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> From John Greaves: > > He [Liller] actually uses an orange bit of glass. Not any old orange bit of glass, > granted, but I know of no standard stars for schott and/or wratten number > whatever it is. Maybe that's the answer? Talk Arne Henden into setting up > some primary standards for kodak kaf chips and wratten orange filters ;) ? > (I'll do the first star: Vega is O_kaf = 0.00). > That may be the reason the AAVSO has that "CCDO" magnitude-type. :-) I can't think of anyone else with such a system. However, remember from the massive Asiago photometric system database that there are over a hundred different photometry systems. One cannot invent a type-code that handles them all; something that handles, say, 95percent of all amateur submissions is a reasonable goal. I think a combination of the "CV,CR" unfiltered set plus "UBVRI" for the filtered folks probably does that. If you want to differentiate between Rj/Ij and Rc/Ic, that also makes sense. Differentiating between PEPV and CCDV does not make sense for analysis, though it might make internal sense for some organization. No, I won't take up John's challenge and standardize CCDO! > > There should be a stromgren ubvy beta (beta's good for luminosity class > determination) satellite up there, with a subexperiment in Wing photometry > for the brighter red stuff onboard too. Maybe a blue-end subset too, as > I don't think IUE went that faint, and was more spectroscopic, though that's > probably not as necessary and/or visual. You can do quite a bit with > Stroemgren c1, m1, beta and the various Wing indices. Information, not > just data. Okay, a survey gives hints and reveals new things, and you > follow up with better, more targeted, kit, at a later tim. But still. > I'll agree to this! Ground-based calibration is difficult at best. But I'll extend it: some satellite should do spectrophotometry, whether with grism or true spectroscopy, so that one has calibrated spectra at reasonable resolution. Then you can make your own standards-list for whatever filter system you want to use. GAIA has promise if you are willing to wait a decade. Putting up a 0.4m telescope, such as is proposed for Space Station, might be sooner if they can be convinced to do spectroscopy rather than photometry. > > (Okay, there's ASAS, and also TASS in Tom D and Arne H and probably other > incarnations, but all still a long way from finishing and the limiting > magnitudes might only be 13 or so at the complete level). > The TASS setup at NOFS will go down to V=16 at the completeness level; there are other surveys underway. I wrote a paper on surveys for a recent GAIA conference that will be ADS-referenced one of these days. > Arne
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