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Paul wrote: >I am also a little concerned about the tone the e-mails are taking.< I understand Sebastian's exasperation with this particular issue. He has had good charts for eta Car published for quite some time. He is more familiar and experienced with observing this particular field than most observers, and more than likely, the chart team that assembled the latest AAVSO charts. The errors he pointed out in the first post were not correctly addressed, even after pointing to the url for his charts, so it appears that his offer to help and the reference to his charts was rejected out of hand. The discrepancies noted were obvious to me upon a cursory examination of the Otero charts and the revised AAVSO charts. Sebastian does make excellent charts. I can tell you from experience that his chart and sequence for V Hya makes a lot more sense to me visually than the AAVSO chart for this beautiful red star. >In spite of that, isn't it accepted that as long as the observer logs which comparison stars were used and which chart was used, any magnitude estimate of a variable star can be corrected once any errors in comparison stars are found and corrected? (Unless of course a comparison star is found to be variable?)< This is stated over and again to be the case, but in the end I think it will be found to be more difficult than is thought, or impossible in some cases all together because of the nature of some of the errors that exist on the charts. For example, if the comp stars are not assigned values that are in fact sequential from brightest to faintest no transformation process will yield reliable data. Garbage in, garbage out. The number of charts with this specific problem is disappointingly great. And as Sebastian pointed out, if the observer actually estimates the magnitude of the wrong star there is no way to recover any useful information. Again, there are in fact many charts with variables mis-identified to this day. >It just seems to me that the important thing is to make the estimate and get all of the information down. The corrections, if need be, will come in time.< On the other hand, it seems to many observers that to wait for corrections to charts that could be improved now with existing photometric data in order to maintain the integrity of a database is more a political decision than a scientific one. I think that is what Sebastian was referring to when he wrote "I think that the huge amount of work in existence is always a justification to keep doing it the wrong way right now." You may disagree with his methods or his tone, but it is hard to argue with his results. A light curve of delta Sco based solely on Otero's observations will prove to be more coherent and scientifically useful than the AAVSO data for that star. I'd venture to guess the comparative data for eta Car for the time he has been observing it will show the same results. From what I have heard and read, eta Car is a particularly challenging target. Good luck to you all who observe it. Perhaps a few pointers from Sebastian would prove more interesting and positive than the re-hashing of the old chart/sequence debate. Regards, Mike Simonsen
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