8475d165-c641-4d29-a4e7-06b84a3e18a0 eng utf8 dataset pointOfContact National Centre for Polar and Ocean Research (NCPOR) +91-832-2525515 voice Headland Sada, Vasco da Gama, Goa 403804 Vasco-da-Gama Goa 403804 IND vssamy@ncpor.res.in Mr. Sakthivel Samy V 2020-12-11T00:00:00 creation ISO 19115-1 Geographic information - Metadata - Part 1: Fundamentals ISO 19115-1:2014 Analysis of an Umbral Flare Observed from Antarctica. 2020-09-08T00:00:00 creation Document digital The observations in Call K of an umbral solar flare of optical importance class SF (subflare) which occurred on 12 Feb, 1990 . These observations have been correlated with the ones taken in H-alpha and in the radio region reported in Solar Geophysical Data (SGD). Though the umbral flare was small, it showed the impulsion behaviour in microwave region. We conclude that this is a special and very rare class of an umbral flare which is more energetic in microwave and radiowave regions than in the optical region. When the sun is observed in white light, the centres of activity on the solar disk (photosphere) are visible as the well known groups of sunspots. Central dark part of the sunspot is known as umbra where strong magnetic field exists and the outer less dark part is known as the penumbra. If we observe the sun through a filter having a very narrow pass band of about, say 1 A or less, centred on the H-alpha line (the first line of the Balmer series of hydrogen, 6563 A) or of the Call K (singly ionized calcium, 3934 A), the centres of activity are seen as bright plages surrounding the sunspot groups. We then observe the higher layers in the chromosphere above the sunspots which are at about 104 K temperature. An optical flare is seen as a rapid brightening of a part of such a plage in the active centres where the magnetic field strength is more and its gradient higher than outside this region. completed principalInvestigator National Centre for Polar and Ocean Research (NCPOR) 8322525515 voice Headland Sada, Vasco da Gama, Goa 403804 Vasco-da-Gama Goa 403804 IND ictd@ncpor.res.in Dr. Wahab Uddin 20.0 140.0 -90.0 30.0 1989-01-01 1990-12-31 Earth Science-Spectral/Engineering Theme Maitri Antarctic Place Analysis of an Umbral Flare Observed from Antarctica Project eng TableDigital unknown unknown unknown distributor National Centre for Polar and Ocean Research (NCPOR) +91-832-2525515 voice Headland Sada, Vasco da Gama, Goa 403804 Vasco-da-Gama Goa 403804 IND vssamy@ncpor.res.in Mr. Sakthivel Samy V http://npdc.ncaor.gov.in/npdc/search_mf_data.action?search=freeText&expedition_type=all&parameter=MF-1232203745&userType=user&freeTextValue=Analysis+of+an+Umbral+Flare+Observed+from+Antarctica.