10 After the Observations

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10.1 Getting the Data

After an observation, the data can be downloaded via internet from our Management of Measurements (MoM) system. While in general the data export in the form of DVDs is not offered anymore, users may contact the sciencesupport [at] astron [dot] nl (WSRT science support group) in special cases and ask for a DVD copy. All WSRT data are written originally in AIPS++ MeasurementSet (MS) format. Translation of MS files to either UVFITS or Newstar SCN format is offered as an (recommended) option for data exported to the users.

PuMa datasets have a separate format, described at

http://www.fys.ruu.nl/ wwwigf/puma-intro.htm; so far, all analysis of PuMa data has taken place with software owned by the PuMa team.

Standard 12-hour observations with the full DZB capacity, at the default integration time of 60 seconds, would yield datasets of 2 Gbytes (reaching 12Gbyfor 10 second integration time!). In order to avoid problems with excessive file sizes and older operating systems, observations will by default be split into a few files covering successive time intervals.

WSRT staff will endeavour to assist users who would strongly prefer exports using a different sub-division (e.g., separate IF bands), or with data pre-averaged, for example fewer, broader frequency channels for continuum work.

10.2 Data Reduction

The WSRT data can be calibrated and analysed using different data reduction packages (Classic AIPS, Miriad, NewStar, AIPS++). The most commonly used are listed here with a few lines of comment on the advantages/disadvantages and possible problems encounterd in transfering WSRT data in each of them.

A reference cookbook for reduction of DZB data in ClassicAIPS (UVFITS) is also available here. In order to calibrate/analyse WSRT data with Miriad a number of programs need an adapted version. Notes on how to proceed are available here.

Experience with parallel computing is being built up at Astron. A computer cluster is available for test purposes, and the Miriad data reduction package (particularly well suited for WSRT spectral line data) has recently been ported to it. Astronomers are therefore invited to consider taking on ambitious projects (wide-area mosaicks are just one example), with a scope that might have been considered too daunting until recently.

We wish to encourage users to come to Dwingeloo to analyze their data and interact with local staff. We will try to assign a support astronomer to novice users who would like to receive assistance with their data reduction. Please make sure that you sciencesupport [at] astron [dot] nl (contact us) well in advance of your intended visit to make this logistically possible.

Transnational Access support available
Successful proposers for WSRT time, who are based in an EU or affiliated country, excluding The Netherlands, are eligible for Transnational Access support. This will, in general, entail payment of travel and accomodation expenses for one of the proposal team members for a 1-week data analysis visit to ASTRON. All WSRT projects are assigned a "Friend of the project" from amongst the local astronomical staff of the Radio Observatory. The Transnational Access programme is one of the activities of RadioNet, an Integrated Infrastructure Initiative (I3), funded under the EC FP6, that has pulled together all of Europe's leading astronomy facilities to produce a focused, coherent and integrated project that will significantly enhance the quality and quantity of science performed by European astronomers. More details can be found on http://www.radionet-eu.org/tna/.

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