Background
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The idea for a
high-resolution spectrograph came during the Eighth Astrophysical Summer School
in Oléron (organised by the French CNRS) in May 2003. During this
workshop, work of professional astronomers overall and result of amateurs using a large
R=12,000 spectrograph on the T620 Cassegrain reflector of AstroQueyras were
presented. This subsequently convinced Christian Buil to push the resolution of
his own spectrograph designs. Christian quickly designed the Lhires (Mark I
version): an R=10,000 portable spectrograph. With the help of Sylvain Rondi, he
then went on to design a Mark II version of this spectrograph, the Lhires2
in 2004 then the Lhires3 in 2005 with several improvements such as a
polished reflective slit to allow guiding during long exposures.
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Discussion during Oleron 2003
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In 2005, François Cochard designed a production version of
Lhires III using professional CAD software. In reality, this development stage
was a true collaborative effort, with a huge number of emails exchanged on the
subject by AUDE members! The objective was to design a light and compact
spectrograph (capable of mounting on a 8-inch f/10 telescope) that was rigid
and solid in construction, with a resolution above 10,000 and within reach of
amateur budgets. These objectives have now been met!
In July, during a study of Beta
Lyrae at Saint-Véran (the AstroQueyras observatory), the initial spectra
were obtained. It was the first opportunity to compare the results with those
obtained using the professional Echelle spectrograph MuSiCoS
installed on the T620. Other spectra were taken at the same time
by other teams - a first coordinated observing session among amateurs!
Additional testing was carried out during the OHP symposium
in August 2005. Patrick Fosanelli was helpful in finding a more optimum
solution for the mirror slit. In September & October, the prototype was
further improved and a cheaper source for the grating was found. Testing with a
grating of 150 lpm was also performed with excellent results.
As with MuSiCoS
for professional astronomers, one of the objectives for the Lhires III was to
provide a spectrograph that was easy to build and to replicate by amateurs.
This should subsequently allow the amateur community to possess a homogenous
set of instruments, for easier comparison of spectral data and analysis.
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