Quiet Periods Research Articles

Detection of long-range correlation causing multifractality in H time series of geomagnetic field over the Northern Hemisphere during quiet geomagnetic conditions

The generation of geomagnetic time series frequently involves intricate spatio-temporal dynamics, wherein nonlinearity and scaling emerge as pivotal mechanisms. The present work investigates the fractal properties of geomagnetic field, and its sources during quiet geomagnetic conditions, by analyzing the horizontal component data of 1 min resolution (H time series) from different latitude regions. Analysis using Auto Correlation Function (ACF), Power spectrum analysis (PSA), Rescaled range analysis (R/S) and Detrended Fluctuation Analysis (DFA) gave indications of the presence of long-range correlations, fractal properties and scaling behaviour of quiet period H time series data. The strong q dependence of generalized Hurst exponent h(q) and scaling exponent Ʈ(q), obtained from the Multifractal Detrended Fluctuation Analysis (MFDFA) method, confirmed the multifractal behaviour of quiet period H time series. The multifractal source analysis of the quiet period H time series with its shuffled and surrogate time series data revealed that, the multifractal characteristics are caused almost entirely by the long-range correlations between small and large fluctuations. The analysis of the latitudinal variations in the multifractal characteristics is also performed as a part of the work, by considering H time series belonging to various latitudes under almost same longitude. The observed decrease in the generalized Hurst exponent values with increase in latitude indicates the change in the multifractal characteristics of the time series with latitude. Also the work revealed that, the H time series from high latitude region shows anti-persistent behaviour, even when the H time series from observatories located at the low and mid latitude regions exhibiting persistent behaviour. The change in the persistence, anti-persistence behaviour can be related to the strength of Earth’s magnetic field.

Near-real-time 3D Reconstruction of the Solar Coronal Parameters Based on the Magnetohydrodynamic Algorithm outside a Sphere Using Deep Learning

For the first time, we generate solar coronal parameters (density, magnetic field, radial velocity, and temperature) on a near-real-time basis by deep learning. For this, we apply the Pix2PixCC deep-learning model to three-dimensional (3D) distributions of these parameters: synoptic maps of the photospheric magnetic field as an input and the magnetohydrodynamic algorithm outside a sphere (MAS) results as an output. To generate the 3D structure of the solar coronal parameters from 1 to 30 solar radii, we train and evaluate 152 distinct deep-learning models. For each parameter, we consider the data of 169 Carrington rotations from 2010 June to 2023 February: 132 for training and 37 for testing. The key findings of our study are as follows: First, our deep-learning models successfully reconstruct the 3D distributions of coronal parameters from 1 to 30 solar radii with an average correlation coefficient of 0.98. Second, during the solar active and quiet periods, the AI-generated data exhibits consistency with the target MAS simulation data. Third, our deep-learning models for each parameter took a remarkably short time (about 16 s for each parameter) to generate the results with an NVIDIA Titan XP GPU. As the MAS simulation is a regularization model, we may significantly reduce the simulation time by using our results as an initial configuration to obtain an equilibrium condition. We hope that the generated 3D solar coronal parameters can be used for the near-real-time forecasting of heliospheric propagation of solar eruptions.

Spatio-Temporal Variation Seismicity Pattern in East Java Between 2002 and 2022 Based on the b-value and Seismic Quiescence z-value

East Java is one of the seismically active regions in part of the Sunda Arc whose seismicity pattern must be studied. Therefore, a spatio-temporal analysis of seismicity between 2002 - 2022 in East Java has been conducted. This analysis aims to investigate the seismotectonic conditions in the East Java region over the last twenty years, especially the seismicity patterns associated with significant earthquakes in East Java. The analysis was carried out by quantifying the spatial and temporal variations of seismicity parameters using b-value and z-value. The used data used are earthquake data from the USGS earthquake catalog during 2002 - 2022 in the East Java region. The analysis was performed using the ZMAP 6.0 program code using the maximum likelihood method. The results of the temporal analysis of b-values show that almost all significant earthquakes in East Java were characterized by a decrease in b-values of up to 0.2. Spatially, the significant earthquake on 10 April 2021 was associated with a low b-value (0.9). Temporal z-value analysis shows that the significant East Java earthquake was preceded by a quiet period (positive z-value) between 4 - 5 years (2003 - 2008 and 2012 - 2016). Spatial analysis of the z-value in the last 7 shows an increase in the z-value before the significant earthquakes occurred on 16 July 2019, 18 March 2020, and 10 April 2021. Therefore, the results of this study indicate that the b-value and z-value potentially can be used as precursors of the significant East Java earthquake. HIGHLIGHTS This is the first time a correlation of b-value and z-value as seismicity parameters has been carried out in East Java, Indonesia, as an attempt to determine the significant earthquake precursors The significant earthquakes in East Java during 2002 - 2022 were marked by a decrease in b-value of up to 0.2 The quiet period in East Java lasted between 4 - 7 years, i.e. 2002 - 2009 and 2012 - 2016, characterized by a positive z-value peaked until +3.5 The z-value at the location of a significant earthquake epicenters show a positive value 2 - 3 years prior to the main quake GRAPHICAL ABSTRACT

History of the development of machine translation systems (from the early stages to the beginning of the 21st century)

The article examines certain periods of machine translation development and the methods used to create various machine translation systems. To ensure correct historical periodization, the author defines the criteria for classifying the development of machine translation. Special attention is paid to the development of individual machine translation systems, as well as the events that had a significant impact on both the development and the hindrance of progress in the field of machine translation. Additionally, the author considers the ALPAC report and its subsequent “quiet period” of machine translation development, analyses the key specialists who have been involved in the development and improvement of machine translation systems and machine translation technologies, categorizing them into four large groups. The article reviews the dominant basis of machine translation research until the late 1980s, rooted in various linguistic rules such as parsing rules, lexical rules, lexical transfer rules, syntactic generation rules, morphology rules, etc.The author traces the emergence of the corpus-based method in machine translation, as well as its further expansion through experiments in computational modelling of cognition and perception, including the study of parallel computing, neural networks and connectionism, which offered the prospect of making the systems “learn” from past successes and failures. Besides, the author also examines the emergence of the interlingualapproach for multilingual translation of technical manuals and the history of the “pivot language”, along with the use of SLLP (specialized languages for linguistic programming).

Cross-Correlation Analysis of Cosmic Ray Intensity with Interplanetary and Geomagnetic Parameters during Disturbed and Quiet Periods

Cross-Correlation Analysis of Cosmic Ray Intensity with Interplanetary and Geomagnetic Parameters during Disturbed and Quiet Periods

Topside Ionospheric Structures Determined via Automatically Detected DEMETER Ion Perturbations during a Geomagnetically Quiet Period

In this study, 117,718 ionospheric perturbations, with a space size (t) of 20–300 s but no amplitude (A) limit, were automatically globally searched via software utilizing ion density data measured by the DEMETER satellite for over 6 years. The influence of geomagnetic storms on the ionosphere was first examined. The results demonstrated that storms can globally enhance positive ionospheric irregularities but rarely induce plasma variations of more than 100%. The probability of PERs with a space size falling in 200–300 s (1400–2100 km if a satellite velocity of 7 km/s is considered) occurring in a geomagnetically perturbed period shows more significance than that in a quiet period. Second, statistical work was performed on ion PERs to check their dependence on local time, and it was shown that 24.8% of the perturbations appeared during the daytime (10:30 LT) and 75.2% appeared during the nighttime (22:30 LT). Ionospheric fluctuations with an absolute amplitude of A < 10% tend to be background variations, and the percentages of positive perturbations with a small A < 20% occur at an amount of 64% during the daytime and 26.8% during the nighttime, but this number is reversed for mid–large-amplitude PERs. Large positive PERs with A > 100% mostly occurred at night and negative ones with A < −100% occurred entirely at night. There was a demarcation point in the space size of t = 120 s, and the occurrence probabilities of day PERs were always higher than that of nighttime ones before this point, while this trend was contrary after this point. Finally, distributions of PERs according to different ranges of amplitude and space scale were characterized by typical seasonal variations either in the daytime or nighttime. EIA only exists in the dayside equinox and winter, occupying two low-latitude crests with a lower Np in both hemispheres. Large WSAs appear within all periods, except for dayside summer, and are full of PERs with an enhanced amplitude, especially on winter nights. The WN-like structure is obvious during all seasons, showing large-scale space. On the other hand, several magnetically anomalous zones of planetary-scale non-dipole fields, such as the SAMA, Northern Africa anomaly, and so on, were also successfully detected by extreme negative ion perturbations during this time.

Impact of the practice of touch-massage® by a nurse on the anxiety of patients with hematological disorders hospitalized in a sterile environment, a randomized, controlled study

ContextIn addition to curative care, supportive care is beneficial in managing the anxiety symptoms common in patients in sterile hematology unit. We hypothesize that personal massage can help the patient, particularly in this isolated setting where physical contact is extremely limited. The main objective of this study was to show that anxiety could be reduced after a touch-massage® performed by a nurse trained in this therapy.MethodsA single-center, randomized, unblinded controlled study in the sterile hematology unit of a French university hospital, validated by an ethics committee. The patients, aged between 18 and 65 years old, and suffering from a serious and progressive hematological pathology, were hospitalized in sterile hematology unit for a minimum of three weeks, patients were randomized into either a group receiving 15-minute touch-massage® sessions or a control group receiving an equivalent amount of quiet time once a week for three weeks. In the treated group, anxiety was assessed before and after each touch-massage® session, using the State-Trait Anxiety Inventory questionnaire with subscale state (STAI-State). In the control group, anxiety was assessed before and after a 15-minute quiet period. For each patient, the difference in the STAI-State score before and after each session (or period) was calculated, the primary endpoint was based on the average of these three differences. Each patient completed the Rosenberg Self-Esteem Questionnaire before the first session and after the last session.ResultsSixty-two patients were randomized. Touch-massage® significantly decreased patient anxiety: a mean decrease in STAI-State scale score of 10.6 [7.65–13.54] was obtained for the massage group (p ≤ 0.001) compared with the control group. The improvement in self-esteem score was not significant.ConclusionThis study provides convincing evidence for integrating touch-massage® in the treatment of patients in sterile hematology unit.Trial registrationNCT02343965.

A Method for Teaching “Safe Listening” Integrated with Early Clinical Exposure for Third-Year Medical Students

OBJECTIVES The primary objective of this study is to describe a method for teaching “Safe Listening” integrated with early clinical exposure (ECE). Additionally, the study aims to assess preferred listening levels (PLLs), expected output levels, and classroom noise levels. METHODS Retrospective cross-sectional study. After pre-activity instruction, medical students were grouped into classrooms. The noise level in each classroom was measured using a sound meter application both in quiet situations and during conversations while the medical students were listening to their personal listening devices (PLDs). A calibrated finger rub auditory screening test and a tuning fork test were conducted and PLLs were recorded. The students discussed the findings and rated their satisfaction with the process at the end of the activity. RESULTS The average PLL of the 171 third-year medical students was 59.00 ± 7.38 dBA. The classroom noise level was 49.66 ± 8.45 dBA in quiet periods, and 77.51 ± 10.05 dBA during conversation and while listening to PLDs via earphones. In quiet periods, 97.65% of the students could hear finger rub in both ears. The average satisfaction score after the activity was 82.57 ± 13.14%. CONCLUSIONS Practice with hearing tests and self-checks of PLLs introduced exposure to clinical learning together with awareness of safe listening. PLLs of medical students and satisfaction with the activity were in the favorable range. KEYWORDS early clinical exposure, medical education, safe listening, preferred listening level

Deformation failure and acoustic emission response characteristics of water-containing concrete under impact load

Concrete materials are widely used in construction projects. Many concrete structures are in an aqueous environment and subjected to impact loads. Under this condition, the mechanical properties and failure modes of concrete will change significantly. In this paper, the drop hammer impact failure experiment of water-containing concrete was established. The deformation and failure characteristics as well as acoustic emission response law of concrete under dynamic load with different immersion time were studied. The failure mechanism and acoustic emission response precursor characteristics of concrete under drop hammer impact were revealed. The results show that the peak impact force of concrete was exponentially related to the immersion time. Its failure cracks were mainly distributed on the diagonal of the impact surface and the central axis of the observation surface. Due to the dual effect of water on the dynamic mechanical properties of concrete, the cracks and damage degree of concrete increased first and then decreased with the increase of immersion time. The peak acoustic emission (AE) count was exponentially related to the immersion time. The acoustic emission “quiet period” could be used as one of the precursor characteristics of concrete instability and failure, and the “quiet period” gradually became shorter with the increase of immersion time. This research results are of great significance for evaluating the stability of concrete structures and warning of concrete impact damage.

Responses of Ionospheric Radial Currents to Subauroral Polarization Streams During Quiet Periods

AbstractUsing 4 years of ionospheric radial current (IRC) from Swarm and ion velocity from the Defense Meteorological Satellite Program, our work investigates the response of IRC to the subauroral polarization streams (SAPS) during the quiet time for the first time. Both noontime (magnetic local time, MLT 11–14) inward and duskside (MLT 18–19) outward IRC get strengthened in amplitude. The noontime inward ΔIRC is attributed to the penetration westward electric field at low‐mid latitudes. It drives the poleward Hall currents and equatorward polarization electric field, which maps to the dip equator to form an inward ΔIRC at F layer. At dusk, the SAPS‐poleward electric field could directly penetrate to the low‐mid latitudes, mapping to the dip equator to drive the outward ΔIRC. The substorms‐associated westward electric field is also critical in modulation of ΔIRC, resulting in a larger inward (weaker outward) ΔIRC under high auroral electrojet (AE) index than that under low AE around noon (dusk).

Deep Learning‐Based Regional Ionospheric Total Electron Content Prediction—Long Short‐Term Memory (LSTM) and Convolutional LSTM Approach

AbstractThis study evaluates the performance of deep learning approach in the prediction of the ionospheric total electron content (TEC) during magnetically quiet periods. Two deep learning techniques, long short‐term memory (LSTM) and convolutional LSTM (ConvLSTM), are employed to predict TEC values 24 hr ahead in the vicinity of the Korean Peninsula (26.5°–40°N, 121°–134.5°E). The LSTM method predicts TEC at a single point based on time series of data at that point, whereas the ConvLSTM method simultaneously predicts TEC values at multiple points using spatiotemporal distribution of TEC. Both the LSTM and ConvLSTM models are trained using the complete regional TEC maps reconstructed by applying the Deep Convolutional Generative Adversarial Network–Poisson Blending (DCGAN‐PB) method to observed TEC data. The training period spans from 2002 to 2018, and the model performance is evaluated using 2019 data. Our results show that the ConvLSTM method outperforms the LSTM method, generating more reliable TEC maps with smaller root mean square errors when compared to the ground truth (DCGAN‐PB TEC maps). This outcome indicates that deep learning models can improve the prediction accuracy of TEC at a specific point by taking into account spatial information of TEC. We conclude that ConvLSTM is a reliable and efficient approach for the prompt ionospheric prediction.

Analyst Information About Peer Firms During the IPO Quiet Period

Analyst Information About Peer Firms During the IPO Quiet Period

25-26 Ağustos 2018 Jeomanyetik Fırtına Sırasında Afrika Bölgesi Üzerindeki Manyetik Eşlenik Çiftleri Üzerindeki TEC Değişikliklerinin İncelenmesi

In this study, the electron transport process resulting from electromagnetic drift between two magnetic conjugate pairs over the African region during the August 25-26 2018 geomagnetic storm was investigated. The effects of geomagnetic conditions presented with Dst index and IMF Bz values on Total Electron Content (TEC) values at conjugate stations were compared separately for stormy and quiet periods. During the storm period, the effect of TEC values at stations in the northern hemisphere (Haifa and Djibouti) on the TEC values at stations in the southern hemisphere (Ambalavao and Malindi) is greater than the effect of TEC values in the southern hemisphere on TEC values in the northern hemisphere. According to this result, it can be said that the south-directed electromagnetic convection was more than the north-directed convection in the examined dates. When the coefficients are examined, it can be said that the interaction is more in the magnetic conjugate pair that is closer to the equator during the storm period, and the interaction is more in the magnetic conjugate pair that is far from the equator during the silent period. Considering the coefficients calculated for Dst and IMF Bz, it is seen that the TEC values are very small compared to their coefficients. From this it can be concluded that the effect of Dst and IMF Bz is much smaller than the effect of TEC values at a station on TEC values at its magnetic conjugates.

Kepastian Hukum dalam Penetapan Kriteria Money Politik menjelang Kampanye Pemilu 2024

The implementation of elections or regional elections is very vulnerable to corruption. Money politics is the origin of political corruption. Money politics is a serious problem in elections and elections in Indonesia, starting from the election of village heads, regional heads, legislative members, and the Regional Representative Council (DPD) to the President and Vice President, it is vulnerable to the practice of buying and selling votes. One recent example of allegations of money politics was the discovery of a case of giving away milk during the CFD on December 3 2023 by Vice President Gibran which according to Bawaslu was not an election violation and the case of distributing envelopes bearing the PDIP logo at a mosque in Sumenep amounting to IDR 300 thousand. Again, Bawaslu stated that it could not investigate the case in terms of violations of money politics provisions. This is because the Election Law only regulates the prohibition of money politics during the campaign period. Therefore, there needs to be a clear determination in determining the criteria for money politics. The type of research used is normative juridical with a statutory approach and a conceptual approach. There is a gap for the practice of money politics to occur in the upcoming 2024 elections due to the weakness of the regulations governing money politics. This weakness is not only in terms of material, such as if there are subjects of criminal acts who are not organizers, participants, and campaign teams who practice money politics during the campaign and quiet periods, then these perpetrators cannot be punished under the Election Law. Only election organizers, participants, and campaign teams are prohibited from engaging in money politics. Transactions giving money are sometimes not carried out by candidates directly but through intermediaries with the success team or parties who have an interest in the candidate. Legal uncertainty was also seen during the campaign period which only lasted 75 days. So if forms of money politics are carried out by candidates and their teams outside the campaign period, they are not included in the category of money politics

Persistent Pitch Angle Anisotropies of Relativistic Electrons in the Outer Radiation Belts

AbstractPitch angle distributions (PADs) in the radiation belts are well characterized with sinn(α). By tracking the exponent “n,” termed pitch angle index, we are able to observe persistent and cross‐energy changes in PADs of Van Allen radiation belt electrons using Van Allen Probes particle observations. The PAD measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine the connection between particles and waves. With this method, we study long‐lasting and high‐energy anisotropic electron PADs during a quiet period over 2 days, 26 and 27 June 2013. One potential driver for these changes is electromagnetic ion cyclotron wave interaction with the particles. We use several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity and Finnish pulsation magnetometer network of Sodankylä Geophysical Observatory to observe waves during the 2 days of interest. The connection between the waves and particles is inconclusive, although there is some temporal overlap of the phenomenon.

Modeling Total Electron Content and Critical Frequency at F1 and E Layer Boundary

This work investigates the variation of the total electron content TEC and the critical frequency fo in the boundary zone of the F1 and E layers at the low-latitude in the ionosphere. This study takes place at the Ouagadougou station (12.4°N and 358.5°E), in West Africa during the quiet geomagnetic activity of solar cycle 23. Ionosphere is the upper layer of the Earth's atmosphere ionized mainly by solar X- and UV-rays, extending from around 80km altitude up to 1000km [1] [2]. Ultraviolet light from the sun ionizes the atoms and molecules in the Earth's upper atmosphere [3]. For this study we use the 2016 version of International Reference Ionosphere (IRI) model. The quiet periods of maximum and minimum phase of solar cycle 23 are considered [4] [5]. From this study, it emerges that at the E and F1 layer boundary zone, TEC and fo increase during the day as solar irradiance increases and decrease as solar irradiance decreases.

Performance Analysis of a Strong Constraint 4DVar and 4DEnVar on Regional Ionosphere Imaging

AbstractData assimilation (DA) techniques have recently gained traction in the ionospheric community, particularly at regional operational centers where more precise data are becoming prevalent. At center stage is the argument over which technique or scheme merits realization. At 4DSpace, we have in‐house developed and assessed the performance of two regional flavors of short‐term forecast strong constraint four‐dimensional (4D, space and time) variational (SC4DVar) DA schemes; the orthodox incremental (SC4DVar‐Inc) and ensemble‐based (SC4DEnVar) approach. SC4DVar‐Inc is bottled‐necked by expensive Tangent Linear Models (TLMs) and model Ad‐joints (MAs), while SC4DEnVar design mitigates these limitations. Both schemes initialize from the same background (IRI‐2016), and electron densities forward propagated (30‐min) by a Gauss Markov filter‐ the densities take on a log‐normal distribution to assert the mandatory ionosphere density positive definiteness. Preliminary assimilation is performed only with ubiquitous Global Navigation Satellite System observables from ground‐based receivers, with a focus on moderately stable mid‐latitudes, specifically the Japanese archipelago and neighboring areas. Using a simulation analysis, we find that under model space localization, 30 member Ensembles are sufficient for regional SC4DEnVar. Verification of reconstructions is with independent observations from ground‐based ionosonde and satellite radio occultations: the performance of both schemes is fairly adequate during the quiet period when the background has a better estimation of the hmF2. SC4DVar‐Inc is slightly better over areas densely populated with measurements, but SC4DEnVar estimates the overall 3D ionosphere picture better, particularly in remote areas and during severe conditions. These results warrant SC4DEnVar as a better candidate for precise short‐time regional forecasts.

PROGRESSIVE STEPS IN PREVENTING AND HANDLING MONEY POLITICS IN INDONESIAN ELECTIONS: AN EFFORT TO REDUCE DEVIANT BEHAVIOR IN DEMOCRATIC ELECTIONS

The practice of money politics in elections is most commonly observed during campaign activities and the distribution of donations, especially in the form of cash contributions. Several factors contribute to this issue, including traditional practices, a desire for recognition, a conducive environment for unethical behavior, the ability to influence laws, wavering ethical values, impoverished communities, limited public awareness, and cultural norms. Money politics typically unfolds in two stages: pre-voting and post-voting. The pre-voting phase includes administrative selection, the campaign period, the quiet period, and the lead-up to the actual election, targeting primarily voters susceptible to influence. The post-election phase occurs after the election, particularly during the General Session of the DPR/DPRD and in decisions concerning the APBN/APBD, with political elites who wield significant authority being the main targets. These egal loopholes can be exploited for fraudulent purposes. Therefore, it is critical to enhance the clarity and enforceability of existing legal provisions.

Analysis of spatial–temporal characteristics for BDS-3 broadcast ionospheric models (BDS Klobuchar and BDGIM) in multi-GNSS real-time single-frequency precise point positioning

With the full operation of BDS-3 broadcast ionospheric models, i.e., the BeiDou global ionospheric delay correction model (BDGIM) and the BDS Klobuchar model, its impact on the multi-GNSS real-time (RT) single-frequency (SF) precise point positioning (PPP) needs to be investigated for low-cost GNSS users. The GPS Klobuchar model as a reference is also considered in this study. Two types of SF-PPP models including the ionosphere-corrected (IC) and ionosphere-weighted (IW) strategies are adopted in the positioning domain. GPS + GLONASS + Galileo + BDS-3 observations from 40 multi-GNSS experiment (MGEX) stations distributed in different latitudes are selected for conducting RT SF-PPP during the ionospheric quiet and active periods. The experiment shows that the positioning accuracy of IC RT SF-PPP can be degraded with the increase of the ionospheric activity levels or the decrease of latitudes. Except for low-latitude regions during the ionospheric active period, the 3D positioning accuracy of the northern hemisphere can be improved by at least 15.2 % compared to the southern hemisphere in the IC model with the BDS Klobuchar. The BDGIM model has the best performance among all IC RT SF-PPP solutions, but its 3D positioning accuracy can reach the sub-meter level only in mid-latitude regions. With the adoption of ionospheric constraints, the convergence of the IW model is always superior to that of the group and phase ionospheric correction (GRAPHIC) model, and the improvement of convergence in mid-latitude regions is clearly better than that in low-latitude regions. Due to the quality limitation of the BDS Klobuchar model, it has the longest convergence time among all IW models regardless of ionospheric conditions or latitude regions. Compared to the GPS Klobuchar, the significant improvement of convergence for the BDGIM-constrained RT SF-PPP is mainly presented in low-latitude regions of the northern hemisphere. The horizontal positioning accuracy of the BDGIM-constrained model is always improved in comparison with the GRAPHIC model, but there is a degradation in the vertical component, and the improvement of 3D positioning accuracy is no more than 11.7 %. In summary, the BDGIM-constrained model has the best performance among all RT SF-PPP solutions, its 3D positioning accuracy has the ability to achieve 0.25 m at present.

The Rapid Optical Variability of the Nearby Radio-loud AGN Pictor A: Introducing the Quaver Pipeline for AGN Science with TESS

The sampling strategy of the Transiting Exoplanet Survey Satellite (TESS) makes TESS light curves extremely valuable for investigating the high cadence optical variability of active galactic nuclei (AGN). However, because the TESS instrument was primarily designed for exoplanet science, the use of the satellite for other applications requires careful treatment of the data. In this paper, we introduce Quaver, a new software tool designed specifically to extract TESS light curves of extended and faint sources presenting stochastic variability. We then use this new tool to extract light curves of the nearby radio-loud AGN Pictor A, and perform a temporal and power spectral analysis of its high-cadence optical variability. The obtained light curves are well fit with a damped random walk (DRW) model, exhibiting both stochastic AGN variations and flaring behavior. The DRW characteristic timescales are τ DRW ∼ 3–6 days during more quiet periods, and τ DRW ∼ 0.8 day for periods with strong flares, even when the flares themselves are masked from the DRW fit. The observed timescales are consistent with the dynamical, orbital, and thermal timescales expected for the low black hole mass of Pictor A.