XMM-Newton Science Analysis System


epevents (epevents-6.55) [xmmsas_20230412_1735-21.0.0]

Pattern related information

The following table may serve as a quick reference to select certain pattern types of recognized events (i.e. away from CCD edges, bad pixels etc.):

PATTERN	Meaning
0	singles
1	doubles in Y with Y(main)$<$Y(secondary)
2	doubles in X with X(main)$<$X(secondary)
3	doubles in Y with Y(main)$>$Y(secondary)
4	doubles in X with X(main)$>$X(secondary)
5–8	triples
9–12	quadruples
128	singles at CCD window (RAWX=1, RAWX=64, RAWY=200)
	or close to bad pixels
205	doubles at CCD window or bad pixels
206	triples at CCD window or bad pixels
207	quadruples at CCD window or bad pixels

Note: as of version 6.30.4 PATTERN values of 128 have been changed to 0 (i.e. $8^{\rm th}$ bit is not set anymore for singles), and PATTERN values of 205 have been changed to 1–4 (i.e. $7^{\rm th}$ and $8^{\rm th}$ bit are not set anymore for doubles)!

Secondary events of those valid doubles, triples, and quadruples ( $\index{Columns!PATTERN}{\tt PATTERN}=1..12$) have ${\rm PATTERN(main)} + 64$ (as listed above), i.e. $7^{\rm th}$ bit set.

1. For the pattern codes in PAT_ID and PATTERN the following bit-wise storing is used:
   
   

   PAT_ID
   bit	value	Meaning
   16	32768	free for additional pattern related flag
   15	16384	– " –
   14	8192	– " –
   13	4096	PAT_ORI first digit (x-coordinate)
   12	2048	– " –
   11	1024	PAT_ORI second digit (y-coordinate)
   10	512	– " –
   9	256	PAT_IND: $1,...,< 512$ (telemetry limit)
   ...	...	– " –
   1	1	– " –

   PATTERN
   bit	value	Meaning
   8	128	sign of PAT_TYP
   7	64	sign of PAT_IND
   6	32		used to flag PAT_TYP $>4$
   5	16		if bit 6, then use next 5 bits
   4	8	MOS code numbers 0 - 12	to store PAT_TYP - 5
   3	4	a combination of	hence, max storage: PAT_TYP = 36
   2	2	PAT_TYP $\le4$ and	– " –
   1	1	PAT_ORI	– " –

   Note: as of version 6.30.4 PATTERN values of 128 have been changed to 0 (i.e. $8^{\rm th}$ bit is not set anymore for singles), and PATTERN values of 205 have been changed to 1–4 (i.e. $7^{\rm th}$ and $8^{\rm th}$ bit are not set anymore for doubles)!

2. Creation of event quality flags in column FLAG. epevents makes use of the common MOS/pn event related flag code (see [3]) and uses the following bits (other flags are set by the epframes task):
   
   

   FLAG
   bit	value	Meaning (information)
   1	0x2	INVALID_PATTERN
   2	0x4	CLOSE_TO_CCD_WINDOW
   5	0x20	CLOSE_TO_ONBOARD_BADPIX
   6	0x40	CLOSE_TO_BRIGHTPIX (not on-board)
   8	0x100	CLOSE_TO_DEADPIX (not on-board)
   16	0x10000	OUT_OF_FOV

   bit	value	Meaning (rejection)
   19	0x80000	COSMIC_RAY
   21	0x200000	ON_BADPIX
   22	0x400000	SECONDARY
   23	0x800000	TRAILING
   total	0xfa0000	EPN rejection mask