Globular cluster candidates in NGC 891

We use deep images taken with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope of the disc galaxy NGC 891 to search for globular cluster (GC) candidates. This galaxy has long been considered to be a close analogue in size and structure to the Milky Way and is nearly edge-on, facilitating studies of its halo population. These extraplanar ACS images, originally intended to study the halo field-star populations, reach deep enough to reveal even the faintest GCs that would be similar to those in the Milky Way. From the three pointings, we have identified a total of 43 candidates after culling by object morphology, magnitude and colour. We present (V, I) photometry for all of these, along with measurements of their effective radius and ellipticity. The 16 highest-rank candidates within the whole sample are found to fall in very much the same regions of parameter space occupied by the classic Milky Way GCs. Our provisional conclusion from this survey is that the total GC population in NGC 891 as a whole may be almost as large as that of the Milky Way.