Bruno Altieri -- SCI-SDX

XMM

EPIC astrometry update

EPIC CAL/OPS meeting

Vilspa, 23-24 March 2003

B. Altieri

XMM-Newton

2

Bruno Altieri -- SCI-SDX

MOS metrology & astrometry

• Goal: improve MOS relative astrometry – MOS metrology in LINCOORD CCF : relative CCD offsets

• How : cross-correlate EPIC source list with 2MASS (NIR)– 2MASS astrometric accuracy < 0.2”

• Tune new BORESIGHT CCF (v17) for possible systematics in absolute astrometry and relative astrometry between EPICs.

XMM-Newton

3

Bruno Altieri -- SCI-SDX

XMM-Newton

4

Bruno Altieri -- SCI-SDX

XMM-Newton

5

Bruno Altieri -- SCI-SDX

XMM-Newton

6

Bruno Altieri -- SCI-SDX

Systematic shift in MOS1 CCD6

MOS1

MOS2

XMM-Newton

7

Bruno Altieri -- SCI-SDX

Hint of systemic astrometry residuals

•Global astrometry shift tends to be in same direction in S/C frame

•But statistics is poor (nobs=14)

•Hint of offset between MOS1 and MOS2

•But correlation is not very good thermal bending effect ?or reaching limit of measurement accuracy

XMM-Newton

8

Bruno Altieri -- SCI-SDX

No residuals with old BORESIGHT CCF

XMM-Newton

9

Bruno Altieri -- SCI-SDX

Astrometry: an old job !

Nebra sky disc: “The oldest concrete representation of the stars in the world”2002, Nebra, Germany, 3600 yr old