FIS Introduction (Part 1)

AKARI/FIS Data Reduction Workshop@ ESAC, 2007/09/18,19
Prepared by Issei Yamamura (ISAS)

ESAC AKARI Workshop 07/09/18

Scope of the presentation(Part 1)
 FIS instrument overview
Hardware overview
 AOT’s

FIS observation data
Data package Data format(Part 2)
 Introduction to the data reduction toolkit
Installation & startup
 Data browser
demonstration
 Running the toolkit
ESAC AKARI Workshop 07/09/18

FIS Photometric ModeBand

N60

WIDE-S

WIDE-L

N160

Wavelength

50–80

60–110

110–180

140–180[μm]Central
Wavelength

65

90

140

160

[μm]

Detector

Monolithic Ge:Ga

Compact Stressed Ge:GaReadout

Charge Trans-Impedance Amplifier (CTIA)

Ge:Ga chips
supplied by NICT

Array format

20 x 220 x 315 x 315 x 2

PixelsPixel size
(Physical size)

27 x 27(0.5 x 0.5)

27 x 27(0.5 x 0.5)

44 x 44(0.9 x 0.9)44 x 44(0.9 x 0.9)

[arcsec2]([mm2])

ESAC AKARI Workshop 07/09/18

FIS: Far-Infrared Surveyor
Simultaneous observation in four FIR bands.
 Detectors:Monolithic Ge:Ga array [SW: 50–110 μm, 20x(3+2) pix)]*
Stressed Ge:Ga array [LW: 110–180 μm , 15x(3+2) pix]Spatial resolution of 30–75 arcsec.

Fourier Transform Spectrometer.
 Martin-Puplette type polarized interferometer.
–1 (R=450 @ 60μm, 170 @ 180 μm)
 0.36 cm*The SW detector was manufactured by NICTESAC AKARI Workshop 07/09/18

Onboard Instruments
Photometric & Spectroscopic Capabilities

Spitzer

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FIS RSRF

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Field of View and Pixel Size

Spitzer

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Field of View

Three aperturesFIS (SW + LW)
IRC (NIR + MIR-S)
IRC (MIR-L)

All instruments can beoperated simultaneously.
Three apertures look at
different areas of the sky.
FIS two channels share thesame area of the sky by beamsplitter.
IRC NIR and MIR-S sharethe same area of the sky bybeam splitter.

Two sets of FSTS (FocalPlane Star Sensor) areused for pointing analysis
in the All-Sky Survey.

ESAC AKARI Workshop 07/09/18

FIS Detectors
13”

WIDE-S: 3x20
N60:
N160:

2x20
2x15

WIDE-L: 3x15

Scan Direction

WIDE-S(3x20)

22”
26.5 deg

WIDE-L

N160(3x15)(2x15)

N60(2x20)~8 arcmin

Overlap each other44.2” x 44.2” / pixel
26.8” x 26.8” / pixel

FoV of the FIS
Scan direction ~ along the constant Ecliptic longitude

ESAC AKARI Workshop 07/09/18

Dead pixels

SW: 1, 11, 71, 84 (98)
LW: 2, 3, 18, 33, (42), 48, 63

ESAC AKARI Workshop 07/09/18

FIS AOT (Astronomical Observation Template)
FIS01: Photometry/Mapping of small areas
 FIS02: Mapping of wider areas
 FIS03: FTS spectroscopyVery complicated: contact to the FTS team!!!

AOT parameters for FIS01/FIS02
Reset interval: 0.5 / 1.0 / 2.0 sec
 Scan speed:
8 / 15 arcsec/sec (FIS01)
15 / 30 arcsec/sec (FIS02)
 Step scan:
70 / 240 arcsec (only FIS01)ESAC AKARI Workshop 07/09/18

Observation Sequence (FIS01)
Step_scan
Shut_cls975
Step 30s
Scan_p15630

Pre cal sequenceSettling time
Shut_opn 420.3

Scan area length:0.66 deg for 15”/s
or0.35 deg for 8”/s

On target708.75

Scan_p15
Shut_opn1005

Post cal sequence
Shut_cls 1351

Calon
990

Cal off
997.6

896.251083.75

On target
1271.25

area center
orsource
Each scan 157.5s

Shut_cls 787.5

Turn 30s
w /cal sequence

Each scan 157.5s

Shut_cls
817.5
Shut_opn 1162.5

Shut_opn 1192.5

Cal_off 810.1

Cal_off 1185.1

802.5
Scan_m15
cal_on1177.5
Scan_m15
cal_onTurn 30s
w/ cal sequence

Observation Sequence (FIS02)630 Scan_p15

Pre cal sequenceSettling time

Post cal sequence

Shut_opn 420.3

Scan area length:1.44 deg for 15”/sor0.77 deg for 8”/s

ESAC AKARI Workshop 07/09/18

Shut_cls 1351

On target
802.5

On target
1177.5area centerorsource
Each scan 345s

Shut_cls 975
Turn 30s
w /calsequence

1005 Shut_opn
997.6 Cal_off
990 Scan_m15, Cal_on

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Flight performance
All-Sky Survey[mJy]
Slow-Scan*
[mJy]




N60

WIDE-S

WIDE-L

N160

2400
(500)
130(45)

550
(100)
26(9)

1400(100)
67(6)

6300
(300)
330(12)

5-sigma noise level per scan
Slow-Scan is for the scan speed of 8 arcsec/sec and reset interval of 2.0sec.
Main causes of the degration:

Detector bias lowered (LW)
Detector temperature was too low (SW).
Glitches cause unstable signal level.

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The data package
A data package consist with;
Two TSD FITS files (SW and LW)
 Two jpeg images as example results.
 Version of the example processing
AKARI_FIS_5110085_001/
Start time of the observation

FIS_LW_20070705213613_1770.fits.gz
FIS_SW_20070705213613_1770.fits.gz
FIS_LW_20070705213613_1770_img.jpg
FIS_SW_20070705213613_1770_img.jpg
VERSION

Length of file [sec]Contents of the TSD file

Detector signals, Position info., Statuses of satellite & instruments,flags, etc.

ESAC AKARI Workshop 07/09/18

Time Series Data (TSD)The FIS detectors are continuously sampled with
~25 and ~17 Hz for SW & LW, respectively, while
the telescope scans the sky.

The FIS data is in the dedicated format called ‘TSD’,a table FITS format. (not image FITS)
 Interface to the TSD FITS files and data browser are
distributed in the software package.
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TSD Format

Flat table:
All information is regridded to thedetector sampling timing.
Unique format:
Raw data are kept in the file.
Reduced results are recorded inthe dedicated area.

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Attitude determination


Two levels
Onboard determination by the AOCU (Attitude and Orbit ControlUnit).
Ground-base attitude determination system (G-ADS)

G-ADS supposed to be more reliable.
 Focal-plane pointing reconstruction is only made for the AllSky Survey data.
 Current status:G-ADS data delivered for all observation periods.
Current data (DR1) only have the latest G-ADS processing results
after mid-December 2006. Older version for August to midDecmeber, 2006
DR2 will have the latest G-ADS information.
G-ADS has about 60 arcsec offset from the ‘true’ position.

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Detector Alignment (FTS)Corresponding information not yet available for theSlow-Scan mode.

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Data ReleaseCurrent version is “Data Release 1” (DR1).

Data Release 2 (DR2) will be released in October.
Slight change in data format (position info.; should notaffect to the slow-scan processing) Processed with the latest pipeline.