相关论文: Crowded-field photometry from HST-imaging

We develop a method to estimate photometric metallicities by simultaneously fitting the dereddened colors u-g, g-r, r-i and i-z from the SDSS with those predicted by the metallicity-dependent stellar loci. The method is tested with a…

An important requirement for the Space Interferometry Mission (SIM) is to carry out precision astrometry in crowded fields. This capability is crucial, for example, to accurately measure proper motions of bright stars in nearby galaxies.…

Traditional artificial-star tests are widely applied to photometry in crowded stellar fields. However, to obtain reliable binary fractions (and their uncertainties) of remote, dense, and rich star clusters, one needs to recover huge numbers…

Recently, we have developed and calibrated the Synthetic Field Method (SFM) to derive the total extinction through disk galaxies. The method is based on the number counts and colors of distant background field galaxies that can be seen…

We present a catalog of 4780 extended sources from the outer field of M33. The catalog includes 73 previously identified clusters or planetary nebulae, 1153 likely background galaxies, and 3554 new candidate stellar clusters. The survey is…

In this paper we test the astrometric precision of VLT/FORS2 observations using a serie of CCD frames taken in Galactic bulge area. A special reduction method based on symmetrization of reference fields was used to reduce the atmospheric…

Multiple populations (MPs) in globular clusters (GCs) are stars distinct by their abundances of light elements. The MPs can be directly separated by measuring abundances of C, N, O, Na, Al, Mg with spectroscopy or indirectly from…

We present a photometric study of the stars in ionizing star clusters embedded in several giant HII regions of M33 (CC93, IC 142, NGC 595, MA2, NGC 604 and NGC 588). Our photometry are based on the HST-WFPC2 images of these clusters.…

We report on the properties of 89 low mass star clusters located in the vicinity of luminous young clusters (blue globulars) in the disk of M31. 82 of the clusters are newly detected. We have determined their integrated magnitudes and…

We demonstrate ground-based submillimagnitude (<10^-3) photometry of widely separated bright stars using snapshot CCD imaging. We routinely achieved this photometric precision by (1) choosing nearby comparison stars of a similar magnitude…

The image subtraction method is a powerful tool to analyze the light variations in crowded fields. This method is able to achieve a nearly optimal differential photometry, even in very dense regions. However, image subtraction is not…

(abridged) We present the first results of our deep survey of lensing clusters aimed at constraining the abundance of star-forming galaxies at z~6-10. Deep near-IR photometry of two lensing clusters (A1835 and AC114) was obtained with…

The installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) will revolutionize the study of high-redshift galaxy populations. Initial observations of the HST Ultra Deep Field (UDF) have yielded multiple z>~7…

The accuracy of the Hubble constant measured with extragalactic Cepheids depends on robust photometry and background estimation in the presence of stellar crowding. The conventional approach accounts for crowding by sampling backgrounds…

Free of any atmospheric contamination, HST provides the best available spectrophotometry from the far-UV to the near-IR for stars as faint as V~16. The HST CALSPEC standard star network is based on 3 standard candles: the hot, pure hydrogen…

BRITE-Constellation is devoted to high-precision optical photometric monitoring of bright stars, distributed all over the Milky Way, in red and/or blue passbands. Photometry from space avoids the turbulent and absorbing terrestrial…

Deep, near-infrared imaging surveys have been motivated by the desire to study the rest-frame optical properties and stellar content of galaxies at high redshift. Here we briefly review their history, and illustrate one application, using…

Stellar sources are identified in the Hubble Deep Field, and accurate colours and magnitudes are presented. The predictions of a Galactic starcounts model are compared with the faint stellar counts in this field. The model reproduces the…

We examine the stellar content of 10 dwarf irregular galaxies of which broad-band CCD photometry was published in Hopp & Schulte-Ladbeck (1995). We also present Halpha images for several of these galaxies. The galaxies in the sample are…

We aim to test a purely photometric approach to statistically identify a young clustered population embedded in a large population of field stars, with no prior knowledge on the nature of stars in the field. We conducted our blind test…