6a.txt and Fig6b.txt contain data shown in
Figure 6, and file Fig7.txt contain data for Figure 7.
Description:
MOUNT WILSON OBSERVATORY 150-foot solar tower, SUNSPOT DRAWINGS,
1917-2016.
File: figs3_5.dat (Contains data shown in Figures 3-5). Three columns
contain information on date of observations (Years), measured Field
strength (gauss), and radius of solar disk on drawings (pixels). For
measurements on drawings that only have information about polarity,
but not amplitude, we assigned a fixed value of "4900".
Files: fig6a.dat and fig6b.dat (Contain data shown in Figure 6).
Entries correspond to same-day measurements of field strengths (in
units of Hundreds of gauss) at Mount Wilson Observatory (MWO, left
column) and Crimean Astrophysical Observatory (CrAO, right column). In
Figure 6, observations from 1994-2003 are shown by black squares, and
data for 2004-2014 are shown as filled red circles.
File: fig7.dat (Contain data for Figure 7). Field strengths of 50
sunspots observed at Mount Wilson Observatory (MWO) and and by Vector
Stokes Magnetograph (VSM) on Synoptic Optical Long-term Investigations
of the Sun (SOLIS) platform. SOLIS/VSM data are derived using SOLIS
Zeemanfit code.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
figs3_5.dat 20 470544 Field strengths and radius of solar disk
fig6a.dat 5 50 Field strengths of 50 sunspots observed at MWO
fig6b.dat 5 50 Field strengths of 50 sunspots observed at
Crimean Astrophysical Observatory
fig7.dat 9 50 Field strengths of 50 sunspots observed at MWO
and by VSM/SOLIS
regions/* . 43 Sunspot group reports,
Mt Wilson Jan 1962- 2004,
USAF/NOAA Dec 1981 - 2004
--------------------------------------------------------------------------------
See also:
ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_REGIONS/Mt_Wilson : Data
Byte-by-byte Description of file: figs3_5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.4 yr Time Time
11- 15 I5 gauss Strength Sunspot field strength
17- 20 I4 pix Rad Radius of solar disk on drawing
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig6a.dat fig6b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 gauss/100 BMWO Field strength measured at MWO
4- 5 I2 gauss/100 BCrAO Field strength measured at CrAO
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 gauss BSOLIS Field strength measured by SOLIS
6- 9 I4 gauss BMWO Field strength measured at MWO
--------------------------------------------------------------------------------
Byte-by-byte Description of file: regions/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Code Data code: always 11 for sunspot data
3- 4 I2 yr Obs.Y Year of observation
5- 6 I2 "month" Obs.M Month of observation
7- 8 I2 d Obs.D Day of observation
10- 13 I4 --- UT Universal time of observation
15 A1 --- N/S N or S for North or South
16- 17 I2 deg Lat Heliographic latitude
18 A1 --- E/W E or W for East or West
19- 20 I2 --- Dist Central meridian distance
21- 25 A5 --- ClassMtW Mt Wilson Magnetic classification; the USAF
records are cast in the form 1X,A3
26 A1 gauss BMax Max magnetic field strength in group
(MWIL only)
27 A1 --- n_BMax [)]
28- 32 I5 --- Spot ? Mount Wilson spot group number (MWIL only)
33 A1 --- m_Spot This field is used by WDC to subscript the
Mt. Wilson sunspot number,
for example, 23197,223197A, etc.
34- 38 I5 --- Spot2 ? NOAA/USAF sunspot group number
after Aug 1982
39 A1 --- m_Spot2 This field is used by WDC to subscript the
NOAA/USAF sunspot number,
for example 4013, 4013A
40 A1 --- ClassZ Zurich class (USAF only)
41 A1 --- ClassP Penumbra class (USAF only)
42 A1 --- ClassC Compactness class (USAF only)
44- 45 I2 --- Nspots ? Number of spots (USAF only)
47- 48 I2 deg Long ? Longitudinal extent in degrees (USAF only)
49- 52 I4 --- Area ? Area in millionths of solar hemisphere
(USAF only)
54- 55 I2 yr YearICM Individual Central Meridian Passage year
56- 57 I2 "month" MonthICM Individual Central Meridian Passage month
58- 62 F5.2 d DayICM Individual Central Meridian Passage day
63- 64 I2 yr YearRCM ? Regional Central Meridian Passage year
65- 66 I2 "month" MonthRCM ? Regional Central Meridian Passage month
67- 71 F5.2 d DayRCM ? Regional Central Meridian Passage day
72- 74 I3 --- StationNo ? Station serial number
76 I1 --- Qual ? Quality (1)
77- 80 A4 --- Station 4-letter station abbreviation
--------------------------------------------------------------------------------
Note (1): Quality flag as follows:
1 = very poor
2 = poor
3 = fair
4 = good
5 = excellent
--------------------------------------------------------------------------------
Acknowledgements:
Alexei Pevtsov, apevtsov(at)nso.edu
References:
Pevtsov et al., Paper I 2016A&A...585A..40P 2016A&A...585A..40P
Virtanen et al., Paper II 2017A&A...604A...8V 2017A&A...604A...8V
Virtanen et al., Paper III 2018A&A...616A.134V 2018A&A...616A.134V
(End) Patricia Vannier [CDS] 04-Jul-2019