Astrometric accuracy of snapshot fast radio burst localisations with ASKAP
The recent increase in well-localised fast radio bursts (FRBs) has facilitated in-depth studies of global FRB host properties, the source circumburst medium, and the potential impacts of these environments on the burst properties. The Australian Square Kilometre Array Pathfinder (ASKAP) has localise...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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CAMBRIDGE UNIV PRESS
2021
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2107.07068 http://hdl.handle.net/20.500.11937/91560 |
| _version_ | 1848765547921014784 |
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| author | Day, C.K. Deller, A.T. James, Clancy Lenc, E. Bhandari, S. Shannon, Ryan Bannister, K.W. |
| author_facet | Day, C.K. Deller, A.T. James, Clancy Lenc, E. Bhandari, S. Shannon, Ryan Bannister, K.W. |
| author_sort | Day, C.K. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The recent increase in well-localised fast radio bursts (FRBs) has facilitated in-depth studies of global FRB host properties, the source circumburst medium, and the potential impacts of these environments on the burst properties. The Australian Square Kilometre Array Pathfinder (ASKAP) has localised 11 FRBs with sub-arcsecond to arcsecond precision, leading to sub-galaxy localisation regions in some cases and those covering much of the host galaxy in others. The method used to astrometrically register the FRB image frame for ASKAP, in order to align it with images taken at other wavelengths, is currently limited by the brightness of continuum sources detected in the short-duration ('snapshot') voltage data captured by the Commensal Real-Time ASKAP Fast Transients (CRAFT) software correlator, which are used to correct for any frame offsets due to imperfect calibration solutions and estimate the accuracy of any required correction. In this paper, we use dedicated observations of bright, compact radio sources in the low-and mid-frequency bands observable by ASKAP to investigate the typical astrometric accuracy of the positions obtained using this so-called 'snapshot' technique. Having captured these data with both the CRAFT software and ASKAP hardware correlators, we also compare the offset distributions obtained from both data products to estimate a typical offset between the image frames resulting from the differing processing paths, laying the groundwork for future use of the longer duration, higher signal-to-noise ratio (S/N) data recorded by the hardware correlator. We find typical offsets between the two frames of and arcsec in the low-and mid-band data, respectively, for both RA and Dec. We also find reasonable agreement between our offset distributions and those of the published FRBs. We detect only a weak dependence in positional offset on the relative separation in time and elevation between target and calibrator scans, with the trends being more pronounced in the low-band data and in Dec. Conversely, the offsets show a clear dependence on frequency in the low band, which we compare to the frequency-dependent Dec. offsets found in FRB 200430. In addition, we present a refined methodology for estimating the overall astrometric accuracy of CRAFT FRBs. |
| first_indexed | 2025-11-14T11:37:00Z |
| format | Journal Article |
| id | curtin-20.500.11937-91560 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:37:00Z |
| publishDate | 2021 |
| publisher | CAMBRIDGE UNIV PRESS |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-915602023-05-16T05:26:59Z Astrometric accuracy of snapshot fast radio burst localisations with ASKAP Day, C.K. Deller, A.T. James, Clancy Lenc, E. Bhandari, S. Shannon, Ryan Bannister, K.W. Science & Technology Physical Sciences Astronomy & Astrophysics astrometry fast radio bursts radio interferometry radio transient sources ENVIRONMENT The recent increase in well-localised fast radio bursts (FRBs) has facilitated in-depth studies of global FRB host properties, the source circumburst medium, and the potential impacts of these environments on the burst properties. The Australian Square Kilometre Array Pathfinder (ASKAP) has localised 11 FRBs with sub-arcsecond to arcsecond precision, leading to sub-galaxy localisation regions in some cases and those covering much of the host galaxy in others. The method used to astrometrically register the FRB image frame for ASKAP, in order to align it with images taken at other wavelengths, is currently limited by the brightness of continuum sources detected in the short-duration ('snapshot') voltage data captured by the Commensal Real-Time ASKAP Fast Transients (CRAFT) software correlator, which are used to correct for any frame offsets due to imperfect calibration solutions and estimate the accuracy of any required correction. In this paper, we use dedicated observations of bright, compact radio sources in the low-and mid-frequency bands observable by ASKAP to investigate the typical astrometric accuracy of the positions obtained using this so-called 'snapshot' technique. Having captured these data with both the CRAFT software and ASKAP hardware correlators, we also compare the offset distributions obtained from both data products to estimate a typical offset between the image frames resulting from the differing processing paths, laying the groundwork for future use of the longer duration, higher signal-to-noise ratio (S/N) data recorded by the hardware correlator. We find typical offsets between the two frames of and arcsec in the low-and mid-band data, respectively, for both RA and Dec. We also find reasonable agreement between our offset distributions and those of the published FRBs. We detect only a weak dependence in positional offset on the relative separation in time and elevation between target and calibrator scans, with the trends being more pronounced in the low-band data and in Dec. Conversely, the offsets show a clear dependence on frequency in the low band, which we compare to the frequency-dependent Dec. offsets found in FRB 200430. In addition, we present a refined methodology for estimating the overall astrometric accuracy of CRAFT FRBs. 2021 Journal Article http://hdl.handle.net/20.500.11937/91560 10.1017/pasa.2021.40 English https://arxiv.org/abs/2107.07068 http://purl.org/au-research/grants/arc/FT150100415 http://purl.org/au-research/grants/arc/FT190100155 http://purl.org/au-research/grants/arc/DP180100857 CAMBRIDGE UNIV PRESS restricted |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics astrometry fast radio bursts radio interferometry radio transient sources ENVIRONMENT Day, C.K. Deller, A.T. James, Clancy Lenc, E. Bhandari, S. Shannon, Ryan Bannister, K.W. Astrometric accuracy of snapshot fast radio burst localisations with ASKAP |
| title | Astrometric accuracy of snapshot fast radio burst localisations with ASKAP |
| title_full | Astrometric accuracy of snapshot fast radio burst localisations with ASKAP |
| title_fullStr | Astrometric accuracy of snapshot fast radio burst localisations with ASKAP |
| title_full_unstemmed | Astrometric accuracy of snapshot fast radio burst localisations with ASKAP |
| title_short | Astrometric accuracy of snapshot fast radio burst localisations with ASKAP |
| title_sort | astrometric accuracy of snapshot fast radio burst localisations with askap |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics astrometry fast radio bursts radio interferometry radio transient sources ENVIRONMENT |
| url | https://arxiv.org/abs/2107.07068 https://arxiv.org/abs/2107.07068 https://arxiv.org/abs/2107.07068 https://arxiv.org/abs/2107.07068 http://hdl.handle.net/20.500.11937/91560 |