Erratum:ComprehensiveStudiesofSolarActivity ontheCORONAS ... · 570 ORAEVSKY,SOBELMAN 1.2 × 10 –5 2600 0 1.2 × 10 –6 Amplitude, arb. units 2900 3200 3500 Frequency, µ Hz Fig.2

Astronomy Letters, Vol. 28, No. 8, 2002, pp. 568–577.

ERRATA

Erratum: Comprehensive Studies of Solar Activityon the CORONAS-F Satellite∗

[Astronomy Letters 28, 401–410 (2002)]

V. N. Oraevsky1 and I. I. Sobelman2

1Institute of Terrestrial Magnetism, Ionosphere, and Radio-Wave Propagation, Russian Academy of Sciences,Troitsk, Moscow oblast, 142090 Russia; E-mail: [email protected]

2Lebedev Physical Institute, Russian Academy of Sciences, Leninskiı pr. 53, Moscow, 117924 RussiaReceived December 27, 2001

Abstract—The first results of comprehensive CORONAS-F observations of solar activity are presented.The CORONAS-F instrumentation and principal scientific objectives are briefly described and examplesof the first results of data reduction are given. c© 2002 MAIK “Nauka/Interperiodica”.

Key words: Sun; astronomical observing techniques, equipment and instruments

THE CORONAS PROGRAMAND THE CORONAS-F PROJECT

The CORONAS (Comprehensive Orbital Near-Earth Solar Activity Observations) InternationalProgram, as part of which the CORONAS-F near-Earth spaceborne solar observatory was launched, isintended for studies of the Sun at various phases ofthe 11-year solar cycle. On the previous CORONAS-I satellite (launched in 1994), the Sun was observednear the minimum of its activity. The CORONAS-Fwill study the solar activity near the maximum of thecurrent cycle 23. On July 31, 2001, CORONAS-Fwas placed in an orbit with the following parameters:an orbital inclination of 82.49◦, a minimum altitudeof 500.9 km, a maximum altitude of 548.5 km, and arevolution period of 94.859 min. Such an orbit pro-vides repetitive ∼20 day-long periods of continuoussolar observations, which is of particular importancein helioseismology and in patrolling solar flares. Theactually achieved spacecraft attitude stabilizationturned out to be a factor of 3 to 5 better than theprojected one (a few arcseconds per second), whichallows the spatial resolution of solar observations tobe appreciably improved.

SCIENTIFIC OBJECTIVESOF THE CORONAS-F PROJECT

The principal scientific objectives of the CORO-NAS-F project are observations of global solar os-cillations, investigation of the seismology of the solar

∗This article was republished due to two color figures (nos. 4and 5)missed in the original translation.Our apologies to theauthors and the readers of the journal.

1063-7737/02/2808-0568$22.00 c©

interior and internal structure, comprehensive studiesof powerful dynamical processes on the active Sun(active regions, flares, plasma ejections) over a widewavelength range, from optical to gamma rays, in-cluding the radiation from solar cosmic-ray particlesaccelerated during active solar events, conditions fortheir escape, propagation in the interplanetary mag-netic field, and impact on the Earth’s magnetosphere.

SCIENTIFIC INSTRUMENTATIONAND THE FIRST OBSERVATIONAL

RESULTS

In accordance with the CORONAS-F objectives,the scientific instrumentation of the spacecraft in-cludes four major groups of instruments: an instru-ment to detect global solar oscillations; X-ray instru-ments to image active regions on the Sun with aspatial resolution of ∼2′′–3′′ instruments to measurethe fluxes of electromagnetic radiation from active

MDI

GOLFLOI

SPM

DIFOS400 800 1200 1600

nm

Fig. 1. Comparison of the DIFOS (CORONAS-F)channels with the SOHO instruments (MDI—Michelson Doppler Imaging of solar oscillations,GOLF—Global low-degree velocity, LOI—LuminosityOscillation Imager, SPM—SunPhotoMeter).

2002 MAIK “Nauka/Interperiodica”

COMPREHENSIVE STUDIES OF SOLAR ACTIVITY 569

Table 1. The CORONAS-F instruments

Instrument Purpose Designer Principalinvestigators

Helioseismology

DIFOS spectrophotometer Helioseismological monitoring IZMIRAN V.N. Oraevsky

High-angular-resolution monochromatic imaging

SRT-C X-raytelescope

Studying the spatial structure and dynamicsof the upper solar atmosphere usingnarrow-band XUV images

FIAN I.I. SobelmanI.A. Zhitnik

RES-C X-rayspectroheliograph

Diagnosing the hot solar atmosphericplasma using images in X and XUV spectrallines

FIAN I.I. SobelmanI.A. Zhitnik

DIOGENESSspectrophotometer

Studying the X-ray radiation from solaractive regions and flares

SRC PAS* J. Silvestr

Measuring the fluxes and polarization of electromagnetic radiation (from UV to γ rays)

RESIK X-rayspectrometer

Studying the solar X-ray radiation with ahigh spectral resolution

SRC PAS* J. Silvestr

SPR-N solarspectropolarimeter

Studying the polarization of X-ray radiationfrom solar flares

FIANNIIYaF

I.I. SobelmanI.P. TindoS.I. Svertilov

IRIS flare spectrometer Studying the X-ray solar flare activity FTI G.E. Kocharov

GELIKON gamma-rayspectrometer

Studying the X-ray and gamma-ray solarflare activity

FTI E.P. Masetz

RPS X-ray spectrometer Studying the X-ray radiation from solarflares and their precursors

IKI RASMIPhI

V.M. PankovYu.D. Kotov

ATS amplitude–timespectrometer

Studying the X-ray and gamma-rayradiation from solar flares

MIPhI Yu.D. Kotov

SUVR-Sp-C solarultraviolet radiometer

Studying the variations in total UV solar flux IPG T.V. Kazachevskaya

VUSS-L ultraviolet solarspectrophotometer

Studying the solar UV radiation near the Lα

resonance lineIPG A.A. Nusinov

Studying solar corpuscular fluxes

Instrumentation to studySCRs

Studying solar cosmic rays NIIYaPhMGU

S.N. Kuznetsov

Gathering and studying of scientific information

Scientific InformationAcquisition System(SSNI)

Controlling the scientific instrumentationand the modes of its operation

IZMIRAN V.N. OraevskyA.I. Stepanov

∗ Space Research Center of the Polish Academy of Sciences.

ASTRONOMY LETTERS Vol. 28 No. 8 2002

570 ORAEVSKY, SOBELMAN

1.2

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10

–5

26000

1.2

×

10

–6

Am

plitu

de, a

rb. u

nits

2900 3200 3500Frequency,

µ

Hz

Fig. 2. The relative amplitudes of 5-min solar oscillation modes at a wavelength of 350 nm as inferred from the results of theDIFOS data reduction.

regions and flares; and instruments to study solar cor-puscular fluxes. The wide range of measurements ofthe electromagnetic spectrum and solar cosmic-rayparticle [both neutral (neutrons) and charged (elec-trons, protons, nuclei)] fluxes yields the fullest pictureof the physical processes in active regions on theSun. The CORONAS-F instruments and their mainpurpose are given in Table 1.

The main operational control of the scientific in-strumentation is performed from the Flight ControlCenter located at the Cosmic Information Technol-ogy Center, Institute of Terrestrial Magnetism, Iono-sphere, and Radio-Wave Propagation (IZMIRAN),Troitsk. Commands are sent to the spacecraft on adaily basis. Up to 24 kbytes of commands are sentsimultaneously. Apart from controlling the modes ofoperation, the controllers of the scientific instrumentsare dynamically reprogrammed in flight, which allows

2

1

0400 1000 1600

Wavelength, nm

Am

plitu

de, a

rb. u

nits

12

Fig. 3. The relative amplitude of free solar oscillationsversus wavelength.

their software to be customized for current observa-tions. Requests for control through the Flight ControlCenter of the Cosmic Information Technology Center(IZMIRAN) are collected via E-mail with no lessthan 10 min before the control session, which ensuresthe required speed and flexibility in controlling thescientific instrumetation.

THE DIFOS SPECTROPHOTOMETER

The DIFOS spectrophotometer is designed tomeasure fluctuations in the intensity of solar opticalradiation in an effort to obtain the spectrum of freeoscillations. The intensity is simultaneously mea-sured in six optical spectral bands: 350, 500, 650,850, 1100, and 1500 nm with a band width equalto 10% of the central frequency. In comparison withthe CORONAS-I project (Lebedev et al. 1995), thephotometer was significantly upgraded: the detectorsensitivity increased by more than an order of mag-nitude and the spectral range of observations wasextended by almost a factor of 2; concurrently, thenumber of spectral channels increased from three tosix. Global solar oscillations are being observed overa wide spectral range, including the most informativeUV line. The intensity of the radiation from globalsolar oscillations in this line appreciably exceeds theradiation intensity in other lines (Oraevsky et al.1999). Figure 1 compares the DIFOS channels withthe SOHO instruments (1988).Figure 2 shows the relative amplitudes of 5-min

solar oscillation modes at a wavelength of 350 nmduring November 28–30, 2001 as inferred from the



Table 2. Characteristics of the SRT-C telescope

Channel Spectral range,A

Ion linesField ofview,arcmin

Angularscaleper cell

Mode of operation

ВР1 171 Fе IX–Fe X 42 × 48 2′′.5 Full disk

195 Fe XII

284 Fe XV

304 Не II

ВР2 175 Fе IX–Fe XI 45 × 50 2′′.6 Full disk, pointing at corona

up to several solar radii304 НеII + SiXI 45 × 50 2

′′.6

Optical sensors OS1and OS2

4000–8000 Circular 11◦ 1′ × 2′ Stars > 12m

results of the DIFOS data reduction. Similar resultswere obtained for the other channels. After averagingover the modes, the mean relative amplitudes weredetermined for each of the six channels and plot-ted against wavelength (see Fig. 3). All data pointsfall on a smooth curve fitted by a λ−1.2 law (1). Asimilar result was established for another interval ofobservations, November 30–December 3, 2001 (2).A comparison of the DIFOS result with the resultsin the range of ground-based observations (Jimenezet al. 1998) gives close agreement. According toground-based measurements, the amplitude ratio ofglobal oscillations at wavelengths of 500 and 680 nmwas 1.6, while for the DIFOS measurements, theamplitude ratio at 500 and 650 nm was 1.5. For a dif-ferent pair of wavelengths, the amplitude ratio at 500and 870 nm was 2.2 for ground-based observations,while the amplitude ratio at 500 and 850 nm for theDIFOS data was 2.

THE SPIRIT (SRT–RES–SPR)ASTROPHYSICAL COMPLEX TO STUDY

THE SOLAR X-RAY RADIATION

The SPIRIT astrophysical complex consists ofthe SRT-C solar X-ray telescope, the RES-C X-rayspectroheliograph, and the SPR-N spectropolarime-ter. It is designed to solve a wide variety of prob-lems in solar physics based on XUV imaging spec-troscopy of the Sun (soft X-ray and extreme UV so-lar spectroscopy). This method consists in obtainingsimultaneously solar images and spectra with highangular and spectral resolutions in narrow portionsof the XUV range that characterize the various tem-perature layers of solar plasma. It was applied in theCORONAS-I project, in which the TEREK-C mul-tichannel telescope and the RES-C spectroheliome-ter in the wavelength range 0.18–30.4 nm designedat the Lebedev Physical Institute (Russian Academy


of Science) were used (Sobelman et al. 1996; Zhitniket al. 1998).

Observations with the SPIRIT astrophysical com-plex onboard the CORONAS-F satellite will allowthe following processes to be investigated: the forma-tion and development of solar flares from temporalvariations and changes in the structure, spectra,and polarization of the flare regions; nonstationaryphenomena in solar plasma (hot points, coronalmass ejections, and others)—the frequency of theiroccurrence, conditions for their emergence, dynamicsof their development, and residual phenomena; andthe helium distribution in the transition layer andin the near and far coronas. They also allow us tosearch for the possible sources of the solar wind, tostudy the processes of its generation, to elucidate therelationships of the observed solar-wind parametersto solar processes, and to diagnose the structuralelements of active regions, areas of the quiet Sun,and coronal holes on time scales from 0.1 s to tens ofdays.

The SPIRIT complex is distinguished by a widespectral range (0.04–100 keV) and by high spatial(up to 3′′), spectral (up to 2 × 103), and temporal(0.01 s) resolutions intended for observations nearmaximum solar activity. The SRT-C telescope is anew instrument with significantly improved charac-teristics compared to the TEREK-C telescope thatsuccessfully operated on the CORONAS-I satellite.The working aperture of the optical channels in-creased from 30 to 100 mm with the simultaneousincrease in actual angular resolution. The numberof spectral subbands also increased. The RES-C-F spectroheliometer is a modification of the RES-C-I spectroheliometer that successfully operated onthe CORONAS-I satellite with an extended spectralrange and improved characteristics. In the SRT-C


Table 3. Characteristics of the RES-C X-ray spectroheliograph

Channel Spectral range,A

Ion linesSpectral resolution,

A per cell

Angularscaleper cell

Mode of operation

Fe XXV 1.85–1.87 Fe XXIV,FeXXV

1.5 × 10−4 1′ Image andspectrum from theentire disk

Mg XII (two crossedsubchannels)

8.41–8.43 Mg XII doublet 3 × 10−3 4.1′′ Same

XUV (two crossedsubchannels)

176–205 Fe VIII, X,XIXII, XIII,XXIV,O VI S IX

0.03 6′′ (perpen-dicular todispersion)

Spectral images ofthe disk in all lines

285–335 He II, Si XI

and RES-C-F instruments, the resolution and sen-sitivity of the imaging detectors were increased, theirdynamical range was expanded, and a powerful high-performance computer with a large amount of randomaccess memory was used in the electronic system.The new instruments provide an increase in temporalresolution and sensitivity by up to a factor of 10 com-pared to the TEREK and RES instruments on theCORONAS-I satellite and by a factor of 3 comparedto the EIT/SOHO telescope.

The SRT -C Solar X-ray Telescope

The SRT-C solar X-ray telescope is designed forX-ray imaging of the Sun with a high spatial resolu-tion. It includes XUV channels, ВР1 and ВР2, andtwo optical sensors for the telescope attitude controlusing stars. The telescope characteristics are listed inTable 2.

X-ray mirrors with multilayer Mo–Si coating areused for imaging in the X-ray channels of the instru-ment: in channel ВР1, a Ritchey–Chretien objectivewith a diameter of 120 mm and a focal length of1660 mm that has four sectors with coverages atwavelengths of 171, 195, 284, and 304 A (an ana-log of the EIT/SOHO telescope objective); and inchannel ВР2, off-axis paraboloids with a diameter of100 mm and a focal length of 1500 mm.

The imaging detectors in all channels are CCD ar-rays; image intensifiers, which also act as electronicshutters, are used in the X-ray channels. The bright-ness dynamic range in the X-ray channels is of theorder of 105. The exposure times can vary between0.01 and 600 s.

The mirrors of channel ВР2 are equipped withangular alignment and focusing systems to correctfor possible changes in alignment when placing the

satellite in orbit. In addition, the channel is sup-plied with artificial moons blocked by commands andwith additional optical windows, which in combina-tion with mirror deflection makes it possible to ob-serve portions of the X-ray corona within several solarradii.

TheRES-C X-ray Spectroheliograph

The RES-C spectroheliograph is designed to im-age the Sun in spectral lines of highly ionized atomsof abundant elements (helium, magnesium, iron, sili-con) with a high spatial resolution and to measure thelinear polarization in spectral lines. The instrumentincludes three XUV channels: Fe, Mg, and XUV. TheRES-C characteristics are listed in Table 3.X-ray optics is used in the RES-C instrument: in

the Fe XXV channel, a ring Bragg mirror made ofcrystalline quartz with a sphere radius of 196.6 mmoperating at a Bragg angle of 52◦; in the Mg XIIchannel, two spherical Bragg mirrors made of crys-talline quartz with a sphere radius of 1286 mm oper-ating at angle 81.7◦; in the XUV channels, two holo-graphic diffraction gratings with a period of 3600-lines per mm whose spectra are focused on the detec-tors using multilayer Mo–Si-coated mirrors with aradius of 1600 mmwere used: spherical and parabolicones for the wavelength ranges 180–205 A and 285–335 A, respectively.

The imaging detectors in the XUV channels, justas those in the SRT-C instrument, are CCD arraysin combination with image intensifiers. The dynamicrange is of the order of 105 and the exposure timeranges from 0.01 to 600 s. In theMgXII and Fe XXVchannels, X-ray radiation is recorded by the openCCD arrays.


A

SRT-C 171 Å

21.08.2001 03:03:38 UT

CORONAS-F FIAN

SRT-C 284 Å

21.08.2001 03:08:40 UT

CORONAS-F FIAN

SRT-C 195 Å

20.08.2001 14:13:49 UT

CORONAS-F FIAN

SRT-C 304 Å

26.08.2001 17:31:30 UT

CORONAS-F FIAN

Fig. 4. The solar images at wavelengths of 171, 195, 284, and 304 Å obtained in channel BP1 of the SRT-C instrument.

STRONOMY LETTERS Vol. 28 No. 8 2002

CORONAS-F FIAN

21.08.2001 20:23:23 UT

RES-C 285–335 Å

Fig. 5. The spectroheliogram in the range 285–335 Å taken in the XUV channel of the RES-C instrument.



8000

4000

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10

4

02000

1000

0

Inte

nsity

3.180 3.200 3.220

Wavelength

,

Å

16:32 UT

16:53 UT

17:44 UT

Fig. 6. Са XIX line spectra with a high spatial resolution (∼ 5′′) at the growth phase, intermediate phase, and the decay phaseof the strongest flare in the current solar cycle (August 25, 2001).

The SPR-N Solar SpectropolarimeterThe SPR-N solar X-ray spectropolarimeter mea-

sures the polarization of continuum X-ray radiationfrom solar flares in the spectral range 20–100 keV(nonthermal radiation from the accelerated electronsgenerated in flares). The instrument has the followingcharacteristics:

Spectral range 20–100 keV

Subbands 20–40 keV

40–60 keV

60–100 keV

Polarization detection sensitivity ∼5% at flux10−6 erg cm−2 s−1

Temporal resolution 4–16 s

The SPR-N instrument has two detection chan-


nels: a polarization detector and a patrol detector.The polarization detector contains an X-ray radia-tion scatterer (a hexahedral Be prism) and a sys-tem of three pairs of scintillation detectors (SSD),which measure the intensity of the scattered radia-tion. СsI(Na) crystal scintillators with photomulti-pliers are used to record X-ray radiation. To elimi-nate the systematic errors during polarization mea-surements attributable to the possible sensitivity driftin individual channels, the polarization detector wasmounted on a turning drive. For typical solar flaresof importance I, II, and III, the expected sensitiv-ity of polarization measurement is ∼5% at a flux of∼106 phot. cm−2 s−1 (E = 20–100 keV) and an in-tegration time of∼8 s. The patrol detector is designedto measure the total intensity of the X-ray radiationfrom solar flares at energies 20–100 keV. It consistsof a СsI(Na) crystal placed behind an anticoincidenceshield and a photomultiplier.Apart from the general scientific program of the


200

100

020 60 100

Cou

ntnu

mbe

r pe

r 0.

01s

Time,

×

10 ms

Fig. 7. An intensity record of hard X-ray radiation on September 27, 2001, 18:26 UT in the energy range 20–100 keV with ahigh temporal resolution in four energy channels (from top to bottom: 20–25, 25–35, 35–100, and 100–200 keV).

CORONAS-F project, the programs of joint obser-vations with instruments on other spacecraft that willoperate simultaneously with CORONAS-F, primarilywith instruments on the SOHO international space-borne observatory, the TRACE telescope, YOHKOH,and others, are envisaged. It is planned that theCORONAS-F observations will be coordinated withobservations at ground-based observatories, in par-ticular, with the Institute of Solar–Terrestrial Physics(Itkutsk), the Crimean Astrophysical Observatory,and other ground-based observatories that carry outsolar observations.

Test experiments and preliminary scientific resultsobtained during the first three months of observa-tions show that the entire instrumentation of theSRT–RES–SPR operates normally. Figure 4 showsthe solar images at 171, 195, 284, and 304 A ob-tained in channel ВР1 of the SRT-C instrument.Figure 5 shows the spectroheliogram in the range285–335 A taken in the XUV channel of the RES-C instrument.

THE DIOGENESS SPECTROPHOTOMETERAND THE RESIK

X-RAY SPECTROMETER

TheRESIK andDIOGENESS instruments mea-sure the solar spectra in the wavelength range 3–7 A.They are designed to investigate the X-ray radiationfrom active regions and flares with a high spectral res-olution. Their solar X-ray spectra are comparable in

spectral and temporal resolution to the best observa-tions performed to date. Because of the CORONAS-F polar orbit and the complete coverage of a widespectral range, they are a valuable complement to theYohkoh spectra. Since the detectors of the RESIK in-strument and the Yohkoh spectrometers are saturatedat high X-ray fluxes, the DIOGENESS instrumentis currently the world’s only operating spectrometerthat takes the spectra of intense flares of importanceabove M2 (as exemplified by the X5.3 flare on Au-gust 25, 2001).

Figure 6 shows Са XIX line spectra with a highspatial resolution (∼5′′) at the growth phase, inter-mediate phase, and the decay phase of the strongestflare in the current solar cycle (August 25, 2001). Thetemperature of the emitting plasma decreases from2.5 × 106 K at the growth phase to 1.2 × 106 K at thedecay phase. The spectra exhibit changes in the linewidth, which points to the role of plasma turbulenceduring the flare evolution. A detailed analysis of therelative intensities will allow one to study the energybalance in flares and the role of non-Maxwellian andnonequilibrium processes in the flare energy releaseregion. In the spectral range in question (3–7 A),such spectra for an Х flare were obtained with such ahigh spatial resolution for the first time. They provideinformation on the many emission lines produced bythe collisional excitation of atoms, the excitation ofinner atomic shells, and dielecton recombination.



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t

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, s

Cou

nts

s

–1

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CORONAS-F GELIKONNovember 23, 2001 8:30:10.354 UT 15–50 keV

15–190 keV

190–700 keV

Fig. 8. The time profile for the intense solar flare of November 23, 2001, in three energy bands with a high temporal resolution,from 2 to 256 ms.

10

–3

100

10

–1

Cou

nt r

ate,

pho

t. s

–1

keV

–1

1000

E

1.2

E

3.6

Location ofof 511-keV line

Energy, keV

Fig. 9. The differential energy spectrum for the September 18, 2001 event.

THE IRIS FLARE SPECTROMETER

The instrument is designed to investigate the solarflare activity in the X-ray spectral range 2–200 keV.It has 12 energy channels with a temporal resolu-tion of 2.5 s in patrol mode and 64 energy channels


with a temporal resolution of 1 s and four channelswith a 10 ms resolution in burst mode. As yet nospectral measurements have been carried out withsuch a temporal resolution in any experiment aimed atinvestigating the solar X-ray radiation. Observations

5
3

1140 170 200

MJD 52 000000+

I

II

Fig. 10. The VUSS-L temporal record of a signal pro-portional to the solar UV flux (I) and the solar radio fluxat a wavelength of 10.7 cm (II).

of the fine temporal structure in hard X-ray fluxeswill provide direct information on the development ofthe energy release at the explosive phase of flares.Figure 7 shows an intensity record of hard X-rayradiation in four energy channels in the range 20–100 keV with a high temporal resolution for the eventof September 27, 2001, 18:26 UT.

THE GELIKON GAMMA-RAYSPECTROMETER

The instrument measures the temporal and spec-tral characteristics of the hard electromagnetic ra-diation from solar flares over a wide energy range,from X-rays to gamma-rays (10 keV–10 MeV). Itis used to monitor the radiation conditions and softsolar flares and to detect and record in detail hard(Eγ > 50 keV) flares and gamma-ray bursts. Overthe observing period from November 14 through De-cember 14, 2001, the temporal profiles and spectrawere measured for 134 solar flares. Most of themhad soft spectra and were recorded in backgroundmode with a temporal resolution of 1 s in eight ad-jacent energy bands from 15 to 200 keV. Figure 8shows the temporal profile for the intense solar flare ofNovember 23, 2001, detected in trigger mode in threeenergy bands with a high temporal resolution from 2to 256 ms.

THE RPS-1 X-RAY SPECTROMETER

The instrument is designed to investigate solarflares and their precursors in the X-ray range 3–30 keV. Over the period of measurements, the instru-ment calibration parameters were refined, the back-ground conditions were mapped, and the experimen-

tal data statistics was accumulated. No SOHOmea-surements are carried out in this energy range, whilethe SXS/Yohkoh results have not yet been published.

THE ATS AMPLITUDE–TIMESPECTROMETER

The instrument is designed to study the X-ray andgamma-ray radiation from solar flares, in particular,to analyze solar-flare or gamma-ray burst events inthe energy bands 3–30 keV, 0.1–8.0 MeV, and 2.0–80.0 MeV. Over the observing period, several tens ofcandidates for solar-flare or gamma-ray burst eventswere recorded and their energy spectra were obtainedfor various phases of the event (before, during, andafter the event). The duration of the candidate eventsranges from 16 s to 3–5 min. In Fig. 9, the differentialenergy spectrum for the event of September 18, 2001,was reconstructed from measurements. It exhibits аkink near energy 300 keV and a possible spectralfeature that can be identified with the 511-keV an-nihilation line.

THE SUVR-Sp-C SOLAR ULTRAVIOLETRADIOMETER

The SUVR-Sp-C instrument measures the fluxesfrom the Sun as a star in several spectral bands, from1 to 130 nm. In contrast to SOHO, it has a widerspectral range. Apart from the scientific objectives,the radiometer monitors one of the most importantelements of cosmic weather—the geoeffective solarradiation. the SUVR obtained data on the intenseХ5.3B flare of August 25 at 16:23 UT at X-ray wave-lengths λ < 12 nm.

THE VUSS-L ULTRAVIOLET SOLARSPECTROPHOTOMETER

The VUSS-L instrument carries out measure-ments in a band near 120 nm and is designed to inves-tigate the solar ultraviolet radiation near the Lα res-onance line. The measurements yield numerous dataon the UV flux and intensity in theLα line, which wastentatively estimated to be ∼10 erg cm−2 s−1. TheVUSS-L temporal record of the UV flux is shown inFig. 10.

THE SCR INSTRUMENTATION TO STUDYSOLAR COSMIC RAYS

The SCR scientific instrumentation consists ofthree instruments: SONG (gamma-ray and neutronspectrometer, principal investigator S.P. Ryumin),CRM (cosmic-ray monitor, principal investigatorS.N. Kuznetsov), and CRS-3 (cosmic-radiationspectrometer, principal investigator A.F.Podorol’skii).



100

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100000

10

49500 49000 50300

N

T, s

I

II

Quiescent background

Onset of increasein X-ray flux fromUSAF/NOAA

16.09.27,5

Fig. 11. The recording of gamma rays with energy 60–150 keV (I) and electrons with energy 0.3–0.6 MeV (II) by the SCRcomplex in the November 4, 2001 event.

It is designed for comprehensive studies of solarcosmic rays. The SONG instrument records X-rayand gamma-ray spectra in the energy range 0.03–100 MeV, detailed gamma-ray line spectra in therange 0.3–20MeV, neutrons with energies >20MeV,and fluxes of charged cosmic-ray particles—protonswith energies >70 MeV and electrons with energies>50 MeV. The SRM instrument measures the fluxesand spectra of protons with energies 1–200 MeV andelectrons with energies 0.5–12 MeV. The CRS-3measures the chemical composition and spectra ofions in the range Z = 1–10 and in the energy range1.5–20 MeV per nucleon for Не and 4–40 MeVper nucleon for Ne. In comparison with the SOHOand Yohkoh instruments, the SONG spectrometeris capable of recording energetic (with energies upto 100 MeV) gamma-rays, which, in turn, makesit possible to observe gamma-rays from the decayof the π0 mesons produced in interactions of high-energy protons. The CORONAS-F measurementsshow that the SONG background for recording solarneutrons is at least a factor of 5 to 7 lower than thatof GRS (SMM) — the only instrument that recordedsolar neutrons in the same energy range. Figure 11shows the SONG recording of gamma-rays withenergy 60–150 keV (I) and electrons with energy0.3–0.6 MeV (II). The first increase in gamma-ray flux correlates with the electron flux and can beexplained in part as electron bremsstrahlung. The tworemaining increases represent solar flare radiation.Since the flare occurred in the western hemisphere,


the recorded increase in relativistic particle flux beganalmost immediately.

ACKNOWLEDGMENTS

V.D. Kuznetsov and I.A. Zhitnik played a majorrole in designing the CORONAS-F complex. Theyalso helped in writing this paper, for which we thankthem. We are also grateful to T.V. Kazachevskaya,Yu.D. Kotov, G.E. Kocharov, S.N. Kuznetsov,N.I. Lebedev, E.P. Masetz, A.A. Nusinov, V.M. Pan-kov, A.F. Podorol’skii, S.P. Ryumin, and J. Silvestr,who provided the reduced data from the CORONAS-F satellite.

REFERENCES1. A. Jimenez, P. L. Palle, T. Roca Cortes, and V. Domin-

go, Astron. Astrophys. 193, 298 (1988).2. N. I. Lebedev, V. E. Oraevsky, Y. D. Zhugzda, et al.,

Astron. Astrophys. 296, L25 (1995).3. V. N. Oraevsky, N. I. Lebedev, I. M. Kopaev, et al., oral

communication (1999).4. I. I. Sobelman, I. A. Zhitnik, and A. P. Ignat’ev, Pis’ma

Astron. Zh. 22, 604 (1996) [Astron. Lett. 22, 539(1996)].

5. The SOHO Mission: Scientific and Technical As-pects of the Instruments (ESA, Paris, 1988), ESASP-1104.

6. I. Zhitnik, A. Ignatiev, V. Korneev, et al., Proc. SPIE3406, 1 (1998).

Translated by V. Astakhov

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Erratum:ComprehensiveStudiesofSolarActivity ontheCORONAS ... · 570 ORAEVSKY,SOBELMAN 1.2 × 10 –5 2600 0 1.2 × 10 –6 Amplitude, arb. units 2900 3200 3500 Frequency, µ Hz Fig.2