arXiv subjects

Anant Telikicherla

Publications and source records attributed to Anant Telikicherla.

3 recordsLinked to original sources

arXiv2026

Solar Extreme Ultraviolet Spectrograph and High-energy Imager (SEUSHI): Design, Development, and Pre-Flight Calibration

Understanding the initiation of solar flares and coronal mass ejections (CMEs) is essential for improving forecasts of extreme space weather. Soft X-ray (SXR) and Extreme Ultraviolet (EUV) observations provide critical diagnostics of the highly dynamic solar corona; however, significant measurement gaps persist despite decades of observations. The Solar Extreme Ultraviolet Spectrograph and High-energy Imager (SEUSHI) aims to address these gaps by combining multi-pinhole SXR imaging with grazing-incidence EUV spectroscopy on a shared camera. SEUSHI delivers spatially-resolved temperature and emission measure maps at 1 arcminute resolution and 5 second cadence to identify Hot Onset Precursor Events (HOPEs), which provide early alerts of flares. Additionally, high-cadence (100 Hz) readouts of selected image rows enable photon-counting spectroscopy over 1.1-6.8 keV with approx. 0.08 keV energy resolution, to investigate elemental abundance evolution in active regions, a key diagnostic of coronal heating. SEUSHI also provides high-resolution (approx. 0.2 nm) EUV spectra measurements across the 16.1-33.8 nm range at 5 second cadence for studies of coronal dimming and generation of early alerts for CMEs. SEUSHI is designed with low power, mass, and volume requirements, making it suitable for small satellite platforms. A technology demonstration version of SEUSHI is currently under development for flight aboard the Solar Dynamics Observatory Extreme Ultraviolet Variability Experiment calibration sounding rocket. This paper presents the instrument design, development, and calibration. Successful demonstration on the sounding rocket platform is an important step towards the opportunity to fly SEUSHI on future satellite missions and thus to improve space weather operations.

astro-ph.SR↗

arXiv2025

Improving Solar Flare Nowcasting with the Hot Onset Precursor Event (HOPE) Technique

This study investigates the statistical behavior of plasma properties during Hot Onset Precursor Events (HOPEs) of solar flares and evaluates their potential for improving flare nowcasting. Two datasets are analyzed: (a) new Soft X-Ray (SXR) spectra of 25 flares (C2.6 to M1.0) obtained from the Dual-zone Aperture X-ray Solar Spectrometer (DAXSS), and (b) SXR irradiance data from 137 flares (C5.0 to X7.1) recorded by the X-Ray Sensor on the Geostationary Operational Environmental Satellite (GOES-XRS). Plasma temperature, emission measure (EM), and low First Ionization Potential (e.g., Mg, Si, Fe) elemental abundance factors (AFs) are derived from DAXSS using Astrophysical Plasma Emission Code model fitting. Isothermal plasma temperature and emission measure are derived from GOES-XRS using the XRS-A/XRS-B ratio method. Results indicate that the HOPE phase exhibits elevated temperatures (10-15 MK) and an order-of-magnitude increase in EM before the impulsive phase. Elemental AFs show a transition from coronal to photospheric values as the flare progresses. Using GOES-XRS data, we develop an improved nowcasting algorithm that detects flares utilizing HOPE signatures. The algorithm is tested across three categories of flares (C5.0-M1.0, M1.0-X1.0, and X1.0+), consistently predicting flare alerts 5-15 minutes ahead of the flare peak. We also explore the possibility of approximate flare magnitude prediction, by calculating correlation between onset parameters and flare peak magnitude. This HOPE-based system shows potential for earlier warnings than current NOAA R3 alerts, which could be useful for High-frequency communication systems operators and targeted flare observation campaigns.

astro-ph.SR↗

arXiv2024

Investigating the Soft X-ray Spectra of Solar Flare Onsets

In this study we present the analysis of six solar flare events that occurred in 2022, using new data from the third-generation Miniature X-Ray Solar Spectrometer (MinXSS), also known as the Dual-zone Aperture X-ray Solar Spectrometer (DAXSS). The primary focus of this study is on the flare's "onset phase", which is characterized by elevated soft X-ray emissions even before the flare's impulsive phase. We analyze the temporal evolution of plasma temperature, emission measure, and elemental abundance factors during the flare onset phase, by fitting the DAXSS spectra with the Astrophysical Plasma Emission Code (APEC) model. The model fitting results indicate that the flaring-plasma is already at a high temperature (10-15 MK) during the onset period. The temperature rises during the onset phase, followed by a decrease and subsequent increase during the impulsive phase. Elemental abundance factors show a trend of falling below pre-flare values during the onset phase, with some recovery before the impulsive phase. During the impulsive phase, the abundance factors decrease from elevated coronal values to about photospheric values. We also analyze images from the 193 Angstrom channel of the Atmospheric Imaging Assembly (AIA), highlighting the formation or brightening of coronal loop structures during the onset phase. Two distinct onset loop configurations are observed which are referred to as 1-loop and 2-loop onsets. Both DAXSS and AIA observations indicate that the flare onset phase exhibits similar hot coronal plasma properties as the impulsive phase, suggesting that the onset phase may act as a preconditioning effect for some flares.

astro-ph.SR↗