PSR J1813−1749 is one of the most energetic rotation-powered pulsars known, producing a pulsar wind nebula (PWN) and gamma-ray and TeV emission, but whose spin period is only measurable in X-ray. We present analysis of two Chandra datasets that are separated by more than ten years and recent NICER data. The long baseline of the Chandra data allows us to derive a pulsar proper motion μR.A. = −(0.″067 ± 0.″010)yr−1 and μdecl. = −(0.″014 ± 0.″007)yr−1 and velocity v⊥ ≈ 900 − 1600kms−1 (assuming a distance d = 3 − 5 kpc), although we cannot exclude a contribution to the change in measured pulsar position due to a change in brightness structure of the PWN very near the pulsar. We model the PWN and pulsar spectra using an absorbed power law and obtain best-fit absorption NH = (13.1 ± 0.9) × 1022cm−2, photon index Γ = 1.5 ± 0.1, and 0.3–10 keV luminosity LX ≈ 5.4 × 1034ergs−1(d/5kpc)2 for the PWN and Γ = 1.2 ± 0.1 and LX ≈ 9.3 × 1033ergs−1(d/5kpc)2 for PSR J1813−1749. These values do not change between the 2006 and 2016 observations. We use NICER observations from 2019 to obtain a timing model of PSR J1813−1749, with spin frequency ν = 22.35Hz and spin frequency time derivative $\dot{\nu }=(-6.428\pm 0.003)\times 10^{-11}\rm {Hz s^{-1}}$. We also fit ν measurements from 2009–2012 and our 2019 value and find a long-term spin-down rate $\dot{\nu }=(-6.3445\pm 0.0004)\times 10^{-11}\rm {Hz s^{-1}}$. We speculate that the difference in spin-down rates is due to glitch activity or emission mode switching.

We propose a novel readout system FIPSER (FIxed Pulse Shape Efficient Readout) to record signals from detectors with a fixed pulse shape. The primarily targeted applications, but not the only ones, are the digitization of signals from fast photon detectors, i.e. classical photomultipliers and Silicon photomultipliers in astroparticle and high-energy physics experiments. FIPSER is based on the flash analog to digital converter (FADC) concept but has the potential of significantly lower power consumption and costs. These savings are realized by reducing the number of comparators in FIPSER by at least one order of magnitude when compared to an FADC. In this paper we present first results of a study that investigates the performance of FIPSER in terms of achievable charge and time resolution and compare the results to the Poisson limit, which is often a requirement to be met in experiments.

We propose a novel readout system FIPSER to record signals from detectors with a fixed pulse shape. The primarily targeted applications, but not the only ones, are the digitization of signals from fast photon detectors, i.e. classical photomultipliers and Silicon photomultipliers in astroparticle and high-energy physics experiments. FIPSER is based on the flash analog to digital converter (FADC) concept but has the potential of significantly lower power consumption and costs. These savings are realized by reducing the number of comparators in FIPSER by at least one order of magnitude when compared to an FADC. In this paper we present first results of a study that investigates the performance of FIPSER in terms of achievable charge and time resolution and compare the results to the Poisson limit, which is often a requirement to be met in experiments.

We discuss the performance of a readout system, Fixed Pulse Shape Efficient Readout (FIPSER), to digitize signals from detectors with a fixed pulse shape. In this study we are mainly interested in the readout of fast photon detectors like photomultipliers or Silicon photomultipliers. But the concept can be equally applied to the digitization of other detector signals. FIPSER is based on the flash analog to digital converter (FADC) concept, but has the potential to lower costs and power consumption by using an order of magnitude fewer discrete voltage levels. Performance is bolstered by combining the discretized signal with the knowledge of the underlying pulse shape. Simulated FIPSER data was reconstructed with two independent methods. One using a maximum likelihood method and the other using a modified χ 2 test. Both methods show that utilizing 12 discrete voltage levels with a sampling rate of 4 samples per full width half maximum (FWHM) of the pulse achieves an amplitude resolution that is better than the Poisson limit for photon-counting experiments. The time resolution achieved in this configuration ranges between 0.02 − 0.16 FWHM and depends on the pulse amplitude. In a situation where the waveform is composed of two consecutive pulses the pulses can be separated if they are at least 0.05 − 0.30 FWHM apart with an amplitude resolution that is better than 20%.