Pan-STARRS Image Processing Pipeline

Pan-STARRS Seminar: IPP Eugene Magnier

IFA Pan-STARRS Seminar 735October 14, 2004


●●●●


●●●●●●

●


● ●galaxy cluster evolution●rare object searches

●high-z QSOs●extremely red galaxies●low-mass objects (L & T dwarfs)●YSOs


●linearize detector flux●apply shutter correction●flatten images●photometer objects●apply image zero point, color correction, airmass correction


●stable light source + variable exposure time?●calibrated light source?


●measure shutter fly-over times: dt(x,y)●apply to flat-field or science images●probably small for 30 second exposures (0.1% = 30 ms jitter●may be significant for 5 second exposures...


●twilight-flat

●pros: continuum source, spatially uniform (usually), bright ●cons: very blue, limited availability, cirrus issues

●dome-flat●pros: continuum source, available anytime, repeatable (?)●cons: spatial structures, low count rates, emission line dangers

●night-sky flat●pros: obtained 'automatically'●cons: low count rates, stellar contaminations,

spatial structures unknown, emission line source


●correct for geometrical distortion & scattered light●stability time scale?


●chip-to-chip color terms (possibly linear, small)●internal system vs external system●external transformations are often ambiguous


●use relative photometry with reference overlaps●measure zero points & atmospheric corrections, apply●combination method (relphot + uniphot)


●system zero-points vary ~0.1 mag on timescales ~ 100 days


●variations in time : Cf(t)●variations in space : Cf(ra,dec)●these variations are NOT strongly correlated


●

●●●

●●●


●●●●


● ●high-quality grid for weak-lensing (starting point)●stellar matching in crowded fields


●

●●●

●●●


●●●●


●●●

●●●●●●●


●


●

●●●●

●●●

Pan-STARRS Image Processing Pipeline

Documents

Transcript of Pan-STARRS Image Processing Pipeline