The Deepest Herschel-SPIRE Field
The Herschel Dark Field was observed regularly by the SPIRE instrument for calibration purposes. We have now combined all this calibration data, amounting to a total of 141 observations, to produce the deepest far-IR image ever achieved. Our current analysis includes use of standard and guided source extraction techniques to produce number counts which are consistent with existing data and models. The depth of the image also allows P(D) analysis to much greater depths to explore far-IR counts at 250, 350 and 500m microns far below previous sensitivities. We find evidence for further evolution in the counts, not predicted by current models. SCUBA2, HST and JWST observations are available for some parts of the SPIRE deep field and we also show progress in identifying and classifying individual sources in this uniqely deep field.
