tokens: not been identified due to the lack of counterparts in the radio/X-ray or GeV γ -ray bands (Aharonian et al. 2005 , 2008a ). Therefore, searching for the counterparts of these unidentified VHE sources in longer-wavelength bands is very helpful to identify and classify them. In the GeV band, more than 7 years of survey data from the Fermi Large Area Telescope ( Fermi -LAT) provides a good opportunity to hunt for the unidentified VHE sources. Indeed, several unidentified VHE sources have been detected with the Fermi -LAT data (Hui et al. 2016 ). HESS J1427−608 is one of the unidentified VHE sources discovered by the HESS Galactic Plane Survey (Aharonian et al. 2008a ). The TeV image shows that it is only slightly extended with a symmetric Gaussian function with a width of σ = 3′. This source is detected with an integral flux above 1 TeV of F γ (>1 TeV) = 4.0 × 10 −12 erg cm −2 s −1 and a power-law spectrum with an index of Γ = 2.16. No nearby SNR or pulsar was detected in the vicinity of HESS J1427−608 (Green 2014 ). The X-ray counterpart of it, Suzaku J1427−6051, was reported by Fujinaga et al. ( 2013 ). The X-ray spatial morphology is clearly extended with a Gaussian width of σ = 09 ± 01, and the spectrum is well fitted by a power law with an index of Γ = , implying nonthermal X-ray continuum emission. The unabsorbed flux in the 2–10 keV band is . Fujinaga et al. ( 2013 ) have discussed the possible nature of HESS J1427−608 as a PWN or nonthermal SNR. Each one can explain some of the observational facts but face difficulties. No radio counterpart was detected in the direction of HESS J1427−608. In the second Fermi -LAT catalog (2FGL; Nolan et al. 2012 ), a GeV source, 2FGL J1427.6−6048c, which is located in the vicinity of HESS J1427−608, was reported. However, their central positions differ moderately from each other. Furthermore, the power-law spectrum index of 2FGL J1427.6−6048c is Γ = 2.7 (Nolan et al. 2012 ), which cannot connect with the TeV spectrum of HESS J1427−608 well. It is very likely that 2FGL J1427.6−6048c is not associated with HESS J1427−608. Meanwhile, it should be noted that no source in the third Fermi -LAT source catalog (3FGL; Acero et al. 2015 ) is associated with 2FGL J1427.6−6048c. In this paper, we carry out a complete analysis of this region using more than 7 years of Fermi -LAT Pass 8 data to investigate the γ -ray emission of HESS J1427−608. In Section 2 , we describe the data analysis and results, including the spatial, spectral, and timing analyses. The possible nature of HESS J1427−608 based on the multiwavelength spectral energy distribution (SED) fitting is discussed in Section 3 , and the conclusion of this work is presented in Section 4 . 2. DATA ANALYSIS 2.1. Data Reduction The following analysis is performed using the latest Fermi -LAT Pass 8 data with the Source event class from 2008 August 4 (Mission Elapsed Time 239557418) to 2015 November 4 (Mission Elapsed Time 468288004). Considering the impact of
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