SIMBAD references

During the last decade, a debate has arisen whether the grouping of stars called NGC 2451 is a real star cluster. We investigate the corresponding area of the sky kinematically, using proper motions of the PPM catalogue. The group of stars that was originally called NGC 2451 shows a large scatter of their proper motions, which proves that they do not form a cluster. However, close-by we find a group of 24 PPM stars with common proper motion. A colour-magnitude diagram of 19 of these shows an extremely well-defined main sequence, giving a distance of about 220 pc. This cluster is not NGC 2451. We tentatively call it Puppis Moving Group (PMG). There is strong indication for a second cluster at about 400 pc. Photometry, radial velocities and proper motions of stars fainter than the magnitude limit of PPM are needed to further investigate the matter.