This report summarizes the activities of the Washington Correlator for 2012. The Washington Correlator provides up to 80 hours of attended processing per week plus up to 40 hours of unattended operation, primarily supporting Earth Orientation and astrometric observations. In 2012, the major programs supported include the IVS-R4, IVS-INT, APSG, and CRF observing sessions

Boboltz, David

Hall, David M.

NASA Technical Reports Server

Washington Correlator U. S. Naval Observatory
Washington Correlator
David M. Hall, David Boboltz
Abstract
This report summarizes the activities of the Washington Correlator for 2012. The Washington
Correlator provides up to 80 hours of attended processing per week plus up to 40 hours of unattended
operation, primarily supporting Earth Orientation and astrometric observations. In 2012, the major
programs supported include the IVS-R4, IVS-INT, APSG, and CRF observing sessions.
1. Introduction
The Washington Correlator (WACO) is located at and staffed by the U.S. Naval Observa-
tory (USNO) in Washington, DC, USA. The correlator is sponsored and funded by the National
Earth Orientation Service (NEOS), which is a joint effort of the USNO and NASA. Dedicated to
processing geodetic and astrometric VLBI observations, the facility spent 100 percent of its time
on these sessions. The weekly IVS-R4 sessions, the IVS-INT01 Intensives, the Asian-Pacific space
geodynamics (APSG), the Australian AuScope (AUST), and the Celestial Reference Frame (CRF)
sessions were processed at WACO. The facility houses a Mark IV correlator and the new DiFX
correlator.
2. Correlator Operations
- The Washington Correlator continues to operate 80 hours per week with an operator on
duty. The correlator has continued to function well unattended, allowing another 40 hours
per week, on average, of extra processing. This has also decreased the time it takes to process
an R4 or other 24-hour session by one day, hence the latency in the data being fully processed
and available by one day.
- The correlator staff continues the testing and repair of Mark 5 modules. Not only were failed
disks replaced, but some modules were upgraded by the replacement of lower capacity disks
with higher capacity disks.
- Intensive observations from Kokee Park and Wettzell were routinely transferred via high
speed data networks (e-VLBI) during 2012. 24-hour sessions from both Hobart anten-
nas, Katherine, Yarragadee, Warkworth, Ny-A˚lesund, Fortaleza, Yebes, Noto, HartRAO,
Tsukuba, Aira, Kashima, Chichijima, and Sintotu were also transferred by high-speed data
networks.
- Table 1 lists the experiments processed during 2012.
3. Software Correlator
In September 2012, Phase I of the new DiFX software correlator was delivered by the National
Radio Astronomy Observatory (NRAO) to the USNO. This Phase I implementation consists of 33
compute nodes with 16 processor cores per node for a total of 528 cores. The compute nodes are
216 IVS 2012 Annual Report
https://ntrs.nasa.gov/search.jsp?R=20150003891 2019-08-31T11:13:17+00:00Z
U. S. Naval Observatory Washington Correlator
Table 1. Experiments processed during 2012.
52 IVS-R4
16 CRF
3 APSG
3 AUST
230 Intensives
connected via 10 Gbps Ethernet over fiber. Cluster management is performed via two infrastruture
servers that are connected to the diskless compute nodes. The new implementation runs the DiFX
software package along with the USNO implementation of the graphical user interface (GUI).
Since delivery, USNO personnel have been involved in the configuration and testing of the new
correlator. Successful processing of VLBI data from the VLBA and the IVS has been performed.
Data have been streamed from the two connected Mark 5C units, as well as directly from the
connected storage area network (SAN). Correlated data have been successfully passed through the
entire geodetic reduction path from correlation to fringing via the Haystack Observatory Postpro-
cessing System (HOPS) package to database generation and analysis via Calc/Solve.
4. Staff
The Washington Correlator is under the management and scientific direction of the Earth
Orientation Department of the U.S. Naval Observatory. Due to a change in policy by the U.S.
Navy, the NVI support contract was ended. At the beginning of 2012 the VLBI division had
filled only three positions, Dr. Kerry Kingham, Mr. David Hall, and Ms. Roxanne Innis. Bruce
Thornton was hired in February, and in May Mr. Daniel Veillette joined the VLBI division. Dr.
Kerry Kingham retired at the beginning of June, and Ms. Maria Davis was hired later that month.
Table 2 lists staff and their duties.
Table 2. Staff.
USNO Staff Duties
Dr. Kerry Kingham Chief VLBI Operations Division and Correlator Project Scientist
David Hall VLBI Correlator Project Manager
Daniel Veillette Astronomer
Bruce Thornton Lead Physical Science Technician
Roxanne Inniss Media Librarian
Maria Davis Physical Science Technician
IVS 2012 Annual Report 217
Washington Correlator U. S. Naval Observatory
5. Outlook
During 2013, the processing load should be transferred from the present Mark IV hardware
correlator to a DiFX software correlator.
218 IVS 2012 Annual Report


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