IVS Observing Program

Session Descriptions: 2002

This section has brief descriptions of each type of session coordinated by IVS. Refer to the master files for the details of each session such as start times, participating stations, correlator, and current status.

• IVS-R1 and IVS-R4
• IVS-T2
• IVS-E3
• IVS-INT1 and IVS-INT2
• APSG
• EUROPE
• Ohiggins
• Syowa Anarctica
• RDV: R&D with VLBA
• IVS-CRF
• IVS-R&D
• IVS-CONT02

The purpose of of the IVS-R1 and IVS-R4 sessions is to provide twice weekly EOP results on a timely basis. These sessions provide continuity with the previous NEOS and CORE series.

The "1" and "4" indicate that the sessions are on Mondays and Thursdays, respectively. Widely separate sessions during the week gives approximately even spacing between these two sessions for monitoring periodic terms in tides and nutation.

The "R" stands for rapid turnaround because the stations, correlators, and analysts have a commitment to make the the time delay from the end of recording to results as short as possible. The time delay goal is a maximum of 15 days. Participating stations are requested to ship tapes to the correlator as rapidly as possible. Tapes from the Monday session should arrive no later than Friday, tapes from the Thursday session (ending late on Friday) should be shipped as early on Monday as possible to arrive no later than Thursday.

Each network for R1 and R4 has 6 stations. There is a core network for each day plus one or two other stations. TIGO is not expected to be ready to observe until several months into the new year, so different stations are added to the network during the first quarter.

The networks and correlators are:

IVS-T2:
The purpose of the IVS-T2 sessions is to monitor the TRF via monthly sessions. All geodetic stations participate in at least three T2 sessions each year. These sessions replace the IRIS-S sessions observed in previous years.

IVS-E3:
The purpose of the IVS-E3 sessions is to provide an additional monthly EOP monitoring session. These sessions will use S2 technology for recording and processing. The network will be fixed because of the limited number of stations currently equipped with geodetic S2 capability. Stations are: Algonquin, Yellowknife, the Canadian Transportable VLBI Antenna (CTVA), TIGO, Kokee, and one other station to be determined. When more stations have geodetic S2 equipment these sessions may be expanded.

IVS-INT1 and IVS-INT2:
The INT1 and INT2 sessions are 1-baseline, 1-hour "intensive" sessions to monitor UT1. These sessions are designed to provide rapid service UT1 results. Sessions for INT1 are observed four times weekly. Sessions for INT2 are observed twice per week during the first quarter of 2002 as a pilot project; sessions after that are being considered.

APSG:
The primary purpose of the APSG sessions is to continue monitoring the relative motions of the plates in the Asia-Pacific region. These sessions involve sites on the four plates. Tsukuba and Fairbanks are on the North American Plate, Hobart is on the Australian Plate, Seshan and Urumqi are on the Eurasian Plate, and Kokee is on the Pacific Plate. Thus, these sessions will produce critical data for the investigation of the current crustal motions in the Asia-Pacific region combined with the data from the APSG SLR and GPS campaigns which will also be performed in the same month as the APSG experiments. Also, these experiments will improve the accuracy of the geocentric coordinates of the participating stations, especially Urumqi and Tuskuba.

EUROPE:
The purpose of this experiment is to determine the station coordinates and their evolution in the European geodetic VLBI network. This process will be done with the highest precision possible.

OHIGGINS:
The purpose of the IVS-OHIG (Southern Terrestrial Reference Frame) sessions is to tie together optimally the sites in the southern hemisphere. The participating sites include all the sites in the south - O'Higgins, Fortaleza, Hartebeesthoek, Hobart - as well as Kokee Park. The last two sites are the southern-most of the northern sites and have been included to make the geometry more robust and to increase the number of observations per scan. TIGO will join the network in the fall campaign. Syowa may participate, depending on their availability. Because these sessions concentrate on the southern sites and do not use observing time to accurately tie these sites to far northern sites (as the Global Sessions do) they should yield a very accurate regional TRF around the South Pole. Syowa (Japan/Antarctica) are willing to participate in this experiment. The characteristics of this network have changed slightly due to more weigh of the southern part.

Syowa Anarctica:
These experiments were designed to strengthen the reference frame in the southern hemisphere, and to detect plate motion, in close collaboration with the JARE (Japanese Antarctic Research Expedition) project.

RDV:
There are six bi-monthly coordinated astrometric/geodetic experiments each year that use the full 10-station VLBA plus up to 10 geodetic stations.

These experiments are being coordinated by the geodetic VLBI programs of three agencies: 1. USNO will perform repeated imaging and correction for source structure.; 2. NASA will analyze this data to determine a high accuracy terrestrial reference frame.; and 3. NRAO will use these sessions to provide a service to users who require high quality positions for small numbers of sources.

IVS-CRF:
The Celestial Reference Frame (CRF) sessions are intended purely to provide astrometric observations useful in improving the current CRF, and in extending and densifying the CRF by observing "new" sources. CRF sessions are scheduled roughly 4 times per year.

IVS-R&D:
The purpose of the R&D sessions is to investigate methods for improving the VLBI technique. This may include studies of instrumental effects or other systematic effects. The sessions occur nominally every month but may be changed depending on the design of the sessions. There are 10 sessions planned because the months before and after the CONT02 session are skipped. Ideas for topics to study are solicited by the Program Committee.

IVS-CONT02:
A two-week continuous VLBI session is proposed for 2002, called CONT02, similar in concept to the extremely successful CONT94 and CONT96 sessions. The purpose of the session is to provide a long series of the highest quality data that VLBI can provide. The weekly R1 and R4 sessions will be observed plus another 10 CONT02 days to cover the two week period. Because of the large resource usage (weekend observing, 200 tapes) a special request will be made to the requested stations for the CONT02 session. The planned time for CONT02 is around September.