feb 4, 20034th solar-b science meeting1 sot scientific observations & operations t. shimizu...

Feb 4, 2003 4th Solar-B Science Meeting 1

SOT Scientific Observations & Operations

T. Shimizu(National Astronomical Observatory of Japan)

[email protected]

Purpose: Look at SOT observational capabilities from operational viewpoints

Some slides from Dr. T.Tarbell presented at 3rd science meeting


SOT On-board Operations

Scientific data are produced by Focal Plane Package (FPP) in SOT Observational sequence is controlled by SOT observation table in MDP

FPP as a slave Users update only the SOT observation table for their observations Macro-command (MC) for taking a science data (observable)

MDPObservation table

(sequence)

FPPObservation

(observable generation)MC

Solar-B


SOT Observation Table in MDP Consists of FG table and SP table, which work independently each other ProgramTable (Main routine) calls Subroutines which call Sequences which are lists of macro-commands and commands

20 programs

Main routine

Obs. Program

SubroutinesSubroutinesSubroutinesSubroutines

100 sequences

Sequence/w repeat # interval

/w interval


Macro-commands

For taking a science data (observable) Contain the following parameters which SOT chief observers may set up

Compression Parameters- MDP bit compression- MDP JPEG/DPCM compression

Operational Parameters FG Extract Region or SP Map Region Parameters

- Defining type of data (observable) (ex. Magnetogram,…)

- CCD/exposure setup (ex. size, binning, exposure duration)

- Wavelength setup (ex. offset)etc


Variety of SOT Data

SOT Scientific Data (Observables) from FPP

Filtergraph (FG) Camera

Stokes-Polarimeter (SP) Camera

Filtergrams

Longitudinal Magnetograms

Dopplergrams

Stokes I/Q/U/V images

Stokes Map

Solar-B

MC (Macro-command)

Issued from MDP observation tables (FG table and SP table)

Broadband filter (G band, continuums etc)Narrowband filter (H), dark frame etc


FG Camera Observables: Filtergrams

G-band 4305 H center

Solar-B

Filtergrams

• 2-D spatial data (a snapshot image)• Size (typical):

2K x 4K pixels (max)2K x 2K

1K x 1K 0.5K x 0.5K (from combination of FOV size + pixel sum)

Full size FOV: Broadband filter 164”x328”Narrowband filter 109”x218”

Pixel sum: 1x1(full), 2x2, 4x4


FG Camera Observables: FiltergramsSolar-B

Filtergrams

• Wavelength (typ.)- Broadband filter (6)

CN I 3883, CaII H 3969, CH I 4305, Continuum 4505Continuum 5551, Continuum 6684

- Narrowband filtervarious positions in H 6563, HeNe, (and bands including

lines mainly used for Magneto/Dopper-grams)- Dark frame

• scan filtergrams (X x Y pixels) x N (N= # of scan)

Feb 4, 2003 4th Solar-B Science Meeting

Filtergrams (NFI & BFI)

• Shutter open/close always synchronized with Polarization Modulator

• Exposure times 0.1 - 1.6 sec in NFI, .03 - .8 sec in BFI (longer exposures possible if desired)

• Full readout in 3.4 sec, 2x2 summing in 1.7 sec, 4x4 summing 0.9 sec

• Partial readout possible for faster cadence & reduced data volume: several discrete sizes from 192 to 2048 rows

• Reconfigure time (filterwheels, TF) < ~2.5 sec

• No onboard processing in FPP, optional data compression in MDP


FG Camera Observables: MagnetogramsSolar-B


• 2-D spatial data generated on-board from multiple exposures

• Maps of Stokes V / Stokes I – Using multiple wavelengths reduces errors caused by Doppler s

hifts– Processing onboard combines many images into two (numerator

& denominator) for reduced telemetry requirement

2/1,1,0,

)(

)(

1

1

orbawhere

Ib

VaMgram

ii

n

iii

i

n

ii


FG Camera Observables: MagnetogramsSolar-B


• Size (typical): 1K x 2K x N (smart memory limit)

1K x 1K x N 0.5K x 0.5K x N (N= 2 [Magnetogram V and I]) or 1) (from combination of FOV size + pixel sum)

• Primary lines are Fe I 6302.5 (photosphere) and Mg I 5172.7 (low chromosphere)

–5250.2, 5250.6, 5247.1, 6301.5, 6303.8 (umbral) are also available–6302 Mgram with 0.08 arcsec px takes ~21 sec for 8 images (4 wavelengths) with 164x164 arcsec FOV, has rms noise of ~1.E15 Mx on a pixel–With 0.16 arcsec px, takes 12.8 sec and has rms noise ~2.E15 Mx


FG Camera Observables: DopplergramsSolar-B

Dopplergrams


Dopplergrams• Maps of line-of-sight component of velocity

– Baseline is simplified version of algorithm used by MDI instrument on SOHO– Derive central wavelength from 4 images uniformly spaced through the line, F1

... F4– R = (F1 + F2 - F3 - F4) / (F1 - F2 - F3 + F4)– Velocity = V(R), implemented on the ground by lookup-table– Use 2 smart memories to make numerator & denominator– Gain and offset variations of CCD cancel out– MDP performs compression & downlink

• Best photospheric line is Fe I 5576 (non-magnetic, g=0)– 1-sigma noise of 30 m/s with 4 images, 2x2 summing, 0.16 arcsec px, 0.8 sec ex

posure, 240,000 electrons/px, 12.8 sec total time– 1-sigma noise of 45 m/s with 0.08 arcsec px, 1.6 sec exposure

• Low chromospheric velocity can be measured in core of Mg I 5173 line– Very dark line, but higher velocities expected– 1-sigma noise ~ 100 m/s with 0.16 arcsec px, 1.6 sec exposures


FG Camera Observables: StokesSolar-B

Stokes IQUV

• A set of 2-4 different images of 2-D spatial data generated on-board from multiple exposures• Size (typical): - Shuttered exposures 1K x 1K x N pixels 0.5K x 0.5K x N - Shutterless exposures 1K x 256 x N 1K x 128 x N (N= 4 or 2) (from combination of FOV size + pixel sum)• Wavelength (typ.)

Mg Ib 5173, Fe I 5247, Fe I 5250, Fe I 5251, Fe I 6302, Fe I 6303, Ti I 6304

• Integration # of Exposures

Stokes IV Stokes IQ Stokes IU


Stokes Parameters

• Shutterless imaging with FOV restricted by focal plane mask– 0.1 sec exposure and readout time: IQUV all measured simultaneously

• FOV = 5.3 x 164 for 0.08 arcsec pixels, 14.7 x 164 for 0.16, 35 x 164 for 0.32• Processing in smart memories identical to that for SP, to make spatial maps of I, Q, U, a

nd V– 0.2 sec exposure and readout time: IQV or IU, measured separately

• FOV = 10.7 x 164 for 0.08 arcsec pixels, 29 x 164 for 0.16, 70 x 164 for 0.32 • Measure I & Q first, then I & U by shifting phase of exposure wrt Pol. Mod.

– 0.4 sec exposure and readout time: IV only• FOV = 21 x 164 for 0.08 arcsec pixels, 58 x 164 for 0.16, or 140 x 164 for 0.32

• Stokes Parameters using shutter– Up to 0.4 sec exposures possible for V, up to 0.2 sec for Q & U– Additional noise sources due to time between frames & cross-talk between polarizations will

appear


SP Camera ObservablesSolar-B

Stokes Map

• Size (typical): One Stokes: 1K x 224 pixels Map: 1K x 224 x 2K pixels

896M bytes (without compression) 135M bytes (15% compression)• Integration # of Exposures• Map center position and # of slit scan positions• Slit scan step size/pixel binning & slit scan summation• Tip-tilt mirror (CTM) reset, repeat observation

Scanning step (1~2K)

I Q U V

1024 (max)

112 or 224 (/w orthogonal)

• 4 images at one scan position generated from multiple exposures (typically 48)

• Wavelength Fe I 6302 & 6303


Spectro-Polarimeter Observing Modes (1 of 2)

• Normal Observing Mode– Expose/Read/Demodulate for 3 full rotations of waveplate, producing polarimetric acc

uracy of 0.001– Optionally, move the slit-scanning mirror one step of 0.16 arcsec in the solar image (t

his takes 0.1 or 0.2 sec ==> 5.0 sec cycle)– Raw data is 120 x 2 spectral pixels x 1024 spatial pixels x 4 Stokes parameters in 4.8 s

ec, which is 983 Kpixels or 205 Kpixels/sec– Send to MDP for optional compression and downlink– Maps area 1.6 arcsec wide in 50 sec or 160 arcsec wide in 83 min.

• Fast Map Mode– Expose/Read/Demodulate for 1 full rotation of waveplate, step the slit 0.16 arcsec, Exp

ose/Read/Demodulate for a 2nd rotation, adding to the previous results– Sum 2 pixels in spatial direction on chip ==> effective pixel size is 0.32 x 0.32 arcsec– Raw data rate is 492 Kpixels in 3.6 sec = 137 Kpixels/sec– Maps area 1.6 arcsec wide in 18 sec, and 160 arcsec in 30 min


SP Observing Modes (2 of 2)• In any mode, Field-of-View and data rate can be restricted by send

ing to the MDP only spectra from a limited spatial portion of the slit

• Dynamics Mode– Expose/Read/Demodulate for only 1 full rotation of waveplate– Optionally step the slit by 0.16 arcsec– Must limit spatial FOV to reduce data rate: maybe 32 arcsec typical slit length – Process as before– For 32 arcsec along the slit, raw data rate is 192 Kpixels in 1.6 sec or 120 Kpixels/s

ec

• Deep Magnetogram Mode– Expose/Read/Demodulate for many full rotations of waveplate– Goal is to detect weakest polarization signals possible– Ignore wrap-around of intensity and strong polarization signals– Downlink data with no compression to avoid artifacts from wrap-around boundaries


SW Tools for Observation Planning

SOT chief observers need SW tools to make macro-commands & program/sequence tables (or reuse existing ones in the database) to carry out a scientific observation Detailed design/task sharing is under discussion An example for macro-command editor used now in FPP flight-model test


For editing SP macro-commands


For FG macro-command

feb 4, 20034th solar-b science meeting1 sot scientific observations & operations t. shimizu...

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