Detection of Line-shaped Tracks in Images with DADD STScI Peter R. McCullough Jul 21,

2007, First Map of an Alien World, SST press release for Nature article of Knutson et al. 2007, First Map of an Alien World, SST press release for Nature article of Knutson et al. 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al. 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al. 2011, Observational Evidence of Sentient Life on an Earth-like Planet, TIPS alternative title of McCullough 2011, Observational Evidence of Sentient Life on an Earth-like Planet, TIPS alternative title of McCullough How fast we are progressing… 2/11

2007, First Map of an Alien World, SST press release for Nature article of Knutson et al. 2007, First Map of an Alien World, SST press release for Nature article of Knutson et al. 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al. 2009, Alien Maps of an Ocean-bearing World, ApJ title of Cowan et al. 2011, Observational Evidence of Sentient Life on an Earth-like Planet, McCullough (this work) 2011, Observational Evidence of Sentient Life on an Earth-like Planet, McCullough (this work) How fast we are progressing… 3/11

Jill Tarter, JHU seminar Richard Stauduhar ( ), mathematician for the SETI Institute and U.C. Berkeley Space Sciences Lab, private communication Cullers & Deans 1992, unpublished*, cited by Backus, P. R. 1993, The NASA SETI Microwave Observing project Targeted Search, in Third Decennial US-USSR Conference on SETI, ASP Conference Series, Vo. 47, p SetiQuest.org, sonata zip * thanks to Jill Lagerstrom (and the authors) for obtaining a scanned copy of this unpublished report. DADD brought to you by … DADD = Doubling Accumulation Drift Detection 4/11

Line-shaped streaks (from bright lights on Earth) appear in ~30% of HST WFC3 observations of the dark-side of Earth, (taken for flat fields, to be described in a future TIPS). DADD automates flagging of pixels within streaks. 5/11

DADD = Doubling Accumulation Drift Detection M spectra, each with N channels Requirement of slow drift: |slope| > 1 Mathematical operations: Brute force: ~2NM 2 DADD: ~2 NM log 2 M DADD accumulates pairwise like the FFT ; DADD reuses sums of pixels common to multiple lines across the 2-D array. To apply DADD to 2-D imagery, we analyze the image successively four times with rotations of 0º, 90º, 180º, and 270º in order to detect trails of arbitrary slope and origin. N Frequencies M Times 6/11

DADD = Doubling Accumulation Drift Detection 0 0continuous functions: 0 1all steps = 0 or 1 channel constant derivatives N Frequencies M Times 7/11

DADD is sensitive 8/11

DADD is sensitive, quick, Execution time per track identified = 0.7 seconds per megapixel = 2.8 s for 2048x2048 9/11

DADD is sensitive, quick, and stands alone Execution time per track identified = 0.7 seconds per megapixel = 2.8 s for 2048x2048 C code operating on 16-bit FITS 2-D images, with an IDL wrapper to facilitate pre- processing and post-processing analysis. (WFC3 ISR coming soon) 10/11

Summary: DADD can be used for detection of … 1.SETI signals, e.g. weak, drifting narrowband CW signal in time series of RF spectra 2.Streaks across dark-Earth flat-fields (as illustrated) 3.Cosmic ray trails* 4.Asteroid or satellite trails* 5.Bleeding (overexposed PSF) trails* ^ 6.Slitless grism spectra* ^ * DADD is less sensitive to shorter line segments. ^ DADD is probably overkill where orientation of trails is fixed and known a priori. 11/11