| CSIRO Astronomy and Space Science ATCA Users Guide |
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This section describes what will be required for the observations to be successful. All observers should read this section!
| 2.5.1 Coming to the Observatory | ||
| 2.5.2 Remote Observing | ||
| 2.5.3 Data Consumption |
For observers unfamiliar with the ATCA, it is recommended that they arrive so that they have at least one full weekday available before their observations, in order for them to become familiar with how to use the array and who to talk to if things go wrong.
To be sure of a successful remote observing session, all observers are required to test their remote observing setup at least a week before their observations.
At a minimum, a remote observer requires:
Remote observations will be easier if a remote observer also has:
To test their setup, observers should contact the Duty Astronomer and ask to be allowed to login and perform the test. If the test will not disturb current observations, the remote observer should follow the instructions on remote observing found in Chapter 3 to ensure that they can monitor and control all the required VNC sessions. If problems are encountered here, they should contact the observatory staff with a description of the problems and ask for advice.
It is recommended that all observers bring their own magnetic disks to the observatory in order to take data back with them. To calculate roughly how much data an observation will generate, use the following formula.
The number of bytes per cycle is:
where N_{channels} is the number of channels per IF, N_{IFs} is the number of IFs, N_{products} is the number of correlation products, b_{corr} is the number of bytes per correlation product, and N_{Stokes} is the number of Stokes quantities.
For a typical continuum observation, N_{channels}=2049, N_{IFs}=2, N_{products}=21 (15 cross-correlations + 6 auto-correlations), N_{Stokes}=4 and b_{corr}=12 (4 bytes each for real, imaginary and weight components). With these numbers, a typical continuum observation produces b_{cycle}=4,130,784 bytes per cycle.
The data-rate per hour therefore is:
where t_{cycle} is the correlator cycle time in seconds. For a typical correlator cycle time of t_{cycle}=10, a typical continuum observation produces b_{hour}=1,487,082,240 bytes (1.385 GiB) per hour.
For each zoom band that is recorded, more space is required. The data-rate per hour is calculated as before. For typical zoom bands, N_{channels}=2049, N_{IFs}=1, and all other values are the same as for a typical continuum observation. Therefore each zoom band will generate an additional 709.1 MiB per hour. Eventually, with a possible 16 zoom bands per continuum IF, CABB will produce up to 23.544 GiB per hour (565 GiB per day!), or even more if the cycle time were to be decreased.
Storing that much data on DVD media would require 142 discs per day, while such a data volume can easily be stored on an inexpensive external hard drive, with the added benefits that data storage and retrieval would be far quicker and more convenient.
Users Guide last modified on 2011-04-27 15:49:06