SYMBA: An end-to-end VLBI synthetic data generation pipeline
F. Roelofs, M. Janssen, I. Natarajan, R. Deane, J. Davelaar, H. Olivares, O. Porth, S. N. Paine, K. L. Bouman, R. P. J. Tilanus, I. M. van Bemmel, H. Falcke, K.… 展开作者
F. Roelofs, M. Janssen, I. Natarajan, R. Deane, J. Davelaar, H. Olivares, O. Porth, S. N. Paine, K. L. Bouman, R. P. J. Tilanus, I. M. van Bemmel, H. Falcke, K. Akiyama, A. Alberdi, W. Alef, K. Asada, R. Azulay, A. Baczko, D. Ball, M. Baloković, J. Barrett, D. Bintley, L. Blackburn, W. Boland, G. C. Bower, M. Bremer, C. D. Brinkerink, R. Brissenden, S. Britzen, A. E. Broderick, D. Broguiere, T. Bronzwaer, D. Byun, J. E. Carlstrom, A. Chael, C. Chan, S. Chatterjee, K. Chatterjee, M. Chen, Y. Chen, I. Cho, P. Christian, J. E. Conway, J. M. Cordes, G. B. Crew, Y. Cui, M. De Laurentis, J. Dempsey, G. Desvignes, J. Dexter, S. S. Doeleman, R. P. Eatough, V. L. Fish, E. Fomalont, R. Fraga-Encinas, P. Friberg, C. M. Fromm, J. L. Gómez, P. Galison, C. F. Gammie, R. García, O. Gentaz, B. Georgiev, C. Goddi, R. Gold, M. Gu, M. Gurwell, K. Hada, M. H. Hecht, R. Hesper, L. C. Ho, P. Ho, M. Honma, C. L. Huang, L. Huang, D. H. Hughes, S. Ikeda, M. Inoue, S. Issaoun, D. J. James, B. T. Jannuzi, B. Jeter, W. Jiang, M. D. Johnson, S. Jorstad, T. Jung, M. Karami, R. Karuppusamy, T. Kawashima, G. K. Keating, M. Kettenis, J. Kim, J. Kim, J. Kim, M. Kino, J. Yi Koay, P. M. Koch, S. Koyama, M. Kramer, C. Kramer, T. P. Krichbaum, C. Kuo, T. R. Lauer, S. Lee, Y. Li, Z. Li, M. Lindqvist, R. Lico, K. Liu, E. Liuzzo, W. Lo, A. P. Lobanov, L. Loinard, C. Lonsdale, R. Lu, N. R. MacDonald, J. Mao, S. Markoff, D. P. Marrone, A. P. Marscher, I. Martí-Vidal, S. Matsushita, L. D. Matthews, L. Medeiros, K. M. Menten, Y. Mizuno, I. Mizuno, J. M. Moran, K. Moriyama, M. Moscibrodzka, C. Müller, H. Nagai, N. M. Nagar, M. Nakamura, R. Narayan, G. Narayanan, R. Neri, C. Ni, A. Noutsos, H. Okino, G. N. Ortiz-León, T. Oyama, F. Özel, D. C. M. Palumbo, N. Patel, U. Pen, D. W. Pesce, V. Piétu, R. Plambeck, A. PopStefanija, B. Prather, J. A. Preciado-López, D. Psaltis, H. Pu, V. Ramakrishnan, R. Rao, M. G. Rawlings, A. W. Raymond, L. Rezzolla, B. Ripperda, A. Rogers, E. Ros, M. Rose, A. Roshanineshat, H. Rottmann, A. L. Roy, C. Ruszczyk, B. R. Ryan, K. L. J. Rygl, S. Sánchez, D. Sánchez-Arguelles, M. Sasada, T. Savolainen, F. Peter Schloerb, K. Schuster, L. Shao, Z. Shen, D. Small, B. Won Sohn, J. SooHoo, F. Tazaki, P. Tiede, M. Titus, K. Toma, P. Torne, T. Trent, S. Trippe, S. Tsuda, H. J. van Langevelde, D. R. van Rossum, J. Wagner, J. Wardle, D. Ward-Thompson, J. Weintroub, N. Wex, R. Wharton, M. Wielgus, G. N. Wong, Q. Wu, A. Young, K. Young, Z. Younsi, F. Yuan, Y. Yuan, J. A. Zensus, G. Zhao, S. Zhao, Z. Zhu
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20 pages, 15 figures, accepted for publication in A&A
Realistic synthetic observations of theoretical source models are essential for our understanding of real observational data. In using synthetic data, one can verify the extent to which source parameters can be recovered and evaluate how various data corruption effects can be calibrated. These studies are important when proposing observations of new sources, in the characterization of the capabilities of new or upgraded instruments, and when verifying model-based theoretical predictions in a comparison with observational data. We present the SYnthetic Measurement creator for long Baseline Arrays (SYMBA), a novel synthetic data generation pipeline for Very Long Baseline Interferometry (VLBI) observations. SYMBA takes into account several realistic atmospheric, instrumental, and calibration effects. We used SYMBA to create synthetic observations for the Event Horizon Telescope (EHT), a mm VLBI array, which has recently captured the first image of a black hole shadow. After testing SYMBA with simple source and corruption models, we study the importance of including all corruption and calibration effects. Based on two example general relativistic magnetohydrodynamics (GRMHD) model images of M87, we performed case studies to assess the attainable image quality with the current and future EHT array for different weather conditions. The results show that the effects of atmospheric and instrumental corruptions on the measured visibilities are significant. Despite these effects, we demonstrate how the overall structure of the input models can be recovered robustly after performing calibration steps. With the planned addition of new stations to the EHT array, images could be reconstructed with higher angular resolution and dynamic range. In our case study, these improvements allowed for a distinction between a thermal and a non-thermal GRMHD model based on salient features in reconstructed images.
We present the design and implementation of an automated data calibration and reduction pipeline for very-long-baseline interferometric (VLBI) observations taken at millimeter wavelengths. These short radio-wavelengths provide the best imaging resolution available from ground-based VLBI networks such as the Event Horizon Telescope (EHT) and the Global Millimeter VLBI Array (GMVA), but require specialized processing due to the strong effects from atmospheric opacity and turbulence as well as the heterogeneous nature of existing global arrays. The pipeline builds upon a calibration suite (HOPS) …
We present the Generalized Polarization CALibration pipeline (GPCAL), an automated pipeline for instrumental polarization calibration of very long baseline interferometry (VLBI) data. The pipeline is designed to achieve a high calibration accuracy by means of fitting the instrumental polarization model, including the second-order terms, to multiple calibrators data simultaneously. It also allows using more accurate linear polarization models of calibrators for D-term estimation compared to the conventional way that assumes similar linear polarization and total intensity structures. This assump…
We report the development of a semi-automatic pipeline for the calibration of 86 GHz full-polarization observations performed with the Global Millimeter-VLBI array (GMVA) and describe the calibration strategy followed in the data reduction. Our calibration pipeline involves non-standard procedures, since VLBI polarimetry at frequencies above 43 GHz is not yet well established. We also present, for the first time, a full-polarization global-VLBI image at 86 GHz (source 3C 345), as an example of the final product of our calibration pipeline, and discuss the effect of instrumental limitations on …
We present VOLKS2, the second release of "VLBI Observation for transient Localization Keen Searcher". The pipeline aims at transient search in regular VLBI observations as well as detection of single pulses from known sources in dedicated VLBI observations. The underlying method takes the idea of geodetic VLBI data processing, including fringe fitting to maximize the signal power and geodetic VLBI solving for localization. By filtering the candidate signals with multiple windows within a baseline and by cross matching with multiple baselines, RFIs are eliminated effectively. Unlike the station…
We present our implementation of an automated VLBI data reduction pipeline dedicated to interferometric data imaging and analysis. The pipeline can handle massive VLBI data efficiently which makes it an appropriate tool to investigate multi-epoch multiband VLBI data. Compared to traditional manual data reduction, our pipeline provides more objective results since less human interference is involved. Source extraction is done in the image plane, while deconvolution and model fitting are done in both the image plane and the uv plane for parallel comparison. The output from the pipeline includes …
(Abridged) The CASA software suite, can now reduce very long baseline interferometry (VLBI) data with the recent addition of a fringe fitter. 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) im…
The calibration of Very Long Baseline Interferometry (VLBI) data has long been a time consuming process. The Korean VLBI Network (KVN) is a simple array consisting of three identical antennas. Because four frequencies are observed simultaneously, phase solutions can be transferred from lower frequencies to higher frequencies in order to improve phase coherence and hence sensitivity at higher frequencies. Due to the homogeneous nature of the array, the KVN is also well suited for automatic calibration. In this paper we describe the automatic calibration of single-polarisation KVN data using the…
In our previous work, we propose a cross spectrum based method to extract single pulse signals from RFI contaminated data, which is originated from geodetic VLBI postprocessing. This method fully utilizes fringe phase information of the cross spectrum and hence maximizes signal power, however the localization was not discussed in that work yet. As the continuation of that work, in this paper, we further study how to localize single pulses using astrometric solving method. Assuming that the burst is a point source, we derive the burst position by solving a set of linear equations given the rela…
Currently, HOPS and AIPS are the primary choices for the time-consuming process of (millimeter) Very Long Baseline Interferometry (VLBI) data calibration. However, for a full end-to-end pipeline, they either lack the ability to perform easily scriptable incremental calibration or do not provide full control over the workflow with the ability to manipulate and edit calibration solutions directly. The Common Astronomy Software Application (CASA) offers all these abilities, together with a secure development future and an intuitive Python interface, which is very attractive for young radio astron…
AVICA: A fully automated CASA pipeline for large volume VLBI data calibration
Institute of Astrophysics, Foundation for Research and Technology – Hellas（希腊研究基金会天体物理研究所）；Department of Physics, University of Crete（克里特大学物理系）；Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University（拉德堡德大学数学、天体物理和粒子物理研究所天体物理学系）
We introduce the cross spectrum based FRB (Fast Radio Burst) search method for VLBI observation. This method optimizes the fringe fitting scheme in geodetic VLBI data post processing, which fully utilizes the cross spectrum fringe phase information and therefore maximizes the power of single pulse signals. Working with cross spectrum greatly reduces the effect of radio frequency interference (RFI) compared with using auto spectrum. Single pulse detection confidence increases by cross identifying detections from multiple baselines. By combining the power of multiple baselines, we may improve th…
New functionality to process Very Long Baseline Interferometry (VLBI) data has been implemented in the CASA package. This includes two new tasks to handle fringe fitting and VLBI-specific amplitude calibration steps. Existing tasks have been adjusted to handle VLBI visibility data and calibration meta-data properly. With these updates, it is now possible to process VLBI continuum and spectral line observations in CASA. This article describes the development and implementation, and presents an outline for the workflow when calibrating European VLBI Network or Very Long Baseline Array data in CA…
Verification of the Polarimetric Capability of the East Asia VLBI Network
School of Space Research, Kyung Hee University（庆熙大学宇宙研究学院）；G-LAMP NEXUS Institute, Kyung Hee University（庆熙大学G-LAMP NEXUS研究所）；Institute of Astronomy and Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）；Korea Astronomy and Space Science Institute（韩国天文学与空间科学研究所）；University of Science and Technology（科学技术联合大学院大学）；Graduate School of Science, Nagoya City University（名古屋市立大学理学研究科）；Mizusawa VLBI Observatory, National Astronomical Observatory of Japan（日本国立天文台水泽VLBI观测站）
GASV: A New VLBI analysis software for Geodesy and Astrometry
National Time Service Center, Chinese Academy of Sciences（中国科学院国家授时中心）；Key Laboratory of Time Reference and Applications, Chinese Academy of Sciences（中国科学院时间频率应用重点实验室）
Reconstructing images from very long baseline interferometry (VLBI) data with sparse sampling of the Fourier domain (uv-coverage) constitutes an ill-posed deconvolution problem. It requires application of robust algorithms maximizing the information extraction from all of the sampled spatial scales and minimizing the influence of the unsampled scales on image quality. We develop a new multiscale wavelet deconvolution algorithm DoG-HiT for imaging sparsely sampled interferometric data which combines the difference of Gaussian (DoG) wavelets and hard image thresholding (HiT). Based on DoG-HiT, w…
We present MeqSilhouette v2.0 (MeqSv2), a fully polarimetric, time-and frequency-resolved synthetic data generation software for simulating millimetre (mm) wavelength very long baseline interferometry (VLBI) observations with heterogeneous arrays. Synthetic data are a critical component in understanding real observations, testing calibration and imaging algorithms, and predicting performance metrics of existing or proposed sites. MeqSv2 applies physics-based instrumental and atmospheric signal corruptions constrained by empirically-derived site and station parameters to the data. The new versi…
The work describes a system for converting VLBI observation data using the algorithms of coherent dedispersion and compensation of two-bit signal sampling. Coherent dedispersion is important for processing pulsar observations to obtain the best temporal resolution, while correction for signal sampling makes it possible to get rid of a number of parasitic effects that interfere with the analysis of the diffraction pattern of pulsars. A pipeline has been established that uses the developed converter and the ASC Software Correlator, which will allow reprocessing all archived data of Radioastron p…
INFN Section of Naples（意大利国家核物理研究所那不勒斯分部）；University of Naples "Federico II"（那不勒斯费德里科二世大学）；ESO（欧洲南方天文台）
We present a Deep-Learning (DL) pipeline developed for the detection and characterization of astronomical sources within simulated Atacama Large Millimeter/submillimeter Array (ALMA) data cubes. The pipeline is composed of six DL models: a Convolutional Autoencoder for source detection within the spatial domain of the integrated data cubes, a Recurrent Neural Network (RNN) for denoising and peak detection within the frequency domain, and four Residual Neural Networks (ResNets) for source characterization. The combination of spatial and frequency information improves completeness while decreasi…
VAPOLA -- A multi-year, multi-band polarization survey of AGN and Sgr A* at mm wavelengths with ALMA I. Survey Overview and Science-Ready Archival Products
Università degli Studi di Cagliari（卡利亚里大学）；INAF - Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）；University of Balearic Islands（巴利阿里群岛大学）；Institute of the Balearic Islands (IAIB)（巴利阿里群岛研究所）；Health Research Institute of the Balearic Islands (IdISBa)（巴利阿里群岛健康研究所）；Universidade São Paulo, Instituto de Astronomia, Geofísica e Ciéencias Atmosféricas（圣保罗大学天文、地球物理与大气科学研究所）；INAF-Istituto di Radioastronomia（意大利国家天体物理研究所射电天文学研究所）；INAF–Italian Centre for Astronomical Archive（意大利天体物理研究所意大利天文档案中心）
Bayesian polarization calibration and imaging in very long baseline interferometry
Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Max Planck Computing and Data Facility（马克斯·普朗克计算与数据中心）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理研究所）；Technische Universität München (TUM)（慕尼黑工业大学）；School of Space Research, Kyung Hee University（庆熙大学宇宙研究学院）；Ludwig-Maximilians-Universität（路德维希-马克西米利安大学）；Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University（拉布德大学数学、天体物理学和粒子物理研究所天体物理学系）；Institut für Experimentalphysik（实验物理研究所）
CASA, the Common Astronomy Software Applications package, is the primary data processing software for the Atacama Large Millimeter/submillimeter Array (ALMA) and NSF's Karl G. Jansky Very Large Array (VLA), and is frequently used also for other radio telescopes. The CASA software can process data from both single-dish and aperture-synthesis telescopes, and one of its core functionalities is to support the data reduction and imaging pipelines for ALMA, VLA and the VLA Sky Survey (VLASS). CASA has recently undergone several exciting new developments, including an increased flexibility in Python …
