The second annual GEOS symposium took place in Marly on 5–6 March 1977, gathering 39 participants, including ten Italian observers. Discussions focused on redefining observing priorities and improving the organization of publications. The group noted that the volume of measurements—184,000 in 1976—exceeded its processing capacity. As the document states, “the number of measurements… exceeds our capacity for processing.” This led to the need for stricter selection of targets.
A hierarchy of scientific results was established, ranging from high‑impact studies (eclipsing‑binary orbits, RR Lyrae Blazhko analyses, detailed δ Scuti and β Cephei curves) to results suitable for IBVS or for updating the GCVS. Routine monitoring of aperiodic stars was considered unproductive, described as “useless competition with the AAVSO.”
A revised GEOS observing programme was adopted, specifying which C, SR, L, M, RV, RR, and eclipsing stars would remain in routine monitoring. Observations outside campaigns or programme would be disregarded, as stated: “observations outside campaigns or outside the programme will be ignored.” Some exploratory work on poorly studied SR and L stars was allowed if coordinated among several observers.
The symposium also defined a structured plan for external publications through specialized GEOS Circulars, covering ppm stars, C stars, eclipsing‑binary orbits, RR Lyrae, and RV/M stars. Procedures for submitting data and centralizing compositings were clarified.
Several data‑analysis methods were presented, including the Russell method for binary orbits, the Kwee & van Woerden method for minima, and Fourier‑based maxima determination for Cepheids. Difficulties in interpreting CY Aqr results from the 1976 campaign were discussed.
General‑interest topics included carbon stars, multicolour photometry, and the 1977 RL1 CVn campaign. Plans for summer observing camps and a possible 1978 southern‑hemisphere expedition were reviewed. The meeting concluded that significant progress had been made in linking observations to meaningful scientific results, marking improvement compared to Marly 76.