ner_tags: O O O O O O O O O O B-Wavelength B-Wavelength O O B-Formula I-Formula O O O O O O O O B-ObservationalTechniques B-ObservationalTechniques O O O O O O O O O O O O O O O O O O O O O O B-ObservationalTechniques O O B-Wavelength B-Wavelength O O O O O O O O O O O O O O B-Software O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O B-Software I-Software O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O B-Wavelength B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength B-Wavelength O O O O O O O O O O O O O
tokens: GHz were respectively, obtained based on the integrated profile of 2.25/8.60 GHz with typical SNRs >10.28 in the middle of each segment. Then, the time-of-arrivals (ToAs) of pulses were obtained by cross-correlating integrated profiles with the standard template of corresponding frequencies with pat command. Next, we combined the ToA sets from 2.25/8.60 GHz after removing the delay of the receiver system, and carried out timing analysis with TEMPO2 software package (Hobbs, Edwards Manchester 2006 ) to measure the spin properties of the magnetar. The length of each segment lasted until there were obvious changes in the integrated profiles or the error of fitted exceeded 2.70 × 10 −12 which was about 10 per cent of mean (Champion et al. 2020a ). In Table 1 , two adjacent segments are distinguished with different background colours. The top three panels of Fig. 1 show the fitted ν, , and DM changing with the time along with some previous published results (Borghese et al. 2020 ; Champion et al. 2020a , b ; Enoto et al. 2020 ; Hu et al. 2020b ; Joshi Bagchi 2020 ; Lower et al. 2020b , c ; Lower Shannon 2020 ; Rajwade et al. 2020 ; Ridolfi et al. 2020 ). The data points from Champion et al. ( 2020a )’s work were captured from the published plots with the open-source software engauge digitizer . 2 Figure 1. The plots about ν, , DM, W 50 , S 2.25 , S 8.60 , and α of Swift J1818.0–1607 changing with the time. The best fit long-term ν for our observation data and all observation data are shown with solid and dot line, respectively, in top panel. Table 1. Parameters of Swift J1818.0–1607 observations. a Start time. b Mean flux density at 2.25/8.60 GHz. c Spectral index. d Integrated profile morphology: single (S), double (D), and triple (T) peaks. It is clear that the long-term decline trend of ν previously reported by Champion et al. ( 2020a ) and Hu et al. ( 2020a ) went on in our observations, though still changes erratically on short time-scale. We did a linear fit to the ν measurements with the least-square method base on only ours and all observation results shown in the top panel of Fig. 1 . The best-fitted was about and , respectively. Champion et al. ( 2020a ) also reported a similar fitted of using the data spanning nearly 100 d. Combined with all observations, the showed continuous oscillations instead of random variations after the discovery burst. It also was noticed that the amplitude of the oscillation seems to decrease in time. The DM values obtained with TMRT are consistent with previous values. The DM range is between 699 and 705 except for three observations before MJD 59040 (Joshi Bagchi 2020 ; Karuppusamy et al. 2020 ; Lower et al. 2020b ). 3.2 Integrated profiles Integrated profiles of pulsars provide important information of the structure of the radiation beam. With updated ephemeris, the integrated profiles for each epoch of 2.25/8.60 GHz observations were obtained and showed chronologically in Fig. 2 . For easier comparison,