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Solar-B 観測性能と制約

Solar-B 観測性能と制約. Toshifumi Shimizu ISAS/JAXA shimizu@solar.isas.jaxa.jp. 今日話すこと. Solar-B 搭載望遠鏡の機器としての機能詳細は話しません  第 5 回サイエンス会議 ( 六本木 ) 収録を見て 観測プランを考えるとき、データ量の考慮が必要。この点を中心に議論する。. Solar-B. Flight model Solar-B under system-level test. (2004 Sep 15). (2005 Oct 4).

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Solar-B 観測性能と制約

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  1. Solar-B 観測性能と制約 Toshifumi Shimizu ISAS/JAXA shimizu@solar.isas.jaxa.jp Solar-B国内会議

  2. 今日話すこと • Solar-B搭載望遠鏡の機器としての機能詳細は話しません  第5回サイエンス会議(六本木)収録を見て • 観測プランを考えるとき、データ量の考慮が必要。この点を中心に議論する。 Solar-B国内会議

  3. Solar-B Flight model Solar-B under system-level test (2004 Sep 15) Solar-B国内会議 (2005 Oct 4)

  4. EUV Imaging Spectrometer (EIS) Diagnostics of the coronal thermal properties and dynamics 3 high-performance telescopes • Solar Optical Telescope (SOT) • High resolutional observations of magnetic and velocity fields at the photosphere • X-Ray Telescope (XRT) • High resolution imaging of the corona Coordinated observations among three telescopes Solar-B国内会議

  5. Solar-B FOV 800arcsec 360arcsec 320arcsec 512arcsec 160arcsec SOT EIS 2000arcsec XRT Maximum size of FOV is shown here. Solar-B国内会議

  6. Solar-B data recorder and downlinks • Data Recorder • 全体容量 8Gbits (1Gbytes) • うち、７Gbitsが科学データの蓄積に使用予定 • SOT/XRT/EISの3機器がシェアして使用 通常 - SOT:XRT:EIS=70%(4.9Gb):15%(1.05Gb):15%(1.05Gb) 運用会議において観測内容に応じて配分を調整 　　　　すなわち、SOT:XRT:EIS=100%:0%:0% =40%:45%:15% といったことは可能 Solar-B国内会議

  7. Solar-B data recorder and downlinks • 1日に取得できるデータ量は? • ダウンリンク局の頻度による • Solar-B軌道：太陽同期極軌道、約95分周期 • 計画されているダウンリンク局 • USC (内之浦) 朝夕最大各2パス • Svalvard (ESA) 毎週回、一日15パス • データ量見積り • Svalvard • 1パス時間 3~11min (El. 6 ~ 90 deg) • 1日合計 138min (ある日の可視時間予測計算より) • USC • 1パス時間 5~11min • 1日合計 32min (ある日の可視時間予測計算より) • データダウンリンクレート ~4Mbps • 1日合計40.8Gbits、うち科学データ 35.7Gbits (4.4Gbytes) Solar-B国内会議

  8. 観測立案のため-取得可能データ量 • 1日合計科学データ 35.7Gbits (4.4Gbytes) • 標準的機器分配 SOT:XRT:EIS = 70%:15%:15% = 25.0Gbits: 5.4Gbits: 5.4Gbits • データ発生レート • 一日平均的にデータを取得した時 SOT= ~300Kbps, XRT= ~60Kbps, EIS= ~60Kbps • 与えられたレコーダ容量の範囲内でバース的観測は可能 ある時間はバース的観測、残りはちょろちょろ的観測 例. SOTの場合 Possible maximum rate ~1.3 Mbps (in nominal) ~1.8 Mbps (in SOT dominant)  ~50 min to occupy 4.9Gbits in data recorder The rest of the time is in idle. 注：圧縮後のデータで Solar-B国内会議

  9. 観測立案のため-データ量予測 • 生成データ量の予測が観測計画上重要となる 　　　観測装置としては高い分解能は可能だが…. 　　　テレメトリ上制限のため • Science data can be compressed in MDP • MDP has an ASIC chip for 12bit JPEG/DPCM • Pixel data is bit-compressed from 16 bit-pixel to 12 bit; 8 look-up tables • 12bit JPEG (DCT): lossy • ~3 bits/pixel for SOT/FG data • ~1.5 bits/pixel for SOT/SP data , when compression noise is comparable to photon noise level • 12bit DPCM: lossless, 6-8 bits/pixel • Compression ratio depends on images and required quality Solar-B国内会議

  10. 観測立案のため-データ量予測 FPP FG Camera simulated image, made from La Palma data Solar-B国内会議

  11. SOT Observational Capabilities- Focal Plane Instruments Package (FPP)- Filter (FG) Observation Typical Observables A 4Kx2K CCD camera shared Broadband Filter Imager (BFI) Filtergram Dopplergram Narrowband Filter Imager (NFI) Long. Magnetogram Stokes IQUV Shutterd exposure Shutterless exposure Spectral (SP) Observation Spectro-Polarimeter (SP) Stokes IQUV Solar-B国内会議

  12. H alpha CaII H Magnetic fields continuum (G-band) Multi-wavelength filter observations with SOT Obtained with SVST @ La Palma Solar-B国内会議

  13. 地上観測例：2005/7スペイン観測から DOT G-band 下記5台CCD同時に走らせた • CaII H • G-band • Blue continuum • H alpha • Red continuum Speckle処理後のデータ 1.3K x 1K 90”x70” 30sec毎  220Kpixel/sec Solar-Bに置き換えて、  3bit/pixel圧縮 650Kbps 視野を限るか時間を落とすかバースト的観測 Solar-B国内会議

  14. Observation Example • To study magnetic/dynamical nature of microflare-associated small emerging fields in AR. • Need telemetry ~300 Kbps continuously for a long period • SP observation • Fast mapping, 80” wide scanning, NS size=80”, 0.32” resolution • One map completed every 15 min • Data size: 229Kpixel every 3.6 sec. • Telemetry: 96 Kbpswith 1.5bits/pixel compression. • FG observation • G-band, 3 wavelengths in Halpha, Longitudinal magnetogram, Dopplergram, repeated every ~45 sec. • 80”x80” FOV, 0.08” resolution for G-band and magnetogram, 0.16” for Halpha and Dopplergram • Data size: 3.25M pixel every 45sec • Telemetry: 222 Kbpswith 3 bits/pixel compression Solar-B国内会議

  15. Observation Example (2) • To study short-term magnetic evolutions of entire AR. • SP observation • Normal mapping, 180” wide scanning, NS size=180”, 0.16” resolution • One map completed every 90 min • Data size: 191Kpixel/sec. • Telemetry: 290 Kbpswith 1.5bits/pixel compression. • FG observation • G-band, 3 wavelengths in Halpha, Longitudinal magnetogram, Dopplergram, repeated every ~ 1 min. • 160”x160” FOV, 0.16” resolution (2x2 summing) • Data size: 8.4M pixel every 60 sec • Telemetry: 420 Kbpswith 3 bits/pixel compression • 合計 710Kbps 300Kbpsの倍1/2観測し、1/2休み Solar-B国内会議

  16. XRTの場合 Observation controlled by observation tables:Typical Time Cadences • typical data rate for XRT(1) ~ 600 k pixel / min • example 1: Continuous Observation (576 k pixel / min) • 384”×384”, 1”-resolution, 30sec-interval of a filter pair. • example 2: High-Speed Observation (576 k pixel / min) • 384”×384”, 1”-resolution, 5sec-interval of a filter pair,10min-continuous observation and 50min intermission. • example 3: Combination of FFI and PFI (586 k pixel / min) • 384”×384”, 1”-resolution, 40sec-interval of a filter pair. • 2048”×2048”, 4”-resolution, 200sec-interval of a filter pair. (1) The total rate of 400kbps (about 15 downlink/day) is assumed. SOT, XRT and EIS usually share this data rate in the ratio of 70%, 15% and 15 %. XRT image data is 12bit/pixel and may be compressed to about 6bit/pixel by DPCM. Solar-B国内会議

  17. EIS Data Flow Data compression DPCM(loss less) or 12bit-JPEG Small spectral window (25 max) CCD Readout Electronics 2Mbps max 1.3 Mbps EIS ICU S/C MDP control Observation table  250 kbps max for short duration,  40 kbps average Large hardware CCD window 1 slit obs. 40 slot obs. 250 slot obs. Spec.width 16 40 250 Spatial width 256 512 256 No. of lines 8 4 4 Compression 20% 20 % 20% Cadence 2 sec 5 sec 15 sec Rate 38.4 kbps 38.4 kbps 40 kbps Average rate depends on number of downlink station. Telemetry data format 10 min cadence for 44 rastering Solar-B国内会議

  18. 最後に、Joint観測案の一例 • MO&DA Action Item: Weber, DePontieu, & Landi will create two examples of Solar-B JOPs. Location: MODA website (SAO)--- http://hea-www.harvard.edu/solarb/documents/MODA/ 中身は良く見ていませんが、観測立案でどのようなことを考えるかを知る参考になるかな。。 Solar-B国内会議

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