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!).

In detail, the rcpmap procedure is:

The duration of this map is (290/5)*360 ~ 1hr.

Typical RCP map observation

To make it more clear, this is how a rcpmap observation must be done.

pako> source J2253+161
pako> bsw 46          ! to make it the same as the throw of the map
pako> roff53          ! to take the same pixe of the map
pako> btaz XXX        ! to go to the azimuth of the source
pako> p60
pako> set pointing X X
pako> bf
pako> set focus X     ! if focus change to much do another pointing
pako> rcpmap
pako> p60
pako> bt

How are the data checked with mopsic?? (CK) (Priveleged users: Pool DB - astro - calib sources - Reduce RCPs DOES NOT WORK YET)

FlatField (last edited 2009-11-19 10:44:57 by gra-lx17)