Abstract
A great sunspot group of October 1991 (NOAA 6891 atL = 189,B = −10) was observed, in which an eruptive flare of importance (X2.5/31B) has been reported. A Caii-line 3933 Å filter was used, and during a time interval of 3 hours more than 90 frames were taken, using a CCD camera. The progress and the distribution in size of the two main flare points have been obtained; they covered an area of about 1800 millionths of the solar disk within a time interval of about 24 min. The average apparent horizontal velocity was 70 km s−1.
This is a preview of subscription content, log in via an institution to check access.
References
Basurah, H. M., Al-Mleaky, Y. M., and Malawi, A. A.: 1994,Astrophys. Space Sci. 215, 131.
Kosugi, T., Sakao, T., Masuda, S., Makishima, K., Inda, M., Murakami, T., Ogawara, Y., Yaji, K., and Matsushita, K.: 1992,Publ. Astron. Soc. Japan 44, L45.
Malawi, A. A.: 1994,International Amateur-Professional Photoelectric Photometry Comm. 57, 1.
Peterson, C. C., Bruner, M., Acton, L., and Ogawara, Y.: 1993,Sky Telesc. 86, 20.
Shimizu, T., Tsuneta, S., Acton, L. W., Lemen, J. R., and Uchida, Y.: 1992,Publ. Astron. Soc. Japan 44, L147.
SIDC (Sunspot Index Data Center): 1991,Sunspot Bulletin 10.
Zirin, H.: 1988,Astrophysics of the Sun, Cambridge University Press, Cambridge.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Basurah, H.M., Malawi, A.A., Al-Mleaky, Y.M. et al. Flare development in active region NOAA 6891, 30 October, 1991. Sol Phys 158, 383–386 (1995). https://doi.org/10.1007/BF00795671
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00795671