Expanded Owens Valley Solar Array
EOVSA (Expanded Owens Valley Solar Array) is a solar-dedicated radio interferometer operated by the New Jersey Institute of Technology and serving as a National Science Foundation Geospace Facility. 
Operation of EOVSA is supported by the National Science Foundation under Grant No. AGS-2130832. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
This wiki serves as the site for EOVSA documentation.
OVRO-LWA (Owens Valley Radio Observatory Long Wavelength Array) is an all-sky imager that has a new solar-dedicated spectroscopic imaging mode. OVRO-LWA is a multi-institutional collaboration led by Caltech. NJIT Solar Radio Group is leading its solar-mode development and science. At the bottom of this page are new links for that facility.
EOVSA Documentation
- General
- Computer-Network
- Control System
- Hardware
- System Software
- Calibration
Using EOVSA Data
- EOVSA Data products
- Analysis Software
- SunCASA A wrapper around CASA (the Common Astronomy Software Applications package) for synthesis imaging and visualizing solar spectral imaging data. CASA is one of the leading software tool for "supporting the data post-processing needs of the next generation of radio astronomical telescopes such as ALMA and VLA", an international effort led by the National Radio Astronomy Observatory. The current version of CASA uses Python (2.7) interface. More information about CASA can be found on NRAO's CASA website . Note, CASA is available ONLY on UNIX-BASED PLATFORMS (and therefore, so is SunCASA).
- GSFIT A IDL-widget(GUI)-based spectral fitting package called gsfit, which provides a user-friendly display of EOVSA image cubes and an interface to fast fitting codes (via platform-dependent shared-object libraries).
- Spectrogram Software
- Mapping Software
- Data Analysis Guides
- EOVSA Data Analysis Tutorial 2022 and EOVSA Workspace at SPHERE 2022 Workshop
- EOVSA Data Analysis Tutorial at RHESSI 19 Workshop
- EOVSA Data Analysis Tutorial at RHESSI XVIII Workshop
- Self-Calibrating Flare Data Example script and guides for self-calibrating EOVSA flare data (to be completed)
- IDB flare pipeline Tutorial to run the flare pipeline for quicklook images
- EOVSA Modeling Guide
- Other helpful links
- Full Disk Simulations
- All-Day Synthesis Issues
- Analyzing Pre-2017 Data
- Fixing Pipeline Problems pre-2021-Feb-07
System Software
- LabVIEW software
- Python code Github repository
- Python3 Code Installation
EOVSA Observing Log
2017 January; February; March; April; May; June; July; August; September; October; November; December
2018 January; February; March; April; May; June; July; August; September; October; November; December
2019 January; February; March; April; May; June; July; August; September; October; November; December
2020 January; February; March; April; May; June; July; August; September; October; November; December
2021 January; February; March; April; May; June; July; August; September; October; November; December
2023 January; February; March; April; May; June; July; August; September; October; November; December
Tohbans
Tohban EOVSA Imaging Tutorial A-Z
Tohban OVRO-LWA Imaging Tutorial
Tohban Guide to Self Calibration and Imaging for EOVSA
Guide to Upgrade SolarSoft(SSW)
EOVSA Flare List
See this link for a list of EOVSA flares as a Google Spreadsheet.
An older link is available at the EOVSA website.
EOVSA Publications
Here is a (partial) list of publications that utilize EOVSA data. See also the collection of EOVSA publications at this NASA/ADS Library.
- 2023
- Mondal, S., Chen, B. & Yu, S. (2023) ApJ, submitted Multifrequency microwave imaging of weak transients from the quiet solar corona
- 2022
- Lörinčík et al (2022) Frontiers, 9, 1 Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence
- Kou et al. (2022) Nature Communications 13, 7680 Microwave imaging of quasi-periodic pulsations at flare current sheet
- Fleishman et al. (2022) Nature 606, 674 Solar flare accelerates nearly all electrons in a large coronal volume
- Li, X., et al., (2022) ApJ, 932, 92 Modeling Electron Acceleration and Transport in the Early Impulsive Phase of the 2017 September 10th Solar Flare
- Liu, N., et al., (2022), ApJ, 930, 154 Multi-instrument Comparative Study of Temperature, Number Density, and Emission Measure during the Precursor Phase of a Solar Flare
- Zhang et al. (2022), ApJ, 932, 53 Implications for additional plasma heating driving the extreme-ultraviolet late phase of a solar flare with microwave imaging spectroscopy
- Lopez et al. (2021), A&A, 657, A51 A solar flare driven by thermal conduction observed in mid-infrared
- 2021
- Wei et al. (2021), ApJ, 923, 213 Coronal Magnetic Field Measurements along a Partially Erupting Filament in a Solar Flare
- Shaik & Gary (2021), ApJ, 919, 44 Implications of Flat Optically Thick Microwave Spectra in Solar Flares for Source Size and Morphology
- Kocharov et al. (2021), ApJ, 915, 12 Multiple Sources of Solar High-energy Protons
- Chen et al. (2021), ApJL, 908, L55 Energetic Electron Distribution of the Coronal Acceleration Region: First results from Joint Microwave and Hard X-ray Imaging Spectroscopy
- Chhabra et al. (2021), ApJ, 906, 132 Imaging Spectroscopy of CME-Associated Solar Radio Bursts
- 2020
- Reeves et al. (2020), ApJ, 905, 165 Hot Plasma Flows and Oscillations in the Loop-top Region During the September 10 2017 X8.2 Solar Flare
- Yu et al. (2020), ApJ, 900, 17 Magnetic Reconnection During the Post Impulsive Phase of the X8.2 Solar Flare: Bi-Directional Outflows as a Cause of Microwave and X-ray Bursts
- Chen et al. (2020b), Nature Astronomy, 4, 1140 Measurement of magnetic field and relativistic electrons along a solar flare current sheet
- Chen et al. (2020a), ApJL, 895, 50 Microwave Spectral Imaging of an Erupting Magnetic Flux Rope: Implications for the Standard Solar Flare Model in Three Dimensions
- Kuroda et al. (2020), Frontiers, 7, 22 Evolution of Flare-accelerated Electrons Quantified by Spatially Resolved Analysis
- Glesener et al. (2020), ApJL, 891, 34 Accelerated Electrons Observed Down to <7 keV in a NuSTAR Solar Microflare
- Karlicky at al. (2020), ApJ, 889, 72 Drifting Pulsation Structure at the Very Beginning of the 2017 September 10 Limb Flare
- Fleishman et al. (2020), Science, 367, 278 Decay of the coronal magnetic field can release sufficient energy to power a solar flare
- Gary et al. (2020), BAAS 52, 385.01 Direct link to AAS iPoster A new view of the solar atmosphere: daily full-disk multifrequency radio images from EOVSA
- 2018
- Polito et al. (2018), ApJ, 864, 63 Broad Non-Gaussian Fe XXIV Line Profiles in the Impulsive Phase of the 2017 September 10 X8.3-class Flare Observed by Hinode/EIS
- Gary et al. (2018), ApJ, 863, 83 Microwave and Hard X-Ray Observations of the 2017 September 10 Solar Limb Flare
- Kuroda et al. (2018), ApJ, 852, 32 Three-dimensional Forward-fit Modeling of the Hard X-ray and the Microwave Emissions of the 2015 June 22 M6.5 flare
- 2017
- Wang et al. (2017), Nature Astronomy, 1, 85 High-resolution observations of flare precursors in the low solar atmosphere
- 2016
- Nita et al. (2016), J. Astron. Instr., 5, 1641009-7366 EOVSA Implementation of a Spectral Kurtosis Correlator for Transient Detection and Classification
VLA Flare List and Publications
See this link for a list of flare observations made by the Karl G. Jansky Very Large Array (VLA). Below is a partial list of publications that utilize VLA solar data (see also this NASA/ADS Library).
- Luo et al. (2022), ApJ, 940, 137 Multiple Regions of Nonthermal Quasiperiodic Pulsations during the Impulsive Phase of a Solar Flare
- Battaglia et al. (2021), ApJ, 922, 134 Multiple Electron Acceleration Instances during a Series of Solar Microflares Observed Simultaneously at X-Rays and Microwaves
- Luo et al. (2021), ApJ, 911, 4 Radio Spectral Imaging of an M8.4 Eruptive Solar Flare: Possible Evidence of a Termination Shock
- Zhang et al. (2021), ApJ, 910, 40 Multiwavelength Observations of the Formation and Eruption of a Complex Filament
- Sharma et al. (2020), ApJ, 904, 94 Radio and X-Ray Observations of Short-lived Episodes of Electron Acceleration in a Solar Microflare
- Chen et al. (2019), ApJ, 884, 63 Radio Spectroscopic Imaging of a Solar Flare Termination Shock: Split-band Feature as Evidence for Shock Compression
- Yu & Chen (2019), ApJ, 872, 71 Possible Detection of Subsecond-period Propagating Magnetohydrodynamics Waves in Post-reconnection Magnetic Loops during a Two-ribbon Solar Flare
- Chen et al. (2018), ApJ, 866, 62 Magnetic Reconnection Null Points as the Origin of Semirelativistic Electron Beams in a Solar Jet
- Wang et al. (2016), ApJ, 848, 77 Dynamic Spectral Imaging of Decimetric Fiber Bursts in an Eruptive Solar Flare
- Chen et al. (2015), Science, 350, 1238 Particle acceleration by a solar flare termination shock
- Chen et al. (2014), ApJ, 794, 149 Direct Evidence of an Eruptive, Filament-hosting Magnetic Flux Rope Leading to a Fast Solar Coronal Mass Ejection
- Chen et al. (2013), ApJL, 763, 21 Tracing Electron Beams in the Sun's Corona with Radio Dynamic Imaging Spectroscopy
Radio Data from Around The Heliosphere
OVRO-LWA Solar-Dedicated Spectroscopic Imager
The OVRO-LWA (Owens Valley Radio Observatory Long Wavelength Array) has recently been upgraded to include a solar-dedicated beam and two solar imaging modes (slow visibilities of 352 antennas with a 10-s cadence, and fast visibilities of 48 antennas with a 0.1-s cadence). The large collecting area and excellent calibration provide unprecedented high-sensitivity imaging of the quiet Sun and bursts. The array is currently in commissioning and observations are not yet continuous, but they are becoming more so. See [the daily realtime data at http://ovsa.njit.edu/status.php] for real-time display of the spectrogram and a selection of images, both updated on a 1-min cadence.
Solar-Dedicated Modes
Beamformer
The beamformer uses the 256 core antennas to form a synthesized beam of more than 1 degree in size that tracks the Sun from sunrise to sunset. This permits a continuous record of the full-Stokes total flux (without spatial resolution) of the Sun (a dynamic spectrum) with 24 kHz frequency resolution (3072 frequencies from 15-90 MHz) and as low as 1 ms time resolution.
Slow Visibility Imaging
In this mode, the entire 352-element array is interferometrically correlated to provide visibilities for imaging at all 3072 frequencies at 10-s time resolution. This is ideal for imaging quiet Sun and slowly-varying emission such as coronal mass ejections and active region variability.
Fast Visibility Imaging
In this mode, a subset of 48 antennas (chosen to include mainly outer antennas to maintain good spatial resolution) is interferometrically correlated to provide visibilities for imaging at 768 frequencies (96 kHz frequency resolution) at 0.1-s time resolution. This is ideal for imaging rapidly varying emission such as type II and type III bursts as well as many other solar spectral fine structures.
Inital Data Access
In its current commissioning state, we try to run the beamformer and imaging pipeline every day in real-time since November 2023 (no latency for beamforming spectrograms and 5-10 min latency for images). Quicklook real-time spectrograms/images can be accessed from http://ovsa.njit.edu/status.php. To access data from previous days, use the following links (replace yyyymmdd with the date you desire):
- Quicklook beamformer total-power spectrograms: http://ovsa.njit.edu/lwa-data/1min_spectra/yyyymmdd/. Check this link for additional daily plots Daily OVRO-LWA Beamformer Data.
- Quicklook multi-frequency movies at 1-min cadence: http://ovsa.njit.edu/lwa-data/1min_images/yyyymmdd/movie_yyyy-mm-dd.html
Note our pipeline processing development is still in the early phase. For example, absolute flux calibrations have not been done for the beamformer spectrograms. Also, artificial effects (including ionospheric refraction effects) are present in the images that cause distortions/shifts. We caution interested users only to consider them for quick-look purposes at this point. Please contact the EOVSA PIs (Dale Gary, Bin Chen) if you intend to use them for science.