The goal of this round-table discussion is to bring up issues which may be of mutual interest to those working on specific flare and variable stars and those performing wide-field searches for, among other things, counterparts to gamma-ray bursts (GRBs). Admittedly, however, trying to unify the interests of the flare people and the GRB people will be an interesting task. Many of the presentations this week have been devoted to future instrumentation and future modes of observations, but there have been also interesting discussions of specific questions regarding flare stars, variable stars and GRBs. Certainly, wide-field observations of the night sky will continue for the foreseeable future: there are a lot of instruments running now, and there are many instruments being planned. Most of these observations cover many square degrees of sky for long periods with a reasonable magnitude limit. How could these observations could be modified or improved to also allow useful data on on variable stars or flare stars to be taken? What sort of information, statistics, periodicities could be gleaned from wide-field searches that will be happening in the future and searches that are going on today? Are there methods in common use by one group of observers that may be useful to the other?

The speakers in this session have volunteered to give a short presentation on issues which may benefit from discussion within this group.

To date we obtained 511 blue plates with multiple exposures of nine young clusters and associations to be used for studying the flare activity-age relation. First attempts showed already that automatic search increases the number of discovered flares by 50% compared to visual inspection (Aniol et al. 1989). Improved algorithms have now been implemented and applied. Automated object identification in existing catalogues (FSDB, GCVS, SIMBAD) is also available.

All plates are digitized with the PDS 2020 GMplus microdensitometers at AIM and reduced with the AIM software. Steps following the reconstruction of images include the transformation of plate to sky coordinates and matching of the multiple exposure chains with the stars on the deep reference plate. All complete chains (generally six exposures) are used to derive average light curves for all objects. For each magnitude interval 10-11, 11-12, … 15-16 the mean deviation and standard error of an image from the overall mean value of the respective chains is determined. If any image in a chain differs by more than a preset multiple of the mean error it is considered a potential flare event and registered for visual inspection, together with the chains immediately preceding and following the suspected flare event, to obtain information on the total duration of the outburst. The candidates are filed and the data of all stars are stored for checks of long-term variability.

The Muenster Redshift Project provides to date 0.9 million low-resolution redshifts obtained from automatic reductions of pairs of direct and low-dispersion objective prism Schmidt plates. Preliminary results obtained from subsamples of the survey are described.

From 1986 to 1988 optical spectroscopy near minimum of all then established recurrent novae (excluding recurrent X-ray novae such as V616 Mon and V404 Cyg) was carried out with the 3.6 m and 1.5 m telescopes of ESO, using EFOSC with CCD and the Cassegrain spectrograph with CCD or IDS, respectively. Flux-calibrated spectra of the six objects are shown in Figs, 1a – f. The most recent recurrent nova, V745 Sco, is included in the present discussion, because 1 month after outburst it had already reached a very late stage of outburst evolution. A spectrum of V745 Sco is shown in Schwarz et al. (1989).

Statistically relevant samples of flare stars in stellar aggregates can be used to specify the stellar mass-age-activity-relation when the ages of the aggregates are known from independent investigations. Associations and clusters of the southern sky are currently surveyed with the GPO astrograph of the European Southern Observatory. The plates are digitized with the PDS 2020 GMplus microdensitometer and the data are reduced automatically at the Astronomical Institute of Muenster University. The programme package “FLARE” is described. First results from the Orion association are presented.

The very slow nova X Ser (t3 = 555d), situated at a large distance from the galactic plane (z ≈ 4kpc), reached maximum light at 9m in May 1903. It was discovered 5 years later on a Harvard plate (Leavitt 1908). No outburst spectrum is known. A photographic outburst light curve is given by Walker (1923); additional photometric data were published by Sakharov (1954) and Kinman et al. (1965). The light curve, shown in Fig. 1, presents 10-day means, based on all published data, and unpublished data taken from Emily Hughes Boyce’s notebook, Harvard College Observatory Plate Collection.

Hughes Boyce (1942) discovered a 275d periodicity during minimum light. From the fragmentary light curve in Fig. 1, including three more recent ‘oscillation’ maxima, a period of 277 days is found. If one assumes that the nova reached Mpg = −6 at maximum, the typical value for a slow nova, the mean absolute magnitude at minimum, Mpg = +2, together with the observed amplitude of about 2m and a relatively long mean period, suggests a very late-type (typically M6e) semi-regular variable.

Exnovae and nova shells are generally faint and difficult to observe. Only a few have been studied, and even less of them in sufficient detail. We give a progress report on our survey of exnovae and nova shells, especially on the results of a spectral survey of novae in the southern Milky Way. The three-dimensional structure in the light of Hα derived for the nebula of GK Per is displayed.