Submillimeter ( l < 1 mm) Continuum Imaging at CSO: a Retrospective C. Darren Dowell (Caltech),

1. Submillimeter (l < 1 mm) Continuum Imaging at CSO: a Retrospective C. Darren Dowell (Caltech), on behalf of all students, postdocs, and staff inspired and supported by Tom to build an instrument and then wait for low water vapor l < 1 mm Continuum Detectors at CSO Case Study: The Galactic Center Sagittarius A region Sagittarius B2 region Lis & Carlstrom (1994, ApJ) Dowell et al. (1999, ASP Conf. Ser.) Bally et al. (2009, in prep.) • To Chop or Not To Chop • The single-bolometer instrument and SHARC I • successfully used: • chopping mirror, • NOD2 image reconstruction. • A known disadvantage of chopping with only one • amplitude and direction is the poor sensitivity to spatial • frequencies which are multiples of the chop, and ringing • around bright sources. • For most observing, SHARC II does not use the • chopper, but instead uses crossing scans: • Lissajous patterns, • “billiards” patterns. • To overcome 1/f noise from the sky and instrument, I • sometimes set zero-signal reference regions in the map, • kind of like chopping/nodding in all directions. Yusef-Zadeh et al. (2006,2008,2009, ApJ): detection of Sgr A* variability at 350,450,850 mm with SHARC II Chuss et al. (2003, ApJ): magnetic fields mapped with Hertz (and also KAO), superposed on radio image Serabyn et al. (1997, ApJL): detection of Sgr A* at 350 mm with SHARC I chopped dual-beam response in sky plane (left) and fourier plane (right) (Emerson, Klein, & Haslam 1979, A&A) Lis & Carlstrom (1994, ApJ) Dowell et al. (1999, ASP Conf. Ser.) Bally et al. (2009, in prep.) SHARC II Photo Gallery Correlated Photon Noise in SHARC II Array Since the SHARC II detectors are closely spaced (0.6 l/D), and the photon mode occupation number is high, adjacent detectors show correlated noise, as can be seen in these normalized detector-detector covariances: Fomalhaut, Vega, e Eri debris disks at 350 mm (Marsh et al. 2005, 2006; Backman et al. 2009; ApJ) CSO 350 mm beam (mapped using Mars) pixels separated by one column (9% correlation) Moon at 850 mm (high-pass filtered on right) pixels separated by one row (9% correlation) disturbed galaxy NGC 3627 (Murphy, in prep.) elliptical galaxy NGC 807 (Leeuw et al. 2006, ApJ) grayscale shows: Sd1d2 / sqrt(Sd12Sd22) Acknowledgments/Bibliography I thank the following people for supplying photos for this poster: Dominic Benford Ed Bufil Sunil Golwala John Vaillancourt CSO bolometer: Lis, Carlstrom, & Keene, 1991, ApJ SHARC I: N. Wang et al., 1996, ApOpt SHARC II: Dowell et al., 2003, SPIE, 4855 Hertz: Schleuning et al., 1997, PASP Dowell et al., 1998, ApJ MKIDcam: Glenn et al., 2008, SPIE, 7020 blank field survey (Khan et al. 2007, ApJ) submm galaxies at z = 0.8-3.4 (Kovacs et al. 2006, ApJ) A851 cluster survey, 5 mJy rms (Marshall, Dowell, et al., in prep.) Contact the author at: cdd@submm.caltech.edu core in Orion (Li et al. 2007, ApJ) symposium honoring T. G. Phillips, Pasadena, CA, February 2009