killer asteroids and exploding galaxies · 1.3 au are neos, or near-earth objects the eventful...

Edward BeshoreLunar and Planetary Laboratory

University of Arizona

George DjorgovskiCenter for Advanced Computing Research

Caltech

Killer Asteroids and Exploding Galaxies The Catalina Sky Survey and the

Catalina Real Time Transient Survey

Photo by Rich Kowalski

• Today there are >500,000 catalogued asteroids, most in the main belt

• Those that come closer than 1.3 AU are NEOs, or Near-Earth Objects

The Eventful Universe — March 2010

• Plenty of evidence for large impacts


In 1998 Congress instructed NASA to begin the search


• Three telescopes– Mt. Bigelow, AZ — 0.7 meter

Schmidt• Vlim ~20 at ~1.5 σ• Field ~8.2 deg2

• Sky 60° > δ > -30° and >20° from galactic plane

• 2.5″ pixels



Schmidt– Mt Lemmon, AZ — 1.5 meter

reflector • Vlim ~22 at ~1.5 σ• Field ~1.2 deg2

• ±10° from ecliptic• 1″ pixels




reflector– Siding Spring, Australia —

0.5 meter Uppsala Schmidt• Vlim ~19.5 at ~1.5 σ• Field ~4.0 deg2

• Sky -80° < δ < -20° and >20° from galactic plane

• 2″ pixels




reflector– Siding Spring, Australia —

0.5 meter Uppsala Schmidt• Identical camera systems

– Spectral Instruments camera with Imager Labs 4K2 CCD thinned by ITL

– ~14 second downloads– CryoTiger cooling


• Survey Strategy– Fixed fields– Four (sometimes five) images

10 minutes apart– Typical exposure time 30 sec– Typical “set” consists of 10-12

fields, with up to 15 sets per night


• New discoveries of NEO candidates reported immediately to the IAU Minor Planet Center

• Candidates posted to NEO Confirmation Page

• “Incidental” astrometry reported at the end of the night

• Early example of successful pro-am collaboration


• Dedicated Followup Telescope• Mt Lemmon, AZ• 1.0 meter reflector • FOV 0.5° on a side• Thinned CCD, Filter wheel• Remote, queued operation• Linked into CSS observing

pipeline• Web accessible• First light late May/early June


• Data processing workflow– Calibration

– Read noise ~11 e- due to fast downloads

– Flats constructed from median averaged data

– Unfiltered– Crosstalk artifacts removed


• Data processing workflow– Calibration– Object extraction

– Sextractor– Detection thresholds

typically 2-3 pixels at >1.2 σ above sky


• Data processing workflow– Calibration– Object extraction– Astrometry

– Typical residuals ~0.2-0.5″– Use UCAC3 catalog


• Data processing workflow– Calibration– Object extraction– Astrometry– Moving object detection

– Identify known object– Rate, magnitude, & shape

consistency– Linear motion

• All unidentified detections reviewed by observer

– 5000-6000 detections/night typical


• All data placed on a 24 TB RAID system with

• Soon will make all data available via the web using same access software as SDSS

Public Access to Data in Preparation


Catalina is the Discovery Leader


• October 6, 2008 11:39 PM, Rich Kowalski at the Mt. Lemmon 1.5-meter discovers a fast-moving object – 2.5 degrees per day– ~19th magnitude– Reported to MPC immediately– Follow up images begin 82

minutes later

2008 TC3


• ~ 570 observations made by 26 professional and amateur observers between time of discovery and impact– 12.4 km/sec– 2-5 meters in diameter

• JPL predicts ~1 kiloton of kinetic energy


• Impact predicted over N. Sudan– Predicted 02:45:38– Actual 02:45:40

• Entered atmosphere at 65 km and detonated at 37 km

• An exceptional and successful exercise


• For the first time, an object was discovered before entry, observed, and recovered for lab study!

– ~280 meteorites (~5 kg.) recovered

– Named Almahata Sita– A Urelite


Catalina Real-Time Transient Survey (CRTS)

• Collaboration with Caltech Center for Advanced Computing Research began in Nov. 2007

• G. Djorgovski, A. Drake, A. Mahabal, R. Williams, M. Catelan

• Uses Palomar Quest detection pipeline• On-site server performs detection in real-time using

deep catalogs, filtering algorithms• Results transmitted to Caltech• CRTS observers classify objects using historical data

from Catalina, others

What’s Next for Catalina?

• Three Small Binocular Telescopes• Largest facility anywhere

dedicated to NEO search• Can be used as three 2.4 meter

telescopes or a single 4.2 meter telescope

• Could cover visible sky ~3 times per month

• Would permit rapid characterization


• Dedicated Followup Telescope• Mt Lemmon, AZ• 1.0 meter reflector • FOV 0.5° on a side• Thinned CCD, Filter wheel• Remote, queued operation• Linked into CSS observing

pipeline• Web accessible• New high-speed network• First light late Spring

Notification

•No proprietary periods

•Skyalert.org•ATELs and CBETs• iPhone App coming

Results

In 2 years —1150 Optical Transients• 300 SNe• 300 CVs• 50 Blazars

Results

Many luminous SNe•SN2008fzMv~ -22.3

ResultsDozens of Faint-Host SNe•SDSS counterpart g = 22.7, r = 22.8• 2008hp Type SN Ia mr =16.2

Results

CSS Archival data used in identifying 2007bi as a pair-instability SN

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Figure 2.

Gal-Yam. et al, Nature, Volume 462, Issue 7273, pp. 624-627 (2009)

CRTS Archival Projects

• CSS observations cover tens of thousands of square degrees since 2005

• Discover and classify variable objects to V~21

• Historical light curves of QSOs, Fermi Blazar targets, SDSS CVs, AMCVn stars

• Light curves for most SDSS spectroscopic targets

• Multi-wavelength studies using sources from NVSS, FIRST, XMM, GALEX, Fermi

• All CSS synoptic data will be made public

More Information

http://www.lpl.arizona.edu/css/Ed Beshore [email protected]

http://crts.caltech.eduA. J. Drake et al 2009 ApJ 696 870-884

Andrew Drake [email protected]

http://www.lpl.arizona.edu/css/

http://www.lpl.arizona.edu/css/

mailto:[email protected]


http://crts.caltech.edu

http://crts.caltech.edu



Additional Slides

Followup observations reduce uncertaintyfor virtual impactors

Image Coadds• 100-200 images for most fields in Catalina Schmidt dataset• Limiting magnitude for most single images around V~19.5 (S/N=3)• Median addition of 24 images easily adds 2 magnitudes


A. W. Harris, “The population of NEAs and PHAs and the current status of surveys,” final report to NASA NEO Program Office, JPL and NASA NEO Observations Program, Washington, 35 pp., 2007.

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completion model was "integrated" using the straight line (constant power law) population model, but as we have seen, this model does not fit the derived integral population very well. Summary One of my all time most popular figures, in terms of the number of times it has been copied, with or without permission, appears as Fig. 2-3 in the 2003 NEO SDT Report. An update of that figure, using the newly computed size-frequency distribution, is a suitable summary figure for this report, and is presented in Figure 25. In this figure, we have adopted the population derived using MPC H magnitudes, which results in somewhat lower numbers than using ASTORB or NEODyS magnitudes. The reason we have made this choice is that, in spite of the annoyance of rounding off magnitudes to 0.1 magnitude, the MPC strongly down-weights LINEAR magnitudes when other reported magnitudes are available, thus reducing the bias caused by the 0.18 magnitude systematic offset of LINEAR magnitudes. One can see, in fact, on a close look at Figure 18, that the horizontal offset between the MPC population and the others is about 0.1 magnitude, as one would expect if about half of the magnitudes carry a systematic bias of 0.18 magnitude with respect to the other magnitude base. In comparing H magnitudes of individual objects between databases, this is about the offset that we see. In updating this figure I have also adjusted the secondary scales using new data from this study. The diameter scale is shifted so that D = 1.0 km corresponds to H = 17.75. Although this equivalence was used in the tabular material and text in the 2003 SDT report, the version of the Figure 2-3 published in the report was an older one that still had H = 18.0 as the equivalence between the scales. In the process of deriving a model synthetic population of NEAs for this study, I computed the impact probability of each synthetic object using the Opik algorithm, and also computed the intersection velocity with the Earth (v!), from which one can calculate the impact velocity (vimp) if the object were to hit the Earth from that orbit. For the synthetic population of 100,000 objects used in this study, I find the mean collision probability per object is 2.11 x 10-9 yr-1, or a mean impact interval of 474 m.y. This is a somewhat higher impact frequency than

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This report (2007)Stuart 2001Harris 2002Brown et al. 2002,annual bolide eventConstant power lawfrom 2003 SDT reportDiscovered to 10/31/06

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Figure 25. The new size frequency distribution of NEAs is plotted along with the number of currently discovered NEAs and a few earlier population estimates. Additional scales are included for asteroid diameter and impact energy, and for the mean impact interval.


CCD CoolingCryogenic cooling via closed-cycle refrigeration units allow theCCD to be held at -100°C. The near elimination of dark currentallows for zero background imaging with very long exposures.

Data InterfaceThe proprietary gigabit fiber optic interface to the 1300S cameraallows for fast communication and data download from thecamera to the host computer utilizing a free PCI express slot.The flexibility of this interface allows the camera head to belocated many meters away from the controlling PC.

Software InterfaceSpectral Instruments provides our own SI Image SGL cameracontrol software that uses an intuitive graphical user interface

for camera control, image acquisition,viewing, processing and archiving. Inaddition, a TCP/IP server is built into thesoftware allowing another program on thesame computer or from another computerto initiate image acquisition and transfer.SI Image SGL is written in LabVIEW andis provided as a Windows application.LabVIEW and C++ SDK packages areavailable as an option for users who needto extend its functionality or incorporatecontrolling other instruments into asingle program.

CCD Sensor16 ports allow maximum data rates to be reached with thissensor despite its large size. More than 110 megapixels canbe read in less than 10 seconds with less than 10e- noise.16-bit digitization captures the full dynamic range of the80,000e- per pixel dynamic range.

Camera SizeConsidering the size of the sensor in the 1300S camera, thebody is roughly a cylinder 8” in diameter by 12” in length.Bolt patterns at the head can be customized for the end-useapplication. Shown below is the rack mount containing thecryo-tiger and power supply.

Spectral Instruments, Inc.® 420 North Bonita Avenue . Tucson, AZ 85745 . Phone: 520.884.8821 . Fax: 520.884.8803 . Email: [email protected] . Web: www.specinst.com

1300 Series

Finding another TC3

• New camera for Bigelow Schmidt– Increase coverage by 2.4X– Allow nightly searches for TC3-like

objects– Improve understanding of small

object population– Create opportunity for additional

sample recovery– Would allow significant new

transient survey opportunities with a daily cadence for a subset of the sky


• Image Characteristics– Rough calibration to V

magnitudes for neutral asteroids using 2MASS colors

– Limiting magnitude at SN=3

• ~19.8 (Bigelow)• ~21.3 (Lemmon)• ~19.5 (Siding Spring)

– Bigelow, Lemmon affected by fringing, particularly at zenith distances > 50°

– Temperature and telescope position-corrected focus


• The Data– Archived to DVD by observer– Images lightly compressed

using Hcompress – Sextractor files contain WCS

for each object, corrected instrumental magnitudes, ellipticity, orientation, pixel count, magnitude above sky, processing flags, others

– Image headers contain WCS, central time to ~ 0.5 sec, detector, and telescope data

– ID’d asteroids, validation results, and observations all archived too

– Data to late 2004

BZERO = 32768 BSCALE = 1 DATE = '2009-11-22T08:35:49' ORIGIN = 'CADDSV3.1' INSTRUME= 'SI 600-277' DATE-OBS= '2009-11-22' EXPTIME = 30.0VACUUM = 0. TIME-OBS= '08:35:06.578' MJD = 55157.35789 CAMTEMP = -102.8 OBSERVAT= 'UA Bigelow Station' IMAGETYP= 'OBJECT ' TELESCOP= 'CATALINA SCHMIDT 003'DETECTOR= 'IMAGER LABS' GAIN = 2.6 RDNOISE = 11.6 NCHANNEL= 2 OBJECT = 'U6U00R ' WRA = '06:00:12.06' WDEC = '+31:49:21.8' WEPOCH = 2000.00 SURVEY = 5 SEQNUM = 1 NMINUS = 2 ST = '05:16:59' HA = '-00:43:50' ZD = 9.3


killer asteroids and exploding galaxies · 1.3 au are neos, or near-earth objects the eventful...

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