Related papers: Solar physics at the Kodaikanal Observatory: A His…
The discovery of extensive air showers by Rossi, Schmeiser, Bothe, Kolh\"orster and Auger at the end of the 1930s, facilitated by the coincidence technique of Bothe and Rossi, led to fundamental contributions in the field of cosmic ray…
The primary task of the Debrecen Heliophysical Observatory (DHO) was to produce the detailed and reliable photographic documentation of the solar photospheric activity since 1958. This long-term effort resulted in various solar catalogues…
We report a solar jet phenomenon associated with successive flares on November 10th 2014. These explosive events were involved with the satellite spots' emergence around a delta-type sunspot in the decaying active region NOAA 12205. The…
Radio bursts from the solar corona can provide clues to forecast space weather hazards. After recent technology advancements, regular monitoring of radio bursts has increased and large observational data sets are produced. Hence, manual…
Chromospheric magnetic fields are of paramount importance in understanding the dynamics of energetic events in the solar atmosphere. At the Kodaikanal Solar Observatory, several polarimeters were developed in the past to study the active…
Advances in instrumentation have made it possible to study sunspots with unprecedented detail. New capabilities include imaging observations at a resolution of 0.1" (70 km on the sun), spectroscopy at ~0.2", and simultaneous…
Sunspots are concentrations of magnetic field on the visible solar surface that strongly affect the convective energy transport in their interior and surroundings. The filamentary outer regions (penumbrae) of sunspots show systematic radial…
Since the discovery by Hale in the early 1900s that sunspots harbor strong magnetic field, magnetism has become increasingly important in our understanding of processes on the Sun and in the Heliosphere. Many current and planned instruments…
R. C. Carrington, C. H. F. Peters, and W. de la Rue observed the sunspots in the second half of the 19th century, determining their heliographic positions between 1853 and 1870, before the establishment of the solar program of the Royal…
I will discuss the interactions of a number of individuals that played major roles in the formation of radio astronomy in India in the period 1952-1962, particularly Dr. Joseph L. Pawsey. The story began in 1953-1954: Pawsey brought Govind…
Did the Indian and Babylonian astronomy evolve in isolation, was there mutual influence, or was one dependent on the other? Scholars have debated these questions for more than two centuries, and opinion has swung one way or the other with…
The phenomena observed at the Sun have a variety of unique radio signatures that can be used to diagnose the processes in the solar atmosphere. The insights provided by radio obervations are further enhanced when they are combined with…
Broad-band observations of the solar photosphere began in Meudon in 1875 under the auspices of Jules Janssen. For his part, Henri Deslandres initiated imaging spectroscopy in 1892 at Paris observatory. He invented, concurrently with George…
Umbral dots (UDs) are small isolated brightenings observed in sunspot umbrae. They are convective phenomena existing inside umbrae. UDs are usually divided into central UDs (CUDs) and peripheral UDs (PUDs) according to their positions…
The photospheric Evershed flow is normally oriented radially outward, yet sometimes opposite velocities are observed not only in the chromosphere but also in the photospheric layers of the penumbra. We study the velocity field in a special…
India's largest 3.6 m aperture optical telescope has been successfully installed in the central Himalayan region at Devasthal, Nainital district, Uttarakhand. The primary mirror of the telescope uses the active optics technology. The…
The ratio of penumbral to umbral area of sunspots is an important topic for solar and geophysical studies. Hathaway (Solar Physics, 286, 347, 2013) found a curious behaviour in this parameter for small sunspot groups (areas smaller than 100…
We present a reconstruction of total solar irradiance since 1610 to the present based on variations of the surface distribution of the solar magnetic field. The latter is calculated from the historical record of the Group sunspot number…
We could infer a secular decreasing trend in the poloidal to toroidal solar magnetic flux amplification factor ( Af) using geomagnetic observations ( classic and IHV corrected aa indices) during the sunspot cycles 9-23. A similar decreasing…
This article reviews atmospheric changes associated with 44 solar eclipses, beginning with the first quantitative results available, from 1834 (earlier qualitative, accounts also exist). Eclipse meteorology attracted relatively few…