We report the timing-analysis results obtained for Rotating Radio Transient (RRAT) J1819−1458 from regular timing observations at 1.54 GHz using the Urumqi 25-m radio telescope between 2007 April and 2008 March. RRAT J1819−1458 is a relatively young and highly magnetized neutron star discovered by its sporadic short bursts in the Parkes Multibeam Pulsar Survey data. In 94 h of observation data, we detected a total of 162 dispersed bursts of RRAT J1819−1458 with the signal-to-noise ratios (S/Ns) above 5 σ threshold. Among them, five bursts clearly show two-component structure. The S/N of the strongest burst is 13.3. The source's DM measured through our data is 196.0 ± 0.4 pc cm −3 . The timing position, frequency and its first derivative were determined using standard pulsar timing techniques on the arrival times of these individual bursts. The accuracy of the solved rotating parameters is improved comparing with that in previous publication. Our timing position with 2σ error is consistent with the position of its X-ray counterpart CXOU J181934.1−145804. The effect of timing noise and the phase fluctuation of the individual short bursts on the timing residuals is briefly discussed. The distribution of the timing residuals is bimodal, which cannot be explained readily by timing irregularity.

In 2003-2004, we obtained 115 new observations of Phoebe, the 9th Saturnian faint satellite (visual magnitude of about 16.5). We used a large CCD detector (2048 × 2048 pixels) mounted on the 1.56 m astrometric reflector at the Sheshan Station, near Shanghai. In our reduction, an up-to-date catalogue of stars, UCAC2 (Zacharias et al. 2004), was chosen to ensure a proper astrometric calibration. A comparison of our observations to three recently available, high quality ephemerides, including the JPL SAT185 by Jacobson (2004b), has shown that most of our observed positions of Phoebe present an accuracy of some tens of mas, which appears to be a very high level for such a faint satellite.

Astrometric positions of the Neptunian Satellite Triton are given for the opposition of Neptune for the years 1996, 2003, 2005 and 2006. The 943 observed positions were obtained at the Cassegrain focus of a 156‐cm reflector. In our reduction, the up‐to‐date catalogue of stars UCAC2 was chosen to ensure a proper astrometric calibration. Our observed positions are compared to theoretical positions provided from JPL and IMCCE ephemerides. The observed minus calculated residuals have s.d. values of the order of 0.04 arcsec.

No abstract

This paper reports on our observing campaign of faint satellites performed at the National Time Service Center and Sheshan station of SHAO from 1994 up to today. In the past few years due to benefit from using a large size CCD and the publication of the modern catalogues (UCAC2), a series of observations of faint satellites were obtained by us. Moreover the work of improving the orbit of Phoebe via numerical fit to the observations over a century is also presented.