We report Shanghai Tian Ma Radio Telescope detections of several long carbonchain molecules at C and Ku band, including HC 3 N, HC 5 N, HC 7 N, HC 9 N, C 3 S, C 6 H and C 8 H toward the starless cloud Serpens South 1a. We detected some transitions (HC 9 N J=13-12 F=12-11 and F=14-13, H 13 CCCN J=2-1 F=1-0 and F=1-1, HC 13 CCN J=2-1 F=2-2, F=1-0 and F=1-1, HCC 13 CN J=2-1 F=1-0 and F=1-1) and resolved some hyperfine components (HC 5 N J=6-5 F=5-4, H 13 CCCN J=2-1 F=2-1) for the first time in the interstellar medium. The column densities of these carbon-chain molecules in a range of 10 12 -10 13 cm −2 are comparable to two carbon-chain molecule rich sources, TMC-1 and Lupus-1A. The abundance ratios are 1.00:(1.11±0.15):(1.47±0.18) for [H 13 CCCN]:[HC 13 CCN]:[HCC 13 CN]. This result implies that the 13 C isotope is also concentrated in the carbon atom adjacent to the nitrogen atom in HC 3 N in Serpens south 1a, which is similar to TMC-1. The [HC 3 N]/[H 13 CCCN] ratio of 78±9, the [HC 3 N]/[HC 13 CCN] ratio of 70±8, and the [HC 3 N]/[HCC 13 CN] ratio of 53±4 are also comparable to those in TMC-1. In any case, Serpens South 1a proves a testing ground for understanding carbon-chain chemistry.
In this paper, we report radio observations of the Galactic Center magnetar PSR J1745−2900 at six epochs between June and October, 2014. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745−2900 show dramatic changes from epoch to epoch showing that the pulsar was in its "erratic" phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was ten times large than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow "spiky" pulses which follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux density is ten times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses was between 0.2 • to 0.9 • , much narrower than that of integrated profile (∼12 • ). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of
We describe a directed search for continuous gravitational waves in data from the sixth initial LIGO science run. The target was the nearby globular cluster NGC 6544 at a distance of ≈2.7 kpc. The search * Deceased.
SEARCH FOR CONTINUOUS GRAVITATIONAL WAVES …PHYSICAL REVIEW D 95, 082005 (2017) 082005-5 covered a broad band of frequencies along with first and second frequency derivatives for a fixed sky position. The search coherently integrated data from the two LIGO interferometers over a time span of 9.2 days using the matched-filtering F -statistic. We found no gravitational-wave signals and set 95% confidence upper limits as stringent as 6.0 × 10 −25 on intrinsic strain and 8.5 × 10 −6 on fiducial ellipticity. These values beat the indirect limits from energy conservation for stars with characteristic spindown ages older than 300 years and are within the range of theoretical predictions for possible neutron-star ellipticities. An important feature of this search was use of a barycentric resampling algorithm which substantially reduced computational cost; this method is used extensively in searches of Advanced LIGO and Virgo detector data.
[1] The Japanese lunar mission, Selenological and Engineering Explorer (Kaguya), which was successfully launched on 14 September 2007, consists of a main satellite and two small satellites, Rstar and Vstar. Same-beam very long baseline interferometry (VLBI) observations of Rstar and Vstar were performed for 15.4 months from November 2007 to February 2009 using eight VLBI stations. In 2008, S band same-beam VLBI observations totaling 476 h on 179 days were undertaken. The differential phase delays were successfully estimated for most (about 85%) of the same-beam VLBI observation periods. The high success rate was mainly due to the continuous data series measuring the differential correlation phase between Rstar and Vstar. The intrinsic measurement error in the differential phase delay was less than 1 mm RMS for small separation angles and increased to approximately 2.5 mm RMS for the largest separation angles (up to 0.56 deg). The long-term atmospheric and ionospheric delays along the line of sight were reduced to a low level (several tens of milimeters) using the same-beam VLBI observations, and further improved through application of GPS techniques. Combining the eight-station (four Japanese telescopes of VLBI Exploration of Radio Astrometry and four international telescopes) S band same-beam VLBI data with Doppler and range data, the accuracy of the orbit determination was improved from a level of several tens of meters when only using Doppler and range data to a level of 10 m. As a preliminary test of the technique, the coefficient sigma degree variance of the lunar gravity field was compared with and without 4 months of VLBI data included. A significant reduction below around 10 deg (especially for the second degree) was observed when the VLBI data were included. These observations confirm that the VLBI data contribute to improvements in the accuracy of the orbit determination and through this to the lunar gravity field model.
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