J/A+A/370/931 BVI photometry of 4 open clusters (Piatti+, 2001) ================================================================================ On the stellar content of the open clusters Melotte 105, Hogg 15, Pismis 21 and Ruprecht 140 Piatti A.E., Claria J.J. =2001A&A...370..931P ================================================================================ ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, UBVRI Keywords: open clusters: individual: Melotte 105, Hogg 15, Pismis 21, Ruprecht 140 - open clusters: general - techniques: photometric Abstract: CCD observations in the B, V and I passbands have been used to generate colour-magnitude diagrams reaching down to V~19mag for two slightly characterized (Melotte 105 and Hogg 15) and two almost unstudied (Pismis 21 and Ruprecht 140) open clusters. The sample consists of about 1300 stars observed in fields of about 4'x4'. Our analysis shows that neither Pismis 21 nor Ruprecht 140 are genuine open clusters since no clear main sequences or other meaningful features can be seen in their colour-magnitude diagrams. Melotte 105 and Hogg 15 are open clusters affected by E(B-V)=0.42+/-0.03 and 0.95+/-0.05, respectively. Their distances to the Sun have been estimated as 2.2+/-0.3 and 2.6+/-0.08kpc, respectively, while the corresponding ages estimated from empirical isochrones fitted to the Main Sequence cluster members are ~350Myr and 300Myr, respectively. The present data are not consistent with the membership of the WN6 star HDE 311884 to Hogg 15. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 11 19 30. -63 30 00 Cl Melotte 105 12 43 36. -63 06 00 Cl Hogg 15 15 16 48. -59 39 00 Cl Pismis 21 18 21 51.7 -33 08 42 Cl Ruprecht 140 ---------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 72 356 Magnitudes and colours of stars in the field of Melotte 105 table3.dat 72 233 Magnitudes and colours of stars in the field of Hogg 15. table4.dat 72 343 Magnitudes and colours of stars in the field of Pismis 21. table5.dat 72 259 Magnitudes and colours of stars in the field of Ruprecht 140. -------------------------------------------------------------------------------- See also: J/A+A/360/529 : Pismis 22, NGC 6178, NGC 6216, Ruprecht 130 (Piatti+, 2000) J/ApJS/116/263 : VI photometry of open clusters (Piatti+ 1998) Byte-by-byte Description of file: table?.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 4- 6 I3 --- ID Star number 8- 14 F7.3 pix Xpos X coordinate (1) 17- 23 F7.3 pix Ypos Y coordinate (1) 26- 31 F6.3 mag Vmag V magnitude 34- 38 F5.3 mag e_Vmag rms uncertainty on Vmag 41- 46 F6.3 mag B-V B-V colour index 49- 53 F5.3 mag e_B-V rms uncertainty on B-V 56- 61 F6.3 mag V-I V-I colour index 64- 68 F5.3 mag e_V-I rms uncertainty on V-I 72 I1 --- o_Vmag Number of measurements -------------------------------------------------------------------------------- Note (1): 1 pix = 0.45". North is up and East is to the left. For Ruprecht 140, the adopted center is (x, y) ~ (350, 100) For Hogg 15, the adopted center is (x, y) ~ (380, 230) -------------------------------------------------------------------------------- Acknowledgements: Andres Piatti ================================================================================ (End) Patricia Bauer [CDS] 27-Apr-2001