Detection of Line-shaped Tracks in Images with DADD

1. Detection of Line-shaped Tracks in Images with DADD STScI Peter R. McCullough Jul 21, 2011

2. How fast we are progressing… • 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. • 2011, Observational Evidence of Sentient Life on an Earth-like Planet, TIPS alternative title of McCullough

3. How fast we are progressing… • 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. • 2011, Observational Evidence of Sentient Life on an Earth-like Planet, McCullough (this work)

4. DADD= Doubling Accumulation Drift Detection DADD brought to you by … • Jill Tarter, JHU seminar 2004-2005 • Richard Stauduhar(1940-2010), mathematician for the SETI Institute and U.C. Berkeley Space Sciences Lab, private communication 2005. • Cullers & Deans 1992, unpublished*, cited by Backus, P. R. 1993, The NASA SETI Microwave Observing project Targeted Search, in Third Decennial US-USSR Conference on SETI, ASP Conference Series,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. 323. • SetiQuest.org, sonata-1.0.16.zip * thanks to Jill Lagerstrom (and the authors) for obtaining a scanned copy of this unpublished report.

5. 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.

6. DADD = Doubling Accumulation Drift Detection M spectra, each with N channels Requirement of slow drift: |slope| > 1 Mathematical operations: Brute force: ~2NM2 DADD: ~2 NM log2 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. M Times N Frequencies

7. DADD = Doubling Accumulation Drift Detection 0 0 continuous functions: 0 1 all steps = 0 or 1 channel 00 00 0001constant derivatives 00 11 0111 01 12 01 23 0000 0000 0000 1111 0011 1122 0011 2233 0112 2334 0112 3445 0123 3456 0123 4567 M Times N Frequencies

8. DADD is sensitive

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

10. 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)

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