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. We present lists of asteroid photometry opportunities for Another reason for denser data sets is that the results from shape objects reaching a favorable apparition and have no or modeling are greatly improved by having good lightcurves from poorly-defined lightcurve parameters. Additional data multiple phase angles within the same apparition. This is in on these objects will help with shape and spin axis addition to lightcurves obtained over several apparitions. modeling using lightcurve inversion. We also include lists of objects that will or might be radar targets. There is no set answer to the number of data points, exposure Lightcurves for these objects can help constrain pole length, observing cadence that satisfies all purposes. However, it solutions and/or remove rotation period ambiguities that might be good to remember that you can always disregard or reject might come from using radar data alone. data points during analysis but you can’t create them after the fact. A good example of balancing the number of H-G data points and On Better Magnitude Calibrations and H-G Data Requirements those needed to derive those points can be seen in the lightcurves In recent times, several catalogs with high-quality photometry and H-G plot (a modified version is shown here) for 86 Semele by have become available. A major advantage of these catalogs for Frederick Pilcher (2020). lightcurve observers is the significant reduction of systematic variations for magnitude calibrations across the sky. This has led to fewer and much smaller nightly zero-point adjustments when trying to do photometric analyses. An excellent example of taking advantage of these new resources was given by Eric Dose (2021), who developed a pipeline using the ATLAS Star Catalog (Tonry et al., 2018). Other catalogs such as Pan-STARRS, SkyMapper, and GAIA2 can be readily accessed with on-line tools to get comparison star magnitudes for a given field. This, of course, requires that an Internet connection be available at some point, either before, during, or after the initial reduction process. The elimination, or significant reduction, of arbitrary zero-point adjustments is critical when trying to find H-G or H-G12 parameters. For asteroid lightcurves, even small zero-point changes can dramatically change a period solution, especially The original plot by Pilcher (2020) has been modified to make the when the amplitude is low. The adjustments can also alter results data points easier to see and a legend replaces the explanatory text when dealing with tumbling or binary asteroids. for the data points. We strongly suggest that all observers adopt one of the above- A final note, the H in the H-G system is, by default, Johnson V. mentioned catalogs as their exclusive source for comparison star For direct comparisons with other reported H values, it may be magnitudes as soon as possible. We also recommend that the necessary to use a transform to go from the native magnitude used native magnitudes of the chosen catalog be used. For example, from the catalog. The web pages for the catalog used in reductions from ATLAS or Pan-STARRS, the r´ (Sloan SR) magnitude, and may provide or have links to the required transformation formulae. not magnitudes that are the result of applying transformations that use a simple constant offset or color index dependency on two of the native magnitudes, e.g., SG/SR to Rc. Minor Planet Bulletin 47 (2020) 90 Back to Regular Programming Brightest LCDB Data Number Name Date Mag Dec Period Amp U ------------------------------------------------------------- We present several lists of asteroids that are prime targets for 26206 1997 PJ4 01 15.2 15.4 +16 photometry during the period 2021 January-March. 2984 Chaucer 01 15.2 15.4 +24 3590 Holst 01 22.8 15.0 +18 12.7635 0.20 2 13709 1998 QE13 01 25.5 15.2 +17 55.961 2 In the first three sets of tables, “Dec” is the declination and “U” is 4612 Greenstein 01 28.8 15.3 +25 the quality code of the lightcurve. See the latest asteroid lightcurve 2546 Libitina 02 01.9 14.3 +18 132.71 0.35 2+ 174050 2002 CC19 02 03.8 14.0 +17 data base (LCDB from here on; Warner et al., 2009a) 87035 2000 KE2 02 04.3 15.5 +20 documentation for an explanation of the U code: 1612 Hirose 02 12.8 14.8 +12 12.295 0.25 2 1724 Vladimir 02 14.0 14.8 +7 12.582 0.14-0.24 2+ 5348 Kennoguchi 02 17.1 15.5 +7 http://www.minorplanet.info/lightcurvedatabase.html 1513 Matra 02 17.1 14.8 +14 > 24. 0.1 1 13521 1991 BK 02 19.7 15.5 +21 The ephemeris generator on the CALL web site allows you to 4107 Rufino 02 21.6 14.4 +13 15.31 0.07-0.15 2 5982 Polykletus 02 28.7 15.5 +0 create custom lists for objects reaching V 18.0 during any month 49483 1999 BP13 03 01.9 15.1 +7 in the current year and up to five years in the future, e.g., limiting 4133 Heureka 03 03.3 15.3 +1 2288 Karolinum 03 05.0 14.4 +29 42.16 0.15-0.40 2+ the results by magnitude and declination, family, and more: 2521 Heidi 03 05.4 15.1 -5 12. 0.02 1 4238 Audrey 03 07.7 15.5 +6 http://www.minorplanet.info/PHP/call_OppLCDBQuery.php 2777 Shukshin 03 10.0 15.3 +10 22295 1989 SZ9 03 16.6 15.5 +4 3.8 0.04 2 3748 Tatum 03 20.7 15.0 +6 58.21 0.54 2+ We refer you to past articles, e.g., Warner et al. (2009b) for more 4794 Bogard 03 20.9 15.5 +1 detailed discussions about the individual lists and points of advice 7685 1997 EP17 03 21.7 15.3 -3 7637 1984 DN 03 25.1 15.5 +5 regarding observations for objects in each list. 10859 1995 GJ7 03 27.5 15.3 +0 9967 Awanoyumi 03 29.6 15.3 +6 Once you’ve obtained and analyzed your data, it’s important to publish your results. Papers appearing in the Minor Planet Bulletin are indexed in the Astrophysical Data System (ADS) and so can Low Phase Angle Opportunities be referenced by others in subsequent papers. It’s also important to make the data available at least on a personal website or upon The Low Phase Angle list includes asteroids that reach very low request. We urge you to consider submitting your raw data to the phase angles ( < 1°). The “” column is the minimum solar ALCDEF database. This can be accessed for uploading and phase angle for the asteroid. Getting accurate, calibrated downloading data at: measurements (usually V band) at or very near the day of opposition can provide important information for those studying http://www.alcdef.org the “opposition effect.” Use the on-line query form for the LCDB to get more details about a specific asteroid: Containing almost 3.8 million observations for 15,000+ objects (2020 October 5), this makes the site one of the larger publicly http://www.minorplanet.info/PHP/call_OppLCDBQuery.php available sources for raw asteroid time-series lightcurve data. You will have the best chance of success working objects with low Now that many backyard astronomers and small colleges have amplitude and periods that allow covering at least half a cycle access to larger telescopes, we have expanded the photometry every night. Objects with large amplitudes and/or long periods are opportunities and spin axis lists to include asteroids reaching much more difficult for phase angle studies since, for proper V = 15.5 and brighter (sometimes 15.0 when the list has too many analysis, the data must be reduced to the average magnitude of the potential targets).