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We present Karl G Jansky Very Large Array molecular line observations of thenearby starburst galaxy NGC 253, from SWAN: "Survey of Water and Ammonia inNearby galaxies". SWAN is a molecular line survey at centimeter wavelengthsdesigned to reveal the physical conditions of star forming gas over a range ofstar forming galaxies. NGC 253 has been observed in four 1GHz bands from 21 to36 GHz at 6" ($\sim100$pc) spatial and 3.5 km s$^{-1}$ spectral resolution. Intotal we detect 19 transitions from seven molecular and atomic species. We havetargeted the metastable inversion transitions of ammonia (NH$_{3}$) from (1,1)to (5,5) and the (9,9) line, the 22.2 GHz water (H$_2$O) ($6_{16}-5_{23}$)maser, and the 36.1 GHz methanol (CH$_3$OH) ($4_{-1}-3_{0}$) maser. UtilizingNH$_{3}$ as a thermometer, we present evidence for uniform heating over thecentral kpc of NGC 253. The molecular gas is best described by a two kinetictemperature model with a warm 130K and a cooler 57K component. A comparison ofthese observations with previous ALMA results suggests that the molecular gasis not heated in photon dominated regions or shocks. It is possible that thegas is heated by turbulence or cosmic rays. In the galaxy center we findevidence for NH$_{3}$(3,3) masers. Furthermore we present velocities andluminosities of three water maser features related to the nuclear starburst. Wepartially resolve CH$_3$OH masers seen at the edges of the bright molecularemission, which coincides with expanding molecular superbubbles. This suggeststhat the masers are pumped by weak shocks in the bubble surfaces.

Survey of Water and Ammonia in Nearby galaxies (SWAN): Resolved Ammonia Thermometry, Water and Methanol Masers in the Nuclear Starburst of NGC 253