The HASHTAG Project: The First Submillimeter Images of the Andromeda Galaxy from the Ground

Abstract Observing nearby galaxies with submillimeter telescopes on the ground has two major challenges. First, brightness is significantly reduced at long wavelengths compared to peak of dust emission. Second, it necessary use a high-pass spatial filter remove atmospheric noise large angular scales, which unwelcome side effect also removing galaxy’s large-scale structure. We have developed technique for producing high-resolution images size by using telescope determine small-scale structure (the Fourier components) and space (Herschel or Planck) small components). Using this technique, we are carrying out HARP SCUBA-2 High Resolution Terahertz Andromeda Galaxy Survey (HASHTAG), an international Large Program James Clerk Maxwell Telescope, one aim being produce first high-fidelity Andromeda. In paper, describe survey, method combining space-based ground-based data, present HASHTAG 450 850 ? m. created predict CO( J = 3–2) line flux across M31, contaminates m band. find that while normally contamination below our sensitivity limit, can be significant (up 28%) in few brightest regions 10 kpc ring. therefore provide predicted emission removed.