CARMA Summer School

L1157: CARMA Full Pol

Ian Stephens Katherine Rosenfeld

Special Thanks: Dick Plambeck

Outline

About L1157 Observations Method of data reduction

Full Pol (1mm only) CO(2-1) and CS(5-4)

~Billion images

L1157

Low-mass Class-0 protostar 250 pc away Outflow

Southern Blue Lobe Northern Red Lobe Spans 5' (~0.36 pc)

Observations

Observations

Bad weather Tau: 0.40-0.71 Tsys: 600-10000 K

5 Gigabyte dataset

Data Reduction: Wides

Full-Pol Calibration Bandpass calibration on wide windows only Separate 6 wide windows, uvaver, and apply phase

calibration Solve for XY-phase offsets for each window

Inspect cross-auto data (LR) for reference ant Average phase offset ~ xyphase

Solve for leakages for each window gpcal: Depends on XY-phase.

options=qusolve,circular Window 1 was the hero.

Mapping: Wides

Solve for I, Q, U, and V invert vis=WIDE.1.uv

map=I1.mp,Q1.mp,U1.mp,V1.mp beam=I1.bm imsize=128 cell=0.5 select='source(L1157)' sup=0 options=nopol,nopass,systemp

Solve for position angle and polarization impol in=Q1.mp,U1.mp,I1.mp poli=poli1.mp

pa=pa1.mp sigma=5.4E-3 sncut=2,3

cgdisp in=I1.mp,poli1.mp,pa1.mp type=pixel,amplitude,angle options=rot90 continuum mapped also

Data Reduction: Narrows

Narrow-bands Separated into two bands Used the wide-band for bandpass Everything else relatively normal

Both CO and CS detected!

CO Channel maps

CO Zero-moment map

First-moment map

L1157