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Transcript
MOST Guide Star Photometry Overview Statistics Recent Results by Rainer Kuschnig & the MOST Team COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Photometry Sources Science CCD open field direct imaging Fabry target Guide stars Direct imaging micro Lens Array targets Star Tracker CCD COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry • typically 4-8 guide stars, in special cases up to 20 are monitored for any given primary target • the magnitude range is 7-10.5, about 80% are of ‘known’ (listed) spectral type • exposure time is usually 1.5 sec (range from 0.3 to 1.5 applied) • no images are recovered, the image data is processed on board: a mean background value is removed and the signal is the sum of high signal pixels (exceeding the background and a 20 ADU threshold) • for the brightest guide stars noise levels as low as 30ppm and high duty cycle can be achieved over 3 weeks of data collection COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry 1.5 sec exposure calculate background apply threshold Sigexp = S (Ipix > backgr+threshold) Sigtot = S N*Sigexp -> stored in the science data stream N = integer (target sampling time / guide Star exposure Time) COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Stars - Stats time base: 7 to 47 days COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Stars – Scatter COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC Recently Observed Targets observing period July - Nov 2005 WR103 HD179949 HD209458 HD224930 Kap1Ceti& NGC752 Eps Eridani + 4 + 2 + 2 + 3 + 4 + 2 + 2 DI DI DI DI DI DI DI and 20 Guide Stars and 10 Guide Stars and 5 Guide Stars and 4 Guide Stars and 5 Guide Stars and 20 Guide Stars and 4 Guide Stars 68 in total over 300 stars measured in all 3 modes: Fabry / Direct Imaging / Guide Star photometry COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC ALL TARGETS – SKY MAP COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC OFF-CVZ Observations: WR103 WR103 20 guide stars 4 field stars COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC OFF-CVZ: WR103 Guide Stars results besides the unprecedented photometry for WR103 nine of the twenty guide stars revealed variability slowly pulsating Be (SPBe) star - ‘classical’ SPB star - gam Dor star - variable B2Ib/II star - B9(p?) star with rotation modulation - delta Scuti star - two K star variables - two unknown type variables - 50% duty cycle – 37 days COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star: HD163868 MOST data Observed and Modeled Frequencies Published in ApJL 2005 (6 weeks after the run) COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry B5II/III – SPB star – 16 modes COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry B5II/III – SPB star – 16 modes V=9.3 COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry B2Ib/II COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry B8(p?) star – 2.4d period COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry B8(p?) star – 2.4d period COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry A3 – del Scuti COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry K0 star COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry unknown spectral type COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry K5 star COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry unknown spectral type COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC MOST Guide Star Photometry gam Dor star COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC “A BAD COMPARISON STAR” HD209775 is an F0 (V=7.59) field star close to (~1.2deg) the well known exo-planet transiting system HD209458 Henry & Henry 2000 (IBVS #4826) checked this star for suitability asa photometric comparison star for HD209458 and found based on 2 nights (each a few hours) that this Object is of delta Scuti nature and hence of no use in the context of their HD209458 study ……… but it was certainly found useful as a MOST Guide Star COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC HD209775 – MOST Observations HD209775 was one of 5 GUIDE STAR used to point to HD209458 (transiting planet system) MOST collected data during a ‘test’ run (~15days) in 2004 to probe the eclipse phase of HD209458 clearly revealing its multi-mode delta Scuti type pulsation modes (~20) ……….. nice but not quite outstanding ……. this year we went back and observed it (and HD209458) for 45 days essentially without gaps and the recent results are in fact quite unique with about 80 modes identified COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC HD209775 ~80 pulsation modes COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC HD209775 ~80 pulsation modes COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC HD209775 ~80 pulsation modes COROT WEEK - 6-9 Dec 2005 – ESA/ESTEC