Flatfield observation
Aim: derive parameters of the 117ch array, i.e. the sensitivity of each pixel and relative offsets of the pixels.
The observation consist in select a strong source and make all the single pixels of MAMBO2 observe this source to be able to derive the parameters of the receivers. This is why this map is also called beam map or rcp map (rcp = receiver parameters).
A flatfield observation must be done at least once per pool session. This observation must be carried out during nights only under very stable weather conditions (tau of 0.5 is ok though). If the conditions are not such stable the flatfield should be redone.
Low tau is not so important, but stable pointing is.
In case MAMBO2 or the mirrors in front of it are readjusted, several flatfields must be done several times.
If not suitable planets are up during the night a strong (10Jy/beam) point source somewhere between 50 and 70 deg (e.g. J1229+021). The source should be point-like (e.g. Uranus and Mars, but not Saturn or Jupiter!).
IMPORTANT: Old p4/p5 values can cause a drift in the array parameters, which will make the data useless.
A pointing and a focus must be done before and after the map
- Map procedure
pako> source J1229+021 !Already done before
pako> roff53 !Central channel for maps
pako> rcpmap
pako> start
In detail, the rcpmap procedure is:
- bsw 46 bmap 360 290 5 6
The duration of this map is (290/5)*360 ~ 1hr.
- Check the array-offsets for stability.
How are the data checked with mopsic?? (CK) (Priveleged users: Pool DB - astro - calib sources - Reduce RCPs DOES NOT WORK YET)