looking @ the sun

...investigating the surface of the sun with the H-alpha sun telescope for Argentina (HASTA)

Full image of the sun just looking at the emission in the H-alpha band (6.563A)

The release of a large amount of energy in sheared magnetic fields and the subsequent acceleration of charged particles is a common phenomena in the universe. Since solar flares, eruptive prominences and coronal mass ejections are the direct results of impulsive energy releases and can be resolved spatially, their observation is of crucial importance in the understanding of these phenomena. In order to study the evolution of solar flares with high spatial (1.5 arcsec) and temporal (up to 3 sec) resolution from ground, a solar telescope in H-alpha (6.563 A) has been set up at the OAFA ("Observatorio Astronómico Félix Aguilar", Univ. de San Juan) High Altitude Station "Carlos U. Cesco" in El Leoncito, San Juan, Argentina, because of the unique clearness of the sky almost all year around. HASTA started operations in May 1998.

Sequence of an eruptive prominence from November 9th, 1998.

HASTA looks at the full sun and through the southern hemisphere. It makes HASTA essential for large-range studies of phenomena such as loops interconnecting active regions, Moreton or other waves that spread all over the solar surface, and that are out of the spatial scope of most reduced field-of-view H-alpha instruments. HASTA provides daily full Sun disk images in the hydrogen H-alpha emission line at 6.563 A. It uses a Lyot filter with a full width at half maximum (FWHM) of
0.3 A. A sensicam long exposure camera with a 1280 x 1024 square pixels CCD chip collects the incoming signal.
HASTA complements three other solar instruments which have been installed at El Leoncito: MICA, a mirror coronagraph to observe the solar corona above the limb from 1.1 to 2 solar radii, a submillimeter solar telescope (SST) for measurements up to far infrared, and a high resolution spectrograph (BLISP). By combining the observations of these four instruments new insights into the active sun phenomena can be expected.

The triple tube of HASTA - the instrument can take images either in patrol or in high-speed mode. The camera takes images every 5 s. Each image is analyzed in real time in order to detect rapid changes in the overall intensity. If no change is detected, the algorithm stores one image every 1.5 min (patrol mode). On the other hand, if a fast change is detected, the camera automatically switches into the high-speed mode. In this mode, the telescope can take and store full-frame images up to every 3 s. These operation modes allow HASTA to be part of most of the international observing campaigns, including those where no specific participation of the instrument was requested, because we are taking full time resolution images in the moments were they are necesary, allways.

HASTA is located at the OAFA "Prof. Ulrico Cesco High Altitude Station" (EACUC) at El Leoncito, in the Argentinian Cordillera de los Andes (latitude 31.80 S, longitude 69.30 W, altitude 2400 m). This site offers major advantages for sun observations:The EACUC is open all year round, with no winter break (and winter is in August!). The sunny hours run normally between 12 and 21 UT. EACUC has excellent infrastructure, with many laboratories and workshop rooms, living apartments, and well-tended cafeteria. There are more than 300 sunny days per year, most of them with clear sky; and only little snow in winter. Due to the wind shadow east of the high Andes mountains the air is usually dry and clean, and similarly good weather conditions prevail throughout the year. Reasonably quiet wind blows for large fractions of most days. Because of the desert climate, there is no significant vegetation nearby, meaning that no colonization that might cause dust, pollution, or insects are found nearby. Furthermore no civil or military airline traffic is found. The observatory is located on a huge terrain that is now a national natural reservation and must not be cultivated.

...if you have further questions, please contact:
Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany, www.mpe.mpg.de
Max-Planck-Institut für Aeronomie, Lindau, Germany, www.linmpi.mpg.de
Institute for Astronomy and Space Physics, Buenos Aires, Argentina, www.iafe.uba.ar
Observatorio Astronómico Félix Aguilar, San Juan, Argentina
Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina

« Back to overview