Table · dataset · 2025
uGMRT Observations for HERA Calibration
Listed in IVOA Registry (Virtual Observatory)
Radio-interferometric arrays require very precise calibration to detect the Epoch of Reionization 21-cm signal.
Description
A remarkably complete and accurate sky model is therefore needed in the patches of the sky used to perform the calibration. Instruments such as HERA, which use a redundant calibration strategy, also require a reference sky model to fix degenerate gain solutions.
We have carried out a deep (20 hours) observation using the upgraded GMRT to make a high-fidelity sky model of one of the HERA calibration fields, GLEAM 02H (J0200-3053). In this paper, we present the results from a 16.7MHz bandwidth dataset centred at 147.4MHz. Multiple GMRT pointings are combined to make a 6.9degx6.9deg mosaic, yielding a median rms of 3.9^+3.7^_-1.4_mJy/beam, which reduces to approximately 2mJy/beam in source-free regions.
Read the rest (2 more)
In the overlapping patch, this rms is deeper than the GLEAM catalogue, which is used for HERA calibration. Using the mosaic, we have made a catalogue of 640 sources (26% extended) with flux densities in the range 0.02-19.08Jy. The catalogue has sub-arcsecond positional accuracy, and the estimated fluxes are consistent with existing catalogues.
The differential source counts are deeper than GLEAM and consistent with LoTSS. A preliminary simulation comparing the sky models from GLEAM and our catalogue shows 10-25% differences in the visibility amplitude, with a relatively small change of approximately 2 degrees in phases. Future work is planned for larger survey areas and wider bandwidths to reduce the rms and measure in-band source spectral indices, which are expected to enhance the fidelity of the HERA calibration model.
Links
Where it is published
- Reference page cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/544/321 ↗
landing page · from IVOA Registry
Documentation and papers
- ADS 2025MNRAS.544..321E ui.adsabs.harvard.edu/abs/2025MNRAS.544..321E ↗
publication · from IVOA Registry
Catalogue records · 2
- VOResource record dc.g-vo.org/oai.xml?verb=GetRecord&metadataPrefix=ivo_vor&identifier=ivo%3… ↗
metadata API · from IVOA Registry
- Registry record (GAVO) dc.g-vo.org/I/cds.vizier/j/mnras/544/321 ↗
catalogue entry · from IVOA Registry
Topics
- Stated by source
- Radio
- From keywords
- Astronomy & Astrophysics
- Inferred from text
- Simulation 75%
Provenance · 1 source records, 9 field assertions
| Source | Key | Last seen | Raw |
|---|---|---|---|
| IVOA Registry (Virtual Observatory) | ivo://cds.vizier/j/mnras/544/321 | 14 d ago | JSON v1 |
| Field | Assertion | Extractor | Evidence |
|---|---|---|---|
| access_level | source · IVOA Registry | connector:ivoa_registry@1.0.0 | |
| concepts[field].local:field:astronomy | mapping · IVOA Registry | connector:ivoa_registry@1.0.0 | |
| concepts[method].local:method:simulation | enrichment · IVOA Registry | keyword-concept-rules@1.0.0 | title+description (75%) |
| concepts[modality].ivoa_waveband:radio | source · IVOA Registry | connector:ivoa_registry@1.0.0 | |
| description | source · IVOA Registry | connector:ivoa_registry@1.0.0 | rr.resource.res_description |
| license_text | source · IVOA Registry | connector:ivoa_registry@1.0.0 | |
| publication_date | source · IVOA Registry | connector:ivoa_registry@1.0.0 | |
| title | source · IVOA Registry | connector:ivoa_registry@1.0.0 | rr.resource.res_title |
| updated_date | source · IVOA Registry | connector:ivoa_registry@1.0.0 |