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SOT Scientific Observations & Operations

SOT Scientific Observations & Operations. Purpose: Look at SOT observational capabilities from operational viewpoints. T. Shimizu (National Astronomical Observatory of Japan) Shimizu@solar.mtk.nao.ac.jp. Some slides from Dr. T.Tarbell presented at 3 rd science meeting.

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SOT Scientific Observations & Operations

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  1. SOT Scientific Observations & Operations Purpose: Look at SOT observational capabilities from operational viewpoints T. Shimizu (National Astronomical Observatory of Japan) Shimizu@solar.mtk.nao.ac.jp Some slides from Dr. T.Tarbell presented at 3rd science meeting 4th Solar-B Science Meeting

  2. Solar-B 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) MDP Observation table (sequence) FPP Observation (observable generation) MC 4th Solar-B Science Meeting

  3. Sequence 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 Obs. Program Main routine /w repeat # interval Subroutines Subroutines Subroutines Subroutines /w interval 100 sequences 20 programs 4th Solar-B Science Meeting

  4. 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. l,l offset) etc 4th Solar-B Science Meeting

  5. Variety of SOT Data Solar-B SOT Scientific Data (Observables) from FPP Filtergraph (FG) Camera Filtergrams Broadband filter (G band, continuums etc) Narrowband filter (Ha), dark frame etc Longitudinal Magnetograms MC (Macro-command) Dopplergrams Issued from MDP observation tables (FG table and SP table) Stokes I/Q/U/V images Stokes-Polarimeter (SP) Camera Stokes Map 4th Solar-B Science Meeting

  6. FG Camera Observables: Filtergrams Solar-B Ha center G-band 4305 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 4th Solar-B Science Meeting

  7. FG Camera Observables: Filtergrams Solar-B Filtergrams • Wavelength (typ.) • Broadband filter (6) • CN I 3883, CaII H 3969, CH I 4305, Continuum 4505 • Continuum 5551, Continuum 6684 • Narrowband filter • various l positions in Ha 6563, HeNe, (and bands including • lines mainly used for Magneto/Dopper-grams) • Dark frame • l scan filtergrams (X x Y pixels) x N (N= # of l scan) 4th Solar-B Science Meeting

  8. 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

  9. FG Camera Observables: Magnetograms Solar-B Longitudinal Magnetograms • 2-D spatial data generated on-board from multiple exposures • Maps of Stokes V / Stokes I • Using multiple wavelengths reduces errors caused by Doppler shifts • Processing onboard combines many images into two (numerator & denominator) for reduced telemetry requirement 4th Solar-B Science Meeting

  10. FG Camera Observables: Magnetograms Solar-B Longitudinal Magnetograms • 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 • 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) 4th Solar-B Science Meeting

  11. FG Camera Observables: Dopplergrams Solar-B Dopplergrams 4th Solar-B Science Meeting

  12. 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 exposure, 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

  13. FG Camera Observables: Stokes Solar-B Stokes IQUV Stokes IV Stokes IQ Stokes IU • 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 4th Solar-B Science Meeting

  14. 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, and 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

  15. SP Camera Observables Solar-B I Q U V Stokes Map • 4 images at one scan position • generated from multiple • exposures (typically 48) • Wavelength • Fe I 6302 & 6303 Scanning step (1~2K) 1024 (max) • 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 112 or 224 (/w orthogonal) 4th Solar-B Science Meeting

  16. Spectro-Polarimeter Observing Modes (1 of 2) • Normal Observing Mode • Expose/Read/Demodulate for 3 full rotations of waveplate, producing polarimetric accuracy of 0.001 • Optionally, move the slit-scanning mirror one step of 0.16 arcsec in the solar image (this 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 sec, 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, Expose/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 4th Solar-B Science Meeting

  17. SP Observing Modes (2 of 2) • In any mode, Field-of-View and data rate can be restricted by sending 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/sec • 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 4th Solar-B Science Meeting

  18. 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 4th Solar-B Science Meeting

  19. For editing SP macro-commands 4th Solar-B Science Meeting

  20. For FG macro-command 4th Solar-B Science Meeting

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