spase://SMWG/Instrument/Ground/MaunaLoaSO/ECHO

The ECHO (Experiment for Coordinated
Helioseismic Observations) is a network of two instruments which
observe solar oscillations as seen in the radial velocity of the
solar surface. The ECHO will use the next generation of the LOWL
[Low degree(L)] instrument, which has been operated at the Mauna Loa
Solar Observatory of the National Center for Atmospheric Research
for the past several years. The first of the new ECHO instruments
became operational on Dec 15, 1999 at the Observatorio del Teide,
located at Izana, Tenerife, Spain. The LOWL instrument at MLSO
was upgraded and became the second instrument in the ECHO
network. The LOWL observes the oscillations as perturbations of
the radial velocity over the surface of the Sun. This is
accomplished by taking images in narrow bandpass filters
displaced slightly redward and blueward of a solar absorption
line.