XMM/WFI Survey Release

7 July 2005

Technical Summary

CURRENT RELEASE
Survey ..................... XMM
Telescope .................. ESO/MPG 2.2m
Instrument ................. WFI
Program IDs ................ 170.A-0789; 70.A-0529; 71.A-0110
Origin ..................... ESO/EIS
Number of regions .......... 12
Region ..................... Selected XMM Serendipitous Survey
Number of Fields ........... 12
Passbands .................. B; V; R; I
Number of Filters........... 4
EIS Release Number ......... 28
Version .................... 0.9.5
Total Data Volume .......... 24.7 Gb
Release Date ............... July 2005
Release prepared by ........ J. P. Dietrich, J.-M. Miralles, L. F. Olsen

PRODUCTS
Product Type ............... Final Stacked Images
Number of Stacked Images ... 44
Data Volume ................ 24.7 Gb

PREVIOUS RELEASE
Origin ..................... ESO/EIS
Number of regions........... 12
Region ..................... Selected XMM Serendipitous Survey
Number of Fields ........... 12
Passbands .................. B; V; R; I
EIS Release Number.......... 22
Version..................... 0.9.0
Release Date................ 04 November 2004

PRODUCTS IN PREVIOUS RELEASE
Product Type................ Final Stacked Images
Number of Stacked Images.... 44

Abstract

Based on ideas submitted by the ESO community and evaluated by ESO's Survey Working Group (SWG), the XMM survey (administered by the ESO Imaging Survey (EIS) and the Public Survey Group (PSG) teams) consists of follow-up optical observations of the XMM-Newton Serendipitous Sky Survey (XSSS) using the ESO Wide Field Imager (WFI) at the ESO/MPG 2.2m telescope at the La Silla Observatory. This survey seeks to obtain WFI images in B-, V-, R- and I- passbands (for minimum spectral discrimination and photometric redshift determination) of XMM fields publicly available in the XMM archive. The fields were selected and prioritized by a collaboration of interested parties from the XMM Survey Science Centre (SSC), the Bonn group (led by P. Schneider) and an appointed committee of the SWG. The observations were originally proposed to cover a total area of approximately 10 square degrees (40 fields) to a limiting magnitude of 25 (AB, 5 sigma, 2 arcsec aperture, see original proposal presented by the SWG to the OPC).

Data for the XMM survey are being provided by:

1. the ESO Large Programme 170.A-0789(A) (Principal Investigator: J. Krautter, as chair of the SWG) which has accumulated data from January 27, 2003 to April 25, 2004 at the time of writing.
2. the contributing programs 70.A-0529(A); 71.A-0110(A); 71.A-0110(B) with P. Schneider as the Principal Investigator, which have contributed data from October 14, 2002 to September 29, 2003

The present release consists of final stacked images for 12 XMM fields including the data from the above programs accumulated until October 16, 2003.

Of the 12 fields being released nine are covered in all intended passbands. Of these seven have at least the planned exposure time, yielding limiting magnitudes close to those requested in the original proposal.

The accuracy of the astrometric calibration is estimated to be better than 0.2 arcsec. The photometric zero-points of the final stacks rely on the zeropoints of the reduced images for which the accuracy was estimated to range from 0.05 to 0.08 mag, with passbands B and R having the largest errors. The quality of the photometric zeropoints of the final stacked images is estimated from the scatter of the computed magnitude difference between the final stacks and the contributing photometric frames. In general, the mean offset are within few hundredths of a magnitude with a scatter of about 0.1 mag.

For more information about the terminology and conventions used in this document refer to the WEB README pages.

Contents of this Release

This release fixes the problem with the noisy weight maps reported by users after the previous release of stacked images. For all other information the reader is referred to the README of the previous release. These images are the ones from which the single passband catalogs released by the EIS team in December 2004 were produced. See /science/eis/surveys/release_65000025_XMM.html.

Since the impact on the science frames is very small, the color images linked on the release page are the same as for the previous release.

The present release consists of 44 fully calibrated ESO/MPG 2.2m WFI stacked images in B- (12), V- (11), R- (10) and I- (11) passbands for the 12 fields observed so far. The 44 stacked images were created from the 146 reduced images released in August 2004 in EIS release number 19 and more details about them can be found in the related documentation.

This data release is described in J.P. Dietrich, J.-M. Miralles, L.F. Olsen, L. da Costa, A. Schwope, C. Benoist, V. Hambaryan, A. Mignano, C. Motch, C. Rite, R. Slijkhuis, J. Tedds B. Vandame M.G. Watson S. Zaggia, ESO Imaging Survey: Optical follow-up of 12 selected XMM-Newton fields, submitted to A&A (2005), to which appropriate reference must be given in all works using these data.

Comparison to Previous Release(s)

This release supersedes the previous release of stacked images to correct the problem of noisy weight maps reported by users. Although the impact on the science images themselves is small, the weight images in this release are of better quality. This especially important if users decide to generate their own catalogs using the provided weight maps instead of using the single passband catalogs released by the EIS team.

Conclusions

This is the final release of stacked images for the EIS XMM-Newton follow-up survey fixing previously reported problems with the weight maps. Due to the termination of the EIS project at the end of December 2004 no further EIS data releases for this survey are anticipated.