New general catalog objects ngc 2450 – 2499 electricity magnetism and light


Historical Identification: Per Dreyer, NGC 2451 (= GC 1573 = JH 3099, 1860 RA 07 40 19, NPD 127 38.3) is "a cluster, very very large, very little compressed, 1 star of magnitude 4.5". (See a discussion of Hodierna for an explanation of why he received no credit for any of his NGC discoveries; in this case, there is the additional problem that he did not include the object in his short catalog of discoveries. Instead, he drew a picture (V.3) of a region in Puppis which is probably of this cluster, but lacking catalog information is not as certainly identified.)

Physical Information: NGC 2451 is actually two clusters, which just happen to be in exactly the same direction, nearly centered on the brightest star in the group, the 3.6 magnitude yellow giant c Puppis. The nearer cluster, NGC 2451A, is about 600 light years away, while the more distant NGC 2451B is about 1200 light years away. Each seems to contain a hundred or more stars (70 Main Sequence stars have been confirmed in NGC 2451A, just counting down to magnitude 15), and to have formed at about the same time, 50 to 60 million years ago; so the two may have formed in the same star-forming region, at about the same time, and gradually drifted apart since their formation. gasbuddy near me The overall apparent size of the "cluster" is about 45 arcmin, which implies that the nearer cluster (which should look larger, given its smaller distance) is about 8 light years across, and although information about the more distant one is harder to come by, it is probably also less than 10 light years across.

Eight of the NGC entries in Lynx have a confused history, discussed here to avoid unnecessary duplication. As noted at their entries, NGC 2463 was discovered by John Herschel, and NGC 2469 by William Herschel, then reobserved by John. gas in dogs stomach Their positions were reasonably accurate, and there is no doubt of their identification. But in 1851 Bindon Stoney, working for the 3rd Lord Rosse, recorded a "great many knots, reckoned 10 nearly in a line pf", meaning running east and west. la gas leak As shown in the image above there are six galaxies running in a nearly east-west line in the area in question, two of which are the Herschels’ previous discoveries. Unfortunately, no positions were measured by Stoney, and in compiling his General Catalog Herschel included the supposed "novae", but with approximate positions presumably based on a general description of the region by Stoney (I seem to recall reading a discussion of a sketch of the region, but have not found the reference involved). Following Herschel’s lead, Dreyer included the eight objects in his NGC, with the designations NGC 2458, 2461, 2462, 2464, 2465, 2471, 2472 and 2473.

Guillaume Bigourdan observed the region in 1886, recording moderately accurate positions for eight of the ten objects (all but NGC 2472 and 2473); Dreyer notes this by crediting the 3rd Lord Rosse and Bigourdan in his entries for the eight objects. types of electricity Only four of Bigourdan’s observations were of galaxies, the other four being groups of one, two or three stars (at least as best estimated by recent review of his positions and the area in question). So two of the six galaxies shown in the illustration were not observed by him, nor does it seem likely that they were observed by anyone else. Since there are two galaxies in the east-west line that have no corresponding NGC entries, and two entries (NGC 2472 and 2473) that do not correspond to any known object, modern usage (or perhaps more accurately mis-usage) has assigned the two unlisted galaxies to the two unused entries, further complicating the situation.

As a result, two of the ten NGC entries correspond to the Herschels’ observations, two to Bigourdan’s observations of actual nebulae, four to Bigourdan’s observations of minor stellar groupings, and two to a modern assignment of the NGC numbers to the two galaxies not otherwise accounted for. With such a history it is hardly surprising that several of these NGC entries are assigned to different objects by different references.

This is one of eight NGC objects for which the history of observation is complex, and identifications are not as certain as might be desired. 4 gas giants For NGC 2461, Bigourdan’s position precesses to RA 07 56 46.7, Dec +56 40 00. There is nothing at that location, so the identification of the star listed above as NGC 2461 is based on the difference between Bigourdan’s measurements for NGC 2461 and 2462. Assuming that although the actual positions are wrong the relative positions are more nearly correct, NGC 2461 should be about 6sW and 11"S of NGC 2462, which see for an image of the region. That corresponds to a position just north of the star listed above, so its identification as NGC 2461 is considered more or less reasonable. (Note: Since Dreyer states that the object is a 13th-magnitude star it is tempting to assume that the 13th-magnitude star directly north of Bigourdan’s position for NGC 2461 is the actual NGC 2461. gas quality by brand But if it were, Bigourdan would have measured its position as east of NGC 2462 instead of southwest, and Herschel and Dreyer should have given it a later listing, instead of an earlier one; so it is believed that the relative positions are a better indicator of what was observed than the magnitude estimate.)

Historical Identification: Per Dreyer, NGC 2472 (= GC 1587, 3rd Lord Rosse, 1860 RA 07 47, NPD 32 57±) is one of "2 of 10 nebulae in line with h469, 470)". (JH)469 and 470 are NGC 2463 and 2469. A full discussion of the historical difficulties covered above reveals that NGC 2472 and 2473 were never observed with sufficient accuracy to identify them with any specific object. A proper description should therefore be "lost or nonexistent". electricity symbols ks3 However, there are six galaxies stretching in an east-west line in the region where the ten objects listed by Dreyer are supposed to have been, and only four of them correspond to specific NGC listings. As a result, there has been a modern "recycling" of the unidentifiable NGC numbers to account for the two unlisted galaxies. This is certainly historically incorrect; but since this usage appears to have gained general acceptance, it seems appropriate to discuss the galaxies associated with those listings, if only to show the modern interpretation of the designation.