Results 211 to 220 of about 546 (232)

Automated Detection of Sunspots and Sunspot Groups in Full-Disk Solar Images

2010
In this paper, a new adopted unsupervised segmentation technique is presented. This technique extracts both sunspots and sunspot groups from the solar disk as whole group that eases the automated sunspot group classification. MacIntosh Classification is used as standard to determine which group belongs to which class.
Sarab F. Majed, Mehmmood A. Abd, V. Zharkova   +2 more
openaire   +1 more source

A Unique High-Latitude Sunspot Group

Publications of the Astronomical Society of the Pacific, 1957
The present sunspot cycle, No. 19, has proved to be exceptional in several respects. One of these is in the number of highlatitude groups which have all or at least some members at or above ± 40° latitude and have lasted more than one day. Normally a few high-latitude groups appear during a cycle, mostly near sunspot minimum.
openaire   +1 more source

A twin flare in symmetrical sunspot groups

Solar Physics, 1981
Two sunspot groups in symmetrical positions relative to the Sun's equator were flaring almost simultaneously. The larger northern group was highly irregular: the two main spots were surrounded by one and the same penumbra, the magnetic polarities were inverted and the inclination of the axis was exceptionally large and of the wrong direction.
openaire   +1 more source

Cycle latitude effects for sunspot groups

Solar Physics, 1991
Digitized Mount Wilson sunspot data from 1917 to 1985 are analyzed to examine meridional motion and rotation properties as a function of latitude and distance (ξ) from the average latitude of activity (ξ0) in each hemisphere. Latitude dependence similar to previous results is found, but only for spot groups whose areas are decreasing from one day to ...
openaire   +1 more source

Historical sunspot records

Living Reviews in Solar Physics, 2020
José Manuel Vaquero
exaly  

A GREAT SUNSPOT GROUP

Bulletin of the American Meteorological Society, 1928
openaire   +1 more source

Revisiting the Sunspot Number

Space Science Reviews, 2014
Frédéric Clette, Edward Cliver, Leif Svalgaard   +2 more
exaly  

A note on the relationship between sunspot numbers and active days

Advances in Space Research, 2014
J M Vaquero
exaly  

Hemispheric asymmetry of long-term sunspot activity: sunspot relative numbers for 1939–2019

Monthly Notices of the Royal Astronomical Society, 2022
exaly  

Sunspot Catalogue of the Valencia Observatory (1920 – 1928)

Solar Physics, 2014
Víctor Manuel Sánchez Carrasco, M C Gallego, José Manuel Vaquero   +2 more
exaly