The 6 September 2017 X9 super flare observed from submillimeter to mid-IR

Active Region 12673 is the most productive active region of solar cycle 24: in a few days of early September 2017, four X‐class and 27 M‐class flares occurred. SOL2017‐09‐06T12:00, an X9.3 flare also produced a two‐ribbon white light emission across the sunspot detected by Solar Dynamics Orbiter/Helioseismic and Magnetic Imager. The flare was observed at 212 and 405 GHz with the arcminute‐sized beams of the Solar Submillimeter Telescope focal array while making a solar map and at 10 μm, with a 17 arcsec diffraction‐limited infrared camera. Images at 10 μm revealed that the sunspot gradually increased in brightness while the event proceeded, reaching a temperature similar to quiet Sun values. From the images we derive a lower bound limit of 180‐K flare peak excess brightness temperature or 7,000 sfu if we consider a similar size as the white light source. The rising phase of mid‐IR and white light is similar, although the latter decays faster, and the maximum of the mid‐IR and white light emission is ∼200 s delayed from the 15.4‐GHz peak occurrence. The submillimeter spectrum has a different origin than that of microwaves from 1 to 15 GHz, although it is not possible to draw a definitive conclusion about its emitting mechanism

Photometry Of Thz Radiation Using Golay Cell Detector

The measurement of THz radiation in the continuum presents new technical challenges concerning materials, frequency filters and detection devices. We present the first results of a radiometric system using Golay cell as a detector, for the whole > 15 THz range, and at discrete frequencies centered at 2, 10 and 30 THz. The system was designed to measure solar THz radiation. It is capable to detect small solar bursts, with a large dynamic range to be able to detect larger events. © 2011 IEEE.Kaufmann, P., New telescopes for ground-based solar observations at submillimeter and mid-infrared (2008) Proc. SPIE, 7012. , Marseille, France, 23-28 June, paper 70120LKaufmann, P., Raulin, J.-P., Gimenez, D.C.C.G., Levato, H., Gary, D.E., Costa, J.E.R., Marun, A., Correia, E., A new solar burst spectral component emitting only in the terahertz range (2004) Astrophysical Journal, 603 (2 II), pp. L121-L124. , DOI 10.1086/383186Kaufmann, P., Klopf, J.M., THz Solar Telescope for Detection Flare Synchrotron Radiation, , this URSI GAKaufmann, P., Selective Spectral Detection of Continuum Terahertz Radiation (2010) Proc. SPIE, 7741. , San Diego, CA, USA, 28 June-2 July, paper 774125Kaufmann, P., Uncooled Detectors of Continuum Terahertz Radiation Proc. MOMAG 14th SBMO and 9thCBMAG, Vila Velha, ES, Brazil, 29 August-2 September, 2010, pp. 133-136Kornberg, M.A., Rough Mirror for the THz Frequency Range Proc. MOMAG 13th SBMO and 8thCBMAG, Florianópolis, SC, Brazil, 7-10 September 2008, pp. 365-367Melo, A.M., Metal Mesh Resonant Filters for THz Frequencies (2008) Applied Optics, 47 (32), pp. 6064-6069. , 10 NovemberGezari, D., Levingston, W., Varosi, F., Thermal Structure in Sunspots and Dynamic Solar Infrared Granulation Imaged at 4. 8, 12. 4, and 18. 1 Microns (1999) ASP Conference Series, 183, p. 559. , High Resolution Solar Physics: Theory, Observations, and Techniques, (ed. By T. R. Rimmele, K. S. Balasubramaniam, R. R. Radick)Marcon, R., Association of Mid-Infrared Solar Plages with Calcium K Line Emissions and Magnetic Structures (2008) PASP, 120 (863), pp. 16-19. , Januar

Spectral Trends Of Solar Bursts At Sub-thz Frequencies

Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012 – 2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5 – 40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena. © 2017, Springer Science+Business Media Dordrecht.292

Continuum Terahertz Radiation Detection Using Membrane Filters

Technology of remote sensing in the terahertz range (frequency interval arbitrarily set between 0.1-30 THz) is the object of considerable development efforts addressed to a number of new civilian and military applications. Technical challenges appear in the THz sensing of temperature differences above an existing hot surface target, such as radiation patterns produced by high energy electrons in laboratory accelerators, and thermal differentiated structures in the solar disk in space. The efficient suppression of radiation in the visible and near infrared (set arbitrarily for wavelengths < 10 μm) is an essential requirement. An experimental setup has been prepared for testing at room temperature THz materials and detectors, aiming the detection of solar radiation. A custom-made detector consisted in a room-temperature micro-bolometer INO camera with HRFZ-Si window. The THz transmission of two "low-pass" membranes were tested for black body temperatures ranging 300-1000 K: Zitex G110G and TydexBlack. It has been demonstrated that both are effective suppressors of radiation at wavelengths < 15 μm, with the first one exhibiting a small radiation excess, that may be attributed to small visible and NIR allowance. We describe optical setups prepared to detect solar radiation, consisting in a microbolometer camera preceded by a photon pipe, low-pass membrane and band-pass resonant metal mesh, placed at the focus of the 1.5 m reflector for submillimeter waves (SST) at El Leoncito, Argentina Andes. ©2009IEEE.262266Harris, D.C., (1999) Materials for Infrared Windows and Domes, , SPIE Optical Engineering Press, Washington, USA, CSiegel, P.H., THz Technology: An Overview (2003) International Journal of High Speed Electronics and Systems, 13 (2), pp. 1-44Mlynczak, M., Johnson, D., Bingham, G., Far-Infrared Spectroscopy of the Troposphere (FIRST) project (2003) Proceedings of Geoscience and Remote Sensing Symposium, 1, p. 512Sherwin, M.S., Schmuttenmaer, C.A., Bucksbaum, P.H., Proceedings of DOE-NSF-NIH Workshop on Opportunities in THz Science, Arlington, VA, 2004Kinch, M.A., Infrared detector materials (2007) SPIE Optical Engineering Press, TT76. , Washington, USA, DCStrabala, K.I., Ackerman, S.A., Menzel, W.P., Cloud Properties inferred from 8-12-μm Data (1994) Journal of Applied Meteorology, 33 (2), p. 212Williams, G.P., FAR-IR/THz radiation from the Jefferson Laboratory, energy recovered linac, free electron laser (2002) Rev. Sci. Instrum., 73, pp. 1461-1463Kaufmann, P., Raulin, J.-P., Can microbunch instability on solar flare accelerated electron beams account for bright broadband coherent synchrotronmicrowaves? (2006) Phys. Plasmas, 13. , 070701-070701-70704Klopf, J.M., 1st SMESE Workshop, 10-12 March, Paris, France, 2008Benford, D.J., Gaidis, M.C., Kooi, J.W., Optical properties of Zitex in the infrared to submillimeter (2003) Applied Optics, 42, pp. 5118-5122(2008) Technical Note on THz Materials and Components, , www.tydex.ruBlackbody Radiance, , http://spectralcalc.com/blackbody_calculator/blackbody.php, GATS, IncKaufmann, P., New telescopes for ground-based solar observations at submillimeter and mid-infrared (2008) Proc. SPIE, 7012, pp. 70120L-1-8Kornberg, M., Rough Mirrors for the THz frequency range (2008) Proc. MOMAG 2008 - 13th SBMO and 8th CBMAG, Florianópolis, SC, Brazil, pp. 365-367(2008), ESSCO, West Concord, MA, USA, private communicationMelo, A.M., Submillimeter-wave Atmospheric Transmission at El Leoncito, Argentina Andes (2005) IEEE Trans Ant. Propagat., 53, p. 1528Gezari, D.Y., Joyce, R.R., Simon, M., Measurement of the Solar Brightness Temperature at 345, 450 and 1000 micrometers (1973) Astron.Astrophys., 26, pp. 409-411Melo, A.M., Metal mesh resonant filters for terahertz frequencies (2008) Applied Optics, 47, pp. 6064-6069Ruze, J., The effect of aperture errors on the antenna radiation pattern (1953) Nuovo Cimento Suppl., 9, pp. 364-38

Selective Spectral Detection Of Continuum Terahertz Radiation

The knowledge of THz continuum spectra is essential to investigate the emission mechanisms by high energy particle acceleration processes. Technical challenges appear for obtaining selective spectral sensing in the far infrared range to diagnose radiation produced by solar flare burst emissions measured from space as well as radiation produced by high energy electrons in laboratory accelerators. Efforts are been carried out intended for the development of solar flare high cadence radiometers at two THz frequencies to operate outside the terrestrial atmosphere (i.e. at 3 and 7 THz). One essential requirement is the efficient suppression of radiation in the visible and near infrared. Experimental setups have been assembled for testing (a) THz transmission of "low-pass" filters: rough surface mirrors; membranes Zitex G110G and TydexBlack; (b) a fabricated 2.4 THz resonant grid band-pass filter transmission response for polarization and angle of incidence; (c) radiation response from distinct detectors: adapted commercial microbolometer array using HRFZ-Si window, pyroelectric module and Golay cell; qualitative detection of solar radiation at a sub-THz frequency has been tested with a microbolometer array placed at the focus of the 1.5 m reflector for submillimeter waves (SST) at El Leoncito, Argentina Andes. © 2010 SPIE.7741Harris, D.C., (1999) Materials for Infrared Windows and Domes, , SPIE Optical Engineering Press, Washington, USASiegel, P.H., THz technology: An overview (2003) International Journal of High Speed Electronics and Systems, 13 (2), pp. 1-44Mlynczak, M., Johnson, D., Bingham, G., Far-Infrared Spectroscopy of the Troposphere (FIRST) project (2003) Proceedings of Geoscience and Remote Sensing Symposium, 1, p. 512Sherwin, M.S., Schmuttenmaer, C.A., Bucksbaum, P.H., (2004) Proceedings of DOE-NSF-NIH Workshop on Opportunities in THz Science, , Arlington, VAKinch, M.A., (2007) Infrared Detector Materials, , SPIE Optical Engineering Press, TT76, Washington, USA, DCStrabala, K.I., Ackerman, S.A., Menzel, W.P., Cloud Properties inferred from 8-12-μm Data (1994) Journal of Applied Meteorology, 33 (2), p. 212Williams, G.P., FAR-IR/THz radiation from the Jefferson Laboratory, energy recovered linac, free electron laser (2002) Rev. Sci. Instrum., 73, pp. 1461-1463Kaufmann, P., Raulin, J.-P., Can microbunch instability on solar flare accelerated electron beams account for bright broadband coherent synchrotron microwaves? (2006) Phys. Plasmas, 13. , 070701-070701-4Klopf, J.M., (2008) 1st SMESE Workshop, , 10-12 March, Paris, FranceKaufmann, P., (2004) Astrophys. J., 603, pp. L121Kaufmann, P., Continuum terahertz radiation detection using membrane filters (2009) International Microwave and Optoelectronics Conference, SBMO & IEEE-MTT, pp. 262-266. , Nov. 3-6 2009, Belem, Para, BrazilBennett, H.E., Porteus, J.O., Relation between surface roughness and specular reflectance at normal incidence (1961) J. Opt. Soc.Am., 51, pp. 123-129Kostiuk, T., Deming, D., A solar infrared photometer for space flight application (1991) Infrared Physics, 32, pp. 225-233Romberg, M., Rough mirrors for the thz frequency range (2008) Proc. MOMAG 2008 - 13th SBMO and 8th CBMAG, pp. 365-367. , Florianópolis, SC, Brazil, 7-10 September 2008Benford, D.J., Gaidis, M.C., Kooi, J.W., Optical properties of Zitex in the infrared to submillimeter (2003) Applied Optics, 42, pp. 5118-5122(2008), www.tydex.ru, Tydex JSCo, St. Petersburg, Russia, Technical Note on THz materials and componentsKaufmann, P., Flare infrared experiment (FIRE) (1998) NASA Proposal to FBMS in Response to AO-98-OSS-01Melo, A.M., Metal mesh resonant filters for terahertz frequencies (2008) Applied Optics, 47, pp. 6064-6069MacDonald, M.E., Spectral transmittance of lossy printed resonant-grid terahertz bandpass filters (2000) IEEE Trans. on Microwave Theory and Techniques, 48, pp. 712-718http://www.ino.ca/en-CAKaufmann, P., New telescopes for ground-based solar observations at submillimeter and mid-infrared (2008) Proc. SPIE, 7012. , Ground-based and airborne telescopes II (ed. By L.M. Stepp and R. Gimozzi), 70120L-1-70120L-8(2008), ESSCO, West Concord, MA, USA, private communicationhttp://www.spectrumdetector.comhttp://www.tydexoptics.com/productsl/thz-optics/golay-cell

Uncooled detectors of continuum terahertz radiation

THz continuum spectral photometry has new and unique applications in different civil and military areas presenting a number of distinctive advantages on the well known microwaves or mid- to near-infrared technologies. THz sensing is essential to investigate the emission mechanisms by high energy particle acceleration processes. Technical challenges appear to diagnose radiation produced by solar flare burst emissions measured from space as well as radiation produced by high energy electrons in laboratory accelerators. THz filters and detectors have been investigated for the construction of solar flare high cadence radiometers to operate outside the terrestrial atmosphere. Experimental setups have been assembled for testing THz continuum radiation response from distinct detectors: adapted commercial microbolometer array, pyroelectric module, and opto-acoustic (Golay cell). The results permitted the final design of a THz double radiometer using Golay cells to be flown in stratosphere balloon missions

Solar-t : Terahertz Photometers To Observe Solar Flare Emission On Stratospheric Balloon Flights

A new solar flare spectral component has been found with intensities increasing for larger sub-THz frequencies, spectrally separated from the well known microwaves component, bringing challenging constraints for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A twofrequency THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. 76 mm diameter telescopes were designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions at 3 and 7 THz. Golay cell detectors are preceded by low-pass filters to suppress visible and near IR radiation, band-pass filters, and choppers. It can detect temperature variations smaller than 1 K with time resolution of a fraction of a second, corresponding to small burst intensities. The telescopes are being assembled in a thermal controlled box to which a data conditioning and acquisition unit is coupled. While all observations are stored on board, a telemetry system will forward solar activity compact data to the ground station. The experiment is planned to fly on board of long-duration stratospheric balloon flights some time in 2013-2015. One will be coupled to the GRIPS gamma-ray experiment in cooperation with University of California, Berkeley, USA. One engineering flight will be flown in the USA, and a 2 weeks flight is planned over Antarctica in southern hemisphere summer. Another long duration stratospheric balloon flight over Russia (one week) is planned in cooperation with the Lebedev Physics Institute, Moscow, in northern hemisphere summer. © 2012 SPIE.8442The Society of Photo-Optical Instrumentation Engineers (SPIE)Erickson, E.F., SOFIA: The next generation airborne observatory (1985) Space Sci. Rev., 84, pp. 91-100Poglitsch, A., The photodetector array camera and spectrometer (PACS) on the Herschel space observatory (2010) Astron. Astrophys., 518 (L2), pp. 1-12Degiacomi, C.G., Kneubühl, F.K., Huguenin, D., Far-infrared solar imaging from a balloon-borne platform (1985) Astrophys. J., 298, pp. 918-933Lawrence, J.S., Infrared and submillimeter atmospheric characteristics of high Antarctic plateau sites (2004) Publ. Astron Soc. Pacific, 116, pp. 482-492Marcon, R., Terahertz photometer to observe solar flares in continuum (2012) J. Infrared, Millimeter and Terahertz Waves, 33, pp. 192-205Marcon, R., Kaufmann, P., (2011) Método Para Maximizar Ganho Na Detecção Simultânea de Radiação de Fontes Pequenas em Campo Extenso de Visão, , Brazil Patent Application, Universidade Estadual de Campinas and Instituto Presbiteriano Mackenzie, March 30Phillips, T.G., (1988) Techniques of Submillimeter Astronomy, in Millimetre and Submillimetre Astronomy, pp. 1-25. , (Ed. by R.D. Wolstencroft and W.B. Burton), Lectures at Summer School, Stirling, Scotland, June 21-27, 1987 (Kluwer Academic Publishers, Dordrecht, NL)http://www.tydexoptics.com/pdf/Golay_cell.pdfShih, A.Y., The gamma-ray imager/polarimeter for solar flares (GRIPS) (2008) American Geophysical Union, , Fall Meeting, abstract SM11B-1602Texereau, J., (1984) How to Make A Telescope, pp. 139-175. , 2th English Edition (Wilmann-Bell Inc. Richmond, VA)Bortolucci, E.C., THz band-pass resonant metal mesh filters for a space solar photometry experiment (2012) VII SEMINATEC 2012 Workshop, , FEI, São Bernardo do Campo, SP, Brazil, 12-13 April(2012), http://www.tydexoptics.com/pdf/THz_Low_Pass_Filter.pdf(2012), http://www.eopc.com/choppers.html(2012), http://www.tydexoptics.com/new_products1/digital_golaycellhttp://www.satrunner.com/en/iridium-9602-sbd-modem.htmlhttp://www.wcclp.com/SBD.as