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ISSN 0038 0946, Solar System Research, 2011, Vol. 45, No. 2, pp. 162­173. © Pleiades Publishing, Inc., 2011. Original Russian Text © S.V. Kuzin, I.A. Zhitnik, S.V. Shestov, S.A. Bogachev, O.I. Bugaenko, A.P. Ignat'ev, A.A. Pertsov, A.S. Ulyanov, A.A. Reva, V.A. Slemzin, N.K. Sukhodrev, Yu.S. Ivanov, L.A. Goncharov, A. V. Mitrofanov, S.G. Popov, T.A. Shergina, V.A. Solov'ev, S.N. Oparin, A.M. Zykov, 2011, published in Astronomicheskii Vestnik, 2011, Vol. 45, No. 2, pp. 166­177.

The TESIS Experiment on the CORONAS PHOTON Spacecraft
S. V. Kuzina, I. A. Zhitnika, S. V. Shestova, S. A. Bogacheva, O. I. Bugaenkob, A. P. Ignat'eva, A. A. Pertsova, A. S. Ulyanova, A. A. Revaa, V. A. Slemzina, N. K. Sukhodreva, Yu. S. Ivanova, L. A. Goncharova, A. V. Mitrofanova, S. G. Popova, T. A. Sherginaa, V. A. Solov'eva, S. N. Oparina, and A. M. Zykova
b

Sternberg State Astronomical Institute, Moscow, Russia Lebedev Physics Institute of the Russian Academy of Sciences, Moscow, Russia
Received April 13, 2010

a

Abstract--On February 26, 2009, the first data was obtained in the TESIS experiment on the research of the solar corona using imaging spectroscopy. The TESIS is a part of the scientific equipment of the CORONAS PHO TON spacecraft and is designed for imaging the solar corona in soft X ray and extreme ultraviolet regions of the spectrum with high spatial, spectral, and temporal resolutions at altitudes from the transition region to three solar radii. The article describes the main characteristics of the instrumentation, management features, and operation modes. DOI: 10.1134/S0038094611020110

INTRODUCTION The research of the solar corona is an important problem in solar physics and in astrophysics in gen eral. Many of the key questions of this study (the mechanism of solar flares, coronal heating physics, and the origin of coronal mass ejections) are still unanswered. Manifestations of the solar activity regis tered in the corona affect the state of the interplane tary medium, the outer ionosphere, and magneto sphere of the Earth. Therefore, their study is not only of fundamental but also practical importance. In the early 1990s, a solar research program was launched in Russia called CORONAS (Complex Orbital Observations Near Earth of Activity of the Sun), which was conceived during the Soviet era. Three satellites were scheduled to be launched during this program to study the solar activity, monitoring of the interplanetary medium, and detection of the radi ation outside the solar atmosphere in different spectral ranges and accelerated flare particles. The first satellite of this series, CORONAS I, was launched in the summer of 1994 and spent several months in orbit (Sobelman et al., 1996). The second satellite, CORONAS F, was launched in the summer of 2001 (Oraevskii, Sobelman, 2002) and worked suc cessfully until the end of 2005. On January 30, 2009, the third spacecraft within the Coronas program, the satellite CORONAS PHOTON, was launched into Earth's orbit (Kotov, 2004). The scientific complex in the satellite includes 12 instruments designed to study various manifestations of the solar activity in wide spectral and energy ranges. The scientific manage ment of the project is carried out by the National

Research Nuclear University at the Moscow Engi neering Physics Institute. For the three satellites of the CORONAS project, complexes of equipment were developed at the Lebe dev Physical Institute for the research of the solar corona using imaging spectroscopy of the Sun in soft X ray (SXRR) and extreme ultraviolet (EUV) ranges of wavelengths, providing a full registration of the disc with high spatial, spectral, and temporal resolution. The principle point in the method of imaging spec troscopy is the registration of monochromatic images in different spectral lines of the short range spectrum. This allows us to determine plasma parameters (tem perature, density, abundance of elements, etc.) of the solar corona with high accuracy characteristic of spec tral methods. THE TESIS EXPERIMENT For the CORONAS PHOTON spacecraft a com plex of telescopes and spectrometers named TESIS was designed at the Lebedev Physical Institute, the main purpose of which is the research of the solar corona and transition region of the Sun with high tem poral, spatial, and spectral resolutions. Among the objectives of the TESIS experiment are the study of the mechanisms of accumulation and release of energy in the solar atmosphere, the study of active solar processes (flares and mass ejections), and diagnostics of physical conditions in the coronal and flare plasmas. The TESIS has high spatial (up to 1.7) and temporary (up to 1 s) resolutions, makes it possi ble to conduct observations both in the lower atmo

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THE TESIS EXPERIMENT ON THE CORONAS PHOTON SPACECRAFT TESIS features Recording channel, wavelength, å 132 171 171 304 304 Optical scheme Herschel Telescope Herschel Telescope Spectro heliograph Angular pixel size, ang. 1.71 Field of view, ang. deg. 1 Selectivity, / 26 (132 å) 28 (171 å) 28 (171 å) 30 (304 å) 7, dispersion ­ 2.9 â 10­2 å/pixel 7

163

F, mm

Dominant ions

The shape Mirror size, of the mirror mm surface Off axis parabola ü100

1630

Fe XIX, Fe XX, Fe XXIII (132 å) Fe IX (171 å)

1630 600

1.71 4.6 (in the direction of dispersion) 4.6

1 2

Off axis Fe IX (171 å) He II, Si XI (304 å) parabola Fe XV, Ni XVIII, Axial Si IX, Ca XVIII, parabola Si XI, He II, Mg VIII . He II, Si XI Axial parabola

ü100 ü80

304

Ritchey­ ChrÈtien

600

2

Primary, 80/20, secondary, 40/10 120 â 80

8.42

Spectro 1200 heliograph

2.3

1.3

210, dispersion ­ 3.8 â 10­4 å/pixel

Mg XII

Sphere

Sphinx

Solid Si spectrometer, 0.5­15 keV

sphere of the Sun and at large distances from its sur face (up to three radii), and also to investigate the plasma over a wide spectral range with high resolution (up to 0.01 å). The TESIS consists of the main unit (MU), block of electronics (BE), and the block of star detectors (BOD). The main unit is the basic block containing scientific equipment for recording solar images and short range spectra. The block of electronics includes a central processor, memory, and electronic interfaces to connect the main unit and block of star detectors, as well as to establish connection with satellite support systems. The star sensor consists of two coaxial contra directional telescopes with the axis of sight, perpen dicular to the axis of the Sun, and is used to determine the current orientation of the instrumentation of TESIS and ESV CORONAS PHOTON. The TESIS scientific instrumentation includes the following six independent channels of registration: (1) telescopes of the EUV range, (2) spectrohelio graphs of soft X ray and EUV ranges, and (3) the X ray spectrometer photometer SphinX (Sylwester et al., 2008). Key features of TESIS recording channels are given in the table. The scheme of the TESIS main unit is shown in Fig. 1.
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PURPOSE AND STRUCTURE OF THE TESIS High Resolution Telescopes High resolution TESIS telescopes are designed to record images of the solar corona in certain intervals of the EUV spectral range. Spectral ranges are chosen specifically for observing structures of the solar atmo sphere over a wide temperature range, i.e., from the transition region (50 000 K, the line of He II 304 å) to the "quiet" corona (~1 million K, the line of Fe IX 171 å) and the hot flare plasma (10­20 million K, the lines of Fe XX, XXI, XXIII 132 å). In the TESIS, two independent channels are used. The first is at wavelengths of 132 and 171 å, and the second at wavelengths of 171 and 304 å. In the first channel, the image is formed simultaneously in two regions of the spectrum, in the second channel the selection of the spectral region is conducted by the rotation of the additional aperture. Both telescopes are based on the Herschel optical scheme with off the axis aspheric mirrors of large aperture. The asphericity of mirrors is made by apply ing the multilayer coating with a specified profile to spherical substrates. On the top of aspherical coatings, multilayer coatings are applied that selectively reflect certain intervals of the EUV range. The schematic dia gram of the telescope channels of the TESIS are shown in Fig. 2.


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KUZIN et al. Mirror of the telescope Mirror of the telescope in 171 and 304 å in 132/171 å

Mg XII spectroheliograph mirror

X ray spectrometer photometer Sphinx

EUV range spectroheliograph

Telescope of the wide field of view
Fig. 1. The scheme of the TESIS main unit.

The first channel with ranges of 132 å and 171 å is designed primarily to study small scale structures and dynamics of the hot flare plasma (10­20 million K) by images in the lines of Fe XX, XXI, and XXIII near 132 å. Since such a plasma is present not on the whole solar disk, but only in selected compact areas (Zhitnik et al., 2003), the image of the "quiet" corona obtained in a cold iron line Fe IX (0.9 million K) close to 171 å is used to determine its position on the solar disk. The second channel of the telescope is designed for observing small scale structures and dynamics of the "quiet" corona (the line Fe IX X 171 å) and the transition region (the line He II 304 å). In the telescopes, normal incidence mirrors with an aperture D = 100 mm are used, the extra axial off set of mirrors is h = 110 mm, and the focal length of the telescopes is F = 1630 mm. The angular size of 1 pixel is approximately ~1.707. The Telescope Coronagraph of the Wide Field of View The telescope coronagraph of the wide field of view is designed to monitor the far solar corona in the EUV range. The telescope is based on the Ritchey­ Chretien optical scheme with two aspherical multi layer mirrors and a detector of images based on the backside CCD. The schematic diagram of the tele

scope is shown in Fig. 3. The telescope has a field of view of 2°, the diameter of the primary mirror is DP = 80/20 mm (outer/inner diameter), the diameter of the secondary mirror is DS = 40 mm, the distance between the tops of the mirrors is l = 225 mm, and the operat ing distance is = 30 mm (the offset of the detector plane from the primary mirror). With such an optical system, the effective focal length is F = 620 mm and the angular size of the first pixel is 4.6. The operating spectral range of the telescope near the 304 å depends on the used multilayer mirrors with coatings on the basis of Mo/Si structure. In contrast to high resolution telescopes of the TESIS, in this chan nel the asphericity of mirrors was made due to the form of the substrate. On the CCD matrix after the Al, an additional Sc filter was also applied to block rela tively strong emission of the solar disk in the line HeII 304 å. Spectroheliograph Mg XII The spectroheliograph Mg XII of the TESIS is designed for recording monochromatic images of the solar corona in the spectral lines of a Mg XII = 8.42 å hydrogen ion . Since the radiation of this line occurs in a sufficiently hot plasma (T > 5 MK), the spectrohe liograph will record direct images only of hot plasma
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THE TESIS EXPERIMENT ON THE CORONAS PHOTON SPACECRAFT
Multilayer mirror with coatings on the ranges 171 and 304 å Channels 171 and 304 å Range switch Filters Detector

165

Channels 132/171 å

Multilayer mirror with coatings on the ranges 171 and 304 å

Filters

Detector

Fig. 2. The optical scheme of telescopes 132/171 å and 171/304 å.

not mixed with the image of colder "quiet" corona (Zhitnik et al., 2003). The spectroheliograph Mg XII of the TESIS is an improved analog of the X ray spectroheliograph of the ESV CORONAS F, data from which were successfully used to study the active flare processes (Zhitnik et al., 2003; Urnov et al., 2007; Shestov et al., 2010). An extremely important feature of the Mg XII channel is its monochromaticity, due to high selectiv ity and lack of other strong lines in the solar spectrum near the Mg XII line. The dependence of the emission intensity of the Mg XII line on the temperature and density of plasma are known with good accuracy. Thus, it is possible to make simultaneous observations with the telescope at 132 å and more accurate diag nostics of the observed phenomena. The principal optical scheme of the spectrohelio graph Mg XII is shown in Fig. 4. The incoming radia tion passes through a prefilter and falls on a spherically curved crystal mirror. The incident radiation is dif fracted on the mirror according to Bragg's law and focuses on the detector. The image detector is a back illuminated CCD matrix. The curvature radius of the mirror is R = 2710 mm, the operating wavelength is = 8.42 å, and the crystal mirror is made in such a way that the operating 2d = 8.501 å. The incidence angle in such a scheme is 8.2°, while the angular size of one pixel is 2.1. According to the Bragg condition of diffraction, a reflection of a parallel beam occurs not on the entire surface of the mirror, but on a separate band, the posi tion and size of which are determined by the angle of
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incidence and its spectral composition. The spherical aberration inherent in this scheme leads to the fact that the focus of lines of the doublet Mg XII = 8.419 and = 8.426 å occurs at different points, which makes it possible to resolve the doublet and measure the characteristics of its individual components. The EUV Range Spectroheliograph The EUV range spectroheliograph is designed to record a series of monochromatic images of the Sun in the spectral lines of the range 280­330 å. A feature of this spectroheliograph is a combination of spectro scopic and imaging properties in one device, which allow for a high precision plasma diagnostics of sepa rate compact structures of the solar corona. The spectroheliograph is developed on the basis of a gapless scheme with a glide incidence grating. The optical scheme of the spectroheliograph is shown in Fig. 5. The incident radiation passes through the pre filter, falls at a small glancing angle (~1.5 ) on a dif fraction grating, diffracts, gets on the multilayer Mo/Si mirror, and is focused on the detector, i.e., on the CCD matrix with a filter. With such an optical scheme, a sequence of monochromatic solar images is constructed on the detector in separate spectral lines of the operating range, shifted along the dispersion, and compressed in this direction (see Fig. 5). In the spectroheliograph, a diffraction grating with the line density of 3600 l/mm and of the size of 80 â 210 mm, the multiaspheric mirror with F = 600, and free aper ture D = 80 mm is used. The spectroheliograph is


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Detector

Filter

Primary mirror

Secondary Filter mirror

Fig. 3. The optical scheme of the telescope­coronagraph.

Crystal Mirror Filters Detector

Fig. 4. The optical scheme of the Mg XII spectroheliograph.

designed to operate at wavelengths of ~ 280­330 å. The variance is 0.0285 å/pixel. Similar spectroheliographs successfully operated on the ESV CORONAS I in the wavelength range 180­ 206 å (Zhitnik et al., 1998) and on the CORONAS F, where there were two spectroheliographs for ranges 176­207 å and 280­330 å (Beigman et al., 2005). Due to the field of view of more than 1°, containing the entire solar disk, during the SPIRIT experiment on the ESV CORONAS F (2001­2005) more than 100 spectra of flares were recorded, including more than 30 spectra of powerful solar flares of the X level. These observations were used to catalog the spectral lines (Beigman et al., 2005; Shestov et al., 2008), determine the plasma density and temperature struc ture in active regions and flares (Shestov et al., 2009; 2010). The EUV spectroheliograph of the TESIS is an improved version of the spectroheliograph 280­330 å, which was on the ESV CORONAS F. It uses a mirror of increased aperture, i.e., a more sensitive detector based on the back illuminated CCD matrix. The operating spectral range 280­330 å contains spectral

lines of various ions, together covering a wide range of temperatures, i.e., from the temperature of the transi tion region (T ~ 50 000 K, He II = 303.8 å), to high temperature flare plasma (T ~ 20 M K, Ca XVIII = 302.3 å, Fe XXII = 292.3 å). Star detectors The ESV CORONAS PHOTON has a uniaxial orientated system, i.e., its Z axis is directed toward the center of the Sun. To determine the angle of rotation of the satellite around the Z axis and image registra tion, obtained from TESIS telescopes, to the solar coordinate system, star detectors are used, which are a part of the equipment complex. The sensors record the stellar sky in a field of view ~7°. The determination of the rotation angle of the satellite is performed on the Earth by linking images obtained by star detectors to the map of the starry sky. Figure 6 shows the dependence of the rotation angle around the Z axis of the satellite on time in Sep tember 2009. During this period, data from star detec
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THE TESIS EXPERIMENT ON THE CORONAS PHOTON SPACECRAFT

167

Multilayer mirror Filter

Image Source


1

2

Diffraction grating Detector
1 2

Diffraction grating

Fig. 5. The optical scheme of the EUV range spectroheliograph.

tors came every 10 minutes, and the accuracy of the rotation angle determination was ~0.5. The Electronic System of the TESIS Instrumentation The TESIS includes a complex system of electron ics, which includes a CPU (central processing unit), RAM (random access memory), controllers of sen sors and motors, interfaces for switching to satellite service systems, secondary power sources, and others. The onboard computer, the basic elements of which are the CPU, RAM, and switching interfaces, is located in the TESIS block of electronics and is in a pressurized compartment of the ESV CORONAS PHOTON. The main unit and star detectors of the TESIS contain image detectors, including controllers, actuators, and temperature sensors. The TESIS onboard computer is designed to con trol the channels of registration, mechanics, and driv ers of the TESIS, as well as to handle, temporarily store, and transfer the obtained information to the SCRSI (the system of collecting and recording scien tific information). Its main processor is a digital signal processor (DSP) ADSP2185 made by AnalogDevices (64 Mips). The minimum set of system software, the so called BIOS, designed to interact with onboard systems, is located in the one time programmable ROM with a capacity of 2 KB. EPROM (erasable pro grammable read only memory) of a capacity of 128 kilobytes is used for operating control programs in the TESIS. A large amount of ROM makes it possible to store four copies of the software in memory, or even four different instances of operation programs, which can be selected by ground commands. The TESIS
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main memory of a capacity of 256 MB is designed to receive and process the information from the CCD matrices and SphinX channel detectors. It may also serve as an intermediate buffer for the transfer of accu mulated data in the SCRSI. The internal logic (for the interaction with onboard systems; and CCD, drive, and memory controllers) is implemented using the one time programmable CDLP 54SXR32A made by Actel. The link between the TESIS onboard computer and peripherals, located in the main unit and star detectors, is performed using serial communication links with a capacity of 8 Mbps. The speed of the TESIS CPU and architecture used make it possible for
250 Rotation angle, deg. 20 150 100 50

0 11.09.2009 21.09.2009 01.10.2009 01.09.2009 06.09.2009 16.09.2009 26.09.2009 Date, September, 2009
Fig. 6. The dependence of the rotation angle of the ESV CORONAS PHOTON around the Z axis according to the star sensor of the TESIS.


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all peripheral devices to operate simultaneously and independently. The onboard software is intended for the process ing and compression of images and service informa tion, as well as their packaging for the transmission to satellite service systems. OPTICAL EQUIPMENT OF THE TESIS INSTRUMENTATION As focusing elements in the TESIS multilayer mir rors of normal incidence (for the EUV range of about 132, 171, and 304 å) and crystal focusing mirror of normal incidence (in the range of 8.42 å) are used. Image detectors of the TESIS are based on backside CCD matrices of the format of 2048 â 2048 px. To block the intense radiation of the visible range in the TESIS, a double filtration system based on multilayer thin film filters is used. Normal Incidence Multilayer Mirrors In telescopic channels of the TESIS, wide aper ture aspherical mirrors with a multilayer reflective coating are used. Mirrors have a free aperture of 100 mm and the radius of curvature at the top of 3250 mm. The asphericity of substrates and deposition of multi layer reflective coatings were carried out at the Insti tute for Physics of Microstructures of the Russian Academy of Sciences (Nizhni Novgorod). The asphe ricity was conducted with an additional compensating deposition (Zuev et al., 2008b). For this purpose, a Cr/Sc multilayer coating with a given distribution of thickness across the aperture was deposited on the mirror substrate surface by the magnetron deposition method. In previous experiments of the Lebedev Physical Institute on CORONAS satellites, telescopic images, taken in a broad spectral range, were complemented by spectroheliograms with lower space but signifi cantly higher spectral resolution. Most channels of the TESIS are telescopic. Thus, to implement the method of imaging spectroscopy, new multilayer coatings on very narrow spectral intervals were developed at the Institute for Physics of Microstructures (Zuev et al., 2008b). The use of mirrors with such coatings in TESIS telescopes makes it possible to conduct accu rate diagnostics of plasma by spectroscopic methods by telescopic images with high spatial resolution. The choice of operating spectral ranges of mirrors was determined by the major scientific objectives of TESIS telescopes. The feature of the TESIS experi ment is the use of mirrors with a relatively narrow operating spectral ranges ( ~ 2 5 ), which, in turn, requires a high peak reflection factor of multilayer coatings.

The coverage for a range near 132 å was performed on the basis of a Mo/Si multilayer structure. The mea surement of the peak reflectivity factor of mirrors and its spectral selectivity, conducted at the Institute for Physics of Microstructures, gave the following results: R 64%, ~ 2 6 . The coating for a range near 171 å is a Al/Zr mul tilayer structure. The peak reflectivity factor and spec tral selectivity were R 56% / ~ 28, respectively. Traditionally, for the spectral range near 304 å coatings, the basis of Mo/Si structures are used. How ever, such structures have a low spectral selectivity ~1 0 . For mirrors of the range of 304 å of the TESIS instrumentation of the Institute for Physics of Microstructures, a new multilayer coating based on the Si/Cr/Mg/B4C structure were specially developed. Measurements of the peak reflectivity factor and spec tral selectivity, conducted at the Institute for Physics of Microstructures, gave the following results: R 30%, ~ 30. To perform spectroscopic diagnostics of plasma in the solar corona by telescope observations, informa tion is required about the relative spectral efficiency of the mirrors near the central wavelength. The measure ment of these parameters was conducted at the Lebe dev Physical Institute (Vishnyakov et al., 2009). The measured spectral characteristics of the mirrors are shown in Fig. 7. Crystal Focusing Mirror For imaging at wavelengths = 8.42 å in the Mg XII spectroheliograph of the TESIS, a crystal focusing mirror is used. The mirror is a thin (0.4 mm) plate of crystalline quartz, mounted by the optical contact method on the spherical substrate with a radius of cur vature of 2700 mm. The crystalline quartz plate was made in such a way that its operating crystallographic plane [10.0] with 2d = 8.501 å is parallel to the geo metric surface of the crystal with high accuracy (local divergence ~5). The mirror has a rectangular shape 80 â 100 mm. The mirror substrate and crystal were made at the Lebedev Physical Institute, and the depo sition of the crystal on the substrate was made at the Institute for Physics of Microstructures. The effectiveness of the reflection of the mirror at the operating wavelength was measured at the syn chrotron source in Beijing, China (Kuzin et al., 2009). The peak reflectivity factor was 10%, and the effective surface area was 2.5 cm2. Image Detectors Image detectors of the TESIS were made on the basis of backside CCD matrices of the format of 2048 â 2048 px. CCD matrices CCD42 40, manufactured by
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THE TESIS EXPERIMENT ON THE CORONAS PHOTON SPACECRAFT 132 å--Mo/Si 1.0 0.8 Reflectivity Reflectivity 0.6 0.4 0.2 0 100 120 140 , å 160 180
Fe XXI Fe XXI Fe XXII Fe XX Fe XX Fe XX Fe XXIII

169

171 å--Al/Zr 1.0 0.8 Reflectivity 0.6 0.4 0.2 0 150 160 170 180 190 200 , å
Fe X Fe XI Fe XII Fe X Fe XI Fe XII Fe XII Fe X Fe IX

304 å--Si/Mg/B4C 1.0 0.8 0.6 0.4 0.2 0 240 260 280 300 320 340 360 , å
Fe XVI Fe XIV SX Si XI Fe XVI Fe XV

He II

Fig. 7. The spectral characteristics of mirrors of TESIS telescopes close to operating wavelengths. The strongest spectral lines of ranges are indicated.

e2v (United Kingdom), were used. The size of one pixel of CCD matrices is 13.5 microns, the size of the operating surface is 27.5 â 27.5 mm. The detectors are equipped with 14 bit ADC and work in low frame rate mode. The image acquisition time (set from the Earth) can vary from 0.1 to 600 s. Image reading time is determined by the speed of reading of the first pixel (~2 ms) and the size of the retrieved image. For com posite images of 2048 â 2048 format, it is about 8 sec onds. At the same time, telescopes can operate in the subframe mode. Time spent on reading of a single frame in this mode decreases in proportion to the used area of the CCD matrix. Image detectors of the TESIS are equipped with single stage Peltier coolers. The heat from the detec tors is removed to radiators that are almost unlit by the sunlight. During the debugging work it was found that image detectors of TESIS telescopes, even when the Peltier coolers are off, have a temperature from ­40° to ­20°. Thus, an additional cooling by Peltier ther moelements is not applied. To investigate the physical conditions in the plasma of the solar corona using observational data, we need information about the absolute sensitivity of the detectors in operating ranges of wavelengths. Such measurements for the wavelength = 8.42 å were per formed at the synchrotron source in Beijing, China (Kuzin et al., 2009), and measurements for the EUV range of 132­304 å measurements were conducted at the synchrotron source in Hefei, China (Kuzin et al., 2008). The sensitivity for the wavelength = 8.42 å was 31 u.ADC/photon, and for the EUV range it was from 0.01 to 0.1 u.ADC/photon.
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Filters In the TESIS hardware the intensive visible light is blocked by a system of input filters and filters of detec tors. Input filters are multilayer structures (Al for ranges near 171 and 304 å; Zr/Si for ranges near 132 å, respectively), deposited on support grids. Filters of detectors are deposited directly on the operating sur face of CCD matrices. All multilayer filters were man ufactured in the Institute for Physics of Microstruc tures (Zuev et al., 2008a). The input filter of the Mg XII spectroheliograph for the wavelength of 8.42 å is an aluminized Dacron 3.8 microns thick, manufactured in the Lebedev Physical Institute. The measurement of spectral characteristics of fil ters in operating ranges of wavelengths was performed on the synchrotron source in Hefei, China, and in the Institute for Physics of Microstructures (Kuzin et al., 2009). The degree of the visible light block was mea sured in the Lebedev Physical Institute and was ~106. TESIS MANAGEMENT The TESIS management is carried out via com mands from the Earth during communication ses sions. Commands are sets of bytes (a number from 0 to 255), executed sequentially. Depending on the pur pose of the command, it may have any length. In gen eral, the TESIS command alphabet is organized so that the most used commands consist of 1 byte. Thus, for imaging in the channel 304 å with an exposure of 1 s it is suffice to transfer one hexadecimal number '4 A'0X. This significantly reduces the amount of con trol. Commands, transmitted to the TESIS, are orga nized in sequences that form a complete program (sequence diagram).


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Fig. 8. The fragment of the channel 171 å of the TESIS, demonstrating the spatial resolution of the device. In the left part of the figure there is a fragment of the full image of the Sun. The selected square area is shown in the right part of the figure. In it, two bright points are clearly distinguishable, separated by a distance of 3.6 pixels.

The program can be executed immediately after arrival of the signal from the Earth or transferred to the device with a delay of several hours or even days. The buffer, in which the sequence diagram is stored before transmitting to the device is the onboard satellite con trol computer. In practice, the main mode for scien tific observation programs is the execution of pro grams at a specified time. The mode of a direct trans mission of commands to the device is used in the reprogramming of the device. Since at a specified time the onboard computer transfers to the TESIS the whole sequence diagram, stored in the memory, the problem of organizing commands by the time inside the device itself arises. To do this, time marking com mands are used in the TESIS: (1) "execute the follow ing command after a specified time after the previous" and (2) "execute the following command at a specified time." Idle times in command of the first type are in the range from 0.1 to 255 min. The execution time in the commands of the second type is within 1 month. Commands "execute the following command after a specified time after the signal SVET" and "execute the following command after a specified time after the sig nal in VSHIR" are also available, but are rarely used in practice. The signal SVET is transmitted to the device when the satellite enters the lit area of the orbit, and the signal VSHIR is transmitted when the satellite enters Earth's radiation belts. In general, the existing set of marking by time makes it possible to generate any schedule of command execution. To simplify the management, the TESIS command alphabet also includes looping commands (LOOP, ENDLOOP), making it possible to repeat the execu tion of the same sequence of commands several times. The number of repeats is from 1 to 255, while the per missible level of cycle nesting is 8. The TESIS internal memory can store onboard up to 128 sequence dia grams up to 256 bytes each. Sequence diagrams are called by a special command from the TESIS alphabet

and then executed in the same manner as programs that are transmitted from the Earth. In practice about 30 onboard sequence diagrams are currently activated. The TESIS frequency control averages 1 session in 2 days. Thus, for the first year of the TESIS operation, from January 31 to December 31, 2009, there were 165 communications sessions, during which about 700 management programs were transmitted onboard. In general, the necessity to control the complex of tele scopes may be assessed as very high. As of January 2010, the TESIS alphabet included 71 commands, controlling all modes of operation of the device. Of these, 68 commands were already installed at the time of launch, and 3 commands were added during the first year of the experiment. TESIS BASIC OPERATION MODES The TESIS operation mode is determined by the following main factors: (1) the selected channels of image registration, (2) the frequency of image acquisi tion, (3) the image format, and (4) the method of image compression. Obviously, the optimal operation mode is when all channels of the device are activated, operate at maximum speed, and get full format images with the best spatial resolution. Unfortunately, this idealized situation is impossible in practice, primarily because of limitations on telemetry. In addition, the simultaneous operation of all channels of the device is not possible from a technical point of view. In terms of the selection of image registration channels, TESIS operating modes may be divided into synoptic and scientific. In the synoptic mode, the maximum number of channels is activated, but with reduced frequency of imaging. Given the restrictions on the daily volume of telemetry (0.5 GB), the tempo ral resolution of synoptic programs of the TESIS is about 5­10 minutes. The purpose of synoptic pro
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2 1

1400 Intensity, rel. units 1300 1200 1100

(b) 1 2

1000 13:58 14:00 14:03 14:06 14:09 14:12 14:15 14:18 Time, UT (October 2, 2009)
Fig. 9. (a) The image of the channel 171 å of the TESIS obtained during the observing program of bright areas with high temporal resolution on October 2, 2009. Explored bright areas are marked. (b) The temporal profile of inten sities of studied areas.

grams is to monitor the Sun's atmosphere (mostly flar ing and explosive processes). An alternative to synoptic modes of operation are scientific target programs of observations, when the main observation is carried out in 1­2 channels of the TESIS. Obviously, the channel selection depends on a scientific problem. For example, in a research pro gram involving high temperature plasma investiga tion, TESIS channels Fe XXIII 132 å and Mg XII 8.42 å are used, in which images are formed at plasma tem peratures of 5­20 million K. The restriction on the number of channels makes it possible to improve the temporal resolution of observations to 1­5 min. During the first year of TESIS operation, about 40% of telemetry was given to synoptic observations, and about 60% was given to target scientific research. In terms of frequency of image acquisition, TESIS modes may be divided into ordinary modes and modes with high temporal resolution. High resolution refers to a frequency of better than 1 min. Series with high temporal resolution refer to scientific programs and are used to study fast transient processes in the solar corona. In 2009, about 10% of telemetry was allocated
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to these series, including about 2% to series of high resolution with a frame rate faster than 10 seconds. In terms of image format, in the course of the TESIS experiment two basic modes are used, i.e., imaging of the full solar disk and of a disk fragment. In the latter case, a composite image is obtained but only a specified fragment is stored in the memory. Parame ters of the reading window (its position and size in pix els) are set by commands from the Earth. Monitoring of the full solar disk is the primary mode of synoptic observation programs. It is also used in the study of mass ejections, huge eruptive promi nences and other phenomena that are global in nature. A windowed mode of observations of the Sun can sig nificantly increase the number of obtained images within the specified telemetry limit. Thus, it is actively used in target scientific programs. In addition, in the windowed mode the image processing is performed much faster, making it possible to reach high and very high temporal resolutions. The main TESIS objectives of the study in this mode are objects and phenomena on the Sun, the size of which is on the order of or less than one solar radius. These are solar active regions and groups of regions, flares, bright points, systems of coronal loops, spicules, and high temperature emis sion sources. Currently, using the TESIS windowed mode, a series of unique programs is conducted for monitoring a number of solar objects with a time reso lution of better than 4 seconds. The most commonly used synoptic observations and research programs are implemented as standard programs, stored in the TESIS onboard memory and called by commands from the Earth. RESULTS OF OBSERVATIONS The first activation of the TESIS scientific equip ment took place on February 20, 2009 (after about 3 weeks after launch), and the first images were received on the Earth on February 26, 2009. During February­April, 2009, TESIS flight tests were con ducted. During this period, together with scientific research programs, calibration and debugging work was carried out, and also major observational pro grams were perfected. Since April 2009, the TESIS entered the stage of the natural experiment. Below the capabilities of the TESIS scientific equipment are demonstrated by the example of spe cific observations. Telescopic Channels Figure 8 shows the fragment of the image in the channel of 171 å, registered on March 5, 2009, at 17:32 UT with an exposure time t = 10 s. Structures


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Fig. 10. The composite image of the solar corona near the 171 å, created on the basis of three images with an exposure of 1, 3, and 100 s. According to observations of the channel 171 å by the TESIS on May 5, 2009.
9­May­2009 13:58:58.000 UT 1000 Mg XII/TESIS 1000 9­May­2009 13:58:58.000 UT Fe132­171/TESIS

500

500

Y (arcsecs)

0

Y (arcsecs) ­1000 ­500 0 X (arcsecs) 500 1000

0

­500

­500

­1000

­1000 ­1000 ­500 0 X (arcsecs) 500 1000

Fig. 11. The image of the solar corona in the line 8.42 å, obtained by the Mg XII spectroheliograph (on the left), and EUV telescope 132/171 å (on the right).

separated by a distance of ~3 pixels can be seen on the images. The temporal resolution of telescopes is deter mined by the system of image reading from CCD matrices. When registering a full frame of 2048 â 2048, the data reading time is about 8 seconds. The device can work in the mode of the registration of the selected part of the frame. At the same time, the temporal res olution is reduced in proportion to the area of the retrieved frame. These modes are commonly used dur ing target observations, when local structures are monitored (active regions, coronal holes, spicules in polar regions, etc.). To date, series of "fast" observa tions were conducted with a temporal resolution of

about 4 s and a duration of one series of about 1 h. Fig ure 9a shows the image of the Sun, on which two bright areas, observed within the target program on October 2, 2009, are marked with a large temporal resolution. Figure 9b shows the time profile of the intensities of these regions, measured from 13:58 to 14:15 UT. The high sensitivity of telescopes, due to the use of mirrors with large aperture, high performance multi layer coatings, and detectors with high sensitivity, made it possible to observe the coronal structure at large R > 1 distances from the Sun's surface for the first time. Figure 10 shows the image of the 171 å channel, consisting of three images with exposure times of 1, 3, and 100 s. The images were recorded May 5, 2009, at
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about 01:40 UT. On the composite image the coronal mass ejection may be seen at a distance of ~1 R. The Mg XII Spectroheliograph Figure 11 shows an example of the image, regis tered by the Mg XII spectroheliograph on May 9, 2009, at 13:58 UT with an exposure time of 100 s. The right part of the figure shows an image recorded by the TESIS telescope 132/171 å at the same time with an exposure time of 1 s. On the telescopic image, two regions with increased activity may be observed. The Mg XII line emission = 8.42 å occurs only in one area, which indicates a significant difference of plasma in bright areas. The bright area, which may be seen in the Mg XII image, contains a large amount of hot plasma (T ~ 10 MK). ACKNOWLEDGMENTS We are grateful to the Astrophysics Institute of the National Research Nuclear University at the Moscow Engineering Physics Institute for the scientific man agement of the CORONAS PHOTON project. This study was supported in part by the Russian Foundation for Basic Research, project nos. 08 02 01301 a and 08 02 13633 ofi_ts, the Basic Research Program of the Presidium of the Russian Academy of Sciences (Program 16, Part 3, Basic Research Pro gram of the Department of Physical Science of the Russian Academy of Sciences "Plasma Processes in the Solar System"), and project no. 218816 (SOTERIA project, www.soteria.eu) of the Seventh Framework Programme of the European Union (FP07/2007 2013). REFERENCES
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