Total Eclipse Research Articles

Does total column ozone change during a solar eclipse?

Abstract. Several publications have reported that total column ozone (TCO) may oscillate with an amplitude of up to 10 DU (Dobson units) during a solar eclipse, whereas other researchers have not seen evidence that an eclipse leads to variations in TCO beyond the typical natural variability. Here, we try to resolve these contradictions by measuring short-term variations (of seconds to minutes) in TCO using “global” (Sun and sky) and direct-Sun observations in the ultraviolet (UV) range with filter radiometers (GUVis-3511 and Microtops II®). Measurements were performed during three solar eclipses: the “Great American Eclipse” of 2024, which was observed in Mazatlán, Mexico, on 8 April 2024; a partial solar eclipse that took place in the United States on 14 October 2023 and was observed at Fort Collins, Colorado (40.57° N, 105.10° W); and a total solar eclipse that occurred in Antarctica on 4 December 2021 and was observed at Union Glacier (79.76° S, 82.84° W). The upper limits of the amplitude of oscillations in TCO observed at Mazatlán, Fort Collins, and Antarctica were 0.4 %, 0.3 %, and 0.03 %, respectively. The variability at all sites was within that observed during times not affected by an eclipse. The slightly larger variability at Mazatlán is due to cirrus clouds occurring throughout the day of the eclipse and the difficulty of separating changes in the ozone layer from cloud effects. These results support the conclusion that a solar eclipse does not lead to variations in TCO of more than ± 1.2 DU and that these variations are likely much lower, drawing into question reports of much larger oscillations. In addition to calculating TCO, we also present changes in the spectral irradiance and aerosol optical depth during eclipses and compare radiation levels observed during totality. The new results augment our understanding of the effect of a solar eclipse on the Earth's upper atmosphere.

BSN: The First Photometric Study of 10 Contact Binary Systems from the Northern and Southern Hemispheres

Photometric observations were made with standard filters in four observatories for 10 contact binary systems. We analyzed the orbital period variations of the systems and found that six of them show long-term changes. The increase in the orbital period of the J07, N65, and PU Vir systems is caused by mass transfer, and the reduction in the orbital period of the J05, LO Psc, and N49 systems is caused by the combination of angular momentum loss and mass transfer. The first light-curve analysis was performed with the PHysics Of Eclipsing BinariEs Python code and Markov Chain Monte Carlo. We discussed the accuracy of photometric mass ratio estimates for contact binary systems with total and partial eclipses compared to spectroscopic results. We also compared our mass ratio findings to a recent method that estimates mass ratios from the light curve’s third derivative. Then, we also discussed this new mass ratio estimate method for photometric data. The systems’ positions were displayed in 18 empirical parameter relationships. According to the light-curve analysis and estimation of absolute parameters, systems BE Mus, J07, J08, N49, and N65 are A subtypes, and the others are W subtypes.

The Impact of Partial Solar Eclipse on the Observation of Neutral Hydrogen Emission Line

The research involves examining the influence of partial solar eclipse on the strength of neutral hydrogen from the Sun. Baghdad University Radio Telescope (BURT) was used to monitor the partial solar eclipse on the 25th of October, 2022. Radio observations from the Sun were recorded from 11:30 AM to 03:36 PM. This means that the HI emission from the Sun was recorded before, during and after the event. It was noticed, that at the moment of maximum eclipse, ~ 46% of the Sun’s disk was covered by the Moon. For the purpose of this research, the solar radio wave intensity was monitored and the solar flux density was determined at different times, i.e. before, during and after the partial solar eclipse. The obtained results showed that both of the solar flux and power spectrum decrease with the progress of the eclipse until the moment of maximum eclipse, i.e. the moment at which the minimum values of solar flux density and antenna temperature were recorded (7 × 104 Jy and ~ 80 K). Then, at the last moments of the partial eclipse, it was noticed that both parameters started to increase again due to the decrease in the area of the Sun’s disk until both reached their normal values. In Conclusion, the partial solar eclipse affects the strength of neutral hydrogen from the Sun because the Moon blocks the neutral hydrogen from the Sun during the solar eclipse.

Unveiling Illumination Variations During a Lunar Eclipse: Multi-Wavelength Spaceborne Observations of the January 21, 2019 Event

Space-based observations of the total lunar eclipse on 21 January 2019 were conducted using the geostationary Earth-orbiting satellite Gaofen-4 (GF-4). This study represents a pioneering effort to address the observational gap in full-disk lunar eclipse photometry from space. With its high resolution and ability to capture the entire lunar disk, GF-4 enabled both quantitative and qualitative analyses of the variations in lunar brightness, as well as spectra and color changes, across two spatial dimensions, from the whole lunar disk to resolved regions. Our results indicate that before the totality phase of the lunar eclipse, the irradiance of the Moon diminishes to below approximately 0.19% of that of the uneclipsed Moon. Additionally, we observed an increase in lunar brightness at the initial entry into the penumbra. This phenomenon is attributed to the opposition effect, providing scientific evidence for this unexpected behavior. To investigate detailed spectral variations, specific calibration sites, including the Chang’E-3 landing site, MS-2 in Mare Serenitatis, and the Apollo 16 highlands, were analyzed. Notably, the red-to-blue ratio dropped below 1 near the umbra, contradicting the common perception that the Moon appears red during lunar eclipses. The red/blue ratio images reveal that as the Moon enters Earth’s umbra, it does not simply turn red; instead, a blue-banded ring appears at the boundary due to ozone absorption and the lunar surface composition. These findings significantly enhance our understanding of atmospheric effects on lunar eclipses and provide crucial reference information for the future modeling of lunar eclipse radiation, promoting the integration of remote sensing science with astronomy.

High-resolution spectroscopy of detached eclipsing binaries during total eclipses

Context. We present results of high-resolution spectroscopic observations of detached eclipsing binaries (DEBs) with total eclipses, for which UVES spectra were obtained during the phase of totality. These observations serve as a key way to determine the age and initial metallicity of the systems and to verify evolutionary phases of their components and distances. Aims. With the additional, independent information concerning the effective temperature and metallicity of one of the components, we aim to estimate the precise ages of the studied binaries and show the usefulness of totality spectra. The second goal was to provide precise orbital and physical stellar parameters of the components of systems in question. Methods. Using the VLT/UVES, we obtained high-resolution spectra of 11 DEBs during their total-eclipse phase. Atmospheric parameters of then-visible (larger) components were obtained with iSpec. With additional spectroscopy from the Comprehensive Research with Échelles on the Most interesting Eclipsing binaries (CRÉME) project, public archives, and literature, we obtained radial-velocity (RV) measurements, from which orbital parameters were calculated. Photometric time-series observations from TESS and ASAS were modelled with the JKTEBOP code, and, combined with RV-based results, they allowed us to obtain physical parameters for nine double-lined systems from our sample. All the available data were used to constrain the ages with our own approach, utilising MESA isochrones. Reddening-free, isochrone-based distances were also estimated and confronted with Gaia Data Release 3 (GDR3) results. Results. We show that single spectroscopic observations taken during a total eclipse can break the age-metallicity degeneracy and allow for the precise determination of the age of a DEB. With high-quality spectroscopic and photometric data, we are able to reach a 5−10% level of uncertainty (e.g. 724−24+52 Myr). Even for single-lined DEBs, where absolute masses are not possible to obtain, the spectroscopic analysis of one of the components allows one to put strong constraints on the properties of both stars. For some cases, we noted inconsistencies between isochrone-based and GDR3 distances. For one binary, which could not be fitted with a single isochrone (RZ Eri), we suggest a new explanation.

Expanded Linear Responsivity for Earth and Planetary Radiometry

Abstract Earth and planetary radiometry requires spectrally dependent observations spanning an expansive range in signal flux due to variability in celestial illumination, spectral albedo, and attenuation. Insufficient dynamic range inhibits contemporaneous measurements of dissimilar signal levels and restricts potential environments, time periods, target types, or spectral ranges that instruments observe. Next-generation (NG) advances in temporal, spectral, and spatial resolution also require further increases in detector sensitivity and dynamic range corresponding to increased sampling rate and decreased field of view (FOV), both of which capture greater intrapixel variability (i.e., variability within the spatial and temporal integration of a pixel observation). Optical detectors typically must support expansive linear radiometric responsivity, while simultaneously enduring the inherent stressors of field, airborne, or satellite deployment. Rationales for significantly improving radiometric observations of nominally dark targets are described herein, along with demonstrations of state-of-the-art (SOTA) capabilities and NG strategies for advancing SOTA. An evaluation of linear dynamic range and efficacy of optical data products is presented based on representative sampling scenarios. Low-illumination (twilight or total lunar eclipse) observations are demonstrated using a SOTA prototype. Finally, a ruggedized and miniaturized commercial-off-the-shelf (COTS) NG capability to obtain absolute radiometric observations spanning an expanded range in target brightness and illumination is presented. The presented NG technology combines a multipixel photon counter (MPPC) with a silicon photodetector (SiPD) to form a dyad optical sensing component supporting expansive dynamic range sensing, i.e., exceeding a nominal 10 decades in usable dynamic range documented for SOTA instruments.

New look at the structure of the nearest circumstellar environment of the weak-line T tauri star V718 Per

In this article we analyze the properties of the photometric and spectral variability of the young star V718 Per, a member of the cluster IC 348, in terms of its possible binarity. The most realistic is the model where the main component of the system V718 Per A — with an effective temperature of 5200 K — is periodically shielded by two extended dust periods structures consisting of large particles and moving around the star in resonance with two planets. Their orbital periods are 4.7 years and 213 days. Their ratio with high accuracy is 1:8, and the ratio of the large semi-axes is 1:4. The masses of the planets do not exceed 6 МJup. At the moments of total eclipses of V718 Per A, the radiation of the system is dominated by a colder component with an effective temperature of 4150 ± 100 K, which explains the reddening of the star observed in the brightness minima, as well as its spectral changes during brightness weakening. Speckle interferometric observations performed on the 2.5-m telescope of the CMO of SAI MSU made it possible to estimate the upper limit of the angular distance between the components of the system: 0.1′′, which is equivalent to a projection distance of 30 a.u. The unique feature of this system is that the planes of the planetary orbits practically coincide with the line of sight. Such an orientation of the system is most favorable for measuring fluctuations in the radial velocity of a star caused by the orbital motion of planets, as well as for observing planetary transits along the disk of the main component of the system.

Features of Earth’s lower ionosphere during solar eclipse and sunset and sunrise hours according to measurements by the API method near Nizhny Novgorod

We present the results of experimental studies into the response of Earth’s lower ionosphere to a partial solar eclipse. The studies have been carried out using the method of resonant scattering of radio waves by artificial periodic irregularities (APIs) in ionospheric plasma. The irregularities were created in the field of a standing wave when a powerful radio wave, generated by radiation to the zenith by transmitters of the mid-latitude heating facility SURA, was reflected from the ionosphere. During location of a periodic structure by probe radio waves when the Wolf—Bragg backscattering condition was met, a scattered signal was received and its amplitude and phase were measured. After the end of the impact on the ionosphere, the irregularities gradually disappeared (relaxed). We have examined variations in characteristics of scattered signals. During the eclipse, the scattered signal amplitude increased by 30–40 dB, and the relaxation time increased 1.5–2.0 times. In some cases, stratification of the signal amplitude in the D-region was observed due to stratification of the electron density profile. By analyzing altitude profiles of relaxation time, we obtained neutral component temperature and density, height of the turbopause, and turbulent velocity. The velocity of vertical regular motion of plasma at each height was measured from the time variation in the scattered signal phase. From the results of measurements of scattered signal characteristics during four partial eclipses, we have obtained that the neutral component temperature decreases, on average, 50–70 K. Variations in the temperature, vertical plasma velocity, and turbopause level exhibited deep quasi-periodic variations with periods from 15 min to several hours, typical of internal gravity wave propagation. The vertical temperature and velocity profiles showed changes with altitude on scales ranging from 5 to 30 km. Comparison between the results of studies of the lower ionosphere during sunrise-sunset hours has revealed that its response during a partial eclipse and the transition to the night regime is identical. According to the measurements by the partial reflection method, during the August 01, 2008 eclipse there was a decrease in the electron density in the D-region 3–5 times. We have concluded that during an eclipse there was a significant change in both the ionized and neutral components of the atmosphere in the lower ionosphere.

Особенности нижней ионосферы Земли во время затмений Солнца и в заходно-восходные часы по измерениям методом ИПН вблизи Нижнего Новгорода

We present the results of experimental studies into the response of Earth’s lower ionosphere to a partial solar eclipse. The studies have been carried out using the method of resonant scattering of radio waves by artificial periodic irregularities (APIs) in ionospheric plasma. The irregularities were created in the field of a standing wave when a powerful radio wave, generated by radiation to the zenith by transmitters of the mid-latitude SURA heating facility, was reflected from the ionosphere. During the eclipse, the scattered signal amplitude increased by 30–40 dB, and the relaxation time increased 1.5–2.0 times. In some cases, stratification of the signal amplitude in the D-region was observed due to stratification of the electron density profile. By analyzing altitude profiles of relaxation time, we obtained neutral component temperature and density, height of the turbopause, and turbulent velocity. The velocity of vertical regular motion of plasma at each height was measured from the time variation in the scattered signal phase. From the results of measurements of scattered signal characteristics during four partial eclipses, we have obtained that the neutral component temperature decreases, on average, 50–70 K. Variations in the temperature, vertical plasma velocity, and turbopause level exhibited deep quasi-periodic variations with periods from 15 min to several hours, typical of internal gravity wave propagation. The vertical temperature and velocity profiles showed changes with altitude on scales ranging from 5 to 30 km. Comparison between the results of studies of the lower ionosphere during sunrise-sunset hours has revealed that its response during a partial eclipse and the transition to the night regime is identical. According to the measurements by the partial reflection method, during the August 01, 2008 eclipse there was a decrease in the electron density in the D-region 3–5 times. We have concluded that during an eclipse there was a significant change in both the ionized and neutral components of the atmosphere in the lower ionosphere.

BSN: The First Light Curve Analysis of the Total Eclipse Binary System EL Tuc

We conducted the first light curve study of the binary star EL Tuc within the Binary Systems of South and North project’s framework. The photometric observations were made using standard multiband BVR c I c filters at an observatory in Argentina. We presented a new ephemeris for EL Tuc and a linear fit to the O – C diagram, utilizing our extracted times of minima and additional literature. We employed the PHysics Of Eclipsing BinariEs Python code and the Markov chain Monte Carlo approach for the system’s light curve analysis. The target system’s light curve solution required a cold starspot on the hotter component. We conclude that EL Tuc is a total contact binary system with a low mass ratio of q = 0.172 ± 0.002, an orbital inclination of i = 83.°74 ± 0.°40, and a fillout factor of f = 53.7% ± 1.6%. We used the P–a relationship and the Gaia Data Release 3 parallax method to determine the absolute parameters of EL Tuc to compare the precision of our results. This system was classified as W-type based on the mass and effective temperature of the companion stars. The positions of the systems were depicted on the M–L, M–R, T–M, and q–L ratio diagrams. The relationship between the spectroscopic and photometric mass ratios of binaries was discussed.

Detection of Two Totally Eclipsing B-type Binaries with Extremely Low Mass Ratios

The detection of O- and B-type stars with extremely low-mass companions is very important for understanding the formation and evolution of binary stars. However, finding them remains a challenge because the low-mass components in such systems contribute such small flux to the total. During our search for pulsations among O- and B-type stars using the Transiting Exoplanet Survey Satellite (TESS) data, we found two short-period and B-type (B9) eclipsing binaries with orbital periods of 1.61613 and 2.37857 days. Photometric solutions of the two close binaries were derived by analyzing the TESS light curves with the Wilson–Devinney method. It is discovered that both of them are detached binaries with extremely low mass ratios of 0.067(2) for TIC 260342097 and 0.140(3) for TIC 209148631. The determined mass ratio indicates that TIC 260342097 is one of the lowest mass ratios among known B-type binary systems. We showed that the two systems have total eclipses with a broad and flat secondary minimum, suggesting that the photometric parameters could be derived reliably. The absolute parameters of the two binaries are estimated and it is found that the secondary components in the two systems are overluminous and oversize when compared with the normal low-mass and cool main-sequence (MS) stars. These findings may imply that the two systems are composed of a B-type MS primary and a cool pre-MS secondary with orbital periods shorter than 2.5 days. They are valuable targets to test theories of binary star formation and evolution.

JWST-TST DREAMS: Nonuniform Dayside Emission for WASP-17b from MIRI/LRS

We present the first spectroscopic characterization of the dayside atmosphere of WASP-17b in the mid-infrared using a single JWST MIRI/LRS eclipse observation. From forward-model fits to the 5–12 μm emission spectrum, we tightly constrain the heat redistribution factor of WASP-17b to be 0.92 ± 0.02 at the pressures probed by this data, indicative of inefficient global heat redistribution. We also marginally detect a supersolar abundance of water, consistent with previous findings for WASP-17b, but note our weak constraints on this parameter. These results reflect the thermodynamically rich but chemically poor information content of MIRI/LRS emission data for high-temperature hot Jupiters. Using the eclipse mapping method, which utilizes the signals that the spatial emission profile of an exoplanet imprints on the eclipse light curve during ingress/egress due to its partial occultation by the host star, we also construct the first eclipse map of WASP-17b, allowing us to diagnose its multidimensional atmospheric dynamics for the first time. We find a day–night temperature contrast of order 1000 K at the pressures probed by this data, consistent with our derived heat redistribution factor, along with an eastward longitudinal hotspot offset of 18.7−3.8+11.1◦ , indicative of the presence of an equatorial jet induced by day–night thermal forcing being the dominant redistributor of heat from the substellar point. These dynamics are consistent with general circulation model predictions for WASP-17b. This work is part of a series of studies by the JWST Telescope Scientist Team, in which we use Guaranteed Time Observations to perform Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy.

Unveiling the nature of two dwarf novae: CRTS J080846.2+313106 and V416 Dra

We present the analysis of optical photometric and spectroscopic observations of two non-magnetic cataclysmic variables, namely CRTS J080846.2+313106 and V416 Dra. We find CRTS J080846.2+313106 to vary with a period of 4.9116pm 0.0003 h, which was not found in earlier studies and which we provisionally suggest is the orbital period of the system. In both long-period systems, the observed dominant signal at the second harmonic of the orbital frequency and the orbital modulation during quiescence are suggestive of ellipsoidal variation from changing aspects of the secondary, with an additional contribution from the accretion stream or hotspot. However, during the outburst, the hotspot itself is overwhelmed by the increased brightness, which is possibly associated with the accretion disc. The mid-eclipse phase for V416 Dra occurs earlier and the width of the eclipse is greater during outbursts compared to quiescence, suggesting an increased accretion disc radius during outbursts. Furthermore, from our investigation of the accretion disc eclipse in V416 Dra, we find that a total disc eclipse is possible during quiescence, whereas the disc seems to be partially obscured during outbursts, which further signifies that the disc may grow in size as the outburst progresses. The optical spectra of CRTS J080846.2+313106 and V416 Dra are typical of dwarf novae during quiescence, and they both show a significant contribution from the M2-4V secondary. The light curve patterns, orbital periods, and spectra observed in the two systems look remarkably similar, and seem to resemble the characteristics of U Gem-type dwarf novae.

Study of the response of the upper atmosphere during the annular solar eclipse on October 14, 2023

A solar eclipse is a fascinating event that gives a unique opportunity to study the ionospheric characteristics in a controlled blockage of solar radiation. We present the upper atmosphere’s response, mostly F-layer, during the annular eclipse on October 14, 2023. This eclipse was mostly visible from the North and South American regions with a maximum obscuration of around 91%. We study the response of the ionospheric Total Electron Content (TEC) and the critical frequency of the F2 layer (f0F2) for three consecutive days (October 13 to 15, 2023) using ground and space-based techniques. We present the ionospheric response for a large area that covers the path of the solar eclipse of latitude and longitude range from 50°N to 10°S and 30°W to 150°W. For the ground-based observation, we use fifty-five International GNSS Service (IGS) stations and eleven Global Ionospheric Radio Observatory (GIRO) Digisonde stations that cover the annular and partial solar eclipse and are in the close vicinity of the annularity belt. We compute the vertical TEC (VTEC) and f0F2 from this database and check their temporal and spatial variations. It is found that the VTEC, as computed from the IGS stations, mostly shows decrements during the partial blockage of the sun by the lunar disc. The VTEC, as computed from the GIRO database, also shows a decreasing trend but with comparatively more oscillating in nature. The f0F2 shows a similar decreasing trend due to the solar eclipse. For space-based observation, we use the Swarm satellite data for the tracks that have gone through the annularity belt. Also, a spatiotemporal study is executed using the Global Ionospheric Map (GIM) database. For both cases, the VTEC shows a prominent depletion. We investigate the variation in the percentage change in VTEC as a function of obscuration and observe a positive correlation between them. We also compute the time difference between the maximum eclipse and the maximum TEC modulation to investigate the response time profiles of the ionosphere at different receiving stations. All the methods give satisfactory and consistent outcomes that corroborate the physical mechanism of ionospheric variabilities due to the effect of the solar eclipse. We check the geomagnetic condition to eliminate the scope of contamination and observe that their values are normal during the study.

Observations of solar eclipses in russia: between the chronicles and the first scientific expeditions (18ʰᵗ – 19ʰᵗ Centuries)

A solar eclipse is a rare and spectacular celestial event that has a powerful emotional impact on people and is often reflected in their writings and communications. The reports of eclipse observations are contained in the 10th–17ʰᵗ century Russian chronicles. Modern observation reports, starting wiʰᵗ the 1887 eclipse, have also been well studied. In the intermediate period, starting from 1706, however, only three eclipses (1748, 1842 and 1851) have been described in publicly available sources despite the fact that 30 total and annular eclipses passed through Russia during this period. Using a computer program, the regions and time intervals were identified to search for the mentions of such eclipses. Possible sources include memoirs, reports and other documents written by educated people – participants in all kinds of campaigns, voyages, and expeditions, not necessarily the astronomical ones. As a result of studying diverse sources, a number of valuable reports of eclipse observations were discovered. Most often, these are the observations of eyewitnesses who had accidentally happened to be in the eclipse path. The firstly discovered materials shed light on the level of astronomical knowledge among various groups of the Russian population as well as equipment available to them, and touch upon the issues of local peoples’ superstitions and prejudices. A periodization of solar eclipse observations is also proposed.

Observations of the Polarized Solar Corona During the Annular Eclipse of 14 October 2023

We present results of a dual eclipse expedition to observe the solar corona from two sites during the annular solar eclipse of 14 October 2023 using a novel coronagraph designed to be accessible for amateurs and students to build and deploy. The coronagraph (CATEcor) builds on the standardized eclipse observing equipment developed for the Citizen CATE 2024 experiment. The observing sites were selected for likelihood of clear observations, for historic relevance (near the Climax site in the Colorado Rocky Mountains), and for centrality to the annular eclipse path (atop Sandia Peak above Albuquerque, New Mexico). The novel portion of CATEcor is an external occulter assembly that slips over the front of a conventional dioptric telescope, forming a shaded-truss externally occulted coronagraph. CATEcor is specifically designed to be easily constructed in a garage or “makerspace” environment. We successfully observed some bright features in the solar corona to an altitude of approximately 2.25 R⊙ during the annular phases of the eclipse. Future improvements to the design, in progress now, will reduce both stray light and image artifacts; our objective is to develop a design that can be operated successfully by amateur astronomers at sufficient altitude even without the darkened skies of a partial or annular eclipse.

CATEcor: An Open Science, Shaded-Truss, Externally-Occulted Coronagraph

We present the design of a portable coronagraph, CATEcor (where CATE stands for Continental-America Telescope Eclipse), that incorporates a novel “shaded-truss” style of external occultation and serves as a proof-of-concept for that family of coronagraphs. The shaded-truss design style has the potential for broad application in various scientific settings. We conceived CATEcor itself as a simple instrument to observe the corona during the darker skies available during a partial solar eclipse, or for students or interested amateurs to detect the corona under ideal noneclipsed conditions. CATEcor is therefore optimized for simplicity and accessibility to the public. It is implemented using an existing dioptric telescope and an adapter rig that mounts in front of the objective lens, restricting the telescope aperture and providing external occultation. The adapter rig, including occulter, is fabricated using fusion deposition modeling (FDM; colloquially “3D printing”), greatly reducing cost. The structure is designed to be integrated with moderate care and may be replicated in a university or amateur setting. While CATEcor is a simple demonstration unit, the design concept, process, and trades are useful for other more sophisticated coronagraphs in the same general family, which might operate under normal daytime skies outside the annular-eclipse conditions used for CATEcor.

The dynamic effects of solar eclipses of October 25, 2022, and October 14, 2023, on GPS-derived total electron content

This study analyzes total electron content (TEC) variations during two solar eclipse events that occurred on October 25, 2022, and October 14, 2023. The solar eclipse of October 25, 2022, was a partial solar eclipse, while the eclipse of October 14, 2023, was an annular solar eclipse. For this study, the data of eight International GNSS Service (IGS) stations from different eclipse coverage zones are used to analyze TEC variations. It is found that the stations located in the maximum eclipse cover zone exhibited notable decreases in TEC values. The minimum variation of about 11.76% in TEC values is observed at the station situating in about 20 percent eclipse cover zone, while it varies from 22% to 38% at the stations falling in about 60 percent eclipse cover zone. The highest variation in TEC values of about 44% is found at the stations in about 80 percent eclipse cover zone. The time of occurrence of maximum depletion in TEC values at each station is in line with their longitudinal sequence. Atmospheric gravity waves (AGWs) are also observed by performing wavelet analysis on TEC data. The global TEC maps visualize and confirm observed TEC variations, providing spatial and temporal insights into the ionospheric response. This analysis highlights the influence of station location and eclipse coverage on the magnitude and spatial distribution of TEC variations.

Spectroscopic and photometric investigations of the totally eclipsing contact binary V1320 Cas

We analyzed the light curve of the total eclipse contact binary V1320 Cas, obtained reliable photometric solutions, confirmed it to be a W-type contact binary with a mass ratio of 3.404 and a contact degree of 23.9%, a cool spot is discovered on the less massive component. Orbital period analysis indicates that the period of V1320 Cas is decreasing at a rate of dPdt=1.78×10−7 day yr−1, superimposed with a cyclic modulation with a period of 1.425 yr, long-term period decrease may be caused by the combination of mass transfer and angular momentum loss, and the cyclic modulation may be caused by the third companion. Using the photometric solutions and Gaia distance, we calculated the absolute physical parameters and plotted mass-luminosity and mass–radius diagrams to analyze the evolutionary status of V1320 Cas, the more massive component is a main sequence star, while the less massive component has higher luminosity and radius than those of main sequence stars with the same mass. With the decreasing orbital period, the two components of V1320 Cas will be gradually closer, while the binary may evolve toward deep contact.

A photometric study of a total-eclipse contact binary V458 Mon

We present light curve solution of V458 Mon firstly by using the Wilson-Devinney code. The total eclipse and deep minima of the light curves of V458 Monenable us to determine reliable orbital parameters of the binary system. The solution suggests that V458 Monis a low mass ratio binary system with about 0.2 possessing a moderate degree of contact. The long-term period investigation showed that the period of V458 Monis increasing at dP/dt=+2.59×10−7days/yr, which could be the reason of mass transfer from the less massive component to more massive primary one, together with a periodic change. The oscillation in orbital period may be due to an unseen tertiary companion with the mass about M3=1.8M⊙ . After removing these change, there is still a weak cyclic change maybe due to magnetic activity. With the increase in orbital period of binary, the separation increases and mass ratio decreases which eventually leads V458 Montowards merger.