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7th of August 2018
LVHIS images of UGCA 365
The Local Volume HI Survey (LVHIS) was conducted with the Australia Telescope Compact Array (ATCA) in the 21cm band. The "Local Volume" of the Universe contains about 1000 galaxies within 30 million light years of the Milky Way. LVHIS studied galaxies previously detected with the Parkes 64-m telescope in the HI Parkes All Sky Survey (HIPASS). LVHIS mapped the distribution of neutral hydrogen with 20 times greater accuracy than LVHIS, and was also able to derive their rotation speeds, which are important for measuring the dark matter content of galaxies.

UGCA 365 (HIPASS J1336-29) is a dwarf irregular galaxy located just over half a degree from the spiral galaxy M 83, at a distance of 5 Mpc (17 million light years) from our Galaxy. The left-hand image above shows a contour of the radio emission overlaid on an optical image of the galaxy, and the right-hand image shows the velocity distribution of material in the galaxy. As the galaxy is viewed largely face-on, only a small range of velocities is apparent. While the low-resolution ATCA HI data of UGCA 365 show an unresolved source, at higher resolution a velocity pattern along the optical major axis is detected. A neutral hydrogen mass of two million solar masses is inferred from the data. More information about LVHIS is given in in this blog post by Baerbel Koribalski.

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