Hi Marc,
you wrote:
Assuming mass transfer has taken place earlier, it is quite possible the predicted/calculated start of the eclipse will be later.In that context Phil Bennet wrote here at the forum:
http://www.spectro-aras.com/forum/viewtopic.php?f=19&t=1219&p=5533&hilit=bennet#p5533“The stars appear to be well-separated, and the M supergiant never comes close to filling its Roche lobe. There is mass accretion onto the hot companion, but this is from *wind* accretion -- gas from the wind of the M supergiant that just happens to be intercepted, and gravitationally captured, by the hot companion.” Furthermore we are at present still around the phase of the apastron (phase 0.63; based on the orbital elements of Wright 1977) what means, there can not be explicit mass transfer in that orbital phase between the components, the distance between the M star and the hot companion is approx. 10-15 AU. As at all, mass transfer takes place only around the phase of the periastron.
Even if the eclipse comes later than the prediction says, there is no reason to become un-patiently. Until now the ARAS community has been able to observe a very well defined base line for both, the EW and peak height. If I see what quality in terms of the definition of the starting point during the last eclipse Kawabata et al. and Möllenhoff/Schaifers have achieved, I would say that our results until now are much better.
And in addition we are in the lucky position to have someone in our community, who contributes with his two remote observatories as much as it possible: Joan Guarro from Barcelona. Joan offers echelle spectra in a high quality which meet all what we could get.
So, from my point of view we should be patiently as we did until now.
Best wishes,
Ernst