Katsuo Ogura , Koji Sugitani, PASA, 15 (1), 91
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Selection Criteria and the Catalogue
Surveys of the Ori OB1 Association have been made in a search for candidate reflection clouds as well as bright-rimmed clouds and cometary globules using the SERC Equatorial EJ Sky Atlas in the b_J band, the Second Palomar Sky Survey B Atlas and deep red plates taken with the UK Schmidt telescope. The survey area is the square of RA = 40.5exh 500.5exm to 60.5exh 100.5exm and Dec = -12
30' to +7 30' (1950). The selection criteria are as follows. Bright-rimmed clouds should be immersed in bright HII regions; but contrary to our previous catalogues (Sugitani et al. 1991, Sugitani and Ogura 1994) we list all of them irrespective of association with IRAS point sources. Cometary globules are located far from bright HII regions or in their peripheries where at most faint H
background emission is discernible, and their outline should be brighter on the red plates than on the IIIaJ plates, especially at their apex. Reflection clouds should also be located outside bright HII regions, but should be brighter on the IIIaJ plates than on the red plates. Further they should lack obvious internal illuminating stars and have more or less sharp boundaries in contrast to ordinary reflection nebulae, which are generally very diffuse. Cometary globules generally have brighter outlines near the apexes than at the rest of their boundaries, whereas reflection clouds are more or less of uniform brightness over their boundaries and insides. Still the discrimination between cometary globules and reflection clouds is sometimes difficult based only on Schmidt atlases and requires spectroscopic data on the rims. These criteria are admittedly subjective.
Table 1 summarizes the results. The first column gives the object number identified in Figure 1. The second and third columns contain the 1950 coordinates of the cloud center. Since most of the objects are more or less elongated with a sparse tail, the coordinates refer to the center of their heads. The fourth and fifth columns give the apparent size and the cloud type, respectively. It is apparent from Figure 1 that remnant clouds of the three categories are essentially similar in size. The mean size of all the objects is 2.6' 
4.9' or 0.35 pc 0.66 pc at the adopted distance of 460 pc with the range of (0.4' - 14.0') (0.4' - 33.6') or (0.05 pc - 1.87 pc) (0.05 pc - 4.49 pc). Identifications from previous catalogues are found in the last column. In addition to these objects one notices a huge structure of roughly cometary shape in the far southwestern region. It stretches about 5.8 with a width of roughly 40'. We name it Cometary Complex (CC)-A.
Table 1. Remnant clouds in the Ori OB 1 association
| No. | RA(1950) | Dec(1950) | Width Length | Type | Identifications |
| (h:m:s) | (:':") | (arcmin) | |||
| 1 | 5:01:57 | -06:16:20 | 1.4 5.1 | r | |
| 2 | 5:03:48 | -04:00:20 | 5.4 7.8 | r | CB28 |
| 3 | 5:04:25 | -03:24:10 | 14.0 33.6 | r? | NGC1788, M0.5ex3P13, LBN916, DG51 |
| 4 | 5:09:32 | -01:59:10 | 3.4 7.8 | r | |
| 5 | 5:10:56 | 06:44:00 | 2.1 4.5 | r | |
| 6 | 5:14:36 | -07:47:50 | 2.5 26.9 | r | |
| 7 | 5:17:13 | -05:54:20 | 11.2 21.3 | c | BRC16, M0.5ex3P14, LBN960 |
| 8 | 5:17:39 | -04:58:20 | 1.8 5.6 | r? | |
| 9 | 5:18:13 | -05:26:40 | 5.8 8.4 | r? | |
| 10 | 5:18:21 | -05:52:40 | 13.4 16.8 | c | S278, LBN956? |
| 11 | 5:18:23 | -05:42:40 | 4.7 10.1 | r | |
| 12 | 5:19:38 | -03:44:20 | 6.3 9.5 | c | CB29 |
| 13 | 5:23:40 | -10:25:40 | 1.1 7.8 | r | |
| 14 | 5:23:46 | -10:34:10 | 1.2 2.7 | r | |
| 15 | 5:23:57 | -10:27:20 | 0.8 3.4 | r | |
| 16 | 5:24:32 | -10:17:00 | 1.2 3.5 | r | |
| 17A | 5:24:51 | -10:31:10 | 2.1 3.7 | r | |
| 17B | 5:24:39 | -10:30:40 | 0.7 1.7 | r | |
| 18 | 5:25:06 | -10:37:50 | 0.4 1.1 | r | |
| 19 | 5:25:28 | -10:38:00 | 1.1 2.9 | r | |
| 20 | 5:27:53 | 03:14:50 | 1.0 3.4 | r | |
| 21 | 5:29:05 | -02:15:00 | 2.3 3.9 | r? | |
| 22 | 5:29:22 | -10:20:00 | 1.7 2.2 | r | |
| 23 | 5:29:55 | -10:20:20 | 2.2 6.2 | r | |
| 24 | 5:30:00 | -02:12:10 | 0.4 0.9 | r | |
| 25A | 5:30:13 | -02:57:50 | 7.8 8.4 | c | |
| 25B | 5:29:59 | -03:02:20 | 2.9 2.5 | c | |
| 26 | 5:30:17 | -00:50:40 | 5.0 6.2 | r | |
| 27 | 5:30:51 | -00:40:00 | 2.8 5.3 | r | IC423, CB31, M0.5ex3P28?, LBN913, DG58 |
| 28 | 5:31:05 | -00:26:50 | 1.3 2.1 | r | IC424, M0.5ex3P29?, DG59? |
| 29A | 5:30:27 | -01:39:00 | 0.4 0.6 | r | |
| 29B | 5:30:42 | -01:35:30 | 1.1 2.2 | r | |
| 29C | 5:30:52 | -01:29:10 | 1.6 2.0 | r | |
| 29D | 5:31:00 | -01:38:20 | 5.4 5.4 | c | |
| 29E | 5:31:05 | -01:27:50 | 1.0 1.9 | r | |
| 29F | 5:31:16 | -01:31:10 | 1.2 1.8 | r? | |
| 29G | 5:31:18 | -01:26:40 | 2.0 3.0 | r | |
| 29H | 5:31:39 | -01:22:40 | 1.0 1.1 | r | |
| 29I | 5:31:44 | -01:13:10 | 1.0 3.9 | r | LBN935? |
| 29J | 5:31:51 | -01:23:50 | 0.9 2.2 | r? | |
| 29K | 5:32:08 | -01:23:50 | 2.7 4.5 | c? | |
| 29L | 5:32:30 | -01:17:40 | 2.0 3.4 | r | |
| 30 | 5:31:28 | -03:43:40 | 5.0 5.3 | c? | M0.5ex3P19? |
| 31 | 5:31:58 | -03:00:30 | 3.7 7.3 | c | BRC19 |
| 32 | 5:32:25 | -00:35:50 | 1.0 1.3 | r |
Table 1. Remnant clouds in the Ori OB 1 association -- Continued
| No. | RA(1950) | Dec(1950) | Width Length | Type | Identifications |
| (h:m:s) | (:':") | (arcmin) | |||
| 33A | 5:33:27 | -03:26:20 | 3.4 4.5 | r | |
| 33B | 5:33:27 | -03:32:20 | 1.9 3.6 | r | |
| 34 | 5:33:44 | -04:02:30 | 1.3 1.3 | c? | |
| 35A | 5:33:56 | -00:19:30 | 5.6 3.9 | r | IC426, CB32, LBN921, DG61 |
| 35B | 5:34:06 | -00:21:50 | 1.8 3.2 | r | |
| 36 | 5:34:06 | -04:03:00 | 2.9 2.7 | c? | |
| 37 | 5:34:14 | -00:25:50 | 0.9 1.6 | r | |
| 38 | 5:34:24 | -00:23:30 | 0.9 2.8 | r | DG62 |
| 39 | 5:34:40 | -00:22:50 | 1.1 0.9 | r | DG63 |
| 40A | 5:35:33 | -01:46:40 | 2.8 4.5 | c | Ori I-2, BRC20 |
| 40B | 5:35:22 | -01:39:00 | 0.7 1.3 | c | |
| 40C | 5:35:19 | -01:37:20 | 0.9 1.1 | c | |
| 40D | 5:35:20 | -01:34:30 | 1.2 2.3 | c | |
| 41 | 5:35:54 | -05:15:30 | 2.6 8.4 | c | BRC22 |
| 42 | 5:36:26 | -07:47:10 | 1.5 3.6 | c | |
| 43 | 5:36:51 | -00:37:40 | 1.1 2.0 | r | DG71 |
| 44A | 5:37:11 | -03:39:50 | 4.7 4.5 | b | BRC21, LBN965 |
| 44B | 5:37:12 | -03:43:20 | 0.9 0.9 | b | |
| 45 | 5:37:15 | -05:22:40 | 1.9 2.5 | c | |
| 46 | 5:37:51 | -05:26:00 | 2.3 3.4 | c | |
| 47A | 5:38:09 | -05:26:30 | 2.5 4.5 | c | |
| 47B | 5:38:31 | -05:28:10 | 6.2 7.3 | c | |
| 48 | 5:37:56 | -00:31:30 | 1.2 1.8 | r | LBN927, DG73 |
| 49 | 5:38:17 | -02:14:10 | 0.7 1.0 | b | |
| 50 | 5:38:24 | -02:19:20 | 1.2 1.3 | b | |
| 51 | 5:38:26 | -02:11:50 | 0.6 1.2 | b | |
| 52 | 5:38:30 | -02:28:40 | 4.0 3.9 | b | Horsehead N., M0.5ex3P31 |
| 53 | 5:38:30 | -02:40:10 | 0.7 0.6 | b | |
| 54 | 5:38:31 | -02:47:20 | 0.9 0.4 | b | |
| 55 | 5:38:42 | -06:37:00 | 0.6 1.5 | c | |
| 56 | 5:39:11 | -06:28:10 | 1.7 14.5 | c | |
| 57A | 5:39:27 | -03:04:30 | 2.7 3.4 | b | |
| 57B | 5:39:25 | -03:02:20 | 2.0 1.3 | b | |
| 58 | 5:39:31 | -02:59:30 | 2.2 1.5 | b | |
| 59 | 5:40:40 | -05:21:40 | 2.1 6.7 | c | |
| 60A | 5:40:54 | -05:02:20 | 4.1 14.5 | c | |
| 60B | 5:41:24 | -05:06:50 | 1.3 6.7 | c | |
| 61A | 5:40:59 | -03:36:50 | 5.0 5.0 | c | |
| 61B | 5:41:02 | -03:30:00 | 2.7 3.9 | c | |
| 62 | 5:44:28 | 00:38:10 | 3.1 4.0 | c | DG82? |
| CC-A tip | 5:04:50 | -06:20:00 | 40 350 | c | IC 2118, LBN959, DG52 |
| CC-A end | 4:54:00 | -11:30:00 |
Note: BRC=Sigitani et al. (1991), CB=Clemens & Barvainis (1988), M0.5ex3P=Maddalena et al. (1986), LBN=Lynds (1965), DG=Dorschner & Gürtler (1964)
| Next Section: Discussion Title/Abstract Page: Remnant Molecular Clouds in Previous Section: Introduction | Contents Page: Volume 15, Number 1 |
© Copyright Astronomical Society of Australia 1997