Swift Deep Galactic Plane Survey Classification of Swift J170800$-$402551.8 as a Candidate Intermediate Polar Cataclysmic Variable

Here, we present the results of our multi-wavelength campaign aimed at classifying $\mathit{\text{Swift}}$ J170800$-$402551.8 as part of the $\mathit{\text{Swift}}$ Deep Galactic Plane Survey (DGPS). We utilized Target of Opportunity (ToO) observations with $\mathit{\text{Swift}}$, $\mathit{\text{NICER}}$, $\mathit{\text{XMM-Newton}}$, $\mathit{\text{NuSTAR}}$, and the Southern African Large Telescope (SALT), as well as multi-wavelength archival observations from $\mathit{\text{Gaia}}$, VPHAS, and VVV. The source displays a periodicity of 784 s in our $\mathit{\text{XMM-Newton}}$ observation. The X-ray spectrum ($\mathit{\text{XMM-Newton}}$ and $\mathit{\text{NuSTAR}}$) can be described by thermal bremsstrahlung radiation with a temperature of $kT$,$\approx$,$30$ keV. The phase-folded X-ray lightcurve displays a double-peaked, energy-dependent pulse-profile. We used $\mathit{\text{Chandra}}$ to precisely localize the source, allowing us to identify and study the multi-wavelength counterpart. Spectroscopy with SALT identified a Balmer H$\alpha$ line, and potential HeI lines, from the optical counterpart. The faintness of the counterpart ($r$,$\approx$,$21$ AB mag) favors a low-mass donor star. Based on these criteria, we classify $\mathit{\text{Swift}}$ J170800$-$402551.8 as a candidate intermediate polar cataclysmic variable, where the spin period of the white dwarf is 784 s.