norman robert pogson, cie (23 march 1829 – 23 june 1891) was an english astronomer who worked in india at the madras observatory.he discovered several minor planets and made observations on comets.he introduced a mathematical scale of stellar magnitudes with the ratio of two successive magnitudes being the fifth root of one hundred (~2.512) and referred to as pogson's ratio.it was intended that he should follow his father into business, and he was accordingly sent for 'commercial education', but he was fascinated by science, and his mother supported and encouraged this interest.his early education was largely informal.he left school at 16, intending to teach mathematics.at the age of eighteen, he calculated with the help of john russell hind of the royal astronomical society, the orbits of two comets.he was introduced to astronomy through george bishop's observatory at south villa regent's park from 1846.he took an interest in comets and studied iris, a minor planet that had been recently discovered.he was engaged as an assistant at the radcliffe observatory in 1852; a new heliometer had been installed there in 1850.he received the lalande medal upon his discovery of the minor planet isis.his oxford period was spent studying variable stars and other routine research.in 1854 he helped sir george airy conduct an experiment to determine the density of the earth.pogson was appointed as director at the hartwell observatory belonging to john lee in 1859.he published around fourteen papers from 1859 to 1860 in the monthly notices of the royal astronomical society, mostly on variable stars and on minor planets.sir charles wood appointed him as government astronomer for madras in october 1860.reaching india in 1861 and working at the madras observatory he worked tirelessly, discovering the asteroid 67 asia.in the next seven years he found five minor planets and seven variable stars.he continued worked on taylor's madras catalogue ('taylor's general catalogue of stars from observations made at the madras observatory during the years 1831-1842') of 11,015 stars which had been published in 1835 based on work begun in 1831 by t. g. taylor.pogson continued work on this to add 51,101 observations (until 1887) and after his death in 1891 the catalogue was revised by arthur downing and published in 1901.despite pogson's isolation he had at the time of his death discovered 134 stars, 106 variable stars, 21 possible variable stars and 7 possible supernovae.pogson also made special expeditions, observing a total solar eclipse on 18 august 1868 at masulipatnam and making spectrometric studies.he observed and commented on the spectral line associated with helium, then yet to be discovered.his most notable contribution was to note that in the stellar magnitude system introduced by the greek astronomer hipparchus, stars of the first magnitude were a hundred times as bright as stars of the sixth magnitude.pogson's suggestion in 1856 was to make this a standard; thus, a first magnitude star is 1001/5 or about 2.512 times as bright as a second magnitude star.this fifth root of 100 is known as pogson's ratio.the magnitude relation is given as follows:  m1 - m2 = -2.5 log10 (l1 / l2)where m is the stellar magnitude and l is the luminosity, for stars 1 and 2.in 1868 and 1871, pogson joined the indian solar eclipse expeditions.he received a telegram from ernst friedrich wilhelm klinkerfues on 30 november 1872 which read biela touched earth on 27th.search near theta centauri, a message so esoteric that it caught the fancy of the newspapers of the time.
n r pogson | deathplace | chennai
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