scholarly journals The VMC survey

2018 ◽  
Vol 612 ◽  
pp. A115 ◽  
Author(s):  
Florian Niederhofer ◽  
Maria-Rosa L. Cioni ◽  
Stefano Rubele ◽  
Thomas Schmidt ◽  
Kenji Bekki ◽  
...  
Keyword(s):  
Proper Motion ◽  
Near Infrared ◽  
Cluster Center ◽  
Proper Motions ◽  
Velocity Measurements ◽  
Naval Observatory ◽  
Point Spread ◽  
Spread Function ◽  
The Galaxy ◽  
Infrared Survey

We use deep multi-epoch point-spread function (PSF) photometry taken with the Visible and Infrared Survey Telescope for Astronomy (VISTA) to measure and analyze the proper motions of stars within the Galactic globular cluster 47 Tucanae (47 Tuc, NGC 104). The observations are part of the ongoing near-infrared VISTA survey of the Magellanic Cloud system (VMC). The data analyzed in this study correspond to one VMC tile, which covers a total sky area of 1.77 deg2. Absolute proper motions with respect to ~9070 background galaxies are calculated from a linear regression model applied to the positions of stars in 11 epochs in the Ks filter. The data extend over a total time baseline of about 17 months. We found an overall median proper motion of the stars within 47 Tuc of (μαcos(δ),  μδ) = (+5.89 ± 0.02 (statistical) ± 0.13 (systematic), −2.14 ± 0.02 (statistical) ± 0.08 (systematic)) mas yr−1, based on the measurements of ~35 000 individual sources between 5′ and 42′ from the cluster center. We compared our result to the proper motions from the newest US Naval Observatory CCD Astrograph Catalog (UCAC5), which includes data from the Gaia data release 1. Selecting cluster members ( ~2700 stars), we found a median proper motion of (μαcos(δ),  μδ) = (+5.30  ± 0.03 (statistical) ± 0.70 (systematic), −2.70 ± 0.03 (statistical) ± 0.70 (systematic)) mas yr−1. Comparing the results with measurements in the literature, we found that the values derived from the VMC data are consistent with the UCAC5 result, and are close to measurements obtained using the Hubble Space Telescope. We combined our proper motion results with radial velocity measurements from the literature and reconstructed the orbit of 47 Tuc, finding that the cluster is on an orbit with a low ellipticity and is confined within the inner ~7.5 kpc of the Galaxy. We show that the use of an increased time baseline in combination with PSF-determined stellar centroids in crowded regions significantly improves the accuracy of the method. In future works, we will apply the methods described here to more VMC tiles to study in detail the kinematics of the Magellanic Clouds.

Near-infrared fundus imaging system with light illumination from an electronic contact lens

2022 ◽  
Vol 15 (2) ◽  
pp. 027001
Author(s):  
Yang Cui ◽  
Taiki Takamatsu ◽  
Koichi Shimizu ◽  
Takeo Miyake
Keyword(s):  
Contact Lens ◽  
Near Infrared ◽  
Imaging System ◽  
Low Cost ◽  
Light Illumination ◽  
Fundus Images ◽  
Fundus Imaging ◽  
Point Spread ◽  
Spread Function ◽  
Dependent Point

Abstract As for the diagnosis and treatment of eye diseases, an ideal fundus imaging system is expected to be portability, low cost, and high resolution. Here, we demonstrate a non-mydriatic near-infrared fundus imaging system with light illumination from an electronic contact lens (E-lens). The E-lens can illuminate the retinal and choroidal structures for capturing the fundus images when voltage is applied wirelessly to the lens. And we also reconstruct the images with a depth-dependent point-spread function to suppress the scattering effect that eventually visualizes the clear fundus images.

scholarly journals Surface Brightness Profiles of 68 Globular Clusters Derived From Electronic Camera Recordings

1980 ◽  
Vol 85 ◽  
pp. 459-460
Author(s):  
Gerald E. Kron ◽  
Katherine C. Gordon ◽  
Anthony V. Hewitt
Keyword(s):  
Point Spread Function ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Naval Observatory ◽  
Point Spread ◽  
Spread Function ◽  
Spacial Information ◽  
Cluster Profiles ◽  
Star Images ◽  
The U.S

Images of 68 globular clusters have been recorded in 125 exposures made with the electronic camera of the U.S. Naval Observatory on the 24-inch, 40-inch and 61-inch reflecting telescopes at the Flagstaff Station. The images were electronically malfocussed to allow the integration of light from the fainter cluster stars without saturation of the central portions of the brighter star images. Spacial information thus lost was partly regained by subsequent linear deconvolution of the cluster profiles by means of a star profile used as the point spread function.

scholarly journals Companion Detection Limits with Adaptive Optics Coronagraphy

2004 ◽  
Vol 202 ◽  
pp. 99-102
Author(s):  
B. R. Oppenheimer ◽  
R. G. Dekany ◽  
M. Troy ◽  
T. Hayward ◽  
B. Brandl
Keyword(s):  
Adaptive Optics ◽  
Focal Plane ◽  
Near Infrared ◽  
Dynamic Range ◽  
Infrared Camera ◽  
Nearby Star ◽  
Point Spread ◽  
Spread Function ◽  
Adaptive Optics System ◽  
Circular Disks

We present a study of the Palomar Adaptive Optics System and the PHARO near infrared camera in coronagraphic mode. The camera provides two different focal plane occulting masks–opaque circular disks 0.43 and 0.97″ across. Three different pupil plane apodizing masks (Lyot masks) are also provided. The six different combinations of Lyot mask and focal plane mask suppress differently the point spread function of a bright star centered on the focal plane mask. We obtained images of the bright nearby star Gliese 614 with all six different configurations in the K filter. We measured the dynamic range achievable with these configurations. Within 2.5″, the dynamic range is at least 8 magnitudes at the 5σ level and as high as 12 in a 1 s exposure. This represents a substantial gain over similar techniques without adaptive optics.

Near infrared survey of the central 12 square degree of the Galaxy

1992 ◽  
Author(s):  
Munetaka Ueno ◽  
Takashi Ichikawa ◽  
Shuji Sato ◽  
Yasumasa Kasaba ◽  
Masanao Ito
Keyword(s):  
Near Infrared ◽  
The Galaxy ◽  
Infrared Survey

scholarly journals Kinematics of Galactic Globular Clusters from Schmidt-Plate Astrometry

1995 ◽  
Vol 164 ◽  
pp. 405-405 ◽  
Author(s):  
R.-D. Scholz ◽  
S. Hirte ◽  
M.J. Irwin ◽  
M. Odenkirchen
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Globular Clusters ◽  
Proper Motions ◽  
Large Numbers ◽  
Solar Motion ◽  
The Galaxy ◽  
Ursa Minor ◽  
Galactic Globular Clusters

From measurements of Tautenburg Schmidt plates with the APM facility in Cambridge we obtained absolute proper motions of the Galactic globular clusters M 3 and M 92 directly with respect to large numbers of background galaxies (Scholz et al. 1993, 1994). We have extended our work to the dSphs in Draco and Ursa Minor (Scholz & Irwin 1994) and to other Galactic globular clusters using Tautenburg, Palomar and UK Schmidt plates. Combining our absolute proper motion of a cluster with its known radial velocity and distance (using common parameters of the solar motion) we derive the cluster orbit in the Galaxy (cf. Odenkirchen & Brosche 1992).

scholarly journals Deep point spread function photometric catalog of the VVV survey data

2019 ◽  
Vol 632 ◽  
pp. A85
Author(s):  
M. Zhang ◽  
J. Kainulainen
Keyword(s):  
Point Spread Function ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Galactic Plane ◽  
High Reliability ◽  
Point Spread ◽  
Deep Point ◽  
Spread Function ◽  
Local Crowding ◽  
Source Number

Context. The Vista Variables in the Vía Láctea (VVV) survey has performed a multi-epoch near-infrared imaging of the inner Galactic plane. High-fidelity photometric catalogs are needed to utilize the data. Aims. We aim at producing a deep, point spread function (PSF) photometric catalog for the VVV survey J-,H-, and Ks-band data. Specifically, we aim to take advantage of multiple epochs of the survey to reach high limiting magnitudes. Methods. We developed an automatic PSF-fitting pipeline based on the DaoPHOT algorithm and performed photometry on the stacked VVV images in J,  H, and Ks bands. Results. We present a PSF photometric catalog in the Vega system that contains about 926 million sources in the J,  H, and Ks filters. About 10% of the sources are flagged as possible spurious detections. The 5σ limiting magnitudes of the sources with high reliability are about 20.8, 19.5, and 18.7 mag in the J,  H, and Ks bands, respectively, depending on the local crowding condition. Our photometric catalog reaches on average about one magnitude deeper than the previously released PSF DoPHOT photometric catalog and includes less spurious detections. There are significant differences in the brightnesses of faint sources between our catalog and the previously released one. The likely origin of these differences is in the different photometric algorithms that are used; it is not straightforward to assess which catalog is more accurate in different situations. Our new catalog is beneficial especially for science goals that require high limiting magnitudes; our catalog reaches such high magnitudes in fields that have a relatively uniform source number density. Overall, the limiting magnitudes and completeness are different in fields with different crowding conditions.

scholarly journals Correction to Absolute Proper Motion Using the IAS-Galaxy Model

1990 ◽  
Vol 141 ◽  
pp. 427-429
Author(s):  
Kavan U. Ratnatunga
Keyword(s):  
Reference Frame ◽  
Proper Motion ◽  
Theoretical Models ◽  
Galactic Structure ◽  
Coordinate Frame ◽  
Proper Motions ◽  
Software Interface ◽  
The Galaxy ◽  
Galaxy Model ◽  
Star Catalogs

The IAS-Galaxy model (Ratnatunga, Bahcall and Casertano 1989) is a software interface between theoretical models of the Galaxy and observed kinematic distributions. It has been developed for analysis of many kinematic catalogs to study global galactic structure. In addition, the IASG model can be used to estimate corrections needed to derive absolute parallax and absolute proper motion by evaluating, on a star-by-star basis, the expected mean motion of the reference stars.A theoretical Galaxy model is defined on an inertial coordinate frame. Proper motions are measured in a reference frame defined by a fundamental catalog. The observed distribution of proper motions in star catalogs can be directly compared with the expected distributions evaluated using IASG to check the accuracy of the adopted reference frame in realizing the inertial coordinate frame in the sky.

scholarly journals Milky Way demographics with the VVV survey

2018 ◽  
Vol 619 ◽  
pp. A4 ◽  
Author(s):  
Javier Alonso-García ◽  
Roberto K. Saito ◽  
Maren Hempel ◽  
Dante Minniti ◽  
Joyce Pullen ◽  
...  
Keyword(s):  
Near Infrared ◽  
Milky Way ◽  
Stellar Populations ◽  
Wide Field ◽  
Public Survey ◽  
Wide Field Of View ◽  
Spread Function ◽  
The Galaxy ◽  
Infrared Wavelengths ◽  
Galactic Stellar Populations

Context. The inner regions of the Galaxy are severely affected by extinction, which limits our capability to study the stellar populations present there. The Vista Variables in the Vía Láctea (VVV) ESO Public Survey has observed this zone at near-infrared wavelengths where reddening is highly diminished. Aims. By exploiting the high resolution and wide field-of-view of the VVV images we aim to produce a deep, homogeneous, and highly complete database of sources that cover the innermost regions of our Galaxy. Methods. To better deal with the high crowding in the surveyed areas, we have used point spread function (PSF)-fitting techniques to obtain a new photometry of the VVV images, in the ZY JHKs near-infrared filters available. Results. Our final catalogs contain close to one billion sources, with precise photometry in up to five near-infrared filters, and they are already being used to provide an unprecedented view of the inner Galactic stellar populations. We make these catalogs publicly available to the community. Our catalogs allow us to build the VVV giga-CMD, a series of color-magnitude diagrams of the inner regions of the Milky Way presented as supplementary videos. We provide a qualitative analysis of some representative CMDs of the inner regions of the Galaxy, and briefly mention some of the studies we have developed with this new dataset so far.

scholarly journals On the Correction to Precession from Proper Motions Referred to Galaxies

1971 ◽  
Vol 9 ◽  
pp. 163-170 ◽  
Author(s):  
S. Vasilevskis ◽  
A. R. Klemola
Keyword(s):  
Proper Motion ◽  
Direct Relationship ◽  
Fundamental System ◽  
Direct Reference ◽  
Meridian Circle ◽  
Proper Motions ◽  
Obvious Advantage ◽  
Naval Observatory ◽  
Cooperative Project ◽  
The U.S

One of the principal aims of the Lick proper motion program, as conceived and initiated by Wright (1950), was to derive the correction to precession. Ideally, proper motions of stars from a fundamental catalogue should be measured with respect to galaxies. Unfortunately, these stars are too bright for a direct reference to faint galaxies, even with an objective grating and two systems of exposures (2 h and 1 min) on every plate, as employed at Lick. For this reason a cooperative project with the U.S. Naval Observatory was initiated in 1953 (Scott, 1954; Vasilevskis, 1954), with an intention to establish a direct relationship between meridian circle and Lick observations. When Heckmann (1954) proposed the formation of the AGK3, it was agreed to discontinue the cooperation mentioned, so as to make the resources of the U.S. Naval Observatory available for observing the AGK3 reference stars, and then to use the AGK3 as an intermediary for relating the Lick proper motions to a fundamental system. An obvious advantage of this change was offered by the abundance of AGK stars for measurement on Lick plates; a disadvantage is the absence of the AGK3 data south of declination –2.°5.

Photoelectric Vilnius Photometry of Stars in the Mega Proper Motion Field KA 10

2003 ◽  
Vol 12 (3) ◽  
Author(s):  
S. Bartašiutė
Keyword(s):  
Proper Motion ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Chemical Properties ◽  
Absolute Magnitude ◽  
Motion Field ◽  
Proper Motions ◽  
Velocity Measurements ◽  
Color Excess ◽  
And Chemical Properties

AbstractPhotoelectric seven-color photometry in the Vilnius medium-band, system is obtained for 87 stars down to V≃13.0 in the Kiev proper motion field KA10 [l = 137°, b = -59°]. The size of the field is 1.4 square degrees. For each star, photometric spectral type, absolute magnitude, metallicity, and color excess due to interstellar reddening have been determined. These data, together with previous Vilnius photometry obtained in other seven KA fields at high Galactic latitudes, will be combined with radial-velocity measurements and available proper motions to yield space velocities and to investigate kinematical and chemical properties of the Galactic disk in the direction perpendicular to the Galactic plane.

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