Context. The majority of stars form in clusters. Therefore a comprehensive view of star formation requires understanding the initial conditions for cluster formation. Aims. The goal of our study is to shed light on the physical properties of infrared dark clouds (IRDCs) and the role they play in the formation of stellar clusters. This article, the first of a series dedicated to the study of IRD...

We built Galactic open star cluster mass functions (CMFs) for different age sub-samples in the wider solar neighbourhood. present a simple formation and evolution model to reproduce main features of CMFs. used an unbiased sample 2227 clusters Milky Way Star Cluster (MWSC) catalogue, which occupy heliocentric cylinders with magnitude-dependent completeness radii 1-5 kpc. derived tidal masses acc...

In paper 167 of his serie published in The Observatory, Griffin presented the spectroscopic orbit of HD 112914, a late main sequence star. He also noticed that this star, also known as HIP 63406, was one of the few for which the DMSA/O Annex of the Hipparcos Catalogue derived an orbit prior to any spectroscopic one. Albeit in agreement with each others, the astrometric orbit was however determi...

Using the surface brightness fluctuations in HST WFPC-2 images, we determine that M87, NGC 4486B, and NGC 4478 are all at a distance of ∼ 16 Mpc, while NGC 4476 lies in the background at ∼ 21 Mpc. We also examine the globular clusters of M87 using archived HST fields. We detect the bimodal color distribution, and find that the amplitude of the red peak relative to the blue peak is greatest near...

Mean proper motions and parallaxes of 205 open clusters were determined from their member stars found in the Hipparcos Catalogue. 360 clusters were searched for possible members, excluding nearby clusters with distances D < 200 pc. Members were selected using ground based information (photometry, radial velocity, proper motion, distance from the cluster centre) and information provided by Hippa...

About 500 photographic plates of the Galilean satellites made with the 26-inch refractor of USNO in Washington DC from 1967 to 1998 were digitized and reduced using the UCAC2 star catalog. Results on the ephemerides of the Galilean satellites and on the determination of the mass of Amalthea will be presented. An evaluation of the accuracy of several ephemerides of Jupiter on the 1967-1998 perio...

We describe TRILEGAL, a new populations synthesis code for simulating the stellar photometry of any Galaxy field. The code attempts to improve upon several technical aspects of star count models, by: dealing with very complete input libraries of evolutionary tracks; using a stellar spectral library to simulate the photometry in virtually any broad-band system; being very versatile allowing easy...

In this paper, we discuss the detection of systematic biases in star positions of the USNO A1.0, A2.0, and B1.0 catalogs, as deduced from the residuals of numbered asteroid observations. We present a technique for the removal of these biases, and validate this technique by illustrating the resulting improvements in numbered asteroid residuals, and by establishing that debiased orbits predict om...

The intention of this paper is to evaluate the sensitivity of the Storm Water Management Model (SWMM) output to its input parameters. A global parameter sensitivity analysis is conducted in order to determine which parameters mostly affect the model simulation results. Two different methods of sensitivity analysis are applied in this study. The first one is the partial rank correlation coeffici...