A series of Ha-spectrograms obtained with the 21 in. Lyot coronagraph has been examined. Measurements of relative distances between spicules (nearly 50 features) embrace the time interval of about 21 min (38 pictures). It is found out that spicules oscillate along the limb with a characteristic time interval (period) about 1 min, characteristic amplitude of 1 arc sec and velocities about 10-15 km/s. The oscillations show no correlation for distant spicules.As was established by numerous observators, Doppler velocities of many features change as a function of time (Mouradian, 1965, Pasachoff et al., 1968, Nikolsky and Sazanov, 1966. The latter two papers state that all spicules, or at least some part of them, reverse the sign of line-of-sight velocities during their life-time, the latter usually being several times longer than the characteristic time of the line-of-sight velocity evolution (see also Beckers, 1968).The reasons for quasiperiodic oscillations of line-of-sight velocities are not clear. As was noted before by Nikolsky (1970) either (a) backward-translational mass movement along the spicule axis or (b) oscillations in the tangential direction (along the solar limb) are possible. The latter point of view seems more acceptable.The first mention of observations of spicule motions along the limb was made by Pasachoffet al. (1968). ObservationsThe observations discussed below were carried out on April 3, 1969 with the 53 cm Lyot coronograph mounted at the High Altitude Astronomical Station near Kislovodsk. 38 He spectrograms of the chromosphere were obtained during about 21 min. The observations were made by one of the authors assisted by Y. V. Platov and A. A. Sazanov. The curved slit of the spectrograph was adjusted concentric to the limb of the Sun at a height of 4200 km. Height and concentricity were controlled to within 0.5 arc sec using a method proposed by Nikolsky (1970). The dispersion is 0.96 A/mm, the scale is 16 arc sec per mm. The time interval between successive frames varied from 14 to 100 s, being on the average 30 s. The exposure time was 0.3 s. 35 mm isopanchromatic film Type-17 was developed with Kodak D-19 for 6 min at a temperature of 20 ~ The quality of the photographs is good and the resolution on each of them is not worse than 1 arc sec. Measurements of SpectrogramsWe used a one-coordinate measuring microscope with a scale division of 1 #. Readings were taken in the direction perpendicular to the dispersion and coinciding with a Solar Physics 18 (1971) 403-409. All Rights Reserved Copyright 9

Time succession of 25 Ha spicules has been studied. The spectra are obtained at a height of 6 arc sec during 21 rain (38 pictures) with the 53 cm Lyot coronagraph. Total intensities W, widths AA and radial velocities Vr are determined (about 650 Ha line profiles). For 14 spicules the sign of V, varies, for the rest the sign variation is absent or it is doubtful. Characterized period of Vr variation is 3-7 rain with a mean amplitude of • km s -1. W and AA also vary with a similar period and mean amplitudes equal to 50% and 30% respectively. AA dependence of W ( Figure 1) points to the existence of two spicules groups: group I (70%) characterized by relatively small W and AA (mean values are 0.08 A, and 1.3/~ respectively); group II comprising brighter (W~0.13/~) spicules with wider profiles (AA = 1.6 ~,). Group II may consist of the unresolved, superimposed group I spicules. We believe, that Ha spicules involve formations consisting of separate elements having the temperature of 6000 K and non-thermal velocities of -25 km s -1. ObservationsA series of spectrograms (38 pictures) obtained by G. M. Nikolsky, Yu. Platov, and A. A. Sazanov on 3 April, 1969 with a large coronagraph mounted at the High Altitude Astronomical Station near Kislovodsk has been examined. The curved slit of the spectrograph was adjusted concentric to the limb of the Sun on the East side at a height of 4200 km. The height was controlled by the method proposed by Nikolsky (1970). The dispersion was 0.962 ~ mm -1 in the second order in coud6 focus, the scale being 16 arc sec per mm. The exposure time was 0.3 s. The resolution on each photograph is not worse than 1 arc sec. The time interval -21 rain. The observations have been reported in detail earlier (Nikolsky and Platova, 1971). Measurements of SpectrogramsWe have chosen 25 spicules traced as single details on many pictures, i.e. not consisting of superimposed spicules. In order to identify the spicules precisely, large-scale prints of each frame were made.Photometric sections were made along the dispersion in the centre of each spicule (microphotometer slit cut 0.03/~ • 0.5 arc sec). Fraunhofer lines of the third order scattered light served as reference lines, from which the wave-length was Solar Physics 59 (1978) 21-28. All Rights Reserved Copyright (~) 1978 by D. Reidel Publishing Company, Dordrecht, Holland

The method of Giovanelli and Brown (1977) has been used with a variety of spectral lines to study oscillating longitudinal gas velocities inside solar magnetic elements. Oscillations have been found inside all elements observed, the amplitudes increasing with height from typically +0.27kms -I in Fe 15166 ~ (a line of low origin) to + 0.75 km s-1 in Ha. Simultaneous observations in pairs of lines show that a given disturbance occurs later with height, so that disturbances propagate outwards. The period is typically 5 rain in all lines originating near or below Mg bx, but is about 3 min in Ha.Simultaneous observations of the gas velocities within the magnetic element and in the immediatelysurrounding non-magnetic region often show closely similar behaviour; the amplitudes are almost the same, and the mean phase difference is effectively zero, but there is a large individual variability of the order of + 0.5 rain. These results imply that either there is a strong local interaction between outside and inside magnetic tubes, or the disturbances are excited by a common mechanism.The velocities observed inside and immediately outside magnetic elements have the same pattern and amplitudes as those far away from magnetic elements. In particular, the disturbance velocities never exceed about 0.1 of the velocity of sound, suggesting the absence of large-amplitude shock waves anywhere in the magnetic or non-magnetic solar atmosphere between the levels of formation of Fe 1 5166 ~ and Ha.

The new Lyot-coronagraph with 53 cm objective is described. The coronagraph has a grating spectrograph. The solar disk image on the slit of the spectrograph is 12.6 cm. The dispersion is 1 ~/mm in the second order. The coronagraph is situated at the Kislovodsk Station of Pulkovo Observatory, 2050 m above sea level.An actual problem in solar physics is the investigation of the fine structure and dynamics of the solar corona, chromosphere and the region in between. At present (and in the very near future) such investigations can only be made with earth-bound equipment, in spite of the successes of space astronomy.In order to investigate the fine structure of the solar corona by means of spectralline observations with a large dispersion and high resolving power it was necessary to construct a big Lyot-coronagraph with grating spectrograph. According to a proposal by M. N. Guevyshev such a coronagraph was built by the common efforts of Pulkovo Observatory and Izmiran (NIKOLSKY and SAZANOV, 1966) and established at the Kislovodsk Station of Pulkovo Observatory, 2050 m above sea level.The optical scheme and the principle of construction were proposed by G. M. Nikolsky and A. A. Sazanov.The optical scheme is given in Figure 2. The main objective O 1 is a boron-silicon flat-convex lens 53 cm in diameter and F= 800 cm for 2 = 5500 A. The angular resolving power is about 100 m-1 for 2 = 5500 A and for all regions 3500-12000 A it is not less than 25 mm -1 (1"). The relative aperture is 1/16. In order to have a large image size it would be necessary to have a long telescope tube, but to overcome the resulting structural deformations it was decided to have an objective with a relatively small focal length and additional optics to increase the image size. According to calculations by the late D. D. Maksutov a 53-cm objective with a resolving power as mentioned above must have a focal length not less than 800 cm. Such an objective was made by V. G. Shreiber (Pulkovo Observatory), who also constructed the further optics of the coronagraph and spectrograph.The mechanical and electrical constructions were for the greater part made in the workshops of Izmiran.The artifical 'moon' M is a flat metallic mirror with a working edge of 60 ~ The 'moon' can rotate in such a way that the middle part of its edge is always on the Solar Physics 2 (1967) [223][224][225][226] 9 D. Reidel Publishing Company,

We describe observations with a new magnetograph capable of recording the whole profile of emission lines in prominences. Two recordings are used simultaneously to study the Zeeman effect in circularly polarized light. The spectral scan is produced by the action of piezo ceramics of a Perot-Fabry inter ferometer combined with a narrow band interference filter.The instrument is calibrated using 100% circularly polarized light and an emission line produced in Laboratory conditions in a simulated longitudinal magnetic field. The magnetograph was attached to the large coronagraph (~ 53 cm) of Kislovodsk to give a series of measurements of the H//line of several quiescent and active prominences. The observed values of the longitudinal component of the magnetic field are between: 25 G + 13 G with a noise level at _+ 2 G for a corresponding resolution of 8 arc sec.Effects produced by the instrumental polarization are discussed.