J/A+A/595/A104 Scheiner drawing sunspot areas and tilt angles (Arlt+, 2016)
Sunspot positions, areas, and group tilt angles for 1611-1631 from observations
by Christoph Scheiner.
Arlt R., Senthamizh Pavai V., Schmiel C., Spada F.
<Astron. Astrophys. 595, A104 (2016)>
=2016A&A...595A.104A 2016A&A...595A.104A (SIMBAD/NED BibCode)
ADC_Keywords: Sun
Keywords: Sun: activity - sunspots - history and philosophy of astronomy
Abstract:
Digital images of observations printed in the books Rosa Ursina sive
solis and Prodromus pro Sole mobili by Christoph Scheiner, as well as
the drawings from Scheiner's letters to Marcus Welser, are analysed
to obtain information on the positions and sizes of sunspots that
appeared before the Maunder minimum.
In most cases, the given orientation of the ecliptic is used to set up
the heliographic coordinate system for the drawings. Positions and
sizes are measured manually on screen. Very early drawings have no
indication of their orientation. A rotational matching using common
spots of adjacent days is used in some cases, while in other cases,
the assumption that images were aligned with a zenith-horizon
coordinate system appeared to be the most probable.
Description:
Christoph Scheiner and his collaborators observed the sunspots from
1611-1631 at five different locations of Rome in Italy, Ingolstadt in
Germany, Douai (Duacum in Latin) in France, Freiburg im Breisgau,
Germany and Vienna, Austria. However, most of his published drawings
were made in Rome. These sunspot drawings are important because they
can tell us how the solar activity declined to a very low-activity
phase which lasted for nearly five decades. The three sources used for
the sunspot data extraction are Scheiner (1630rour.book.....S, Rosa
Ursina sive solis), Scheiner (1651ppsm.book.....S, Prodromus pro sole
mobili et terra stabili contra Academicum Florentinum Galilaeum a
Galilaeis), and Reeves & Van Helden (2010, On sunspots. Galileo
Galilei and Christoph Scheiner (University of Chicago Press)). The
suspot drawings show the sunspot groups traversing the solar disk in a
single full-disk drawing. The positions and areas of the sunspots were
measured using 13 circular cursor shapes with different diameters.
Umbral areas for 8167 sunspots and tilt angles for 697 manually
selected, supposedly bipolar groups were obtained from Scheiner's
sunspot drawings. The database does not contain spotless days. There
is, of course, no polarity information in the sunspot drawings, so the
tilt angles are actually pseudo-tilt angles.
Both an updated sunspot database and a tilt angle database may be
available at http://www.aip.de/Members/rarlt/sunspots for further
study.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
area.dat 105 8167 Sunspot positions and areas
tilt.dat 108 697 Tilt angles of the sunspot groups with two or
more spots
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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)
http://www.aip.de/Members/rarlt/sunspots : Sunspot and tilt angle databases
Byte-by-byte Description of file: area.dat
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Bytes Format Units Label Explanations
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1- 4 I4 yr Obs.Y Observation date (YYYY)
6- 7 I2 "month" Obs.M Observation date (MM)
9- 10 I2 d Obs.D Observation date, day referring to the civil
calendar running from midnight to midnight,
Gregorian calendar (DD)
12- 13 I2 h Obs.h Observation time in mean local time
at the observer's location (HH)
15- 16 I2 min Obs.m Observation time, typically accurate
to 15 minutes (MI)
18 I1 --- T [0/2] Indicates how accurate the time is (1)
20- 24 F5.1 deg HLON0 Heliographic longitude of apparent disk centre
seen from Rome (L0)
26- 30 F5.1 deg HLAT0 Heliographic latitude of apparent disk centre
seen from Rome (B0)
32- 36 F5.1 deg CMD ?=- Central meridian distance, difference in
longitude from disk centre (2)
38- 42 F5.1 deg HLON ?=- Heliographic longitude in the Carrington
rotation frame (LLL.L) (2)
44- 48 F5.1 deg HLAT ?=- Heliographic latitude,
southern latitudes are negative (BBB.B) (2)
50 A1 --- M [AEHQ] Method of determining the
orientation (3)
52 I1 --- Q [0/4] Subjective quality (4)
54- 55 I2 --- SS Size estimate in 13 classes running from 1 to
13 (5)
57- 64 A8 --- Group Arbitrary group name; the order of numbers
has no meaning
66- 75 A10 --- Measurer Last name of person who obtained position
77- 81 F5.1 deg HLONM ?=- Model longitude from rotational matching
(only spots used for matching have this)
(MOD_L)
83- 87 F5.1 deg HLATM ?=- Model latitude from rotational matching
(only spots used for matching have this)
(MOD_B)
89- 93 F5.3 deg Sigma ?=- Total residual of model positions compared
with measurements of reference spots in
rotational matching (only spots used for the
matching have this). Holds for entire day
95- 98 F4.1 deg delta ?=- Heliocentric angle between the spot and
the apparent disk centre in degrees
(disk-centre distance)(2)
100-103 I4 --- Umb ?=- Umbral area in millionths of the
solar hemisphere (MSH), corrected for
foreshortening (2)
105 A1 --- A [!-] Flag for highly uncertain area (6)
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Note (1): Timeflag as follows:
0 = time has been inferred by the measurer (in most cases to be 12h local time)
1 = the time is as given by the observer
2 = time was inferred from the elevation of the Sun and the morning/afternoon
discrimination given by the observer.
Note (2): Code for no data as follows:
--- = position of spot could not be measured
Note (3): Method of determining the orientation as follows:
E = ecliptic present in drawing
H = book aligned with azimuth-elevation
A = arbitrarily chosen orientation according to the distribution of groups
Q = rotational matching with other drawings (spots used for the matching have
MHLON, HLAT and sigma {diff} "-")
Note (4): Subjective quality as follows:
1 = all directly connected to the ecliptic drawn by Scheiner
2 = The rotated sunspot groups (cf. Fig. 2) are probably slightly less accurate
and get Q = 2. Also used for the positions derived from rotational
matching resulting in not very sharp probability distributions for the
position angle of the drawing.
3 = Positions derived from rotational matching resulting in broad or asymmetric
probability distributions for the position angle of the drawing. Also
methods 'H' and 'A' always obtain Q = 3, because of the assumptions made.
4 = spots for which no position could be derived, but have sizes
Note (5): The classes are different from the ones used in Arlt et al.
(2013MNRAS.433.3165A 2013MNRAS.433.3165A) and Senthamizh Pavai et al. (2015, Cat. J/A+A/584/A73)
by the fact that we introduced a smaller size at the low end and named it "1".
The classes are arbitrary anyway.
Note (6): Flag as follows:
! = Flag marking areas which are highly uncertain since the spots appear to
be drawn at too large sizes.
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Byte-by-byte Description of file: tilt.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Obs.Y Observation date (YYY)
6- 7 I2 "month" Obs.M Observation date (MM)
9- 10 I2 d Obs.D Observation date, day referring to the civil
calendar running from midnight to midnight,
Gregorian calendar (DD)
12- 13 I2 h Obs.h Observation time in mean local time
at the observer's location (HH)
15- 16 I2 min Obs.m Observation time, typically accurate
to 15 minutes (MI)
18- 25 A8 --- Group Arbitrary group name; the order of numbers has
no meaning
27- 28 I2 --- SP Number of spots in a group
30- 32 I3 --- ARA Sum of umbral area of all spots in a group,
in millionths of the solar hemisphere (MSH)
34- 38 F5.1 deg HLONA Area-weighted heliographic longitude of the
group (AWL.L)
40- 44 F5.1 deg HLATA Area-weighted heliographic latitude of the
group (AWB.B)
46- 51 F6.2 deg TiltAn Tilt angle of the group (1)
53- 58 F6.2 deg TiltHo Tilt angle computed as in Howard (1991,
Sol. Phys., 136, 251) for compatibility
reasons (2)
60- 64 F5.2 deg PolSP Polarity separation of the group in degrees on
the solar sphere (3)
66- 67 I2 --- FN Number of spots in the following polarity
69- 70 I2 --- LN Number of spots in the leading polarity
72- 74 I3 --- FAR Umbral area of the following polarity, in MSH
76- 78 I3 --- LAR Umbral area of the leading polarity, in MSH
80- 84 F5.1 deg HLONF Area-weighted longitude of the following
polarity (FLL.L) (3)
86- 90 F5.1 deg HLATF Area-weighted latitude of the following
polarity (FBB.B) (3)
92- 96 F5.1 deg HLONL Area-weighted longitude of the leading
polarity (LLL.L) (3)
98-102 F5.1 deg HLATL Area-weighted latitude of the leading
polarity (BBB.B) (3)
104-108 F5.1 deg GFC Heliocentric distance of the group from the
disk centre in degrees
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Note (1): Tilt angle of the group ; positive sign means leading polarity closer
to equator in either hemisphere. This tilt angle was found using an isotropic
search for the most likely dividing line between the polarities.
Note (2): It is based on a fixed vertical dividing line between the polarities
and an approximative formula for the tilt angle.
Note (3): Polarity separation and the following columns are based on the
polarity definition for TiltAn.
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Acknowledgements:
Library of Leibniz Institute for Astrophysics Potsdam.
Library of Swiss Federal Institute of Technology in Zurich.
Valliappan Senthamizh Pavai, svalliappan(at)aip.de
Rainer Arlt, rarlt(at)aip.de
Leibniz Institute for Astrophysics Potsdam
References:
Scheiner C., 1630rour.book.....S, Rosa Ursina sive solis
Scheiner C., 1651ppsm.book.....S, Prodromus pro sole mobili et terra stabili
contra Academicum Florentinum Galilaeum a Galilaeis
Reeves E. & Van Helden A., On sunspots. Galileo Galilei and Christoph
Scheiner (University of Chicago Press)
(End) Rainer Arlt [Leibniz Inst. Astrpohys.], Patricia Vannier [CDS] 09-Sep-2016