Observing Program

CONT05

Continuous VLBI Campaign 2005

This web page will undergo frequent updates as the planning of the CONT05 campaign progresses. Please send a message to the Coordinating Center if you have updates or links to be included on this page.

Purpose

CONT05 is a two-week campaign of continuous VLBI sessions, scheduled for observing during September 2005. The CONT05 sessions are the follow-on to the spectacularly successful CONT94 observed in January 1994 and the follow-up CONT95 (August 1995), CONT96 (fall 1996), and CONT02 (October 2002).

Goals

The plan for the CONT05 campaign is to acquire state of the art VLBI data over a two-week period to demonstrate the highest accuracy of which VLBI is capable. A number of scientific and technical goals are set for the campaign:

• Science: Analysis of the two weeks of continuous high frequency (sub-daily) EOP will address the discrepancies seen between the models (tidal and atmospheric) and the observations at the M2 and S1 frequencies as well as between long-term and short-term values of tidal amplitudes. With 256 Mb/s recording and a network with larger geographical coverage the sub-daily precision should be better than CONT94, thus clarifying even more the deviations from the ocean tide model.
• Technique improvement: Continuous data allows comparison of estimates of troposphere zenith delay and gradients across experiment boundaries as a measure of the accuracy of the observations and analysis. Comparison with WVR measurements where possible will be especially useful, as will be comparisons with GPS estimates and with Numerical Weather Models.
• Accuracy assessment: Analysis of reference frame repeatability day to day can be made and compared with previous continuous VLBI series.
• Comparisons: CONT05 is strongly endorsed by the IERS and will be an important source of data for the IERS Combination Pilot Project. All stations have IGS GPS systems relatively nearby that are considered Global Stations, three stations are co-located with an ILRS SLR system, and four stations are co-located with an IDS DORIS station. The continuous high accuracy allows investigation of daily and sub-daily site motions for comparison with external factors such as atmospheric effects and temperature distortions of the antennas or pedestals.

Observation Period

The 15 days of continuous VLBI observation have been fixed as follows:

• first observation: Monday September 12, 2005 @ 1700 UTC
• last observation: Tuesday September 27, 2005 @ 1630 UTC

Network Resources

The following network resources will be used during the CONT05 campaign:

• Observation network: 11 stations alloted observing time for the 15 session days of the CONT05 campaign. The stations are:
  
  

  Algonquin Park, Canada	Gilmore Creek, Alaska, USA	HartRAO, South Africa
  Kokee Park, Hawaii, USA	Ny Alesund, Norway	Onsala, Sweden
  Svetloe, Russia	TIGO, Concepcion, Chile	Tsukuba, Japan
  Westford, Massachusetts, USA	Wettzell, Germany

  
  
  
  The geographical distribution of these stations is depicted in the network map . A 12th station, Fortaleza, Brazil, also has alloted observation time for the CONT05. But in order to be able to participate Fortaleza needs to upgrade to the Mark 5 recording system. At the current time it seems unlikely that the upgrade will be completed and fully tested before the beginning of the CONT campaign.
• The CONT05 stations committed to a pre-campaign station checkout to ensure that the data acquired during the campaign are of the highest quality. Instructions and advice about what to check and how are handled by the Network Coordinator.
• Rapid disk return for the "R" type sessions during the CONT period so that IVS can keep up its commitment for two rapid-turnaround sessions each week.

Station Testing

In order to make sure the stations are in good operating condition before CONT05, a set of tests was developed under the direction of Brian Corey and Ed Himwich for each station to perform. These tests are based on the similar tests that were done for previous CONT experiments, the last of which was three years ago.

The CONT05 pre-checks consist of 16 separate tests. A description of the tests is available in the CONT05 mail archive . The test description was sent out in three parts:

• Tests 1-7 and 11-13
• Tests 8-10 and 14-15
• Test 16

Expected Accuracies

The schedule will be a standard geodetic schedule which achieves simulated EOP results of at least as good as 40 micro-arcsec for pole position and 1.5 micro-sec for UT1. The recording mode will be the Mark 4 fanout mode with 256 Mb/s data rate.

Shipping

The media usage plan and shipment schedule as of September 9, 2005 is posted. The information will be updated when new information comes in.

Mark 5 Power Supply Issue

The Mark 5 systems with serial numbers prior to Mark5-638 (including BR-RS numbers) may experience problems with newer disk modules that employ Maxtor or Seagate disks. Please read a memo from MIT Haystack Observatory to learn more about the power supply issue. The following table shows how the CONT05 stations are affected.

† n/a not applicable; n/s not specified

Please inform the Coordinating Center if any entry in the table is incorrect.

Schedules

The detailed observing schedules for CONT05 were generated using the automatic scheduling algorithms of the NASA sked program. We investigated the best combination of scheduling parameters, minimum SNR levels, source list, and flux models. The "best" schedule was determined as a compromise between the optimum simulated formal errors, number of observations, number of scans per hour, sky coverage, and robustness.

The schedule and corresponding notes files are available from the Data Centers. Each CONT05 day has its own schedule. There is a break of 30 minutes between two campaign days. A detailed description of the observing schedule is available in the CONT05 session notes .

Water Vapor Radiometer (WVR) Data

At several stations water vapor radiometers (WVR) observed the atmospheric water vapor content. You can browse and download the WVR data for the following stations:

• Algonquin
• Kokee Park
• Onsala (in progress)
• Tsukuba
• Wettzell

Inter-technique Coordination Group

An inter-technique coordination group for observing and analysis was formed. The group has representatives from the measurement services (IGS, ILRS, IDS, and IVS) as well as from the IERS. The members are:

• Markus Rothacher (IERS)
• Dirk Behrend , Axel Nothnagel , Arthur Niell (IVS)
• Mike Pearlman , Ron Noomen (ILRS)
• Pascal Willis , Martine Feissel (IDS)
• Gerd Gendt , Angie Moore (IGS)

For the duration of the CONT05 campaign, all techniques will make sure that the best possible observations be taken. That means that no unnecessary maintenance work or upgrades will be performed at the stations. Furthermore, it is envisaged that all sites will be analyzed in the regular analysis of the particular service. For combination purposes the group will put emphasis on the models and parameters to be used in the analysis. A first meeting of the group is foreseen at the IAG Scientific Assembly in Cairns, Australia in August.

Experience Reports

HartRAO. The Hartebeesthoek Radio Astronomy Observatory compiled the experiences of their CONT05 participation. This southern hemisphere station has all space techniques co-located at the site and, in addition, had two water vapor radiometers running during the campaign. Please visit the HartRAO site to see a photo-essay of the CONT05 campaign with a station in action.

Bonn. The Bonn Correlator compiled an informal diary of their CONT05 experience. Thanks to Alessandra Bertarini for giving us insight into the happenings at a correlator.