J/other/FrASS/9.1019751 Sunspot on 1904-2017 (Jha+, 2022)
Extending the sunspot area series from Kodaikanal Solar Observatory.
Jha B.K., Hegde M., Priyadarshi A., Mandal S., Ravindra B., Banerjee D.
<Front. Astron. Space Sci., 9, 1019751 (2022)>
=2022FrASS...919751J 2022FrASS...919751J (SIMBAD/NED BibCode)
ADC_Keywords: Sun
Keywords: Sun - sunspots - solar cycle - Kodaikanal Solar Observatory -
white-light - sunspot area - umbra area
Abstract:
Kodaikanal Solar Observatory (KoSO) possesses one of world's longest
and homogeneous records of sunspot observations that span more than a
century (1904-2017). Interestingly, these observations (originally
recorded in photographic plates/films) were taken with the same setup
over this entire time period which makes this data unique and best
suitable for long-term solar variability studies. A large part of this
data, between 1921-2011, were digitized earlier and a catalog
containing the detected sunspot parameters (e.g., area and location)
was published in Mandal et al. (2017A&A...601A.106M 2017A&A...601A.106M, Cat.
J/A+A/601/A106). In this article, we extend the earlier catalog by
including new sets of data between 1904-1921 and 2011-2017. To this
end, we digitize and calibrate these new datasets which include
resolving the issue of random image orientation. We fix this by
comparing the KoSO images with co-temporal data from Royal Greenwich
Observatory. Following that, a semi-automated sunspot detection and
automated umbra detection algorithm are implemented onto these
calibrated images to detect sunspots and umbra. Additionally, during
this catalog updation, we also filled data gaps in the existing KoSO
sunspot catalog (1921-2011) by virtue of re-calibrating the 'rouge'
plates. This updated sunspot area series covering nearly 115 years
(1904-2017) are being made available to the community and will be a
unique source to study the long term variability of the Sun.
Description:
Regular observations at the Kodaikanal observatory began in 1904 using
a white-light telescope with a 10-cm aperture lens and a f/15 light
beam. Between 1912 and 1917, the objective lens was changed several
times and in 1918, a 15-cm achromatic lens was installed. This
newconfiguration produced a 20.4cm size image of the Sun in the
imageplane. Photographic plates were used to capture the image. The
same telescope has been used since 1918 up until 2011 to take regular
white-light observation of the sun.
We present observations from 1904 to 2017.
For quarries, contact Dipankar Banerjee (dipu(at)iiap.res.in)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
wlareav2.dat 49 178568 Kodaikanal White light Sunspot and Umbra Area
Time: 1904-2017, Version no: kodaiWLV2.0
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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/599/A131 : Butterfly diagram wings (Leussu+, 2017)
J/A+A/601/A106 : Sunspot on 1921-2011 (Mandal+, 2017)
J/A+A/601/A109 : Monthly numbers of sunspot groups 1749-1996 (Usoskin+, 2017)
Byte-by-byte Description of file: wlareav2.dat
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Bytes Format Units Label Explanations
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1- 22 A22 "datime" Time Time of Observation
24- 28 F5.1 deg Lat Latitude of Sunspot
30- 34 F5.1 deg Lon Longitude of Sunspot
36- 41 F6.1 --- SpotArea Area of Sunspot in Millionth of hemisphere
(in muHem units)
43- 49 F7.1 --- UmbraArea Area of Umbra in Millionth of hemisphere
(in muHem units)
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Acknowledgements:
Bibhuti Jha, bibhuti(at)aries.res.in
References:
Ravindra et al., Paper I 2013A&A...550A..19R 2013A&A...550A..19R
Mandal et al., Paper II 2017A&A...601A.106M 2017A&A...601A.106M
Jha et al., Paper III 2022FrASS...919751J 2022FrASS...919751J
(End) Patricia Vannier [CDS] 28-Nov-2022