Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000pasj...52..967k&link_type=abstract
Publications of the Astronomical Society of Japan, v.52, p.967-L973.
Astronomy and Astrophysics
Astronomy
8
Space Vehicles: Instruments, Techniques: Interferometric
Scientific paper
The first space VLBI satellite, HALCA, was launched on 1997 February 12. We report the characteristics of HALCA as an orbiting VLBI station with 8-m deployment antenna. It is required the high system gain, low system noise, and high stability of phase transfer. And the stabilities of system gain and system noise are needed for imaging of VLBI. HALCA achieved the requirement as a VLBI stations and has made almost 3 times longer baselines than ground global VLBI networks. It means observations with 3 times higher angular resolution have been carried out. We have measured aperture efficiencies of the deployment antenna, system noise temperatures, stability of onboard local oscillators, and stability of phase link. HALCA's onboard radio astronomy system has 1.60-1.73 GHz, 4.7-5.0 GHz, and 21.9-22.3 GHz receivers and two-channel high-rate samplers. Typical values of system noise temperature in orbit are 70 K and 90 K at 1.6 and 5 GHz respectively. At 22 GHz, the apparent system noise temperature is 400 K; however, this is mostly due to attenuation between the main antenna and the 22 GHz low noise amplifier. A reference tone signal is transmitted from a ground tracking station which is locked on a ground hydrogen maser oscillator. The internal phase stability of local oscillators is around 5deg r.m.s. at 5 GHz. The total gain of the receiving system and the bit distribution of the high-rate samplers have also been checked. With the exception of the 22 GHz attenuation, the in-orbit performance of the VLBI observing system matches the ground-test results very well.
Fujisawa Kenta
Hirabayashi Hisashi
Hirosawa Haruto
Inoue Makoto
Kameno Seiji
No associations
LandOfFree
HALCA's Onboard VLBI Observing System does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with HALCA's Onboard VLBI Observing System, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HALCA's Onboard VLBI Observing System will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1055033