GRASSP: a spectrograph for the study of transient luminous events

We present the main parameters, design features, and optical characterization of the Granada Sprite Spectrograph and Polarimeter (GRASSP), a ground- based spectrographic system intended for the analysis of the spectroscopic signature of transient luminous events (TLEs) occurring in the mesosphere of the Earth. It has been designed to measure the spectra of the light emitted from TLEs with a mean spectral resolution of 0.235 nm and 0.07 nm/px dispersion in the wavelength range between 700 and 800 nm. (C) 2016 Optical Society of AmericaSpanish Ministry of Science and Innovation, Ministerio de Economia y Competitividad (MINECO) (ESP2013-48032-C5-5-R, ESP2015-69909-C5-2-R, FIS2014-61774-EXP); European Union FEDER Program; Ramon y Cajal Contract (RYC-2011-07801).Peer reviewe

Design and development of a spectrograph and polarimeter for the analysis of air plasmas produced by transient luminous events in the mesosphere of the Earth

In this work of thesis we describe the design, development and characterization of a new diagnosis instrument intended to perform systematic campaigns of simultaneous measurement of the spectrum and polarization degree of the light emitted by transient luminous events (TLEs) as a ground support to space missions ASIM (ESA) and TARANIS (CNES) to be launched by early and late 2018, respectively. The GRASSP instrument (GRAnada Sprite Spectrograph and Polarimeter) includes the rst medium{high spectrograph specifically designed for the analysis of air plasmas generated by TLEs. All versions of GRASSP have been developed and characterized by our group at the Institute of Astrophysics of Andalusia (IAA, Granada, Spain) and the Institute of Matter Structure (IEM, Madrid, Spain) laboratories, both dependencies of the National Research Council of Spain (CSIC).We have developed four di erent versions of GRASSP to date. We installed the rst (2012 { 2014) and second (2014 { 2015) versions of GRASSP at the Spanish{German Astronomic Center (CAHA) in Calar Alto, Almer a, Spain. Both worked in an autonomous way, without the support of an operator. Every sunset, the system powered on automatically, took the calibration images, opened the blinds of the system and aimed the spectrograph to the region of the sky where a TLE was more probable to appear. This could be done thanks to an aiming algorithm we developed that queried the databases of the Spanish Weather Agency (AEMET) in real-time and calculated the coordinates of the closest storm. When the system detected a change of the brightness level in the sky, an audio trigger system launched the simultaneous recording of both eld image and spectral image to store them in a data repository. This way we could discern the origin of the recorded spectra. Every sunrise, after the observation night, the algorithm closed blinds and switched o all the GRASSP subsystems. From this location we obtained the rst TLE images recorded with GRASSP, we recorded several spectra from lightning optical emissions dispersed on clouds and we had the chance of recording a meteoroid spectrum while it passed in front of GRASSP. Unfortunately, from this location we did not record any TLE spectra because of the remoteness of the storms, that occur most frequently in Spain in the Ebro Delta valley.Hence we decided to relocate our spectrograph in a new and compact version of GRASSP. We installed GRASSP versions three (2015 { 2016) and four (2016 { now) in Castellgal , Barcelona, Spain. This last compact version is currently located within the stormiest region of north-eastern Spain, with a eld of view of almost 360 degrees, and it is manually aimed by an experienced colleague (Oscar Van der Velde, from Polytechnic University of Catalonia). Since the installation of the third version of GRASSP we have recorded up to 44 medium{ high resolution TLE spectra, that allowed us to quantify, for the rst time, the (rotational) temperature of gas surrounding TLEs. It can be done through the spectral tting of the recorded spectrum to synthetic spectrum that we have modelled, thanks to the high resolution of our spectrograph (0.235 nm) that allows us to t the rovibrational bands of the nitrogen molecule. This way we can understand TLEs as natural probes of the air temperature in the Earth mesosphere. It is the rst time that systematic campaigns of spectroscopic measurements of TLEs with such high resolution have been developed (the best spectral resolution to date intended to sporadically analyze TLEs spectra is 3 nm), with the goal of feeding a database to statistically characterize the TLEs from a spectroscopic point of view in a near future. The GRASSP polarimeter is currently in calibration stage within our laboratories. It is intended to be operative from summer 2017.This work has been made possible with the nancial assistance of the Spanish Ministry of Science and Innovation, MINECO (previously MICINN) under projects AYA2009-14027-C05-02, AYA2011-29936-546-C05-02, ESP2013- 48032-C5-5-R, FIS2014-61774-EXP, ESP2015-69909-C5-2-R and FQM{5965; the European Science Foundation (ESF) Research Networking Programmes under project 09-RNP-101 and the EU through the FEDER program.Peer reviewe

Diseño e implementación de un espectrómetro y un polarímetro para la diagnosis de plasmas de aire producidos por eventos luminosos transitorios en la mesofera terrestre

In this work of thesis we thoroughly describe the design, development and characterization of a new diagnosis instrument intended to perform systematic campaigns of simultaneous measurement of the spectrum and polarization degree of the light emitted by transient luminous events (TLEs) as a ground support to space missions ASIM (ESA) and TARANIS (CNES) to be launched by early and late 2018, respectively. The GRASSP instrument (GRAnada Sprite Spectrograph and Polarimeter) includes the first medium{high spectrograph specifically designed for the analysis of air plasmas generated by TLEs. All versions of GRASSP have been developed and characterized by our group at the Institute of Astrophysics of Andalusia (IAA, Granada, Spain) and the Institute of Matter Structure (IEM, Madrid, Spain) laboratories, both dependencies of the National Research Council of Spain (CSIC). We have developed four different versions of GRASSP to date. We installed the first (2012 { 2014) and second (2014 { 2015) versions of GRASSP at the Spanish{German Astronomic Center (CAHA) in Calar Alto, Almería, Spain. Both worked in an autonomous way, without the support of an operator. Every sunset, the system powered on automatically, took the calibration images, opened the blinds of the system and aimed the spectrograph to the region of the sky where a TLE was more probable to appear. This could be done thanks to an aiming algorithm we developed that queried the databases of the Spanish Weather Agency in real-time and calculated the coordinates of the closest storm. When the system detected a change of the brightness level in the sky, an audio trigger system launched the simultaneous recording of both field image and spectral image to store them in a data repository. This way we could discern the origin of the recorded spectra. Every sunrise, after the observation night, the algorithm closed blinds and switched off all the GRASSP subsystems. From this location we obtained the first TLE images recorded with GRASSP, we recorded several spectra from lightning optical emissions dispersed on clouds and we had the chance of recording a meteoroid spectrum while it passed in front of GRASSP. Unfortunately, from this location we did not record any TLE spectra because of the remoteness of the storms, that occur most frequently in Spain in the Ebro Delta valley. Hence we decided to relocate our spectrograph in a new and compact version of GRASSP. We installed GRASSP versions three (2015 { 2016) and four (2016 { now) in Castellgallí, Barcelona, Spain. This last compact version is currently located within the stormiest region of north-eastern Spain, with a field of view of almost 360 degrees, and it is manually aimed by an experienced colleague (Oscar Van der Velde, from Polytechnic University of Catalonia). Since the installation of the third version of GRASSP we have recorded up to 44 medium{high resolution TLE spectra, that allowed us to quantify, for the first time, the (rotational) temperature of gas surrounding TLEs. It can be done through the spectral fitting of the recorded spectrum to synthetic spectrum that we have modelled, thanks to the high resolution of our spectrograph (0.235 nm) that allows us to fit the rovibrational bands of the nitrogen molecule. This way we can understand TLEs as natural probes of the air temperature in the Earth mesosphere. It is the first time that systematic campaigns of spectroscopic measurements of TLEs with such high resolution have been developed (the best spectral resolution to date intended to sporadically analyze TLEs spectra is 3 nm), with the goal of feeding a database to statistically characterize the TLEs from a spectroscopic point of view in a near future. The GRASSP polarimeter is currently in calibration stage within our laboratories. It is intended to be operative from summer 2017.Tesis Univ. Granada. Programa Oficial de Doctorado en: Física y Ciencias del EspacioThis work has been made possible with the nancial assistance of the Spanish Ministry of Science and Innovation, MINECO (previously MICINN) under projects AYA2009-14027-C05-02, AYA2011-29936-546-C05-02, ESP2013- 48032-C5-5-R, FIS2014-61774-EXP, ESP2015-69909-C5-2-R and FQM{5965; the European Science Foundation (ESF) Research Networking Programmes under project 09-RNP-101 and the EU through the FEDER program

Diseño e implementación de un espectrómetro y un polarímetro para la diagnosis de plasmas de aire producidos por eventos luminosos transitorios en la mesofera terrestre

In this work of thesis we thoroughly describe the design, development and characterization of a new diagnosis instrument intended to perform systematic campaigns of simultaneous measurement of the spectrum and polarization degree of the light emitted by transient luminous events (TLEs) as a ground support to space missions ASIM (ESA) and TARANIS (CNES) to be launched by early and late 2018, respectively. The GRASSP instrument (GRAnada Sprite Spectrograph and Polarimeter) includes the first medium{high spectrograph specifically designed for the analysis of air plasmas generated by TLEs. All versions of GRASSP have been developed and characterized by our group at the Institute of Astrophysics of Andalusia (IAA, Granada, Spain) and the Institute of Matter Structure (IEM, Madrid, Spain) laboratories, both dependencies of the National Research Council of Spain (CSIC). We have developed four different versions of GRASSP to date. We installed the first (2012 { 2014) and second (2014 { 2015) versions of GRASSP at the Spanish{German Astronomic Center (CAHA) in Calar Alto, Almería, Spain. Both worked in an autonomous way, without the support of an operator. Every sunset, the system powered on automatically, took the calibration images, opened the blinds of the system and aimed the spectrograph to the region of the sky where a TLE was more probable to appear. This could be done thanks to an aiming algorithm we developed that queried the databases of the Spanish Weather Agency in real-time and calculated the coordinates of the closest storm. When the system detected a change of the brightness level in the sky, an audio trigger system launched the simultaneous recording of both field image and spectral image to store them in a data repository. This way we could discern the origin of the recorded spectra. Every sunrise, after the observation night, the algorithm closed blinds and switched off all the GRASSP subsystems. From this location we obtained the first TLE images recorded with GRASSP, we recorded several spectra from lightning optical emissions dispersed on clouds and we had the chance of recording a meteoroid spectrum while it passed in front of GRASSP. Unfortunately, from this location we did not record any TLE spectra because of the remoteness of the storms, that occur most frequently in Spain in the Ebro Delta valley. Hence we decided to relocate our spectrograph in a new and compact version of GRASSP. We installed GRASSP versions three (2015 { 2016) and four (2016 { now) in Castellgallí, Barcelona, Spain. This last compact version is currently located within the stormiest region of north-eastern Spain, with a field of view of almost 360 degrees, and it is manually aimed by an experienced colleague (Oscar Van der Velde, from Polytechnic University of Catalonia). Since the installation of the third version of GRASSP we have recorded up to 44 medium{high resolution TLE spectra, that allowed us to quantify, for the first time, the (rotational) temperature of gas surrounding TLEs. It can be done through the spectral fitting of the recorded spectrum to synthetic spectrum that we have modelled, thanks to the high resolution of our spectrograph (0.235 nm) that allows us to fit the rovibrational bands of the nitrogen molecule. This way we can understand TLEs as natural probes of the air temperature in the Earth mesosphere. It is the first time that systematic campaigns of spectroscopic measurements of TLEs with such high resolution have been developed (the best spectral resolution to date intended to sporadically analyze TLEs spectra is 3 nm), with the goal of feeding a database to statistically characterize the TLEs from a spectroscopic point of view in a near future. The GRASSP polarimeter is currently in calibration stage within our laboratories. It is intended to be operative from summer 2017.Tesis Univ. Granada. Programa Oficial de Doctorado en: Física y Ciencias del EspacioThis work has been made possible with the nancial assistance of the Spanish Ministry of Science and Innovation, MINECO (previously MICINN) under projects AYA2009-14027-C05-02, AYA2011-29936-546-C05-02, ESP2013- 48032-C5-5-R, FIS2014-61774-EXP, ESP2015-69909-C5-2-R and FQM{5965; the European Science Foundation (ESF) Research Networking Programmes under project 09-RNP-101 and the EU through the FEDER program

Experimental Radial Profiles of Early Time (<4 μs) Neutral and Ion Spectroscopic Signatures in Lightning-Like Discharges

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivsLicense, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.This study presents experimental results for the radial and temporal variation of neutral and ion spectroscopic signatures emerging from the heated channel of lightning-like discharges diagnosed with a high speed (900,000 fps) imaging spectrograph. Light emissions emanate from three regions: an inner core (up to ∼2 mm), an external sheath (up to ∼4 mm) featuring a sudden temperature increase, and further optical emissions forming a dim glow from 4 mm up to 16 mm. The optical emissions are initially (<1.11 μs) dominated by the N2 first positive system at 660.8 nm and by the N II ion line at 661.05 nm. Between 1.11 and 3.33 μs the optical emissions are dominated by Hα (656.3 nm) and O II ion (656.54 nm) lines. The N II ion line at 648.20 nm prevails in the outer dim glow region (9–12 mm) before 2.22 μs. Spectroscopic signals were used to experimentally derive the time dynamics of the electron density and electron/gas temperature radial profiles, which allowed the estimation of the early time overpressure pulse, electrical conductivity and concentrations of key molecular species (N2, NO, O2, OH, H2, N2O, NO2, HO2, O3, and H2O) along the radial axis of the heated air plasma channel. These populations were calculated from the overpressure pulse, assuming that they were produced from humid (50%) air under thermal equilibrium conditions. OH is found to be the second most abundant molecular species (after NO) directly generated by heated lightning-like channels. © 2022. The Authors.This work has received funding from the European Union Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement SAINT 722337. Additionally, this work was supported by the Spanish Ministry of Science and Innovation, MINECO, under project PID2019-109269RB-C43 and FEDER program. M. Passas-Varo, F. J. Gordillo-Vázquez, J. Sánchez, and N. Kieu acknowledge financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa's award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709).Peer reviewe

Spectroscopic diagnostics of laboratory air plasmas as a benchmark for spectral rotational (gas) temperature determination in TLEs

13 p.: gráf.We have studied laboratory low pressure (0.1 mbar ≤ p ≤2 mbar) glow air discharges by optical emission spectroscopy to discuss several spectroscopic techniques that could be implemented by field spectrographs, depending on the available spectral resolution, to experimentally quantify the gas temperature associated to transient luminous events (TLEs) occurring at different altitudes including blue jets, giant blue jets, and sprites. Laboratory air plasmas have been analyzed from the near UV (300 nm) to the near IR (1060 nm) with high (up to 0.01 nm) and low (2 nm) spectral resolution commercial grating spectrographs and by an in-house intensified CCD grating spectrograph that we have recently developed for TLE spectral diagnostic surveys with ≃0.45 nm spectral resolution. We discuss the results of lab tests and comment on the convenience of using one or another technique for rotational (gas) temperature determination depending on the altitude and available spectral resolution. Moreover, we compare available low resolution (3 nm ≤Δλ≤7 nm) N2 1PG field recorded sprite spectra at 53 km (≃1 mbar), and resulting vibrational distribution function, with 1 mbar laboratory glow discharge spectrum (Δλ=2 nm) and synthetic sprite spectra from models. We found that while the relative population of N2(B3Πg,v=2−7) in sprites and laboratory produced air glow plasmas are similar, the N2(B3Πg,v=1) vibrational level in sprites is more efficiently populated (in agreement with model predictions) than in laboratory air glow plasmas at similar pressures.Supported by the Spanish Ministry of Science and Innovation, MINECO under projects AYA2011-29936-C05-02, CSD2009-00038, and FIS2010-16455 and by the Junta de Andalucia, Proyecto de Excelencia FQM-5965. MINECO for a FPI grant BES-2010-042367. support by a Ramón y Cajal contract, code RYC-2011-07801. support by a Juan de la Cierva contract, code JdC-2009-04949.Peer reviewe

IAA : Información y actualidad astronómica (48)

El número contiene las siguientes contribuciones: Rayos en el Sistema Solar.--Galaxias activas: alimentando al monstruo.--Estrellas de la población III.--Planetas azules en torno a estrellas rojas.--Cien años de agujeros negros.--La imagen con mayor resolución de la historia de la astronomía muestra las entrañas de un núcleo galáctico.--La concentración de dióxido de carbono también aumenta en la alta atmósfera.--Se cuestionan los resultados obtenidos hasta ahora en el estudio de estrellas pulsantes.--Estudian la historia de la galaxia Andrómeda a través de sus cadáveres estelares.--Rosetta confirma que el cometa 67P se formó por la fusión de dos objetos.--Sala limpia.--El origen del universo.--Destacados.La página web de esta revista ha sido financiada por la Sociedad Española de Astronomía (SEA).N

IAA : Información y actualidad astronómica (68) (2022)

En busca de las estrellas perdidas del centro de la Vía Láctea.- No solo Thor dispara rayos de tormenta.-Historias ... ¿Qué podría salir mal?.- Deconstrucción. Las mujeres de la Luna.- El Moby Dick de ... Silbia López de Lacalle (IAA-CSIC).- Actualidad.Este número ha contado con el apoyo económico de la Agencia Estatal de Investigación (Ministerio de Ciencia, Innovación y Universidades) a través de la acreditación de Centro de Excelencia Severo Ochoa para el Instituto de Astrofísica de Andalucía (SEV-2017-0709). La página web de esta revista ha sido financiada por la Sociedad Española de Astronomía (SEA).Peer reviewe

Galius: an ultrafast imaging spectrograph for the study of lightning

We present the main parameters, design features, and optical characterization of the GrAnada LIghtning Ultrafast Spectrograph (GALIUS): a portable, ground-based spectrographic system intended for analysis of the spectroscopic signature of lightning. It has been designed to measure the spectra of the light emitted from natural and triggered lightning and artificial electrostatic discharges at recording speeds up to 2.1 Mfps. It includes a set of four interchangeable grisms covering different spectral ranges (from 375 nm to 854.5 nm) with spectral resolutions from 0.29 nm to 0.76 nm. A set of 10 collector lenses allows the recording of the spectrum of electrostatic discharges and lightning in different scenarios. © 2019 Optical Society of AmericaMinisterio de Economia y Competitividad (ESP2017-86263-C4-4-R); Agencia Estatal de Investigacion (SEV-2017-0709); H2020 Marie Sklodowska-Curie Actions (722337).Peer reviewe

Diagnosis de plasmas de aire en laboratorio como banco de prueba para la obtención de la temperatura del gas en plasmas de aire generados por Eventos Luminosos Transitorios

Peer Reviewe