Photometry of the Kuiper-Belt object 1999 TD$_{\sf\sl 10}$ at different phase angles

Abstract

Abstract. We present photometric observations of the Kuiper-Belt object 1999 TD 10 at different phase angles and for three different broad band filters (B, V and R). This object was observed with the Danish 1.54-m telescope of ESO in Chile during six different observing nights corresponding to a phase angle of 0. 30, 0.37, 0.92, 3.43, 3.48 and 3.66 • . Extra observations were obtained in September 2002 with the VLT UT1/FORS1 combination to confirm that 1999 TD 10 does not exhibit any cometary activity, and in October 2001 with the Sierra Nevada Observatory 1.50-m telescope in order to add relative magnitudes to improve the determination of the rotation period. The observations are compatible with a single-peaked rotational lightcurve with a 7h41.5min ± 0.1 min period or a doublepeaked lightcurve with a 15h22.9min ± 0.1 min period. If a single-peaked rotational lightcurve is assumed the amplitude is 0.51 ± 0.03, 0.49 ± 0.05 and 0.60 ± 0.09 mag for the R, V and B bands, respectively. We present the phase curve obtained when assuming that the lightcurve is single-peaked. This phase curve reveals clearly an increase of about 0.3 mag and of similar importance for the three bands when phase angle decreases from 3.7 • to 0.3 • . The phase curve reveals a linear increase of the brightness with the decreasing phase angle and, consequently, does not permit a modeling of the opposition surge. Neverthless the poor repartition of the observational data does not permit a firm conclusion concerning the presence or absence of an opposition surge on the phase angle range covered by our data. Complementary observations are needed.

Simultaneous visible and near-infrared time resolved observations of the outer Solar System object (29981) 1999 TD10

“…If we assume a maximum difference in absolute magnitudes of 0.012 mag between the two runs, then the corresponding change in the derived solar phase coefficient β is 0.015 mag deg −1 which is of the same order as the error of β quoted above. R 0 is consistent with R opp derived by Choi et al (2003) and H R by Rousselot et al (2003). …”

“…Their derivation is also widely different from the range of linear solar phase coefficients for seven TNOs by Sheppard and Jewitt (2002). The derived phase coefficient of β = 0.121 mag deg −1 by Rousselot et al (2003) is in agreement with the mean solar phase coefficient by Sheppard and Jewitt (2002). However, our mean absolute magnitudes in September 2001 and October 2002 using this coefficient are still inconsistent with each other.…”

“…A phase plot of our data with the period from Rousselot et al (2003) is acceptable. A phase plot with the period from Choi et al (2003) does not fit our data at all.…”

“…They find a periodicity in the lightcurve of 5.8 hr (which corresponds to a single peaked lightcurve) and a gray color. Rousselot et al (2003) derive a solar phase dependence in the H − G scattering formalism and a period of 15.382 ± 0.002 hr. Choi et al (2003) report a period of 15.448 ± 0.012 hr and derive a solar phase dependence and an effective radius of 58 km.…”

174P/Echeclus: a strange case of outburst

“…Two TNOs have also been reported by some authors to have cometary activity. Choi et al (2003) reported cometary activity for the SDO (29981) 1999 TD 10 but other observations with larger telescopes (Rousselot et al 2003;Mueller et al 2004) detected nothing for this object. Hainaut et al (2000) presented a change in the lightcurve of the TNO (19308) 1996 TO 66 that could possibly be interpreted as the result of cometary activity.…”