Articles | Volume 42, issue 1
https://doi.org/10.5194/angeo-42-179-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-42-179-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
29 May 2024
Regular paper |
| 29 May 2024
| 29 May 2024
Application of generalized aurora computed tomography to the EISCAT_3D project
Yoshimasa Tanaka
CORRESPONDING AUTHOR
Space and Upper Atmospheric Sciences Group, National Institute of Polar Research, Tachikawa, 190-8518, Japan
Polar Environment Data Science Center, ROIS-DS, Tachikawa, 190-0014, Japan
Polar Science Program, Graduate Institute for Advanced Studies, SOKENDAI, Tachikawa, 190-8518, Japan
Yasunobu Ogawa
Space and Upper Atmospheric Sciences Group, National Institute of Polar Research, Tachikawa, 190-8518, Japan
Polar Environment Data Science Center, ROIS-DS, Tachikawa, 190-0014, Japan
Polar Science Program, Graduate Institute for Advanced Studies, SOKENDAI, Tachikawa, 190-8518, Japan
Akira Kadokura
Space and Upper Atmospheric Sciences Group, National Institute of Polar Research, Tachikawa, 190-8518, Japan
Polar Environment Data Science Center, ROIS-DS, Tachikawa, 190-0014, Japan
Polar Science Program, Graduate Institute for Advanced Studies, SOKENDAI, Tachikawa, 190-8518, Japan
Takehiko Aso
Space and Upper Atmospheric Sciences Group, National Institute of Polar Research, Tachikawa, 190-8518, Japan
Björn Gustavsson
UiT The Arctic University of Norway, Tromsø, 6050, Norway
Urban Brändström
Swedish Institute of Space Physics, Kiruna, 812, Sweden
Tima Sergienko
Swedish Institute of Space Physics, Kiruna, 812, Sweden
Genta Ueno
The Institute of Statistical Mathematics, Tachikawa, 190-8562, Japan
Satoko Saita
Department of Creative Engineering, Kitakyushu National College of Technology, Kitakyushu, 802-0985 Japan
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Mizuki Fukizawa, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Tero Raita, and Kirsti Kauristie
Ann. Geophys., 41, 511–528, https://doi.org/10.5194/angeo-41-511-2023, https://doi.org/10.5194/angeo-41-511-2023, 2023
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We use computed tomography to reconstruct the three-dimensional distributions of the Hall and Pedersen conductivities of pulsating auroras, a key research target for understanding the magnetosphere–ionosphere coupling process. It is suggested that the high-energy electron precipitation associated with pulsating auroras may have a greater impact on the closure of field-aligned currents in the ionosphere than has been previously reported.
Mizuki Fukizawa, Takeshi Sakanoi, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Björn Gustavsson, Kirsti Kauristie, Alexander Kozlovsky, Tero Raita, Urban Brändström, and Tima Sergienko
Ann. Geophys., 40, 475–484, https://doi.org/10.5194/angeo-40-475-2022, https://doi.org/10.5194/angeo-40-475-2022, 2022
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The pulsating auroral generation mechanism has been investigated by observing precipitating electrons using rockets or satellites. However, it is difficult for such observations to distinguish temporal changes from spatial ones. In this study, we reconstructed the horizontal 2-D distribution of precipitating electrons using only auroral images. The 3-D aurora structure was also reconstructed. We found that there were both spatial and temporal changes in the precipitating electron energy.
Tinna L. Gunnarsdottir, Ingrid Mann, Wuhu Feng, Devin R. Huyghebaert, Ingemar Haeggstroem, Yasunobu Ogawa, Norihito Saito, Satonori Nozawa, and Takuya D. Kawahara
Ann. Geophys., 42, 213–228, https://doi.org/10.5194/angeo-42-213-2024, https://doi.org/10.5194/angeo-42-213-2024, 2024
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Several tons of meteoric particles burn up in our atmosphere each day. This deposits a great deal of material that binds with other atmospheric particles and forms so-called meteoric smoke particles. These particles are assumed to influence radar measurements. Here, we have compared radar measurements with simulations of a radar spectrum with and without dust particles and found that dust influences the radar spectrum in the altitude range of 75–85 km.
Devin Huyghebaert, Björn Gustavsson, Juha Vierinen, Andreas Kvammen, Matthew Zettergren, John Swoboda, Ilkka Virtanen, Spencer Hatch, and Karl M. Laundal
EGUsphere, https://doi.org/10.5194/egusphere-2024-802, https://doi.org/10.5194/egusphere-2024-802, 2024
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The EISCAT_3D radar is a new ionospheric radar under construction in the Fennoscandia region. The radar will make measurements of plasma characteristics at altitudes above approximately 60 km. The capability of the system to make these measurements on spatial scales of less than 100 m using the multiple digitised signals from each of the radar antenna panels is highlighted. There are many ionospheric small-scale processes that will be further resolved using the techniques discussed here.
Peter Dalin, Urban Brändström, Johan Kero, Peter Voelger, Takanori Nishiyama, Trond Trondsen, Devin Wyatt, Craig Unick, Vladimir Perminov, Nikolay Pertsev, and Jonas Hedin
Atmos. Meas. Tech., 17, 1561–1576, https://doi.org/10.5194/amt-17-1561-2024, https://doi.org/10.5194/amt-17-1561-2024, 2024
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A novel infrared imaging instrument (OH imager) was put into operation in November 2022 at the Swedish Institute of Space Physics in Kiruna (Sweden). The OH imager is dedicated to the study of nightglow emissions coming from the hydroxyl (OH) and molecular oxygen (O2) layers in the mesopause (80–100 km). Based on a brightness ratio of two OH emission lines, the neutral temperature is estimated at around 87 km. The average daily winter temperature for the period January–April 2023 is 203±10 K.
Theresa Rexer, Björn Gustavsson, Juha Vierinen, Andres Spicher, Devin Ray Huyghebaert, Andreas Kvammen, Robert Gillies, and Asti Bhatt
Geosci. Instrum. Method. Data Syst. Discuss., https://doi.org/10.5194/gi-2023-18, https://doi.org/10.5194/gi-2023-18, 2024
Preprint under review for GI
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We present a second-level calibration method for electron density measurements from multi-beam incoherent scatter radars. It is based on the well-known Flat field correction method used in imaging and photography. The methods improve data quality and useability as they account for unaccounted, and unpredictable variations in the radar system. This is valuable for studies where inter-beam calibration is important such as studies of polar cap patches, plasma irregularities and turbulence.
Thomas B. Leyser, Tima Sergienko, Urban Brändström, Björn Gustavsson, and Michael T. Rietveld
Ann. Geophys., 41, 589–600, https://doi.org/10.5194/angeo-41-589-2023, https://doi.org/10.5194/angeo-41-589-2023, 2023
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Powerful radio waves transmitted into the ionosphere from the ground were used to study electron energization in the pumped ionospheric plasma turbulence, by detecting optical emissions from atomic oxygen. Our results obtained with the EISCAT (European Incoherent Scatter Scientific Association) facilities in northern Norway and optical detection with the ALIS (Auroral Large Imaging System) in northern Sweden suggest that long-wavelength upper hybrid waves are important in accelerating electrons.
Mizuki Fukizawa, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Tero Raita, and Kirsti Kauristie
Ann. Geophys., 41, 511–528, https://doi.org/10.5194/angeo-41-511-2023, https://doi.org/10.5194/angeo-41-511-2023, 2023
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We use computed tomography to reconstruct the three-dimensional distributions of the Hall and Pedersen conductivities of pulsating auroras, a key research target for understanding the magnetosphere–ionosphere coupling process. It is suggested that the high-energy electron precipitation associated with pulsating auroras may have a greater impact on the closure of field-aligned currents in the ionosphere than has been previously reported.
Masatoshi Yamauchi and Urban Brändström
Geosci. Instrum. Method. Data Syst., 12, 71–90, https://doi.org/10.5194/gi-12-71-2023, https://doi.org/10.5194/gi-12-71-2023, 2023
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Potential users of all-sky aurora images even include power companies, tourists, and aurora enthusiasts. However, these potential users are normally not familiar with interpreting these images. To make them comprehensive for more users, we developed an automatic evaluation system of auroral activity level. The method involves two steps: first making a simple set of numbers that describes the auroral activity and then further simplifying them into several levels (Level 6 is an auroral explosion).
Johann Stamm, Juha Vierinen, Björn Gustavsson, and Andres Spicher
Ann. Geophys., 41, 55–67, https://doi.org/10.5194/angeo-41-55-2023, https://doi.org/10.5194/angeo-41-55-2023, 2023
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The study of some ionospheric events benefit from the knowledge of how the physics varies over a volume and over time. Examples are studies of aurora or energy deposition. With EISCAT3D, measurements of ion velocity vectors in a volume will be possible for the first time. We present a technique that uses a set of such measurements to estimate electric field and neutral wind. The technique relies on adding restrictions to the estimates. We successfully consider restrictions based on physics.
Daniel K. Whiter, Noora Partamies, Björn Gustavsson, and Kirsti Kauristie
Ann. Geophys., 41, 1–12, https://doi.org/10.5194/angeo-41-1-2023, https://doi.org/10.5194/angeo-41-1-2023, 2023
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We measured the height of green and blue aurorae using thousands of camera images recorded over a 7-year period. Both colours are typically brightest at about 114 km altitude. When they peak at higher altitudes the blue aurora is usually higher than the green aurora. This information will help other studies which need an estimate of the auroral height. We used a computer model to explain our observations and to investigate how the green aurora is produced.
Mizuki Fukizawa, Takeshi Sakanoi, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Björn Gustavsson, Kirsti Kauristie, Alexander Kozlovsky, Tero Raita, Urban Brändström, and Tima Sergienko
Ann. Geophys., 40, 475–484, https://doi.org/10.5194/angeo-40-475-2022, https://doi.org/10.5194/angeo-40-475-2022, 2022
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The pulsating auroral generation mechanism has been investigated by observing precipitating electrons using rockets or satellites. However, it is difficult for such observations to distinguish temporal changes from spatial ones. In this study, we reconstructed the horizontal 2-D distribution of precipitating electrons using only auroral images. The 3-D aurora structure was also reconstructed. We found that there were both spatial and temporal changes in the precipitating electron energy.
Fasil Tesema, Noora Partamies, Daniel K. Whiter, and Yasunobu Ogawa
Ann. Geophys., 40, 1–10, https://doi.org/10.5194/angeo-40-1-2022, https://doi.org/10.5194/angeo-40-1-2022, 2022
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In this study, we present the comparison between an auroral model and EISCAT radar electron densities during pulsating aurorae. We test whether an overpassing satellite measurement of the average energy spectrum is a reasonable estimate for pulsating aurora electron precipitation. When patchy pulsating aurora is dominant in the morning sector, the overpass-averaged spectrum is found to be a reasonable estimate – but not when there is a mix of pulsating aurora types in the post-midnight sector.
Johann Stamm, Juha Vierinen, and Björn Gustavsson
Ann. Geophys., 39, 961–974, https://doi.org/10.5194/angeo-39-961-2021, https://doi.org/10.5194/angeo-39-961-2021, 2021
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Measurements of the electric field and neutral wind in the ionosphere are important for understanding energy flows or electric currents. With incoherent scatter radars (ISRs), we can measure the velocity of the ions, which depends on both the electrical field and the neutral wind. In this paper, we investigate methods to use ISR data to find reasonable values for both parameters. We find that electric field can be well measured down to 125 km height and neutral wind below this height.
Torbjørn Tveito, Juha Vierinen, Björn Gustavsson, and Viswanathan Lakshmi Narayanan
Ann. Geophys., 39, 427–438, https://doi.org/10.5194/angeo-39-427-2021, https://doi.org/10.5194/angeo-39-427-2021, 2021
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This work explores the role of EISCAT 3D as a tool for planetary mapping. Due to the challenges inherent in detecting the signals reflected from faraway bodies, we have concluded that only the Moon is a viable mapping target. We estimate the impact of the ionosphere on lunar mapping, concluding that its distorting effects should be easily manageable. EISCAT 3D will be useful for mapping the lunar nearside due to its previously unused frequency (233 MHz) and its interferometric capabilities.
Johann Stamm, Juha Vierinen, Juan M. Urco, Björn Gustavsson, and Jorge L. Chau
Ann. Geophys., 39, 119–134, https://doi.org/10.5194/angeo-39-119-2021, https://doi.org/10.5194/angeo-39-119-2021, 2021
Sam Tuttle, Betty Lanchester, Björn Gustavsson, Daniel Whiter, Nickolay Ivchenko, Robert Fear, and Mark Lester
Ann. Geophys., 38, 845–859, https://doi.org/10.5194/angeo-38-845-2020, https://doi.org/10.5194/angeo-38-845-2020, 2020
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Electric fields in the atmosphere near dynamic aurora are important in the physics of the electric circuit within the Earth's magnetic field. Oxygen ions emit light as they move under the influence of these electric fields; the flow of this emission is used to find the electric field at high temporal resolution. The solution needs two other simultaneous measurements of auroral emissions to give key parameters such as the auroral energy. The electric fields increase with brightness of the aurora.
Thomas B. Leyser, Björn Gustavsson, Theresa Rexer, and Michael T. Rietveld
Ann. Geophys., 38, 297–307, https://doi.org/10.5194/angeo-38-297-2020, https://doi.org/10.5194/angeo-38-297-2020, 2020
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Powerful radio waves transmitted into the ionosphere give the strongest turbulence effects in geomagnetic zenith, antiparallel to the magnetic field in the Northern Hemisphere. Our results obtained with the EISCAT (European Incoherent SCATter association) Heating facility in Norway and the EISCAT UHF incoherent scatter radar together with modelling suggest that the pump wave propagates in the L mode, rather than in the O mode that is usually assumed to be involved in such experiments.
Thomas B. Leyser, H. Gordon James, Björn Gustavsson, and Michael T. Rietveld
Ann. Geophys., 36, 243–251, https://doi.org/10.5194/angeo-36-243-2018, https://doi.org/10.5194/angeo-36-243-2018, 2018
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Transmission of powerful radio waves into the overhead ionosphere is used to study plasma turbulence processes. It is well known that the ionospheric response to radio waves is the strongest in the direction of the geomagnetic field. We have found evidence that the transmitted radio wave can propagate in a mode that enables the wave to propagate much higher in altitude and deeper into the ionosphere than what is usually expected, which may account for the strong plasma response observed.
Nickolay Ivchenko, Nicola M. Schlatter, Hanna Dahlgren, Yasunobu Ogawa, Yuka Sato, and Ingemar Häggström
Ann. Geophys., 35, 1143–1149, https://doi.org/10.5194/angeo-35-1143-2017, https://doi.org/10.5194/angeo-35-1143-2017, 2017
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Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. A plasma line gives an accurate measure of the electron density and can be used to estimate electron temperature. The occurrence of plasma line enhancements in the EISCAT Svalbard Radar data was investigated. During summer daytime hours the plasma line is detectable in up to 90 % of the data. In winter time the occurrence is a few percent.
T. Takahashi, S. Nozawa, T. T. Tsuda, Y. Ogawa, N. Saito, T. Hidemori, T. D. Kawahara, C. Hall, H. Fujiwara, N. Matuura, A. Brekke, M. Tsutsumi, S. Wada, T. Kawabata, S. Oyama, and R. Fujii
Ann. Geophys., 33, 941–953, https://doi.org/10.5194/angeo-33-941-2015, https://doi.org/10.5194/angeo-33-941-2015, 2015
T. Ishida, Y. Ogawa, A. Kadokura, K. Hosokawa, and Y. Otsuka
Ann. Geophys., 33, 525–530, https://doi.org/10.5194/angeo-33-525-2015, https://doi.org/10.5194/angeo-33-525-2015, 2015
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We studied the localized plasma density enhancements called blobs, which are often produced in the high-latitude ionosphere by the transportation process of plasma or particle precipitations. This subject is important because such structures affect radio wave propagation and can cause scintillation of GNSS signals in the deformation process. This paper is the first report of direct observations of blob deformation during a substorm.
F. Sigernes, S. E. Holmen, D. Biles, H. Bjørklund, X. Chen, M. Dyrland, D. A. Lorentzen, L. Baddeley, T. Trondsen, U. Brändström, E. Trondsen, B. Lybekk, J. Moen, S. Chernouss, and C. S. Deehr
Geosci. Instrum. Method. Data Syst., 3, 241–245, https://doi.org/10.5194/gi-3-241-2014, https://doi.org/10.5194/gi-3-241-2014, 2014
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A two-step procedure to calibrate the spectral sensitivity of auroral all-sky (fish-eye) cameras is outlined. First, center pixel response is obtained by the use of a Lambertian surface and a standard tungsten lamp. Second, all-sky flat-field correction is carried out with an integrating sphere.
H. Fujiwara, S. Nozawa, Y. Ogawa, R. Kataoka, Y. Miyoshi, H. Jin, and H. Shinagawa
Ann. Geophys., 32, 831–839, https://doi.org/10.5194/angeo-32-831-2014, https://doi.org/10.5194/angeo-32-831-2014, 2014
K. Axelsson, T. Sergienko, H. Nilsson, U. Brändström, K. Asamura, and T. Sakanoi
Ann. Geophys., 32, 499–506, https://doi.org/10.5194/angeo-32-499-2014, https://doi.org/10.5194/angeo-32-499-2014, 2014
N. M. Schlatter, N. Ivchenko, T. Sergienko, B. Gustavsson, and B. U. E. Brändström
Ann. Geophys., 31, 1681–1687, https://doi.org/10.5194/angeo-31-1681-2013, https://doi.org/10.5194/angeo-31-1681-2013, 2013
E. Belova, S. Kirkwood, and T. Sergienko
Ann. Geophys., 31, 1177–1190, https://doi.org/10.5194/angeo-31-1177-2013, https://doi.org/10.5194/angeo-31-1177-2013, 2013
N. M. Schlatter, N. Ivchenko, B. Gustavsson, T. Leyser, and M. Rietveld
Ann. Geophys., 31, 1103–1108, https://doi.org/10.5194/angeo-31-1103-2013, https://doi.org/10.5194/angeo-31-1103-2013, 2013
K. Axelsson, T. Sergienko, H. Nilsson, U. Brändström, Y. Ebihara, K. Asamura, and M. Hirahara
Ann. Geophys., 30, 1693–1701, https://doi.org/10.5194/angeo-30-1693-2012, https://doi.org/10.5194/angeo-30-1693-2012, 2012
Related subject area
Subject: Earth's ionosphere & aeronomy | Keywords: Auroral ionosphere
Auroral breakup detection in all-sky images by unsupervised learning
Three-dimensional ionospheric conductivity associated with pulsating auroral patches: reconstruction from ground-based optical observations
The altitude of green OI 557.7 nm and blue N2+ 427.8 nm aurora
Reconstruction of precipitating electrons and three-dimensional structure of a pulsating auroral patch from monochromatic auroral images obtained from multiple observation points
Spatio-temporal development of large-scale auroral electrojet currents relative to substorm onsets
Validation of SSUSI-derived auroral electron densities: comparisons to EISCAT data
Observations of sunlit N2+ aurora at high altitudes during the RENU2 flight
Noora Partamies, Bas Dol, Vincent Teissier, Liisa Juusola, Mikko Syrjäsuo, and Hjalmar Mulders
Ann. Geophys., 42, 103–115, https://doi.org/10.5194/angeo-42-103-2024, https://doi.org/10.5194/angeo-42-103-2024, 2024
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Auroral imaging produces large amounts of image data that can no longer be analyzed by visual inspection. Thus, every step towards automatic analysis tools is crucial. Previously supervised learning methods have been used in auroral physics, with a human expert providing ground truth. However, this ground truth is debatable. We present an unsupervised learning method, which shows promising results in detecting auroral breakups in the all-sky image data.
Mizuki Fukizawa, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Tero Raita, and Kirsti Kauristie
Ann. Geophys., 41, 511–528, https://doi.org/10.5194/angeo-41-511-2023, https://doi.org/10.5194/angeo-41-511-2023, 2023
Short summary
Short summary
We use computed tomography to reconstruct the three-dimensional distributions of the Hall and Pedersen conductivities of pulsating auroras, a key research target for understanding the magnetosphere–ionosphere coupling process. It is suggested that the high-energy electron precipitation associated with pulsating auroras may have a greater impact on the closure of field-aligned currents in the ionosphere than has been previously reported.
Daniel K. Whiter, Noora Partamies, Björn Gustavsson, and Kirsti Kauristie
Ann. Geophys., 41, 1–12, https://doi.org/10.5194/angeo-41-1-2023, https://doi.org/10.5194/angeo-41-1-2023, 2023
Short summary
Short summary
We measured the height of green and blue aurorae using thousands of camera images recorded over a 7-year period. Both colours are typically brightest at about 114 km altitude. When they peak at higher altitudes the blue aurora is usually higher than the green aurora. This information will help other studies which need an estimate of the auroral height. We used a computer model to explain our observations and to investigate how the green aurora is produced.
Mizuki Fukizawa, Takeshi Sakanoi, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Björn Gustavsson, Kirsti Kauristie, Alexander Kozlovsky, Tero Raita, Urban Brändström, and Tima Sergienko
Ann. Geophys., 40, 475–484, https://doi.org/10.5194/angeo-40-475-2022, https://doi.org/10.5194/angeo-40-475-2022, 2022
Short summary
Short summary
The pulsating auroral generation mechanism has been investigated by observing precipitating electrons using rockets or satellites. However, it is difficult for such observations to distinguish temporal changes from spatial ones. In this study, we reconstructed the horizontal 2-D distribution of precipitating electrons using only auroral images. The 3-D aurora structure was also reconstructed. We found that there were both spatial and temporal changes in the precipitating electron energy.
Sebastian Käki, Ari Viljanen, Liisa Juusola, and Kirsti Kauristie
Ann. Geophys., 40, 107–119, https://doi.org/10.5194/angeo-40-107-2022, https://doi.org/10.5194/angeo-40-107-2022, 2022
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During auroral substorms, the ionospheric electric currents change rapidly, and a large amount of energy is dissipated. We combine ionospheric current data derived from the Swarm satellite mission with the substorm database from the SuperMAG ground magnetometer network. We obtain statistics of the strength and location of the currents relative to the substorm onset. Our results show that low-earth orbit satellites give a coherent picture of the main features in the substorm current system.
Stefan Bender, Patrick J. Espy, and Larry J. Paxton
Ann. Geophys., 39, 899–910, https://doi.org/10.5194/angeo-39-899-2021, https://doi.org/10.5194/angeo-39-899-2021, 2021
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The coupling of the atmosphere to the space environment has become recognized as an important driver of atmospheric chemistry and dynamics. We have validated the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) products for average electron energy and electron energy flux by comparison to EISCAT electron density profiles. The good agreement shows that SSUSI far-UV observations can be used to provide ionization rate profiles throughout the auroral region.
Pål Gunnar Ellingsen, Dag Lorentzen, David Kenward, James H. Hecht, J. Scott Evans, Fred Sigernes, and Marc Lessard
Ann. Geophys., 39, 849–859, https://doi.org/10.5194/angeo-39-849-2021, https://doi.org/10.5194/angeo-39-849-2021, 2021
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Using the RENU2 rocket and ground-based instruments, we show that significant parts of the blue aurora above Svalbard at the time of launch were sunlit aurora. A sunlit aurora occurs when nitrogen molecules are ionised by extreme UV sunlight and subsequently hit by electrons from the Sun, resulting in blue and violet emissions. Understanding the source of an auroral emission gives insight into the interaction between the Sun and the Earth's upper atmosphere.
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Short summary
We present via simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized-aurora computed tomography (G-ACT) to modeled multiple auroral images and ionospheric electron density data. It is demonstrated that G-ACT provides better reconstruction results than the normal ACT and can interpolate ionospheric electron density at a much higher spatial resolution than observed by the EISCAT_3D radar.
We present via simulation how useful monochromatic images taken by a multi-point imager network...
