- Tmt India
The path of the Moon's umbral shadow crosses the South Pacific Ocean where it makes no landfall except for Mangaia (Cook Islands), Easter Island (Isla de Pascua) and several isolated atolls. The path of totality ends just after reaching southern Chile and Argentina. The Moon's penumbral shadow produces a partial eclipse visible from a much larger region covering the South Pacific and southern South America. A group of scientists from Indian Institute of Astrophysics is heading for Easter Island to observe this total solar eclipse. The participants are Prof. S. S. Hasan (Director, IIA), Prof. Jagdev Singh, Dipankar Banerjee, K. Ravi and F. Gabriel.
We intend to perform spectroscopy of the solar corona in the green and red emission lines simultaneously with a frequency of about 0.2 Hz from Easter Island during 11th July, 2010 total solar eclipse. The aim of the experiment is to detect high frequency oscillations in the solar corona. A 30 cm two mirror system (coelostat) will be used to direct the sun and coronal light to a 10 cm objective to form an image of the corona on the slit of the Littrow type spectrograph. A 14 cm objective will collimate the beam and image the spectrum on the two CCD cameras. Broad band filters will be used to separate the orders. A grating with 600 lines per mm blazed at 2 microns will provide a reasonable dispersion (2 Angstrom per mm) to determine the emission line profiles. Two CCD cameras of 1K x 1K format with pixel size of 13.0 x 13.0 microns will be used to take the images. The CCD chip will be back illuminated for high efficiency and camera will operate in frame transfer mode to obtain data with high frequency. The read out is in 10-bit format at 10 MHz.
With this ground based experiment we would like to have a simultaneous campaign with Hinode. Using the strongest lines present in the EIS spectrum, we look for high frequency oscillations in active region loops (if they are present off-limb) otherwise we will point in the polar region to look for plume and inter-plume region. We use a small number of lines to try and keep the cadence of the observations as low as possible. Recent Eclipse observations have indicated presence of oscillations with periods in the range of 6 - 30 s (Singh et al. 2009). We also find signatures of Alfven like waves from the variation of line width studies. We intend to verify this with this joint spectroscopic campaign from Hinode and our ground based experiment.
Green (left panel) and Red line (right panel) processed images taken from 40 cm telescopes (http://www.iiap.res.in/solareclipse1 )