89 LIGHTCURVE PHOTOMETRY OPPORTUNITIES: The SR magnitudes should be used when observing without (or 2021 JANUARY-MARCH with a Clear) filter and typical CCD cameras (e.g., FLI, SBIG, etc.) with a KAF-E chip (blue enhanced) or another chip with Brian D. Warner similar response. This is because those chips have a very good Center for Solar System Studies / MoreData! linear fit of catalog versus instrumental magnitude for the Rc and 446 Sycamore Ave. SR bands and so, if using near-solar color stars, there is no need Eaton, CO 80615 USA for additional reductions such as color term correction.
[email protected] Regarding H-G observations, the question of how much data is Alan W. Harris enough is often raised. The answer is, “It depends on the nature of MoreData! the observing project.” To that, we’d add that having just a few La Cañada, CA 91011-3364 USA data points at each observing run places a much greater demand on having accurate magnitudes. If those requirements are on the order Josef Ďurech of 0.02 mag, that stretches the limits even when using the high- Astronomical Institute quality catalogs. Charles University 18000 Prague, CZECH REPUBLIC The H-G system is based on average light at the time of the
[email protected] observations, i.e., the amplitude of the lightcurve at the time must be known and, if necessary, those few data points be corrected so Lance A.M. Benner that they correspond to “mid-light” at the time. Since the Jet Propulsion Laboratory amplitude often changes as the asteroid recedes or approaches, it’s Pasadena, CA 91109-8099 USA necessary to obtain enough data points during each observing run
[email protected] to establish or reasonably predict the mid-light magnitude.