# Chapter 3. Observing

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This chapter describes the steps necessary to observe with the ATCA. It assumes that observing strategy has been determined and schedule files created. See Chapter 2 for information on determining observing strategy and Section 2.3 for information on creating schedule files.

In general, observing takes place in the SOC in Marsfield. It is possible to remote observe from anywhere with adequate network and phone connectivity: see the remote observing web page for details on remote observing.

We are currently in the process of creating ATCA Tutorial videos that are available on our YouTube channel. These videos are intended to help new observers familiarise themselves with the various applications and operational processes related to the ATCA and are provided as “refresher courses” for more experienced observers.

Observers are responsible for the collection of their own data and appropriate checks to ensure the quality of the data. They are also expected to ensure the safety of the array (to the best of their ability). This is always secondary to any personal safety concerns.

An ATNF staff astronomer or student is rostered to support observers with setting up and training new observers to use the array (the Duty Astronomer or DA). The DA should be the first point of call if there are problems or queries with observations.

The steps to observe with the compact array are:

• taking control from the previous observer

• set up and calibrate the array

• observe target source(s)

• monitor observations for problems

• end observations

## 3.1. Changeover

Before the start of observations, observers need to log into the ATCA Portal.

Two VNC sessions are set up for control of the array:

• The xbones session runs caobs, vis, assistance and winds.

• The caccc1 session runs tasks associated with the correlator.

If observations are remote, these should be connected to before the start of observations. See http://www.narrabri.atnf.csiro.au/observing/rem_obs.html for information on setting up remote observations (In Marsfield the necessary windows are already set up on Ara in the SOC, along with a number of additional windows with additional information and observing tasks.)

When it is time to take over, check on the portal and chat with the previous observer or observatory staff if it is ok to get going. The Duty Astronomer should be on hand to help inexperienced observers set up their observations.

The main observing program that the observer interacts with is caobs. caobs usually runs in a black screen with yellow writing in the xbones VNC session. The program cacor is the interface to the correlator. cacor commands can be executed for caobs by prefixing the command with corr [command]. Other programs that observers need to use include spd, vis and MoniCA.

For details on using these programs see Appendix A, Appendix B, Appendix C, Appendix D and Appendix E.

To start observing, load a schedule with a strong calibrator into caobs and drive to the source:

 caobs> set file sched_filename loads the schedule file caobs> track # drives the telescope to scan # in the schedule file