Related papers: Variable stars in the globular cluster M28 (NGC 66…
Results are presented of a study of the variable star populations in the dwarf spheroidal galaxy Leo I and in the dwarf irregular galaxy NGC 6822, based on time series photometry obtained with the Wide Field Imager of the 2.2 m ESO/MPI…
We present the results of a photometric survey for variable stars in the nearby globular cluster M5. A 14.8x22.8 arcmin^2 field centered on the cluster was monitored for a total of 37 hours with a CCD camera mounted on the 1.0-m Swope…
We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. NGC 2158 is one of the targets we have chosen -- an intermediate age, populous, rather metal…
We show the benefits of using Electron-Multiplying CCDs and the shift-and-add technique as a tool to minimise the effects of the atmospheric turbulence such as blending between stars in crowded fields and to avoid saturated stars in the…
We present a new, deep (V ~ 26) study of the Galactic globular cluster NGC 2419 based on B,V,I time-series CCD photometry over about 10 years and extending beyond the cluster published tidal radius. We have identified 101 variable stars of…
We present a CCD $VI$ time-series analysis of the globular cluster NGC 6139 and its variable star population. Using the astrometric data available in $Gaia$-DR3 we performed a membership analysis that enabled the construction of a clean…
We present a CCD survey of variable stars in the Draco dwarf spheroidal galaxy. This survey, which has the largest areal coverage since the original variable star survey by Baade & Swope, includes photometry for 270 RR Lyrae stars, 9…
[ABRIDGED] $\omega$ Centauri (NGC 5139) contains large numbers of variable stars of different types and, in particular, more than a hundred RR Lyrae stars. We have conducted a variability survey of $\omega$ Cen in the NIR, using ESO's 4.1m…
The VISTA Variables in the Via Lactea (VVV) ESO Public Survey is opening a new window to study the inner Galactic globular clusters using their variable stars. These globular clusters have been neglected in the past due to the difficulties…
We report the discovery of a large number of short-period variable stars in the dwarf irregular galaxy NGC6822, based on deep time-series imaging carried out with the ESO Very Large Telescope. In particular, we found a modest population of…
We present new $BVI$ CCD photometry for variables in the globular cluster M15. Our photometry was obtained using both the image subtraction package ISIS and DAOPHOT/ALLFRAME. The data were acquired in 2001 on two observing runs on 11…
We have conducted a photometric survey of the globular cluster NGC 6397 in a search for variable stars. We obtained ~11h of time-resolved photometric images with one ne European Southern Observatory-Very Large Telescope using the FOcal…
We report the discovery of a variable blue straggler in the core of the globular cluster M5, based on a 12-hour long series of images obtained with the Planetary Camera aboard the Hubble Space Telescope. In addition, we present the light…
We present results of a CCD variability search in the field of the young open cluster NGC 6834. We discover 15 stars to be variable in light. The brightest, a multiperiodic Gamma Doradus-type variable is a foreground star. The eight fainter…
We report CCD V and I time series photometry of the globular cluster NGC 5024 (M53). The technique of difference image analysis has been used which enables photometric precisions better than 10 mmag for stars brighter than V 18.5mag even in…
We present the results from 10 nights of observations of the globular cluster NGC 6981 (M72) in the V, R and I Johnson wavebands. We employed the technique of difference image analysis to perform precision differential photometry on the…
A CCD VI imaging time-series over 11-year is employed to explore the light curves of stars in the field of Palomar 2. We discovered 20 RRab and 1 RRc variables. A revision of Gaia-DR3 data enabled us to identify 10 more variables and…
The Galactic globular clusters (GGCs) located in the inner regions of the Milky Way suffer from high extinction that makes their observation challenging. The VVV survey provides a way to explore these GGCs in the near-infrared where…
We present results of a variability search in the intermediate-age open cluster NGC 6866 from 29 nights over two observing seasons. We find 28 periodic variables, of which 19 are newly identified. The periods of these variables, which have…
We report on new B, V and I CCD photometry of the globular cluster M54 that was aimed at the study of its variable stars. With respect to the previous most recent work on M54 we have nearly doubled the number of detected variable stars: M54…