Authors: Kim et al.
Date: August 12th, 2020
Primary Reference: Kim et al. 2020, A&A, 640, A69
Data Product Code: 2020-D01-01
Brief Description:
We release a data set to accompany the First 3C279 Event Horizon Telescope Results paper (Kim et al. 2020). The data set is derived from the Science Release 1 (SR1) of the Event Horizon Telescope (EHT)'s April 2017 observation campaign (EHTC et al. 2019).
This data set contains 3C279 data for both low and high bands for all observed days (April 5th, 6th, 10th, 11th, 2017). Data from the 2017 observations were processed through three independent reduction pipelines (Blackburn et al. 2019, Janssen et al. 2019, EHTC et al. 2019). This release includes the fringe fitted, a-priori calibrated, and network calibrated data from the EHT-HOPS pipeline, which is the primary data set for the First 3C279 EHT results. Independent flux calibration is performed based on estimated station sensitivities during the campaign (Issaoun et al. 2017, Janssen et al. 2019). A description of the data properties, their validation, and estimated systematic errors is given in EHTC et al. (2019) with additional details in Wielgus et al. (2019).
The data are time averaged to 10 seconds and frequency averaged over all 32
intermediate frequencies (IFs). All polarization information is explicitly
removed. To make the resulting uvfits files compatible with popular
very-long-baseline interferometry (VLBI) software packages, the circularly
polarized cross-hand visibilities RL and LR are set to zero along with
their errors, while parallel-hands RR and LL are both set to an estimated
Stokes I value. Measurement errors for RR and LL are each set to sqrt(2)
times the statistical errors for Stokes I.
All uvfits files are located in the "uvfits/" subdirectory. Easy-to-read
csv and txt files are derived from the uvfits files and provided in
"csv/" and "txt/", respectively. Scripts that generate these files from the
original SR1 data are also included. Finally, the run.sh script in the top
directory will convert uvfits files into csv and txt files.
The three tgz files are gzipped tarballs that contains uvfits, txt, and
csv files, respectively. They are included in this repository for convenience.
File Name Convention:
The data files are named in the following convention:
[Data-Release-Tag]_[Source]_[year]_[day-of-year]_[band]_[pipeline]_[stage]_StokesI.[format]
Station Code Table:
| UVFITS Code | Station Name | Location |
|---|---|---|
| AA | ALMA | Chile |
| AP | APEX | Chile |
| AZ | Submillimeter Telescope | Arizona |
| JC | James Clerk Maxwell Telescope | Hawai'i |
| LM | Large Millimeter Telescope | Mexico |
| PV | IRAM | Spain |
| SM | Submillimeter Array | Hawai'i |
| SP | South Pole Telescope | South Pole |
References:
- EHT Collaboration Data Portal Website
- EHTC et al. 2019, ApJL, 875, L3
- Blackburn, L., Chan, C.-k., Crew, G., et al. 2019, ApJ, 882, 23
- Janssen, M., Goddi, C., van Bemmel, I., et al. 2019, A&A, 626, A75
- Issaoun, S., Folkers, T., Blackburn, L., et al. 2017, EHT Memo 2017-CE-02
- Janssen, M., Blackburn, L., Issaoun, S., et al. 2019, EHT Memo 2019-CE-01
- Wielgus, M., Blackburn, L., Issaoun, S., et al. 2019, EHT Memo 2019-CE-02