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The Sheshan 25m radio telescope is an alt-az antenna run by SHAO.
The telescope is located in the Sheshan area, about 40km west of
Shanghai.
The radio telescope has been in operation since
1987, and it is one of the five main facilities of the Chinese
National Astronomical Observatory. The station is a member of the
European VLBI Network (EVN), the International VLBI Service for
Geodesy and Astrometry (IVS), and the Asia Pacific Telescope
The telescope is located at longitude
121＜11' 59" E and latitude 31＜05' 57" N, 5m above sea level. Some parameters of the antenna are listed
below:
Diameter: 25m
Antenna type: Kashegelun Beam wave-guide
Seat-rack type: Azimuth-pitching ring
Main surface precision: 0.65 mm (rms)
Point precision: 20" (rms)
Rolling range: Azimuth : -860 ~to~ 4250; Elevation: 50 ~to~ 880
Maximum rolling speed: Azimuth : 0.550/sec; Elevation: 0.280/sec
Receivers:
Five bands of VLBI observation are available at Sheshan. These are:
L band (18 cm), C band (6 cm), K band (1.3 cm), and S/X band (13/3.6
cm). The parameters of the receivers are listed in Table 1. The
observation band, frequency range, and the efficiency of each band
are given in the first three columns respectively. The type,
polarization model, and system temperature are given in the final
three columns. The L, C, and K bands are used for astrophysics, and
the S/X double frequencies used for geodesy. The X band is also
sometimes used for astrophysical observations.
The
X-band receiver system was upgraded to a wide-band system in
December 2000. Thus the Sheshan station has been able to participate
in the wide-band geodynamics experiments of IVS since 2001.
Table 1.
The VLBI receivers of Sheshan satation
|
Band(cm) |
Bandwidth(MHz) |
Eff.(%) |
Type |
Polarization(K) |
T_{system}
|
|
(1) |
(2) |
(3)
|
(4)
|
(5)
|
(6)
|
|
18(L) |
1620-1680
|
38 |
Room Temperature |
LCP &RCP |
゛100
|
|
13 (S)
|
2150-2350 |
26 |
Room Temperature |
RCP |
゛100
|
|
6 (C) |
4700-5100 |
56 |
Room Temperature |
LCP |
゛100
|
|
3.6 (X) |
8200-9000 |
49 |
Cryogenic |
RCP |
゛50
|
|
1.3 (K) |
22100-22600
|
20 |
Cryogenic |
RCP & LCP |
゛110 |
A new twin-polarization receiver for the C band is currently
under construction with the cooperation of ASTRON (the
Netherlands), and will be available in mid 2004.
The
upgrade of the frequency switching system of Sheshan station was
finished by the end of 2002. The switch of frequency between any two
of the C, K, and S/X bands can now be carried out in only three
minutes. The system is thus very useful for multi-frequency
observations.
The VLBI recording System:
There are three recording systems at the Sheshan VLBI station (VLBA,
MKIV, and S2). Both thick and thin tapes are available for the
VLBA and MKIV recording systems.
The
MKIV upgrade was completed successfully in 2000, and the Sheshan
station has participated in the two-head recording test at 512Mbit/s
carried out by the EVN organization in October 2001. Fringes were
measured successfully on both head-stacks. The performance of the
observing system is presently undergoing further improvement, and
the MKV system will be available from mid 2004.
The
Sheshan station is also equipped with a Canadian S2 VLBI recording
system, used for APT, VSOP, and other VLBI observations. In
addition, hydrogen masers were recently made by SHAO.
Leading
Professor:
HONG Xiaoyu
Group members
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