The Shanghai observatory of the Chinese Academy of Sciences may
be expanded to include a new astronomical observation station in
Zhejiang Province that would be out of range of adverse effects
caused by the bright lights of Shanghai.
The director of the Sheshan base, Tao Juan, said that the light
from Shanghai has already reduced visibility there, so the
observatory must seek a more suitable site, a morning paper
reported on Tuesday.
The Shanghai observatory said on Monday that it has signed
agreements with departments in Zhejiang to build a protective, low
light zone, two professional astronomical observation rooms and a
scientific observation station in the Tianhuangping zone in Anji
County. Some instruments from the Sheshan base will be moved to the
new observatory at Tianhuangping.
Tao Juan said that according to the International Astronomical
Union (IAU) in 1985, the background artificial light levels around
world-class observatories should be less than ten percent of the
magnitude. This means the brightness of the background light should
be less than 0.1 degree of the brightness of a celestial body. The
background artificial light levels around national level
observatories should be less than 20.2 percent of the
magnitude.
A 1998 test of Sheshan station revealed that light pollution at
the station is as high as 591 percent, and Tao believes the current
light pollution is even more severe. Although the observatory has
installed better observation instruments in last few years,
visibility is still unsatisfactory.
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Regular astronomical observation stations should be ideally be
located in areas with a clean atmosphere, little interference from
artificial lights and more clear days each year. However, the light
sources within three kilometers of the Sheshan station include
streetlamps, floodlights and the hotel lights, preventing
astronomers at the station from photographing darker celestial
bodies. Indeed, visitors to the observatory should consider
themselves to be lucky to spot stars with magnitudes of -16 or -17,
even though the facility has the second-largest optical telescope
in China. Due to the light pollution, the observatory has seldom
participated in world-class astronomical observation projects in
recent years.
The Shanghai observatory began to seek suitable locations for a
new astronomical observation station in 2001. At the Tianhuangping
observation base, 1,000 meters above sea level, observers can view
–20 magnitude stars through the telescope. To avoid future light
pollution around Tianhuangping, the Shanghai observatory has
insisted on controlling lamplight installation around the site in
its agreement with the Zhejiang side.
The Shanghai observatory has no plans to acquire additional
equipment for the Shanghai facility.
(CRI January 22, 2008)
