2019A&A...626A..75J


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.14CEST18:25:54

2019A&A...626A..75J - Astronomy and Astrophysics, volume 626A, 75-75 (2019/6-1)

rPICARD: A CASA-based calibration pipeline for VLBI data. Calibration and imaging of 7 mm VLBA observations of the AGN jet in M 87.

JANSSEN M., GODDI C., VAN BEMMEL I.M., KETTENIS M., SMALL D., LIUZZO E., RYGL K., MARTI-VIDAL I., BLACKBURN L., WIELGUS M. and FALCKE H.

Abstract (from CDS):


Context. The Common Astronomy Software Application (CASA) software suite, which is a state-of-the-art package for radio astronomy, can now reduce very long baseline interferometry (VLBI) data with the recent addition of a fringe fitter.
Aims. Here, we present the Radboud PIpeline for the Calibration of high Angular Resolution Data (rPICARD), which is an open-source VLBI calibration and imaging pipeline built on top of the CASA framework. The pipeline is capable of reducing data from different VLBI arrays. It can be run non-interactively after only a few non-default input parameters are set and delivers high-quality calibrated data. CPU scalability based on a message-passing interface (MPI) implementation ensures that large bandwidth data from future arrays can be processed within reasonable computing times.
Methods. Phase calibration is done with a Schwab-Cotton fringe fit algorithm. For the calibration of residual atmospheric effects, optimal solution intervals are determined based on the signal-to-noise ratio (S/N) of the data for each scan. Different solution intervals can be set for different antennas in the same scan to increase the number of detections in the low S/N regime. These novel techniques allow rPICARD to calibrate data from different arrays, including high-frequency and low-sensitivity arrays. The amplitude calibration is based on standard telescope metadata, and a robust algorithm can solve for atmospheric opacity attenuation in the high-frequency regime. Standard CASA tasks are used for CLEAN imaging and self-calibration.
Results. In this work we demonstrate the capabilities of rPICARD by calibrating and imaging 7mm Very Long Baseline Array (VLBA) data of the central radio source in the M 87 galaxy. The reconstructed jet image reveals a complex collimation profile and edge-brightened structure, in accordance with previous results. A potential counter-jet is detected that has 10% of the brightness of the approaching jet. This constrains jet speeds close to the radio core to about half the speed of light for small inclination angles.

Abstract Copyright: © ESO 2019

Journal keyword(s): atmospheric effects - techniques: high angular resolution - instrumentation: interferometers - methods: data analysis

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 QSO J0854+2006 BLL 08 54 48.8749311881 +20 06 30.642936668   15.91 15.43 15.56   ~ 2000 1
2 M 87 BiC 12 30 49.42338230 +12 23 28.0438581 10.16 9.59 8.63   7.49 ~ 6213 3
3 3C 279 QSO 12 56 11.1664521013 -05 47 21.531840471   18.01 17.75 15.87   ~ 2704 2

    Equat.    Gal    SGal    Ecl

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2020.07.14-18:25:54

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