Schmidt survey in the Galactic anticentre direction. 1. Investigation of open clusters

Abstract

A study of four open clusters in the direction of the Galactic anticentre (I = 186O, b = + 2 O ) is presented. In a field of 8.32 square degrees proper motions and B magnitudes for about 79000 stars down to 19.5 were determined on Tautenburg Schmidt plates. For more than 15 500 of them U magnitudes down to 17.3 could be obtained. Additionally, OCA Schmidt plates were used to determine V, R magnitudes in a larger field of 24.45 square degrees for 271 000 stars down to V = 18.2. For stars brighter than V = 15.5 an accuracy of about 1.5 mas/yr has been estimated for proper motions. The rms errors of stellar magnitudes and colour indices are 0.09 -0.12 mag.Several open clusters have been already known in this direction of the sky, e.g. NGC 2168 or M 35 (C 0605+243), NGC 2158 (C 0604+241) and IC 2157 (C 0601+240). Inspecting the plates and analysing the colour-magnitude diagrams and published data, we could identify an additional anonymous cluster C 0605+242 with a projection on the sky near the centre of M 35 but at a larger distance from the Sun.The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour-magnitude diagrams were derived down to the limiting stellar magnitude. For each cluster the interstellar extinction A v , the diameters of the core and corona, the ages and spatial velocity components (V, W ) relative to the LSR in the Y, Z -Galactic directions were determined.The distances to the clusters of 960 pc, 2 600 pc, 2 520 pc and 3700 pc were obtained for M 35, IC 2157, C 0605+242 and NGC 2158. They show the loci of the clusters in the Local and Perseus spiral arms and at external border of Perseus arm, respectively. K e y words: proper motionsopen clusters -HR diagram -Galaxy A A A subject classification: 111; 115; 153;155; ~ ~~ Exposure Survey time [min] 15 P.M. 15 P.M. 22 P.M. 22 P.M. 72 U mag. 41 P.M.+E mag. 46 P.M.+E mag. 20

Ensemble Analysis of Open Cluster Transit Surveys: Upper Limits on the Frequency of Short-Period Planets Consistent With the Field

“…This is a 11 ′ .4 × 11 ′ .4 region centered roughly 16' from the cluster center. Kharchenko et al (1997) estimates the max-imum radius of the cluster to be ∼ 15 ′ , so this field likely contains at least some cluster stars, although the steep radial density profile of the cluster (see Fig. 6 in Kharchenko et al 1997) suggests it will be minimal.…”

“…Kharchenko et al (1997) estimates the max-imum radius of the cluster to be ∼ 15 ′ , so this field likely contains at least some cluster stars, although the steep radial density profile of the cluster (see Fig. 6 in Kharchenko et al 1997) suggests it will be minimal. Note also that field 1 in M06 is also the most distant field of the four from nearby M35, which produces a slight gradient in the star counts across the M06 fields.…”

The intermediate-age open cluster NGC 2158

“…The first investigation was carried out by Arp & Cuffey (1962), who obtained photographic BV photometry for about 900 stars down to V =18.5. Photographic photometry was also obtained by Karchenko, Andruk & Schilbach (1997) for more than 2000 stars down to the same limiting magnitude, together with proper motions.…”

“…Absolute proper motions have been derived by Kharchenko et al (1997), and amount to μ x =+0.66±2.03, μ y =‐3.23±2.16, where μ x = μ ×cos δ and μ y = μ .…”

Schmidt plate survey in the Galactic centre and anticentre direction. Luminosity and mass functions of open clusters

“…As our Schmidt plate survey (Schilbach 1988) contains proper motions and photometric data for several distant open clusters of various ages, LFs and MFs could be constructed for their members. The membership selection is based on "spatial-kinematical" and photometric criteria described in previous papers (Kharchenko andSchilbach 1995 andKharchenko et al 1997, hereafter referred t o as KS95 and KSA97). Additionally, an independent statistical method of luminosity function (LF) construction was applied and both approaches were compared in the cluster MF analysis context.…”