2026ApJ...998..315Y

IGR J19173+0747 was discovered as an X-ray source by the INTEGRAL satellite and was initially classified as either a high-mass X-ray binary (HMXB) or a magnetic cataclysmic variable. Here, we report the detection of a coherent X-ray pulsation with a period of 792.9 ± 1.1 s in recent NuSTAR data, which we interpret as the spin period of the central compact object. Based on TESS optical photometry, we have also identified a periodic modulation of 793.38 ± 0.02 s, a value consistent, within uncertainties, with that determined from the X-ray data. This period lies outside the typical orbital period range for polars but falls within the characteristic spin-period range of intermediate polars (IPs). Furthermore, the X-ray spectrum exhibits a clear emission-line feature dominated by a fluorescent Fe Kα line at 6.4 keV. We derive an X-ray luminosity of ${L}_{{\rm{X}}}=1.3{1}_{-0.56}^{+0.88}\times 1{0}^{34}\,{\rm{erg}}\,{{\rm{s}}}^{-1}$ and an absolute G-band magnitude of ${M}_{G}=5.6{9}_{-0.56}^{+0.61}$ for IGR J19173+0747, both of which are consistent with typical values for IPs. Based on these findings, we rule out both the HMXB and polar scenarios and classify IGR J19173+0747 as an IP. Spectral fitting yields a white dwarf mass estimate of 0.948 ± 0.044 M_⊙ for this source.