We developed a pulsar search pipeline based on PulsaR Exploration and Search TOolkit (PRESTO). This pipeline simply runs dedispersion, Fast Fourier Transform (FFT) and acceleration search in process-level parallel to shorten the processing time.With two parallel strategies, the pipeline can highly shorten the processing time in both normal searches and acceleration searches. This pipeline was first tested with Parkes Multibeam Pulsar Survery (PMPS) data and discovered two new faint pulsars. Then, it was successfully applied in processing the Five-hundred-meterAperture Spherical radio Telescope (FAST) drift scan data with tens of new pulsar discoveries up to now. The pipeline is only CPU-based and can be easily and quickly deployed in computing nodes for testing purposes or data processing.
Although ammonia is a widely used interstellar thermometer, the estimation of its rotational and kinetic temperatures can be affected by the blended hyperfine components (HFCs). We have developed a new recipe, referred to as the hyperfine group ratio (HFGR), which utilizes only direct observables, namely the intensity ratios between the grouped HFCs. As tested on the model spectra, the empirical formulae in the HFGR can derive the rotational temperature (Trot) from the HFC group ratios in an unambiguous manner. We compared the HFGR with two other classical methods, intensity ratio and hyperfine fitting, based on both simulated spectra and real data. The HFGR has three major improvements. First, it does not require modelling the HFC or fitting the line profiles, so it is more robust against the effect of HFC blending. Second, the simulation-enabled empirical formulae are much faster than fitting the spectra over the parameter space, so both computer time and human time can be saved. Third, the statistical uncertainty of the temperature ΔTrot as a function of the signal-to-noise ratio (S/N) is a natural product of the HFGR recipe. The internal error of the HFGR is ΔTrot ≤ 0.5 K over a broad parameter space of rotational temperature (10–60 K), linewidth (0.3–4 km s−1) and optical depth (0–5). When there is spectral noise, the HFGR can also maintain a reasonable uncertainty level at ΔTrot ≤ 1.0 K when S/N > 4.
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