TIPS/JIM July 21, 2011

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1 TIPS/JIM July 21, 2011 Agenda: INS Division News (Danny Lennon) Improved COS Medium Resolution FUV Line Spread Functions (Jerry Kriss)! Detection of Line-shaped Tracks in Images with DADD (Peter McCullough)! Persistence from Cosmic Rays in JWST NIR Detectors (Mike Regan)! Next TIPS/JIM: August 18, 2011

2 INS NEWS HST Instruments: continue to work well and Hubble passed the milestone of its 1,000,000th image with a WFC3/IR Grism observation of HAT-P-7b. On JWST the main piece of news is that TFI will be descoped. It will now feature interferometric imaging through a non-redundant mask aperture, wide field grism spectroscopy, single object grism spectroscopy for exoplanet transits, and broad band imaging. Staff changes: Aparna Maybhate has taken on the role of RIAB Deputy. Luigi Bedin, Sami Niemi and Brian Ferguson have all left STScI. Keith Noll will leave in October. Housing: Bloomberg/Muller moves are almost finished. Our thanks to all concerned. Keswick lease is signed, expect take up occupancy in fall 2012.

3 TIPS/JIM July 21, 2011 Agenda: INS Division News (Danny Lennon) Improved COS Medium Resolution FUV Line Spread Functions (Jerry Kriss)! Detection of Line-shaped Tracks in Images with DADD (Peter McCullough)! Persistence from Cosmic Rays in JWST NIR Detectors (Mike Regan)! Next TIPS/JIM: August 18, 2011

4 Improved COS Medium Resolution FUV Line Spread Functions TIPS July 21, 2011 Jerry Kriss

5 The COS LSF has Broad Wings n The broad wings on the COS Line Spread Function (LSF) were discovered during SMOV (Ghavamian+2009). n The wings are caused by mid-frequency wave-front errors (MFWFEs) produced by polishing errors on the HST primary and secondary mirrors. n Ghavamian+2009 used WFPC2 measurements of the OTA MFWFEs (Krist & Burrows 1995) and modeling of the COS optics to derive model LSFs that appeared to be a good match. 6/16/2011 TIPS 2/14

6 The Modeled COS LSF 6/16/2011 TIPS 3/14

7 Model LSF is a Good Match! 6/16/2011 TIPS 4/14

8 But, there are shortcomings 6/16/2011 TIPS 5/14

9 Si II Interstellar Line isn t Black Since the deconvolved absorption line isn t black, ==> The wings on the LSF must be even broader 6/16/2011 TIPS 6/14

10 Optimizing the LSF---How broad? Geocoronal Lyα in the Mrk 509 observation Light filling the aperture (as scattered light does) extends to ±100 pixels 6/16/2011 TIPS 7/14

11 Optimizing the LSF---What Shape? n In addition to the MFWFEs on the mirrors, there should be scattering from microroughness. n Hasan & Burroughs (1993), using WFPC observations, predict scattering due to microroughness as a power law for the PSF with index 2.5. (In the far field, diffraction will have a limiting power-law index of 3.) u Integrating the PSF over 1 dimension to obtain an LSF for COS will reduce this index by 1: a prediction of 1.5 for scattering due to microroughness, and a limit of 2.0 for simple diffraction. n Empirically test a grid of models with two free parameters: u Core of the new empirical LSF is the same as the current model. u The relative normalization of the power law. u Power-law indices ranging from 1 to /16/2011 TIPS 8/14

12 Optimizing the LSF---What Shape? n Best fit index is 2.25 n Normalization is 1.4% to 2.5% of the peak of the core LSF. n Transition radius is pixels. n Additional power in the extended wings is ~3%. 6/16/2011 TIPS 9/14

13 Improvement is slight, but significant Sk 155/STIS E140H convolved with old and new COS LSFs 6/16/2011 TIPS 10/14

14 The New LSF Improves Deconvolutions Sk 155/STIS E140H compared to deconvolved COS spectrum 6/16/2011 TIPS 11/14

15 Now the ISM lines in Mrk 509 are black 6/16/2011 TIPS 12/14

16 Conclusions n Adding extended power-law wings to the model COS LSFs with a power-law index of 2.25 improves the characterization of the LSF. n LSF wings this steep are even steeper than diffraction alone. This implies that scattering due to microroughness on the HST mirrors is negligible, even in the far UV, and that scattering within COS itself is also negligible. n The additional power in the wings is only ~3%, but this significantly improves modeling of saturated absorption features. 6/16/2011 TIPS 13/14

17 References n The ISR is online at: u ISR2011_01(v1).pdf n The improved LSFs are online at: u G130M: spectral_resolution/fuv_130m_lsf_empir.html u G160M: spectral_resolution/fuv_160m_lsf_empi.html n Preprint on Mrk 509 results appeared on astro-ph on July 5: 6/16/2011 TIPS 14/14

18 TIPS/JIM July 21, 2011 Agenda: INS Division News (Danny Lennon) Improved COS Medium Resolution FUV Line Spread Functions (Jerry Kriss)! Detection of Line-shaped Tracks in Images with DADD (Peter McCullough)! Persistence from Cosmic Rays in JWST NIR Detectors (Mike Regan)! Next TIPS/JIM: August 18, 2011

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

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

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

DADD = Doubling Accumulation Drift Detection DADD brought to you by n Jill Tarter, JHU seminar 2004-2005 n Richard Stauduhar (1940-2010), mathematician for the SETI Institute and U.C.

22 DADD = Doubling Accumulation Drift Detection DADD brought to you by n Jill Tarter, JHU seminar n Richard Stauduhar ( ), mathematician for the SETI Institute and U.C. Berkeley Space Sciences Lab, private communication n Cullers & Deans 1992, unpublished*, cited by n 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. 4/11

23 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

24 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. M Times 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 6/11

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

26 DADD is sensitive 8/11

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

8 s for 2048x2048 C code operating on 16-bit FITS 2-D images, with an

28 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 preprocessing and post-processing analysis. (WFC3 ISR coming soon) 10/11

29 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

30 TIPS/JIM July 21, 2011 Agenda: INS Division News (Danny Lennon) Improved COS Medium Resolution FUV Line Spread Functions (Jerry Kriss)! Detection of Line-shaped Tracks in Images with DADD (Peter McCullough)! Persistence from Cosmic Rays in JWST NIR Detectors (Mike Regan)! Next TIPS/JIM: August 18, 2011

31 Persistence Caused by Cosmic Rays Mike Regan

32 Cosmic rays on JWST will be much more common than on HST Around 20% of pixels will be affected in a 1000 sec exposure. If there is long lasting persistence Could lead to a noise floor Experiment Use existing ground test dark cubes 20 ~1 hour NIRSpec Darks 20 ~25 min NIRCAM Darks Look at effect of CRs in subsequent darks

33 Example dark measurement for NIRSpec shows low dark current.

34 Results show that both time and fluence affect the amount of persistence

35 Results extend to the lowest fluence events.

36 There is still persistence in the 2 nd and 3 rd exposures after the CR.

37 There is still persistence in the 2 nd and 3 rd exposures after the CR.

38 Conclusions The total observed persistence depends on both the magnitude of the CR and the amount of time before reset. CRs during idle should not affect the total noise. The persistence signal should be able to be modeled since we will have all the information. Bright sources in long science exposures will be the major sources of persistence. Sets of long dark exposures are very useful.

COS FUV Focus Determination for the G140L Grating

Instrument Science Report COS 2012-01 COS FUV Focus Determination for the G140L Grating Parviz Ghavamian 1 Space Telescope Science Institute, Baltimore, MD October 03, 2012 ABSTRACT The procedures for