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We illustrate a method for estimating the vertical position of the Sun abovethe Galactic plane by $\gamma$-ray observations. Photons of $\gamma$-raywavelengths are particularly well suited for geometrical and kinematic studiesof the Milky Way because they are not subject to extinction by interstellar gasor dust. Here, we use the radioactive decay line of $\mathrm{^{26}Al}$ at$1.809\,\mathrm{MeV}$ to perform maximum likelihood fits to data from thespectrometer SPI on board the INTEGRAL satellite as a proof-of-concept study.Our simple analytic 3D emissivity models are line-of-sight integrated, andvaried as a function of the Sun's vertical position, given a known distance tothe Galactic centre. We find a vertical position of the Sun of $z_0 = 15 \pm17\,\mathrm{pc}$ above the Galactic plane, consistent with previous studies,finding $z_0$ in a range between $5$ and $29\,\mathrm{pc}$. Even though thesensitivity of current MeV instruments is several orders of magnitude belowthat of telescopes for other wavelengths, this result reveals once more thedisregarded capability of soft $\gamma$-ray telescopes. We further investigatepossible biases in estimating the vertical extent of $\gamma$-ray emission ifthe Sun's position is set incorrectly, and find that the larger the trueextent, the less is it affected by the observer position. In the case of$\mathrm{^{26}Al}$ with an exponential scale height of $150,\mathrm{pc}$($700\,\mathrm{pc}$) in the inner (full) Galaxy, this may lead to misestimatesof up to $25\,\%$.

Vertical position of the Sun with $\gamma$-rays