Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the 2018 outburst of the accreting millisecond X-ray pulsar Swift
  J1756.9-2508 as seen with NICER   We report on the coherent timing analysis of the 182 Hz accreting millisecond
X-ray pulsar Swift J1756.9$-$2508 during its 2018 outburst as observed with the
Neutron Star Interior Composition Explorer (NICER). Combining our NICER
observations with Rossi X-ray Timing Explorer observations of the 2007 and 2009
outbursts, we also studied the long-term spin and orbital evolution of this
source. We find that the binary system is well described by a constant orbital
period model, with an upper limit on the orbital period derivative of $|\dot
P_b| < 7.4\times 10^{-13}$ s s$^{-1}$. Additionally, we improve upon the source
coordinates through astrometric analysis of the pulse arrival times, finding
R.A. = $17^{\rm h}56^{\rm m}57.18^{\rm s}\pm0.08^{\rm s}$ and Decl. =
$-25^{\circ}06'27.8''\pm3.5''$, while simultaneously measuring the long-term
spin frequency derivative as $\dot\nu = -7.3\times 10^{-16}$ Hz s$^{-1}$. We
briefly discuss the implications of these measurements in the context of the
wider population of accreting millisecond pulsars.

24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg