J/A+AS/118/503 Proper motions of stars in Ori Nebula (Tian+ 1996) ================================================================================ Proper motions of stars in the region of the Orion Nebula cluster (C 0532-054) Tian K.P., van Leeuwen F., Zhao J.L., Su C.G. =1996A&AS..118..503T (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Clusters, open ; Proper motions Keywords: open clusters - C 0532-054 - astrometry Description: Relative proper motions and membership probabilities for 333 stars within an area of 1.6deg by 1.8deg centred on the Orion Nebula M 42 are determined using plates taken over a period of 83 years with the double astrograph of Shanghai Observatory (scale of 30"/mm). The plates were measured with the ASTROSCAN automatic plate-measuring machine of Leiden Observatory. The average proper motion accuracy obtained for stars in the photographic magnitude range 7 to 14 is 0.3mas/yr. Errors are somewhat larger towards fainter and brighter magnitude, but the majority lie well below 1mas/yr. 64% of the stars have been measured successfully on at least 13 out of 18 plates. The number of stars with membership probabilities higher than 0.7 is 184. It is shown by a detailed discussion that the proper motions and membership probabilities of the stars determined in this paper are in good agreement with the results presented recently by other authors. Although there is a clear concentration in the proper motion diagram, both the remaining dispersion of the internal motions and the distribution of "members" as projected on the sky indicate that the stars in this region are not bound as one system, but do have a common origin. A similar conclusion can be drawn from a comparison with spectroscopic and radial velocity data. Objects: ------------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------------ 05 35.4 -05 23 C 0532-054 = M 42 = Ori Nebula ------------------------------------------------------ File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table3 100 333 Results of the astrometric study -------------------------------------------------------------------------------- See also: II/171 : PARENAGO Catalogue of stars in the area of the Orion Nebula Byte-by-byte Description of file: table3 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 4- 6 I3 --- No [1/406]+ Sequential number 10- 13 I4 --- Parenago Parenago number (Catalogue ) 17- 21 F5.2 mag Pmag Photographic magnitude 25 I1 h RAh Right ascension (J2000, Epoch 1950) 28- 29 I2 min RAm Right ascension (J2000, Epoch 1950) 32- 37 F6.3 s RAs Right ascension (J2000, Epoch 1950) 41 I1 ms e_RAs rms uncertainty on RA 43 A1 --- DE- Declination sign 44 I1 deg DEd Declination (J2000, Epoch 1950) 47- 48 I2 arcmin DEm Declination (J2000, Epoch 1950) 51- 55 F5.2 arcsec DEs Declination (J2000, Epoch 1950) 58- 59 I2 mas e_DEs rms uncertainty on DE 62- 66 F5.1 mas/yr pmRA Proper motion along RA 69- 71 F3.1 mas/yr e_pmRA rms uncertainty on proper motion RA 74- 78 F5.1 mag/yr pmDE Proper motion in DE 81- 83 F3.1 mag/yr e_pmDE rms uncertainty on proper motion DE 87- 88 I2 --- Plate Number of plates used 91- 95 F5.1 yr Ep-1950 Mean epoch in years, relative to 1950.0 99-100 I2 % Memb Membership probability in percents -------------------------------------------------------------------------------- References: Parenago, P.P. 1954, Trudy Sternberg Astron.Inst. Vol.25 =Catalogue ================================================================================ (End) Patricia Bauer [CDS] 06-May-1996