COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3376

                                          Konkoly Observatory
                                          Budapest
                                          22 September 1989

                                          HU ISSN 0374 - 0676


CAMPAIGN OF SIMULTANEOUS, MULTIWAVELENGTH OBSERVATIONS OF THE FLARE/SPOTTED
                         VARIABLE, CC ERI


A multiwavelength campaign is being mounted on 2 and 3 November 1989 to observe
the 1.56 day period spectroscopic binary and flare/spotted variable, CC Eri
(K7Ve+~dM4), continuously over its complete orbital period in order to locate
and measure the ultraviolet and optical line emission from it's active regions,
as well as its quiescent chromosphere and transition region, and to study
flares which are likely to occur during the observing run. CC Eri is the
second brightest member of the BY Draconis class of spotted cool dwarfs and,
with its short orbital and rotational period is one of the fastest rotating.
For these reasons it is a very active BY Dra/flare star and probably has one of
the brightest ultraviolet line spectra of its class. Only one LW LORES IUE
spectrum has so far been obtained of this important object and a very small
number of optical spectra. We therefore propose to carry out a detailed study
of its quiescent and flaring emission properties and request collaborative,
simultaneous ground-based observations from as geographically widely spaced
sites as possible.

With IUE we will obtain a continuous series of SWP-LO and LWP-LO spectra over
the full orbital (= rotational) period in order to identify bright active
regions (from the rotational modulation of emission line fluxes) and to
correlate the location of these active regions with dark starspots obtained
from contemporaneous optical photometry and spectroscopy. We will also study
the time behavior of flares in different spectral lines with coordinated
optical photometry and microwave observations. Flares with optical U-band
enhancements greater than 1 magnitude are known to occur on average once per 12
hours. We plan to model the quiescent, active, and flaring atmospheres
separately using emission measure diagnostics.

Observers interested in collaborating in this campaign should contact the
undersigned.


P.B. BYRNE              SPAN: 19457::ARVAD::PBB
Armagh Observatory      Bitnet: PBB%UK.AC.QUB.ARM
Armagh BT61 9DG         Tel.:(44)861 522928
N. Ireland              Fax: (44)861 526187
                        Tlx. 265871 MONREF G, 1st line must be: MAG32510