VISTA Magellanic Survey - Data Release 1

Provided by Maria-Rosa Cioni

Release Date: 25.09.2011

Abstract

This data release refers to ESO program 179.B-2003. Observations were obtained with the VISTA telescope as part of the VISTA survey of the Magellanic Cloud system (VMC) in three filters: Y, J and Ks. The main goals of the VMC survey are the determination of the spatially resolved star formation history and the three-dimensional geometry of the Magellanic system. The sensitivity of the data is designed to reach sources below the oldest main-sequence turn off point of the stellar population.

Release Content

This release covers two tiles in the Large Magellanic Cloud: one overlapping the 30 Doradus and the other the South Ecliptic Pole region.

Tiles were oriented with the Y axis more or less along the declination direction and cover about 1.0 x 1.5 sq. degrees. Tiles centres are at:

30-Dor/6_6 05:37:40.008 -69:22:18.120
SEP/8_8 05:59:23.136 -66:20:28.680

A deep tile image, with associated confidence map and catalogue, is released per band per field. A band-merged catalogue is also released for each field comprising observations obtained from November 2009 to November 2010 included. Preview images in JPEG format are associated to each science FITS image.

Catalogues were created from images that were filtered for nebulosity with size of the order of 30 arcsec, but to the images released here the filtering process was not applied. See Irwin (2010, UKIRT Newsletter 26, 14).

The average data quality per deep tile is as follows:
Field Filter Time (s) FWHM (") Ellip. (") Mag.Lim AB (5_sigma) Mag.Sat AB
30-Dor/6_6 Y 2400 1.07 0.06 21.271 14.097

J 2600 1.04 0.05 21.191 13.711

Ks 9375 1.00 0.04 21.567 13.427
SEP/8_8 Y 2400 1.11 0.04 22.489 13.819
J 2600 1.07 0.04 22.537 13.659
Ks 9375 0.97 0.04 22.545 13.548

Known Issues

These VISTA data may present the following issues, for which a full description is given in http://casu.ast.cam.ac.uk/surveys-projects/vista/technical/known-issues. A variable depth due to bad pixels in detectors 1, 4 and 16 as well as some bad rows. Point-like objects residuals of flatfielding, variable vignetting and spurious detections around bright stars.

The issue with detector 16 affects the magnitude of stars in its upper stripe. This may cause a shift in the distribution of stars in colour magnitude and colour-colour diagrams. This effect is more pronounced in those diagrams involving the Y band. The affected sources will be flagged in subsequent data releases.

Data in this release comprise observations obtained prior to 20 November 2009 when detector 6 had an intermittently bad channel. Note also that 15% of the tile, corresponding to two edges, has only half the total effective exposure time.

File naming convention

Deep tiles, tile confidence images, jpegs:

vmc_erR_XXhMM±XXXdMM_f_image_multiframeID.fits.fz

vmc_erR_XXhMM±XXXdMM_f_conf_multiframeID.fits.fz

vmc_erR_XXhMM±XXXdMM_f_jpeg_multiframeID.jpg

where the position comes from vmcMergeLog, f is the filter name (y,j ks) and R is the release number (1). multiframeID is the unique identifier for each FITS image.

Deep Pawprints, pawprint confidence images, jpegs:

vmc_erR_XXhMM±XXXdMM_offN_f_image_multiframeID.fits.fz

vmc_erR_XXhMM±XXXdMM_offN_f_conf_multiframeID.fits.fz

vmc_erR_XXhMM±XXXdMM_offN_f_jpeg_multiframID.jpg

where offN specifies the offset position (from RequiredStack in the archive)

0 (offsetX=-329.779, offsetY=-329.779)

1 (offsetX=-329.779, offsetY=0)

2 (offsetX=-329.779, offsetY=+329.779)

3 (offsetX=329.779, offsetY=-329.779)

4 (offsetX=329.779, offsetY=0)

5 (offsetX=329.779, offsetY=+329.779)

Single band source lists:

vmc_erR_XXhMM±XXXdMM_f_cat_multiframeID.fits

Multi-band source lists:

vmc_erR_XXhMM±XXXdMM_allFilters_srcCat_frameSetID.fits

where allFilters = yjks. framesetID is the unique identifier for each pointing in the source table.

Release Notes

The data for this release were prepared by the Cambridge Astronomy Survey Unit (CASU), the Wide Field Astronomy Unit (WFAU) and the VMC team. 

The main processing steps are described in Hambly et al. (2008, MNRAS 384, 637) and Cross et al. (2009, MNRAS 399, 1730). Deep tiles were created using the software suite provided by CASU (casutools-1.0.13). The single and multi-band source lists were out-gested from the VISTA Science Archive by WFAU using data in the VMCv20110218 release. Deep tiles are produced only from data that meet the observing criteria for the VMC survey (see table above). Multi-band source list data come from merged deep tile catalogues.

Data retrieval

Go to the data products query form to find and retrieve the data from the ESO Science Archive. Just press the Search button to find all data belonging to this release, or specify search constraints to find a subset thereof.

Acknowledgements

If using these data please reference Cioni et al. 2011, A&A, 527, A116. Users of data products provided in this release are required to acknowledge the source of the data with an appropriate citation in their publications in the form:

Based on data products from observations made with ESO Telescopes at the La Silla or Paranal Observatories under ESO programme ID 179.B-2003.