2006/4/17Extended Image Co-alignment of Solar-B SOT/XRT/EIS Data T. Shimizu (ISAS/JAXA)

2006/4/17Extended Solar-B Introduction Position information is included in Solar-B image header In order to indicate where on the disk is observed. Mainly used for database search and operation planning Accuracy may not be adequate for data analysis. A few tens arcsec deviation at worst case. Image co-alignment needs to be performed in data analysis To co-align among data from Solar-B telescopes Relative relation among the telescope pointings 0.5 arcsec or better accuracy required To co-align Solar-B data with data from other observations Other observations: satellites, ground-based Absolute coordinate on the solar disk ~1 arcsec accuracy required

2006/4/17Extended 2D trajectory map of orbital variation of pointings) (Prediction based on thermal deformation test, Hot case) OBU Telescopes are mounted on “stable” cylindrical optical bench (OBU) However, each telescope pointing has different orbital variation due to thermal deformation including barbecue effect

2006/4/17Extended Baseline between-telescopes alignment procedure Common solar features are used to co-align the data from different telescopes with each other. Common features are sunspots seen both in SOT continuum/G-band image and XRT VLS images. Accuracy is in order of 0.1 arcsec. There is a time gap between sunspot image and images of interest. The time series of each telescope’s images are co-aligned by the procedure shown later. Images of interest Need a visible image in XRT sequence within ~10 minutes

2006/4/17Extended Solar-B Between-telescopes alignment procedure (1) Co-Alignment between XRT and SOT time Images of interest for comparison Zoom up

2006/4/17Extended Solar-B Between-telescopes alignment procedure (2) Co-aligning series of SOT images SOT (Filtergram, Spectro-Polarimeter) Data time Satellite jitter is already removed in series of SOT images Tip-tilt mirror with correlation tracker removes satellite jitter Tip-tilt mirror control tracks the group motion of granules seen in the correlation-tracker’s field of view (11x11arcsec). If 0.5km/s group flow exists in CT FOV, 600 sec (10 min) period produces ~0.4 arcsec alignment shift.

2006/4/17Extended Solar-B Between-telescopes alignment procedure (3) Co-aligning series of XRT images time XRT and EIS Data Satellite jitter is included in series of XRT images. Sun sensor (UFSS)’s information can be used to remove satellite jitter. Sensor’s random error is ~0.3 arcsec (0-p). S/C jitter

2006/4/17Extended Solar-B Between-telescopes alignment procedure XRT VLS micro-vibration concern There is a concern on slight degradation of SOT image performance when XRT VLS (visible light shutter) is rotating (< a few sec). VLS produces fairly large micro-vibration during its rotation, which may shake SOT optics during the rotation. (Result from satellite-level micro-vibration test) 10 minutes cadence of VLS images may not be performed. If not, VLS cadence may be once per orbit (90 min). Alternate co-alignment concept may apply (next page).

2006/4/17Extended Visible light (x 0,y 0 ) (x 1,y 1 ) (x 0,y 0 ) (x 1,y 1 ) (x p,y p ) at the corner of FOV is known from the X-ray limb and UFSS XRT SOT X-ray Visible light ~90min X-ray (x’ p,y’ p ) Sunspot ‘position’ wrt the limb is interpolated from (x 0,y 0 ) and (x 1,y 1 ) t t0t0 t 0 +90min Sunspot ‘position’ wrt the limb No limb info in data Alternate co-alignment concept (by SAO) Short-term satellite jitter removed with UFSS data Alignment using limb for ~45min (max) Includes drift due to granule motions

2006/4/17Extended Solar-B Co-Alignment with Non-Solar-B Data To co-align Solar-B data with data from other observations Other observations: satellites, ground-based Absolute coordinate on the solar disk ~1 arcsec accuracy required The way to have ~1 arcsec accuracy in absolute coordinate is to use limb position in full- disk images from XRT.

2006/4/17Extended