Abstract
The solar UV continuum has been derived from intensity-calibrated observations with the High-Resolution Telescope and Spectrograph - HRTS - on its second rocket flight in 1978. A database has been constructed using the spatially-resolved solar spectrum 1180–1700 Å along a slit extending from near disk center to the solar limb and crossing a sunspot and two active regions. The angular resolution is approximately 1.8″.
The data consist of 1772 spectral scans in the full center-to-limb range, including both quiet and active solar regions. The distribution of solar UV intensities has been derived and the center-to-limb variations of the continuum intensities in the quiet Sun are studied. Both quantities show spectral variations, particularly across the Sii continuum edge at 1521 Å. The spectra have been fitted to curves of constant color temperature above and below the Sii edge.
The derived center-to-limb variations have been compared to the values of Samain (1979) which are frequently referred to in the literature. A relatively large discrepancy may be explained by the higher spectral and angular resolution of the HRTS as compared to the rocket instrument used by Samain. Comparisons with the VAL III model calculations by Vernazza, Avrett, and Loeser (1981) show discrepancies between the observations and the model predictions, particularly with regard to the sign and amount of the intensity change across the Sii continuum edge.
It is noted that some of the results presented, i.e., absolute intensities and brightness temperatures may change, pending confirmation of the SUSIM Spacelab 2 irradiance results (VanHoosieret al., 1988).
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References
Avrett, E. H.: 1985, in B. Lites (ed.),Chromospheric Diagnostics and Modeling, NSO Conference, Sacramento Peak, Sunspot, p. 67.
Bartoe, J.-D. F. and Brueckner, G. E.: 1975,J. Opt. Soc. Am. 65, 13.
Bonnet, R. M.: 1968,Ann. Astrophys. 31, 597.
Brekke, P.: 1993a, Dr. Scient. Thesis, University of Oslo.
Brekke, P.: 1993b,Astrophys. J. Suppl. Ser. 87, 443.
Brekke, P., Kjeldseth-Moe, O., Bartoe, J.-D. F., and Brueckner, G. E.: 1991,Astrophys. J. Suppl. Ser. 75, 1337.
Brueckner, G. E. and Moe, O. K.: 1972,Spac Res. 12, 1595.
Cook, J. W., Brueckner, G. E., and Bartoe, J.-D. F.: 1983,Astrophys. J. 270, L89.
Kelly, R.: 1987, ‘Atomic and Ionic Spectral Lines Below 2000 Ångstrom’, Part I-III,J. Phys. Chem. Reference Data, Supplement No. 1, Vol. 16.
Kjeldseth-Moe, O. and Milone, E. F.: 1978,Astrophys. J. 226, 301.
Kjeldseth-Moe, O., VanHoosier, M. E., Bartoe, J.-D. F., and Brueckner, G. E.: 1976,A Spectral Atlas of the Sun between 1175–2100 Å, NRL Report 8056.
Rich, J. C.: 1966, Ph.D. Thesis, Harvard University.
Samain, D.: 1979,Astron. Astrophys. 74, 225.
Samain, D., Bonnet, R. M., Gayet, R., and Lizambert, C.: 1975,Astron. Astrophys. 39, 71.
Sandlin, G. D., Bartoe, J.-D. F., Brueckner, G. E., Tousey, R., and VanHoosier, M.: 1986,Astrophys. J. Suppl. Ser. 61, 801.
Tousey, R.: 1963,Space Sci. Rev. 2, 35.
VanHoosier, M. E., Bartoe, J.-D. F., Brueckner, G. E., and Prinz, D. K.: 1988,Astrophysics Letters Comm. 27, 163.
Vernazza, J. E., Avrett, E. H., and Loeser, R.: 1981,Astrophys. J. Suppl. Ser. 45, 635.
Widing, K. G., Purcell, J. D., and Sandlin, G. D.: 1970,Solar Phys. 12, 52.
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Brekke, P., Kjeldseth-moe, O. The solar UV continuum 1440–1680 Å and its center-to-limb variation. Sol Phys 150, 19–47 (1994). https://doi.org/10.1007/BF00712874
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DOI: https://doi.org/10.1007/BF00712874