Status of Calibration and Data Analysis of MAXI GSC M. Sugizaki (RIKEN) on behalf of MAXI Team...

GSC Calibration and Analysis Status 1

Status of Calibration and Data Analysis of MAXI GSC

M. Sugizaki (RIKEN)

on behalf of MAXI Team

2010.11.30 MAXI 2010


Outline• In-orbit Operation and Performance

– HV Operation History– Background, Sky Coverage, Exposure

• Calibration Status– Alignment (Position)– Light curve (Effective area)– Spectrum (Response matrix)

• Data Reduction and Analysis Process – Event data reduction, All-sky Image– Pre-registered source archive

• Light curve, Spectrum, Image• Future Plan

2010.11.30 MAXI 2010


HV Operation History

2010.11.30 MAXI 2010

• GSC operation started on 2009/8/15 with a nominal 1650V for full 12 counters.

• 4 out of 12 counters suffered from breakdown within the first 2 months. The damage on carbon-anode wire by heavy particle irradiation is suspected.

• Operation at high earth latitude (Lat.>40o) was stopped.

• One another camera stopped on 3/23/2010. The nominal HV is reduced to 1550 V for suspicious counters.

Count-rate map of Radiation-Belt Monitor

• Observation Efficiency– Detector area 8/12=66.6%, – Effective exposure 40% of the pre-flight plan.


Exposure Map (since 2010/1/2 00:00:00 UT)

2010.11.30 MAXI 2010

1 orbit = 92 minutes 1 day

27 days1-day exposure = 4000 cm2 s (typical)

100% full sky is covered by 3 weeks

85% sky coverage 95% sky coverage

Thanks to the two FOVs (horizon/zenith) and redundant design, almost full sky are covered every orbit!


Daily Exposure for a Celestial X-ray Source

2010.11.30 MAXI 2010

Example: Crab

20098/12

201011/30

1-day exposure = 4000 cm2 s (typical)

Initial 2 month


Background and Sensitivity

2010.11.30 MAXI 2010

• CXB Confusion is included• GSC BGD rate ~2 mCrab at 4keV, ~ 10 mCrab at 10 keV• Comparable to the Ginga-LAC

5-s sensitivity~ 15 mCrab per day

MAXI / GSC Ginga/LAC

RXTE/PCA


Instrument Calibration

• Position Accuracy• Effective area• Energy response• Timing

2010.11.30 MAXI 2010


Attitude and Alignment Calibration(See Poster P-59 by Sugimori et al.)

• Attitude of MAXI payload module is always monitored by ADS (Attitude Determination System) using Visual Star Camera and Ring Laser Gyro. Its accuracy is << 0.1 deg. (calibration is in progress)

• Source position of incident X-ray is determined from the attitude and alignments of collimator and detector.

• These alignments can be calibrated using standard X-ray sources whose positions and intensities are well-known.

2010.11.30 MAXI 2010


• Sco X-1 90% containment radius

0.9 deg

Alignment Cal. Progress(See Poster P-59 by Sugimori et al.)

0.14 deg

2009/08 2010/01

PSF

2010.11.30 MAXI 2010

Estimated systematic uncertainty

= 0.2o

5o


Effective Area and Light Curve

2010.11.30 MAXI 2010

20 min.

1 day

100 days

Sun

SAA

Area-corrected light curve

1bin=1orbit(90min)

1bin=1day

Observed count rate for stable point source (simulation)

100 days

Effective-area correction

Modulated by triangular transmission function of slat collimator

Area variation due to source acquisition angle Ideal case !

1 scan per 92 minutes

15 scans per day


Effective area correction of real data• Light curve of Crab Nebula (on the MAXI public web)

• Soft X-ray band has a large systematic errors for insufficient calibration of absorption at the beryllium window, hardware/software LD variation, …

• Med/Hard Bands are OK.• Background subtraction error• Down time for occultation by

solar-battery paddle are implemented. However, the precision is not good enough.

• Occultation by docked shuttle vehicle was not implemented.

2010.11.30 MAXI 2010

1.5-20 keV

1.5-4 keV

4-10 keV

10-20 keV


Light Curve by Updated Process

• Info of in-orbit energy-response is implemented.– gain variation– LD change

• Data of a few anodes (2 out of 6 wires) with extraordinary responses are ignored.

• 1650 V data only

• Need more extensive response calibration to use full data.

2010.11.30 MAXI 2010

Crab

GSC Calibration and Analysis Status 132010.11.30 MAXI 2010

Energy Response: CALDB from ground tests

Gain: YZ map

Energy resolution map

Energy-PHA response matrix

Gain: XY map on gas counter

Effective area

Energy [keV]

PH

A

chan

nels

GSC Calibration and Analysis Status

Response Builder

14

DetX

★ X-ray source (RA, Dec)

GSC cross section

Weight map on detector planecollimator

detector

PHA(DetX,DetY) PI

Energy [keV]

PI

chan

nels

Energy-PI Response Matrix

2010.11.30 MAXI 2010

Slit


In-orbit Calibration (Nakahira et al.)

• The gas gains should increase from the ground test. ~ 2-10%

• The detector gas cells expanded in the vacuum.

• The ground calibration test would suffer from the space charge effects. The test was done with high-rate pencil X-ray beam.

Ti

Cu

2010.11.30 MAXI 2010

Data: BGD spectrum including Ti, Cu lines

Model: folded with a response built from ground CALDB


Crab Spectrum fit• 2009/8/15 1-day all available GSC data• Data of anode #1,#2 are currently not used for their insufficient

calibration. (They have an extraordinary response.)• Applicable to 1650V data only

2010.11.30 MAXI 2010

Wabs*Powerlaw Model parameters:

NH = 0.72 +/- 0.22G = 2.15 +/- 0.05Norm. = 11.4 +/- 1.0c2

n = 1.08

Reasonably agree with standard Crab model


• GSC event data has a 50-ms time resolution• MAXI DP time clock can always be calibrated using

on-board GPS.• Timing will be calibrated by Crab pulsar, ms pulsar,

binary X-ray pulsars.

GSC Event Timing

2010.11.30 MAXI 2010

GPS1s

Time Clock 1sGSC Elec.

Free-Run Clock50 ms

Latch FRC on DP-clock trigger

GasCounter

Reset DP FRCon GPS trigger

UTC timeand sec. trigger

Latch FRC on event trigger

Free-Run Clock 1 ms

Data Processor

Event timing scheme


Timing Cal. with Crab Pulsar (Yamamoto, Morii)

• Period, stability is verified (10-9)• Need calibration of absolute timing

2010.11.30 MAXI 2010

Dot line: Radio (Jodrell B

ank)

Comparison of pulse period with radio-pulse period

Epoch Time(3 months)

Red, green: MAXI

…….

200910/30

20101/30

GSC every 3-day folded pulse

Residual


Calibration Summary• Effective Area, Energy response

– Acceptable Level• HV=1650V data • Med (4-10keV), Hard Band (10-20 keV)

– Not ready, Unacceptable • HV=1550V data. 3 out of 8 operating counters.

Important to optimize the observation efficiency. • Soft band (<4 keV):

Error ~25% if anode#1,#2 is included.

• Timing– Stability is good in 10-9 level verified by Crab pulsar– Absolute-timing calibration is necessary.

2010.11.30 MAXI 2010


Data reduction, Analysis, and Archive

2010.11.30 MAXI 2010


Data Reduction and Analysis flow (for standard daily data products)

raw event file

processedeventfile

AUXIL file• attitude• orbit• time

target event file

HK file• GSCHK• ISSANC• …

ISStelemetry

Database(MAXIDB)

• raw count rate• image• (spectrum)

• light curve• image• spectrum

cleanedeventfile

CALDB

Response• Effective area curve• (RMF)

For each target

MKF

These processes run once per day.All required data are dumped into files (FITS formatted).

every second

Real-time transient search

Standard HEADAS-format tools are used.

TimeCoordinatePI (energy)

2010.11.30 MAXI 2010

Negro talkOzawa, Suwa (P-63,64)


Data Archive Products (http://maxi.riken.jp)• Daily All-sky Image (3-10 keV band)

• Pre-registered sources (~ 200 targets)– Light Curve– Daily Image

1.5-20 / 1.5-4

4-10 / 10-20

keV band

– Daily Spectrum (first 10 targets)

2010.11.30 MAXI 2010


Daily Spectrum Archive (test phase)• Archive of first 10 targets starts on 10/28

– Crab, Sco X-1, Cen X-3, Her X-1, GX 9+9, GX 9+1, GX 13+1, GX 17+2, GRS 1915+105, Cyg X-2

– Source, BGD spectra and response file for each UT day.– Best-fit wabs*power-law model

2010.11.30 MAXI 2010

Crab2010/10/1


Crab Daily Spectral Parameters (2009/08/15 - 2010/10/31)

• Error bar: 90% conf. limit

• NH: slightly higher than the standard value

• Automatic analysis process is not always perfect.

2010.11.30 MAXI 2010

Photon index

Flux (2-10 keV)

Absorption column density

Crab standard model


Archive Update Plan• Light Curve

– Soft-band calibration, Use 1550-V counter data– Early update (1.5-day delay in the current process)

• Energy Spectrum– Response calibration of the soft band and 1550-V data– Increase archive targets

• Data Access– Spectrum data of only the latest one day is accessible

in the current test phase.– Extension of daily-base archive over the first year is not

difficult. It will come soon.– More flexible data access will be important to increase

the MAXI data analysis and the science outputs.

2010.11.30 MAXI 2010


Final Remarks

• MAXI just completed the first year operation. • Although there were a some troubles for the

special environmental on the ISS, the operation is getting stable.

• The calibration, data analysis environment, archive system are now being developed and close to ready.

• The time to enjoy the data will come soon !

2010.11.30 MAXI 2010


Backup

2010.11.30 MAXI 2010


In-Orbit Environment on ISS

• Orbit: Alt.=340-360 km, Period~92 min. Incl.=51deg– Ginga,…,Suzaku : Alt.=530-590 km, Period~95 min. Incl.=31 deg.– XTE: Alt.=580 km, Period~100 min. Incl.=23 deg.

• Large ISS structure. ~108 m, ~408 ton

Direction of Motion

2010.11.30 MAXI 2010


GSC on MAXI

GSC-Z

GSC-H

FOV of 6 cameras

FOV of 6 cameras160o

80cm

107cm

Gas Slit Cameras (GSC)Xe-filled proportional counter2—30 keV; 5350 cm2

1.5o (FWHM)

ISS motion

2010.11.30 MAXI 2010


Scan Observation for a Celestial Target

• Effective-area curve for a point source

2010.11.30 MAXI 2010

slat-collimator transmission function duration ~ 40 sec.(typical)

~ 15 scans

1 day

25 min.

1 scan per 92 minduty cycle ~ 0.8 % (typical)

Outage for SAA

1/3 cycle

1 day

1/4 cycle from H to Z


Point-Spread Function (PSF)

• PSF along anode wire

2010.11.30 MAXI 2010


Scan-Transit Profile

2010.11.30 MAXI 2010


Residual BGD Spectrum

2010.11.30 MAXI 2010

Ti-K

Cu-K COR dependence suggests that the origins are cosmic rays whose momentum is over the selection criteria.

MIP energy loss ~ 40 keV


BGD Spatial Distribution

2010.11.30 MAXI 2010

Anode wire(250 mm)

Efficiency of anti-coincidence cut is downed at the counter edge

Sensitivity gap for support structure

Residual BGD profile is almost flat.


In-orbit BGD-rate Variation• BGD-rate v.s. cutoff-rigidity relation

2010.11.30 MAXI 2010


• Daily all-sky map

• Light curve, image, (spectrum) of pre-listed sources

(130 sources on 4/10/2010)

Samples of early archive products (http://maxi.riken.jp)

2010.11.30 MAXI 2010


90% containment (other sources)

Cyg X-10.18 deg

GX349+20.21 deg

GRS1915+1050.17 deg

Cyg X-20.17 deg

Crab0.16 deg

2010.11.30 MAXI 2010


GSC HV-Down Area

• SAA

• SAA• |Latitude|>40o

2009 8/15-9/23

2009 9/23-

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HV operation efficiency

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20098/12

201011/30

20098/12

201011/30

GSC_0

GSC_1

GSC_2

GSC_3

GSC_4

GSC_5

GSC_6

GSC_7

GSC_8

GSC_9

GSC_A

GSC_B

20099/23

40%

80%

Redundant

Status of Calibration and Data Analysis of MAXI GSC M. Sugizaki (RIKEN) on behalf of MAXI Team...

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