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Re: photometry software problem > I don't think we are in disagreement, just describing the effect > differently. The area involved in the sky annulus is usually > larger than for the star aperture, so it depends on how the sky level > is determined from that annulus. Okay, this is often misunderstood procedure, and I feel I need to mention something when an observer want to move the "background" aperture. Please don't, in any case, search for the "darkest region" in the image. > My point is that not all interesting stars are faint. Why not, in > general, pay more attention to the brighter stars when you have > a small telescope? There will always be exceptions, but the average > amateur will have more success if they stay within reasonable limits > with their systems. The objects of current astrophysical interest are mostly faint. This is why we need 10 meter telescopes. This is not restricted to professional observing. In more realistic cases, large-amplitude dwarf novae have amplitudes usually larger than 6 mag. Eclipsing dwarf novae tend to have eclipses more than 1 magnitude. An ideal photoetry package can easily handle this degree dynamic range, but the actuality with commonly used software packages does not. Observations will be meaningless when one avoid eclipse minima simply because of the inability of the software. While we are primarily talking about "faint end" observations, we are not confident whether the same or a different problem in the same package may affect bright star photometry. This probably needs to be independently checked. For example, a recent experiment by Reszelski and Otero with PIXY software (although this is not a commercial one) indicates, contrary to expectation, that all magnitude ranges are more or less affected by some unidentified(?) problems. The result was probably worse than visual photometry by Otero. This software, for example, is not expected to give "more success" even if an observer would confine their interest within bright star photometry. > Again, I do not disagree that you are seeing problems. I contend that > it is unfair to blame the software without further information. I am almost ready to provide a comparison of light curves (they are already present). The result correctly reflects what I explained by words. It's okay some people would more trust figures than literal description, but the description would be already sufficient for the programmer before displaying the most critical results. Regards, Taichi Kato
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