Young stars in the disk of M82

We present CCD VI_C photometry in a field 1.9 ? 1.3 square arcmin and positioned about 3 arcmin north-east of the centre of M82. More than 100 stars have been identified and measured above the photometric limits V = 23^m.5, I = 22^m. Most of the objects fainter than V ≈? 20^m should be members of M82 as expected from the statistics of foreground stars. Starlike as well as 2–3 somewhat diffuse objects - candidates of globular clusters - preferentially occupy yellow colours in the colour-magnitude diagram; extreme blue and red objects are missing. The colour-magnitude diagram indicates continuing star formation in this part of the disk. The absence of blue stars is caused by reddening; no convincing explanation is found for the missing red supergiants. Young stars are distributed throughout the whole field, the youngest being concentrated in associations at the SW edge of the field. To cope with the very irregular background created by the galaxy' s main body and with the low contrast of many of the stars against this background, a modified photometric method is introduced in which the background is estimated using the intensities in a ring drawn very tightly around the star in the wings of the point spread function.