Revisiting SHADES

In mid-April, we obtained some data towards the Lockman Hole, a region of the sky located in the constellation Ursa Major whose line-of-sight is devoid of interstellar hydrogen. Consequently, this provides a clear window to the rest of the Universe beyond our Milky Way and the Lockman Hole has become a popular field to observe by cosmologists.

SCUBA-2’s predecessor on the JCMT, SCUBA, also observed the Lockman Hole as part of the SHADES project. The region observed by SCUBA is represented by the black outline in the image above and took about 175 hours to observe. The underlying image from SCUBA-2 represents a hodge-podge of data taken with different and non-optimal, observing modes, all observed in less than 7 hours. Nevertheless, Kristen Coppin and Jim Geach managed to reduce the data to produce this result. The white outline represents the region where the sensitivity of the map is similar to that of SHADES. The white circles are locations where sources are present in the SHADES catalogue. The green squares are sources which are significant enough to be considered as potential new extragalactic sources not detected by SHADES – a search for possible new sources was only conducted within the white outline. This is encouraging for the extragalactic research that is planned to be conducted with SCUBA-2.

Given that we are still in the experimentation stage, and we have not yet arrived at the most efficient mapping strategy, it is pleasing to note that with SCUBA-2 we are able to map a similar area to SHADES in just a few hours. Furthermore, not only do we detect the same sources as we previously did, but we are also finding new extragalactic sources.

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One Response to Revisiting SHADES

  1. Pingback: abell 1835, a lensing cluster « SCUBA-2 News Blog

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