The original evaluation of NGC1333 as a source, compiled by Alyssa Goodman, is found here.
This map shows the positions observed (as open circles) under the plan outlined by Rene Laureijs below, and the results of the observations are given below.
Rene Laureijs' reply to the original evaluation of NGC1333:
"Based on your descriptions and the references you gave, we (Ulrich Klaas andI) came to the following observing plan of NGC 1333. We first note that therotation of the focal plane around the source is very small in time, at most15 degrees in the period January - April 98. We doubt whether a multi-epochobservation would give a better elimination of the instrumental polarisationwith such small angle differences.
The plan is to observe a 2x2 "minimap" centred on the Akeson et al. position. Since the C200 detector has four pixels 92" apart from each other in a square, a 2x2 map with 92" step in both directions would give a 3x3 pixel map. The pointings in the map should be aligned with the orientation of the array. Such a map yields the spatial variation of the polarisation (covering the outflow) as well as a safe redundancy because different pixels observe same positions on the sky.
--> Sequence of observations:
- 1 background pointing [NGC 1333 back(1)]
I have selected a position outside the bright areas SE of the emission peaks.
RA = 3h26m21.19848s DEC = +31d00m15.1416s (B1950) Ibck = 100 +/- 10 MJy/sr
- 4 target pointings around Akeson's centre (03 26 05.0,+31 03 14 - 1950) these are:
hh mm ss dd am as
Fsrc = 400+/-100 MJy/sr Ibck = 100 MJy/sr
I assumed a rotation angle of 350 degrees, which corresponds to the rotation of the spacecraft at the end of January.
- 1 background pointing with the same position as before. [NGC 1333 back(2)]
This pointing will be used to check the consistency of the data and to have a reliable estimate of the accuracy of the background polarisation determination."
The results of these "test" observations are:
4 .ps files of detector signals versus time, one .ps file per pixel. You will notice 6 sets of 8 measurements: 2x3 polarisers+open+FCS on the off -> 2x2 minimap -> off position. (Rene needs to please decode this statement...)
click here to return to main ISOPHOT polarimetry planning page