VGOS
The installation of the 12-meter VGOS antenna at KPGO began on September 1, 2015; the VGOS signal chain was installed in January 2016. Development and construction of the VGOS antenna at KPGO was documented in the SGP website’s KPGO blog. In February 2016, the world’s first 3-way broadband VLBI measurement between KPGO, GGAO, and Westford occurred. It was also the first long baseline broadband VLBI measurement, demonstrating the viability of the next-generation antenna for improving determination of the Terrestrial Reference Frame and Earth Orientation Parameters. The three antennas can now routinely observe in broadband continuously for 24 hours.
The KPGO 12-m VGOS antenna
The IVS is currently implementing a new generation of antennas, the VGOS (broadband) antennas, as part of an effort to improve VLBI data to meet increasing demands upon the data. Plans for a KGPO VGOS antenna have been underway since 2012. A 12-m VGOS antenna was installed at KPGO in 2015, and its signal chain was installed between November 2015 and February 2016. The KPGO 12-m antenna now participates fully in the IVS VGOS observing schedule.
The 12-m antenna meets the VGOS slew rate standards, with an azimuth velocity of 12 degrees per second and an elevation velocity of 6 degrees per second. The antenna also includes the following features:
- four bands of 512 MHz each, in contrast to the two bands (S and X) of the legacy antennas,
- dual-linear polarization in all bands,
- coaxial cable delay for low frequency bands and multi-tone phase cal for all channels and polarizations,
- simultaneous estimation of the group delay and the total electron content difference (dTEC) between sites using the phases across all four bands.
20-meter Antenna
The 20-meter antenna at KPGO has been contributing to global VLBI experiments since 1993. This antenna is currently configured to observe with the legacy S-band and X-band receivers that are operational at VLBI geodetic sites worldwide but can also form baselines with the new broadband systems under a "mixed-mode" configuration that makes the broadband and the legacy S/X networks compatible. It regularly participates in international VLBI 24-hour observing sessions, and it is one of the two main stations for the weekday one-hour INT01 sessions, as well a backup for weekend INT02 sessions. The 20-meter telescope has observed in VLBI sessions since the 1993 NEOS-A6 experiment.
The KPGO 20-m VLBI antenna
While the next generation VGOS radio telescopes are being developed and implemented, the day-to-day observing within the international VLBI community is carried out by legacy antennas. Monday through Friday, KPGO's 20-m antenna is one of the two main participating stations in daily one-hour Intensive sessions that provide preliminary but rapid estimates of UT1-TAI. As needed, the 20-m antenna is a backup for weekend Intensive sessions.
The 20-m antenna also participates in, on average, two 24-hour sessions per week. These sessions are scheduled for a variety of purposes. R1 and R4 sessions provide data used for the routine estimation of station, source, and earth orientation parameters for distribution in VLBI products. Other sessions have supported other purposes, such as source position imaging, improvement of the Celestial Reference Frame, and support of a regional (Southern Hemisphere) terrestrial reference frame.
The KPGO 20-m antenna generates data that yield products that are used in specialized scientific and every day applications. For example, the earth orientation products are ultimately used for satellite orbit prediction and GPS. KPGO is a vital part of the international VLBI network.
