mm Observing Summary

The scientific goals of different experiments, and the conditions of a given day are going to mean that no two experiments will need exactly the same observing strategies, however, observing at 3mm generally involves most of the following steps:

• before your observing, create schedules (this is somewhat more complicated than cm observing, so ensure that you have enough time allocated to this task)
• when you start your observations, consider the weather situation - is it appropriate for 3mm observations? If not, consider a swap
• stow and detach antenna 6 (if it is unstowed)
• track a strong source (in 2005 these were 0407$-$678, 1253$-$055 and 1921$-$293)
• ensure that the auto attenuation algorithm is active
• set course attenuators so that the power levels (GTP) are less than 3.5V, the samplers are stable and between 10 and 246, and the fine attenuator settings are in the range 1-5.
• Assuming that the delay plot on vis is stable, calibrate the delays using cacal (you may need to use a correlator config with less channels e.g. full_16_32-128 instead of full_16_256-128)
• determine the system temperature with a paddle scan
• before pointing, ensure that you have the intended pointing pattern set up in caobs. See Setting up IFs for pointing at mm
• if you plan to use this source for a bandpass or pointing calibrator, you need to check (and correct) the antenna pointing
• move to your astronomy source
• again (since you are in a different part of the sky) check and correct pointing
• again determine the system temperature (with a paddle scan)
• start observing program proper

The following tasks will probably need to be completed during your observing cycle

• setup (as described above)
• point approximately once an hour
• paddle approximately every half hour
• observing secondary calibrator
• observing astronomy source

Things to be aware of

• you may need to change the point_if settings in caobs so that you are using only the wide bandwidth IFs for your pointing calibration