Owens Valley Solar Arrays: Difference between revisions
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== Latest OVSA Science Highlights == | == Latest OVSA Science Highlights == | ||
[[OVSA Science Highlight No. 2: Two Phases of Impulsive SEP Acceleration]] | |||
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[https://iopscience.iop.org/article/10.3847/1538-4357/adbdd0 M. Wang et al.] analyze a solar energetic particle (SEP) event associated with an eruptive X-class flare and found two distinct impulsive SEP acceleration phases. They are suggested to link to different magnetic reconnection regimes during the eruption, which govern the timing and energy of particles released into interplanetary space. [Contributed by Meiqi Wang (New Jersey Institute of Technology); Edited by B. Chen. Posted on August 19, 2025.] | |||
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[[OVSA Science Highlight No. 1: Microwave Precursor of a Major Solar Eruption]] | [[OVSA Science Highlight No. 1: Microwave Precursor of a Major Solar Eruption]] | ||
[[File:solar_eruption_nasa.jpeg|left|100px]] | [[File:solar_eruption_nasa.jpeg|left|100px]] | ||
A study by [https://iopscience.iop.org/article/10.3847/2041-8213/adf063 Kou et al.] presents the first spatially resolved microwave imaging spectroscopy of the precursor phase of a major solar eruption. The findings reveal that thermal electron emissions dominate during the slow-rise phase, supporting a scenario of moderate magnetic reconnection prior to the flare’s impulsive onset. [Contributed by Yuankun Kou (Nanjing | A study by [https://iopscience.iop.org/article/10.3847/2041-8213/adf063 Y. Kou et al.] presents the first spatially resolved microwave imaging spectroscopy of the precursor phase of a major solar eruption. The findings reveal that thermal electron emissions dominate during the slow-rise phase, supporting a scenario of moderate magnetic reconnection prior to the flare’s impulsive onset. [Contributed by Yuankun Kou (Nanjing University); Edited by B. Chen. Posted on August 2, 2025.] | ||
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Revision as of 14:02, 19 August 2025
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.
Latest OVSA Science Highlights
OVSA Science Highlight No. 2: Two Phases of Impulsive SEP Acceleration
M. Wang et al. analyze a solar energetic particle (SEP) event associated with an eruptive X-class flare and found two distinct impulsive SEP acceleration phases. They are suggested to link to different magnetic reconnection regimes during the eruption, which govern the timing and energy of particles released into interplanetary space. [Contributed by Meiqi Wang (New Jersey Institute of Technology); Edited by B. Chen. Posted on August 19, 2025.]
OVSA Science Highlight No. 1: Microwave Precursor of a Major Solar Eruption
A study by Y. Kou et al. presents the first spatially resolved microwave imaging spectroscopy of the precursor phase of a major solar eruption. The findings reveal that thermal electron emissions dominate during the slow-rise phase, supporting a scenario of moderate magnetic reconnection prior to the flare’s impulsive onset. [Contributed by Yuankun Kou (Nanjing University); Edited by B. Chen. Posted on August 2, 2025.]
We welcome contributions at all times. Please refer to the OVSA Science Highlights page for guidelines and a complete list of highlights.
OVSA Publications
Our collection of publications that utilize OVSA data is available at this NASA/ADS Library. If you have a paper that is missing from this library, please email Bin Chen (bin.chen [at] njit.edu).
EOVSA Flare List
- Query EOVSA Flare list
- List of EOVSA flares in separate years: 2025, 2024, 2023, 2022, 2021, 2020, 2019, 2017
Using OVSA Data
- EOVSA Data Products: An introduction to standard EOVSA spectrogram and spectral image products with example scripts for reading and plotting.
- EOVSA Data Policy: Policy for using EOVSA data products.
- Analysis Software: These are for in-depth use of EOVSA data (from calibrated visibilities) and tools for quantitative analysis.
- 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).
- pyGSFIT A Python-widget(pyQT)-based spectral fitting package, which provides a user-friendly display of EOVSA image cubes, spatially resolved spectra, and an interface to scipy-based fitting codes.
- Spectrogram Software
- Mapping Software
- Data Analysis Guides (for those who start from raw data)
- Tohban Guide to Self Calibration and Imaging for EOVSA Step-to-step guide for manually making images from raw visibility data.
- EOVSA flare pipeline Description of the EOVSA flare pipeline and tutorial for running it to produce 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
EOVSA Documentation
- General
- Computer-Network
- Control System
- Hardware
- System Software
- Calibration
EOVSA System Software
- LabVIEW software
- Python code Github repository
- Python3 Code Installation
Using OVRO-LWA data
- OVRO-LWA Data Products: An introduction to standard OVRO-LWA spectrogram and spectral image products with example scripts for reading and plotting.
- OVRO-LWA Data Policy: Policy for using OVRO-LWA data products.
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
2024 January; February; March; April; May; June; July; August; September; October; November; December
2025 January; February; March; April; May; June; July; August; September; October; November; December
OVSA Scientist on Duty
- Scientist on Duty (SoD): OVSA team members take turns and serve as a SoD to work with our onsite observatory staff on day-to-day observing. They are also responsible for monitoring solar activities and ensuring that the data we collect is of high quality.
- SoD observing logs (directory to all logs):
- SoD instructions:
- Daily routines: see SoD Routines for detailed instructions.
- Instructions for making quick-look flare spectrograms and movies
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.
OVRO-LWA Operation Notes
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)
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
Radio Astronomy Lecture Notes
Here is a link to the Radio Astronomy Lecture Notes adapted from the Phys728: Radio Astronomy graduate-level course Prof. Dale Gary taught at NJIT until Spring 2019.