The Minor planet bulletin最新文献

CCD photometric observations of the near-Earth asteroid (6053) 1993 BW3 were made at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) in 2015 January and March. Analysis of the individual and combined data sets produced a period on the order of 2.8 hours. This differs significantly from the results of Pravec et al. (1997; P = 2.573 h) and from shape models by Durech (2002) and Kaasalainen (2002). While this discordance is not resolved, the 2.573 h value has the greatest amount of data supporting it, and for now, remains the favored period solution.

We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and have no or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and have no or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

The near-Earth asteroid 2015 CN13 made a fly-by of Earth in late 2015 February. We observed the asteroid on Feb 25, 26, and 28. Analysis of the data set found two possible periods, the most likely being P = 22.7 ± 0.3 h. Given the estimated diameter of 70 meters and long period, this puts 2015 CN13 in a small group of NEAs with D ≤ 140 meters and periods well below the spin barrier, i.e., approximately P ≥ 2.2 hours.

CCD photometry observations of the Hungaria asteroid 4868 Knushevia were made in 2013 April-June at the Center for Solar System Studies. Analysis of the data indicates that the asteroid may be a binary with a primary period P₁ = 3.4122 ± 0.0001 h, A₁ = 0.05 ± 0.01 mag and a secondary period of P₂ = 11.922 ± 0.003 h with possible mutual events, i.e., occultations and/or eclipses, of about 0.02 mag depth. On that assumption, this leads to an estimated effective size ratio of D_S/D_P ≥ 0.13 ± 0.03, which fits well within a model of binary asteroids developed by Pravec et al. (2010).

Initial CCD photometry observations of the Hungaria asteroid 5426 Sharp in 2014 December and 2015 January at the Center of Solar System Studies-Palmer Divide Station in Landers, CA, showed attenuations from the general lightcurve, indicating the possibility of the asteroid being a binary system. The secondary period was almost exactly an Earth day, prompting a collaboration to be formed with observers in Europe, which eventually allowed establishing two periods: P₁ = 4.5609 ± 0.0003 h, A₁ = 0.18 ± 0.01 mag and P₂ = 24.22 ± 0.02 h, A₂ = 0.08 ± 0.01 mag. No mutual events, i.e., occultations and/or eclipses, were seen, therefore the asteroid is considered a probable and not confirmed binary.

Lightcurves for 13 main-belt asteroids were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2014 December through 2015 March. All but two were members of the Hungaria orbital group or collisional family and observed as follow-up to previous apparitions to check for undiscovered satellites or to obtain data for spin axis and shape modeling.

Three Hungaria asteroids observed at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) in 2015 January-March showed unusual characteristics. 2449 Kenos, a probable member of the Hungaria collisional family, is likely to be a binary object with period P ₁ = 3.8481 h and P ₂ = 15.85 h. The 2015 observations of 6901 Roybishop, a member of the Hungaria orbital group, showed signs of a weak secondary period, P ₂ = 10.58 h. The secondary period is in contradiction with previous results. (23615) 1996 FK12 may be another example of so-called wide binaries, showing a strong short period, P ₂ = 3.6456 h, presumably due to a widely-separated satellite that is not tidally locked to a very long orbital period. The primary in such a system has a very long period, P ₁ = 368 h in this instance. The main question for 1996 FK12 is the validity of the long period.

Lightcurves for 35 near-Earth asteroids (NEAs) were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2014 December through 2015 March. One object, (159454) 2000 DJ8, may be a highly bifurcated body, or a close binary.

Lightcurves for 43 near-Earth asteroids (NEAs) were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2014 October through December.