XMM-Newton Slew Survey

Introduction

The first catalogue of XMM slew sources (XMMSL1) was released in May 2006 and updated in August 2007 (xmmsl1d1), April 2008 (xmmsl1d2), July 2009 (xmmsl1d3), April 2010 (xmmsl1d4) and June 2011 (xmmsl1d5) and is available from the XMM-Newton Science Archive (XSA) . Pictures from the survey, together with presentations related to XMMSL1 can be found at Andy Read's site at the University of Leicester.

Normally, XMM-Newton slews through the sky at ~90 degrees/hour, which means that a source passes through the detector field-of-view in about 15 seconds. The EPIC-pn camera has a short CCD frame time which allows slew sources to be imaged essentially as point sources. This is not possible with the EPIC-MOS cameras which detect sources as streaks in the sky. For this reason, only EPIC-pn data have been used to construct XMMSL1.

This survey should not be confused with slower, dedicated, slew-survey observations, which have a different set of characteristics. Information on the slow-slew survey may be found here.

Image of a typical XMM slew
(click for jpg)

Data

XMMSL1 has been constructed from 218 slews and a further 109, 236, 110, 151 and 131 were used in the first, second, third, fourth and fifth updates respectively. The user guide and explanatory information for the catalogue is available here

The full slew data from XMMSL1 in Galactic coordinates.
	Slew Paths (click for jpg)

To avoid bias, three source lists have been constructed in parallel, and combined to form a catalogue:

• soft (0.2-2 keV)
• hard (2-12 keV)
• total catalogue (0.2-12 keV)

Sources

XMMSL1 contains 26806 detections, which after removing spurious and low significance sources leave 13617 "clean" sources. Many of these have been identified. Below are shown the slew sources logarithmically scaled with strength and colour-coded so that hard sources are blue and very soft sources, light-red.

Slew sources in Galactic coordinates.
	Slew sources (click for pdf)

Processing technique and strategy

XMM-Newton slews have an average length of 70 degrees. A slew is divided into individual images of rough size one square degree in the soft, hard and total bands. Exposure maps, using the vignetting and CCD distributions are created and are used together with the images in the source searching process. This uses a pipeline of eboxdetect and emldetect equivalent to that which is used in creating the catalogue of serendipitous sources from pointed observations 2XMM.

Increments

The Current Processing Status will be maintained during the course of the project. As slew data continues to be taken by the satellite further iterations of the catalogue will be produced and released via the XSA.

Problems

Slew data are clean compared with pointed observations where the long integration times produce a much higher absolute background level that complicates source detection. A small fraction of spurious sources are seen in slew data due to spurious detections, artifacts due to extremely bright sources and bright extended sources.

Further Details

For further details please contact the XMM-Newton Slew Survey Team