J/ApJS/256/38 SCO daily sunspot area measurements (1886-1940) (Carrasco+, 2021)
Sunspot catalog (1921-1935) and area series (1886-1940) from the Stonyhurst
College Observatory.
Carrasco V.M.S., Munoz-Jaramillo A., Nogales J.M., Gallego M.C.,
Vaquero J.M.
<Astrophys. J. Suppl. Ser., 256, 38-38 (2021)>
=2021ApJS..256...38C 2021ApJS..256...38C (SIMBAD/NED BibCode)
ADC_Keywords: Sun
Keywords: Astronomy databases; Catalogs; sunspot cycle; sunspot groups
Abstract:
A sunspot observation program was started at the end of the 19th
century at the Stonyhurst College Observatory (hereafter SCO) by
Father Perry, director of the observatory at that time. A digitization
of the daily sunspot area series recorded in this observatory from
1886 to 1940 (with a gap between 1889 and 1897) is provided in this
work. This depicts one of the oldest sunspot area series available. A
comparison of this series with contemporary area series made in other
observatories shows that SCO generally recorded larger areas than
those in some of the observatories of that time such as, for example,
the Royal Greenwich Observatory (RGO). Furthermore, SCO published a
sunspot group catalog for the period 1921-1935. We provide a
machine-readable version of this catalog. We compared the SCO group
number series with other sunspot data obtained from other
observatories. In this case, for example, the RGO systematically
recorded more groups than the SCO. We compared SCO and RGO area
distribution functions obtaining the calibration constant between both
data sets. We also obtained the butterfly diagram from the group
latitudes recorded by SCO and compared the percentages of group types
computed from the SCO catalog with those from Valencia Observatory
(following the Cortie morphological classification of sunspot groups),
identifying their similarities and differences.
Description:
The yearbooks published by the Stonyhurst College Observatory (SCO)
are available online:
http://www.geomag.bgs.ac.uk/data_service/data/yearbooks/sto.html
See Section 2.
Fortunately, we know some details of the instruments used in these
solar observations. An 8 inch (around 0.2m) refractor telescope was
used to observe sunspots until 1893 (Stonyhurst College Observatory
1892). In 1893, that telescope was dismounted and replaced by a new
15-inch (∼0.4m) refractor. In 1893, while the installation of the new
telescope was finished, the sunspot drawings were carried out with a
6-inch (∼0.15m) refractor. Moreover, the observatory also had another
7-inch Newtonian refractor and a 9 1/2 inch altazimuth reflector.
In order to carry out the sunspot drawings, the observers at SCO put a
light board at the eye end of the telescope and made the drawing from
the projected image (Stonyhurst College Observatory 1881). The
diameter of the projected image was 10.5 inches (∼0.26m). In the case
of sunspots with special interest, an enlarged drawing was made on a
scale of 30 inches (∼0.76m) to the solar diameter.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 12952 Daily area values published by the Stonyhurst
College Observatory (SCO) for the period 1886-1940
table2.dat 164 2756 The sunspot group catalogue published
by the SCO for the period 1921-1935
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See also:
VI/138 : Sunspots catalogues, 1853-1870 (Casas+, 2013)
J/A+A/390/707 : Hemispheric Sunspot Numbers 1975-2000 (Temmer+, 2002)
J/A+A/447/735 : Hemispheric Sunspot Numbers 1945-2004 (Temmer+, 2006)
J/A+A/584/A73 : Sunspot areas and tilt angles (Senthamizh Pavai+, 2015)
J/A+A/595/A104 : Scheiner drawing sunspot areas and tilt angles (Arlt+, 2016)
J/A+A/601/A106 : Sunspot on 1921-2011 (Mandal+, 2017)
J/A+A/601/A109 : Monthly numbers of sunspot groups 1749-1996 (Willamo+, 2017)
J/A+A/602/A69 : Group sunspot number series since 1739 (Chatzistergos+, 2017)
J/A+A/615/A93 : Reconstructed decadal sunspot numbers (Wu+, 2018)
J/A+A/627/A46 : Sunspot penumbra and umbral flashes models (Bose+, 2019)
J/A+A/628/A103 : Mt Wilson sunspot magnetic field measurements (Pevtsov+, 2019)
J/A+A/640/A78 : Sunspot area catalogue revisited (1874-2019) (Mandal+, 2020)
J/A+A/649/A141 : 1000-year sunspot series (Usoskin+, 2021)
J/A+A/652/A56 : Hemispheric Sunspot Numbers 1874-2020 (Veronig+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 yr Obs.Y [1886/1940] Year of the observation
6- 7 I2 "month" Obs.M Month of the observation
9- 10 I2 d Obs.D Day of the observation
12- 19 F8.2 --- OArea [0/2459]?=-9999 Original daily area (1)
21- 25 I5 --- Area [0/10000]?=-9999 Daily area in millionths of
solar hemisphere
27- 68 A42 --- Notes Observation annotations
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Note (1): In millionths of solar hemisphere for the period 1886-1888 and
in units of 1/5000th of solar hemisphere from 1908 to 1940).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Obs Observatory identifier (1)
20- 24 F5.1 --- Group [1/470] Sunspot group code
26- 29 I4 yr First.Y [1921/1935] Year of the first group observation
31- 32 I2 "month" First.M Month of the first group observation
34- 35 I2 d First.D Day of the first group observation
37- 40 I4 yr Last.Y [1921/1935] Year of the last group observation
42- 43 I2 "month" Last.M Month of the last group observation
45- 46 I2 d Last.D Day of the last group observation
48- 55 F8.2 deg HLAT [-37/37.9]?=-9999 Mean group heliographic
latitude
57- 63 F7.1 deg HLON [0.3/462.5]?=-9999 Mean group heliographic
longitude
65- 72 F8.2 --- Area [0/26.7]?=-9999 Maximum area reached
by the group (2)
74- 94 A21 --- Ref Measurement reference point (3)
96-105 A10 --- Type Group Cortie morphological classification (4)
107-111 A5 d CMer Decimal day group passed the central
meridian (5)
113-164 A52 --- Notes Extra observational notes
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Note (1): Observatory identifier as follows:
STONYHURST = 2653 occurrences
ZURICH = 75 occurrences
ZURICH AND CATANIA = 15 occurrences
CATANIA = Observatory of Catania, Italy; 13 occurrences
Note (2): In units of 1/5000th of solar hemisphere. Any area lower than
0.1 units (20 millionths of solar hemisphere) was entered as
0 between 1921 and 1932.
Note (3):
s = chief spot;
g = center of group;
p = preceding spot;
f = following spot.
Note (4): Cortie (1901ApJ....13..260C 1901ApJ....13..260C) morphological classification as follows:
I = A group of one or more small scattered spots
II = Two-spot formation
III = A train of spots
IIIb = Without well-defined principal spots, but consisting mostly of
penumbral patches with shattered irregular umbra
IV = Single spots
V = An irregular group of larger spots
-9999 = missing information
Note (5): Or if the group appeared after the central meridian (indicated
by letter "a") or disappeared before it (indicated by "b").
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-Feb-2022