MAMBO observations on Absorber: How to proceed
Ideally the measurements should be done with the moving telescope to be as close as possible in the observation condition, i.e. to have also the same synchronization signals as during real on-sky observations.
The absorber should lie on the ABBA rack and it has to be moved into the entrance window by hand.
> Pick-up a source at the requested elevation (see XEphem) > cd pako >> more ihet.sou | grep G34.3 >>> G34.3 EQ 2000 18:53:18.56 +01:14:58.2 LSR 0.0 FLUX 19.90 0.0 PROJECT CALIB pako> source ABSORBER EQ 2000 18:53:18.56 +01:14:58.2 LSR 0.0 FLUX 19.90 0.0 PROJECT CALIB > After this, test the different observing modes with different parameters: pako> onf 8 80 pako> onf 20 40 pako> bmap 360 360 5 6 pako> bmap 360 290 5 6 pako> ...
The observations needed should be mainly onf 8 80, but longer scans, and other observing modes should be also tried. JP recommended to set the wobbler throw to 40 to avoid putting to much stress on the wobbler itself.
Note that the ABSORBER test must be done with a wind speed lower than ~14 m/s. Anyhow, if the wind is high, keep on with it. It is better than nothing.
ABSORBER with the antenna stopped
In the case the antenna need to be on stow, absorber observations are still possible.
- TOTAL POWER
These observations are made with one phase (i.e. total power).
The way of doing it is the following:
- tell the operator that you want to use the telescope without moving it.
- source ABSORBER EQ 2000 18:53:18.56 +01:14:58.2 LSR 0.0 FLUX 19.90 0.0 PROJECT CALIB
onf-total scans 0.25
NOTE: the source selected for the absorber observations should be a visible object at the moment of the observations, even if the telescope is in stow position.
B. CHOPPED SIGNAL
The operator must changes the input signal in the connectors from the regular wobbler signal to the fsw signal. He must also open program that keeps the system in fsw. The observations must be done exactly as if the antenna was moving, but without doing any bmap.