Gilmore Creek Geophysical Observatory
Rich Strand
Gilmore Creek Geophysical Observatory
Abstract:
The following report provides a general technical description and operational
overview of the Gilmore Creek Geophysical Observatory located near Fairbanks,
Alaska.
Gilmore Creek Geophysical Observatory (GCGO) is located 22 km NorthEast
of Fairbanks, Alaska. The observatory is co-located with the NOAA weather
satellite command and data acquisition station. The station sits on an 8,500
acre reservation that is mostly undeveloped wilderness. Ten antennas are in
operation.
Figure 1:
NOAA/NASA Data Acquisition and Geophysical Observatory, Fairbanks, Alaska.
 |
The GCGO telescope can be seen in Figure 1 as the last antenna
on the right in the valley. GCGO was instrumented by NASA's Crustal Dynamics
Project in the mid 1980s for the Alaskan mobile VLBI campaign and used as the
base station for those geodetic measurements [1]. The GCGO is part of
the NASA Space Geodesy program in cooperation with the U.S. Naval Observatory.
Table 1:
Address of GCGO near Fairbanks.
| Gilmore Creek Geophysical Observatory |
| NOAA/NESDIS FCDAS |
| 1300 Eisele Road |
| Fairbanks, AK 99712 |
| http://www.fcdas.noaa.gov |
The 26 meter telescope is hydraulic operated and controlled by a Modcomp
computer system (see table 2). The DAT rack is a VLBA
terminal and recorder (thin tape). The X/S band microwave receiver has
a cryogenic low noise front end. VLBI Field System version 9.3.25 is used
with a PC. Hydrogen maser NR 5 is the time standard with an HP Cesium
for the telescope computer. A TAC receiver is used with an HP 5334 counter for
GPS offset measurements. The station also runs a NASA/JPL Rogue receiver
8100 running software v. 3.2.32.8. UCLA maintains the HIPAS system located
at the GCGO and currently is operating an ionosonde. The Institut
Geographique National in France operates the DORIS beacon that is located
near the NOAA transmitter area.
Figure 2:
GCGO 26-meter radio telescope, Fairbanks, Alaska. Monument number 4047.
X-East, Y-North. Latitute N 64 degrees 58' 43.81288" and
Longitude E 147 degrees 29' 42.18552". Height 306.418 meters.
 |
Table 2:
Technical parameters of the GCGO radio telescope for geodetic VLBI.
| Parameter |
GCGO |
| owner and operating agency |
NOAA/NASA |
| year of construction |
1962 |
| receiving feed |
primary focus |
| diameter of main reflector |
26 meters |
| focal length |
10.9728 meters |
| surface accuracy of reflector |
889 mm rms |
| X Y mount |
1 degree per second |
| S-band |
2.2-2.4 GHz |
 |
62 K |
| SEFD (CASA) |
650 Jy |
| G/T |
35.3 dBK |
| X-band |
8.1-8.9 GHz |
|
58 K |
| SEFD CASA |
550 Jy |
| G/T |
44.5 dBK |
GCGO is a major NOAA data collection facility and does not have a science staff.
The NOAA Manager is Jim Budd. The site is operated by the Lockheed Technology
Services Group with Doug Ooms as Lockheed Project Manager and Mike Simmons
as Lockheed Operational Manager. R. Strand and S. Caskey are assigned to GCGO
technical staff with T. Knuutila, Z. Padilla, H. Grotsema, and D. Eubanks assisting.
The telescope hydraulic system is maintained by M. Meindl, A. Sanders and W. Powell.
Gilmore Creek continues to observe in the CORE, NEOS, and RDV experiments.
Yasuhiro Koyama arrived on site Jan/Mar to install the K4 DFC2100 for K4TIE
observing. GCGO was used for Mars Pathfinder and USNO intensive as well as
fringe sessions for equipment verification checks for other stations. The
NASA/JPL Rogue receiver was replaced in June. It is now running Y2K compliant
software. The Doris beacon was reprogrammed by station staff to continue
support of precision satellite-based orbit determination. The VLBI receiver
was pulled from the telescope several times this year for DEWAR repair.
D. Rhine, AlliedSignal, arrived on site in September for maser preventive
maintenance. The PRARE satellite tracking instrument failed in June and has been
shipped to Germany for repair. Field System software development continues by
Ed Himwich, NVI, using the station's DAT racks for testing. The majority of
Gilmore Creek's data loss has been due to telescope hydraulic failures.
Table 3:
VLBI observing at Gilmore Creek between 03/01/98 and 03/01/99.
| Experiments assigned to GCGO - 101 |
| Observations scheduled - 27757 |
| Observations recorded - 27078 |
| Efficiency - 97.55% |
Increased observing in the CORE program is scheduled. RFI studies are being
completed due to full time operation of a gold mine near the station.
Plans are being made to move this observatory to the NOAA operations
building and installing a new 20 meter electric drive telescope.
-
- 1
-
C.Ma,J.Sauber,L.Bell,T.Clark,D.Gordon,W.Himwich, and J.Ryan
Measurement of Horizontal Motion in Alaska Using VLBI 1990,
In:Journal of Geophysical Research, vol 95, No.B13, Pg 21991-22011,
December 10,1990
![[*]](../icons/prev.gif){kind=icon}
![[*]](../icons/toc.gif){kind=icon}
![[*]](../icons/next.gif){kind=icon}