XMM-Newton-NEWS


XMM-Newton-NEWS  #29,    11-Mar-2003

ESA, XMM-Newton Science Operations Centre at
European Space Astronomy Centre (ESAC)
P.O. Box - Apdo. 50727, 28080 Madrid, Spain

SOC Home Page: http://xmm.esac.esa.int/
Helpdesk web interface: https://www.cosmos.esa.int/web/xmm-newton/xmm-newton-helpdesk
Helpdesk email address: xmmhelp@sciops.esa.int
News Mailing List: https://www.cosmos.esa.int/web/xmm-newton/newsletter

Contents:

XMM-Newton Users' Handbook update for AO-3

The XMM-Newton Users' Handbook (UHB) has been updated in preparation for the next Announcement of Opportunity (AO-3) reflecting latest in-flight experience.

The UHB contains information on the instrumentation on board XMM-Newton and serves as the proposal preparation document, based on which potential XMM-Newton users can assess the technical feasibility of their planned observations.

The updated XMM-Newton Users' Handbook is available now from the URL;
http://xmm.esac.esa.int/external/xmm_user_support/documentation/

Users' Guide to the XMM-Newton Science Analysis System: update

XMM-Newton SOC has updated the Users' Guide to the XMM-Newton Science Analysis System for SAS version 5.4.1. The updated guide will be available from Monday, March 17, in different formats (postscript, pdf and html) from the XMM-Newton Proposer's Info and Manuals Web page (Section: Data Analysis) at URL;
http://xmm.esac.esa.int/external/xmm_user_support/documentation/

emldetect likelihoods

A coding error has recently been discovered in the SAS task emldetect which performs EPIC source parameterisation. Due to this error, the detection likelihood values reported by emldetect (i.e. in the column DET_ML in the output files) are overestimated by a factor 2 or more, depending on the number of input images. Other aspects of the performance of emldetect are unaffected.

As emldetect is used in the standard XMM-Newton processing pipeline, this problem affects EPIC source lists produced with SAS 5.4.1 or earlier. Users are advised to treat with caution any detections in existing source lists with low DET_ML values (especially DET_ML <~ 20) as the number of spurious sources per EPIC image becomes significant at these values.

This error will be corrected in the next version of the SAS.

The attached table provides the conversion to correct DET_ML values with some examples.

DET_ML conversion table

Table to convert emldetect (v4.11.15 and earlier) likelihood values (column DET_ML) to correct values.

Examples for pipeline source lists:
  1. The old DET_ML value for a single energy band (ID_BAND=1,2,3,4 or 5) is 18.0, the correct value is 8.51
  2. The old DET_ML value for the summary band (5 bands, ID_BAND=0) is 27.0, the correct value is 11.29
old value correct values
  1 band 2 bands 5 bands
5.00 2.24 2.03 1.59
6.00 2.71 2.48 1.99
7.00 3.18 2.93 2.39
8.00 3.66 3.39 2.80
9.00 4.14 3.85 3.21
10.00 4.62 4.32 3.64
11.00 5.10 4.78 4.06
12.00 5.59 5.25 4.50
13.00 6.07 5.72 4.93
14.00 6.56 6.20 5.37
15.00 7.04 6.67 5.82
16.00 7.53 7.15 6.26
17.00 8.02 7.62 6.71
18.00 8.51 8.10 7.16
19.00 9.00 8.58 7.61
20.00 9.48 9.06 8.07
21.00 9.97 9.54 8.52
22.0010.4710.02 8.98
23.0010.9610.50 9.44
24.0011.4510.99 9.90
25.0011.9411.4710.36
26.0012.4311.9510.82
27.0012.9212.4411.29
28.0013.4112.9211.75
29.0013.9113.4112.22
30.0014.4013.8912.69
31.0014.8914.3813.16
32.0015.3814.8713.62
33.0015.8815.3514.09
34.0016.3715.8414.57
35.0016.8616.3315.04
36.0017.3616.8215.51
37.0017.8517.3015.98
38.0018.3517.7916.45
39.0018.8418.2816.93
40.0019.3318.7717.40
41.0019.8319.2617.88
42.0020.3219.7518.35
43.0020.8220.2418.83
44.0021.3120.7319.30
45.0021.8121.2219.78
46.0022.3021.7120.26
47.0022.8022.2020.74
48.0023.2922.6921.21
49.0023.7923.1821.69
50.0024.2823.6722.17
51.0024.7824.1622.65
52.0025.2724.6523.13
53.0025.7725.1523.61
54.0026.2725.6424.09

RGS Background files available

RGS Background template event files have been provided by T. Tamura, from the RGS Team at SRON. These files have been derived from blank-sky observations, and have total exposure times ranging from 80 to 390 ksec. They are useful when the background cannot be accurately derived from the standard off-axis regions, e.g. in the case of extended sources.

These files are accessible through the XMM-Newton Calibration Portal at the following URL:
http://xmm.esac.esa.int/external/xmm_sw_cal/calib/index.shtml

OM Flux conversion factors

Flux conversion factors for the different filters of the Optical Monitor (OM) have been added as keywords FCF* in the COLORMAG extension of the current calibration file (CCF) OM_COLORTRANS since SAS version 5.4.1. These conversion factors help users to get a rough estimation of flux densities (expressed in erg/cm^2/s/A) directly from OM count rates. The throughput of the OM is stable over time to within a few percent.


Yours sincerely,
XMM-Newton SOC