Since projects are spread over typically two months, the presence of visiting astronomers when their observations are scheduled is practically impossible to guarantee. In the course of observations and data processing, four ``people'' will play a role: the observer, i.e. any member of the team that proposed the observations, the local contact, the on-duty astronomer, an IRAM staff member present on the site, and the array operator. The local contact is an IRAM astronomer assigned to each project. His role is to help the observer in preparing the observations and in properly calibrating the data. In case of any problem, question, or doubt, the observer should contact his local contact. Note that monitoring the progress of a project (that is checking results obtained in a given configuration, making intermediate data reductions, etc.) is the responsibility of the observer, not of the local contact. Facilities such as remote login to the Grenoble computers, faxes, or E-mail, is possible to help the observer in this task.
The array is regularly operated by one operator and one on-duty astronomer. The operator has responsibility for conducting all observations, following pre-established observing procedures or under the supervision of the on-duty astronomer in case of unanticipated events. Operators have also full authority for all safety measures. Receiver tuning is done by the operator. The on-duty astronomer must assess the data quality during the observations by monitoring the array performance on standard calibrators. The observer usually will not be present on the site, but may (or even should) have a look at the data as soon as possible after the observations are performed.