Mining the ESO WFI and INT WFC archives for known Near Earth Asteroids. Mega-Precovery software

0.34 MB·English

by  O. Vaduvescu

Astron.Nachr./AN000,No.00,1–9(0000)/DOIpleasesetDOI!
Mining the ESO WFI and INT WFC archives for known Near Earth
Asteroids. Mega-Precovery software ⋆
O. Vaduvescu1,2,3,⋆⋆, M. Popescu2,4,7, I. Comsa5, A. Paraschiv9,10, D. Lacatus9,10, A. Sonka6,7, A.
Tudorica11,12,M.Birlan2,O.Suciu5,13,F.Char14,M.Constantinescu7,T.Badescu8,12,M.Badea8,11,12,
D.Vidican7,C.Opriseanu7
1 IsaacNewtonGroupofTelescopes,ApartadodeCorreos321,E-38700SantaCruzdelaPalma,CanaryIslands,Spain
2 IMCCE,ObservatoiredeParis,77AvenueDenfert-Rochereau,75014ParisCedex,France
3 InstitutodeAstrofisicadeCanarias,c/ViaLacteas/n,38200LaLaguna,Tenerife,Spain
4 PolytechnicUniversityofBucharest,FacultyofAppliedSciences,DepartmentofPhysics,Bucharest,Romania
5 Babes-BolyaiUniversity,FacultyofMathematicsandInformatics,400084Cluj-Napoca,Romania
3 6 AdmiralVasileUrseanuObservatory,B-dulLascarCatargiu21,sect1,Bucharest,Romania
1 7 BucharestAstroclub,B-dulLascarCatargiu21,sect1,Bucharest,Romania
0 8 UniversityofBucharest,FacultyofPhysics,Str.Atomistilor405,077125Magurele-Ilfov,Romania
2 9 InstituteofGeodynamicsSabbaS.Stefanescu,Jean-LouisCalderon19-21,Bucharest,Romania,RO-020032,Romania
n 10 ResearchCenterforAtomicPhysicsandAstrophysics,FacultyofPhysics,UniversityofBucharest,Atomistilor405,
a CPMg-11,077125Magurele-Ilfov,Romania
J 11 BonnCologneGraduateSchoolofPhysicsandAstronomy,Germany
9 12 Rheinische-Friedrich-WilhelmsUniversitaet Bonn,Argelander-InstitutfurAstronomie,AufdemHugel 71D-53121
2 Bonn,Germany
13 TheRomanianSocietyforMeteorsandAstronomy,OP14OP1,130170,Targoviste,Romania

] 14 UnidaddeAstronomia,UniversidaddeAntofagasta,AvenidaAngamos601,Antofagasta1270300,Chile
P
E
. AcceptedforpublicationinAstronomischeNachrichten(Sep2012)
h
p
- Keywords MinorPlanets,NearEarthAsteroids,DataMining,ImageArchives,OrbitalAmelioration
o
r Abstract:TheESO/MPGWFIandtheINTWFCwidefieldarchivescomprising330,000imageswereminedtosearch
t forserendipitousencountersofknownNearEarthAsteroids(NEAs)andPotentiallyHazardousAsteroids(PHAs).Atotal
s
a of152asteroids(44PHAsand108otherNEAs)wereidentifiedusingthePRECOVERYsoftware,theirastrometrybeing
[ measuredon761imagesandsenttotheMinorPlanetCentre.Bothrecoveriesandprecoverieswerereported,including
prolongedorbitalarcsfor18precoveredobjectsand10recoveries.Weanalyzeallnewoppositiondatabycomparingthe

1 orbitsfittedbeforeandafterincludingourcontributions.WeconcludethepaperpresentingMega-Precovery,anewonline
v servicefocusedondataminingofmanyinstrumentarchivessimultaneouslyforoneorafewgivenasteroids.Atotalof28
2 instrumentarchiveshavebeenmadeavailableforminingusingthistool,addingtogetherabout2.5millionimagesforming
0 theMega-Archive.
9
6 (cid:13)c 0000WILEY-VCHVerlagGmbH&Co.KGaA,Weinheim
.
1
0
3 1 Introduction a simple observing log recorded in a standard format
1 (Vaduvescuetal.,2009). This tool uses the SkyBoT web
: Telescopesendowedwithlargefieldmosaiccamerashaving service (Berthieretal.,2006) to predict accurate positions
v
i theirimagesarchivedandstoredforpubliconlineaccessare for all known asteroids. Using PRECOVERY, all known
X
becomingveryappealingnowadaystodataminingworkfor asteroids could be searched in any archive for serenditip-
r manyscienceaims.Oneofsuchaiminvolvestheimprove- itous recoveries and precoveries (apparitions before dis-
a
mentofthe orbitalknowledgeofthe NearEarthAsteroids covery) including all known NEAs, PHAs, as well as all
(NEAs)andPotentiallyHazardousAsteroids(PHAs)which other numbered and provisionally named asteroids cata-
isoneoftheaimsoftheEuropeanNearEarthAsteroidRe- loguedtodate.Usingthisserver,wesearchedtheCFHTLS
search(EURONEAR)projectsince2006. archivefinding143encountersofknownNEAsandPHAs
To achieve this goal, few years ago we intro- (Vaduvescuetal.,2011a).
duced the PRECOVERY software devoted to search all
known asteroids to date in any archive uploaded as A recent similar initiative coordinated with the EU-
RONEAR efforts includes a citizen-science project led
⋆ Using ESO/MPG WFI images served by the ESOScience Archive by E. Solano from the Spanish Virtual Observatory
Facility and INTWFCimages served bythe CASU Astronomical Data
(SVO,2011; Solanoetal.,2011). Following its press an-
Centre.
⋆⋆ e-mail:[email protected] nouncement (Tristan,2011), this Spanish service has reg-
istered more than 3,000 users who measured and reported
(cid:13)c 0000WILEY-VCHVerlagGmbH&Co.KGaA,Weinheim
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
morethan600positionsofsome150NEAs(Solano,2011). Thepaperisstructuredin5sections.Section2presents
Besidesitspublicoutreachvalue,thisworkhasameritori- the ESO/MPG WFI and INT WFC archives, giving an
ous contribution to report moving sources not detected by overview of their basic characteristics. Section 3 presents
theSDSSautomateddetectionalgorithmandnotpublished the data mining results, counting the encounters of NEAs
in theSDSSmovingsourcecatalogues(Ivezic,2008).The andPHAs,listingtheprecoveriesandrecoveriesatanewor
abovenumberofdetectionscouldbecomparedwithanother thelastoppositionwhoseorbitalimprovementisanalyzed.
SDSS NEO project which found 104 NEAs in the SDSS Section 4 presents Mega-Precovery software and its asso-
archive(Kentetal.,2009). ciated Mega-Archive.Section 5 lists the conclusionsand a
A similar focused tool of NASA was announced re- fewrelatedprojects.
cently (Yauetal.,2011). The Moving Object Search Tool
forNEOWISEandIRSA(MOST)isanewweb-basedserver
2 Data Mining theWFIand WFCArchives
thatenablesresearcherstolookforserendipiouslyobserved
solar system objects (NEAs, asteroids and comets) con-
Until the apparitionof the SDSS 2.5msurveyin 2000and
tainedintheimagesheldbytheNASA/IPACInfraredSci-
laterthededicationofPan-STARRS1.8msurveytelescope
ence Archive (IRSA), including single epoch exposures
in 2007, the ESO/MPG 2.2m telescope equipped with the
from WISE. MOST takes as input an object name or set
WFI mosaic camera and the INT 2.5mtelescope endowed
oforbitalparameters.
with the WFC mosaic camera have been two of the most
Part of a student bachelorproject, the ESO/MPG WFI
powerful2mclass largefield facilitiesin the world.Avail-
archive (1999 to 2003) was data mined for photometry of
able since 1999 and 1998, respectively,and still operating
knownasteroidsusingtheAstro-WISEandSkyBoTservers
and partially devoted to survey work, these two facilities
(Bout,2007). Taking into account three selection param-
have given to European astronomers access to both hemi-
eters, the author measured mostly two colour photometry
spheres using mosaic cameras more than half degree field
from354occurrencesof144asteroids(primarilyMainBelt
each.
Asteroids-MBAs)on1380WFIimages.
Another asteroid data mining tool was announced re-
2.1 ESO/MPGWFIArchive
cently(Gwynetal.,2011).TheSolarSystemObjectSearch
(SSOS)oftheCanadianAstronomicalDataCenter(CADC) The Max Planck Garching (MPG) 2.2m telescope is
allowsuserstosearchforimagesfromavarietyofarchives owned by the European Southern Observatory (ESO) in
for single movingobjects,acceptingas inputeitheran ob- La Silla, Chile. In 1999the Wide Field Imager(WFI) was
ject designation,a list of observations,a set of orbitalele- mounted at the Cassegrain F/5.9 focus of the ESO/MPG
mentsorauser-generatedephemerisforanobject. (Baadeetal.,1999).WFI isa mosaiccameraconsistingof
During the last years we applied our PRECOV- a2×4CCDs2K ×4K pixelseach,coveringatotalfield
ERY work to other large field archives, also ap- ofviewof34′×33′(0.30squaredegrees)withapixelscale
plying our work to other data mining facilities of0.24′′/pix.
(Vaduvescuetal.,2009; Vaduvescuetal.,2011a). InthispaperwestudiedtheESO/MPGWFIarchivedur-
In the same frame of the EURONEAR project, ingtheperiod25-10-1999(firstlight)to27-08-2009(when
we introduced the Mega-Precovery project westartedthisESOproject),althoughWFIhascontinuedto
(Popescuetal.,2010; PopescuandVaduvescu,2010; beofferedbyESOandMPGbeyondthisdate.Duringthis
PopescuandVaduvescu,2011),a web service dedicatedto period, the WFI acquired 96,913 science images. In Fig-
data mining of image archives for some given asteroids. ure1(top)we plotincyan(fainterdots)theWFIskycov-
Using this tool, one could search one or more existing erage during the above period. This shows random point-
archives for any given asteroid or a list of few asteroids ings between δ ∼ −90◦ and δ ∼ +30◦ drivenby various
(numberedorprovisionallynumbered). science interests with some small patches covered by few
Inthepresentpaperwepresentnewdataminingcontri- extragalacticprograms.Wedrawinmagenta(faintercurve)
butions carried out in the frame of EURONEAR project. the ecliptic,whichhasbeenfollowedbyatleast two NEA
Firstly, the ESO/MPG WFI and INT WFC archives ob- surveyandfollow-upprogramsledbyBoattinietal.,2004;
served between 1998 and 2009 are mined for all known Vaduvescuetal.,2011bandotherSolarSystemworkledby
NEAs and PHAs. We distributed this workload to a team otherPIs.
of 13 Romanian students and amateur astronomers, thus
theprojecthassomeeducationalaim,besidesitsmainEU-
2.2 INTWFCArchive
RONEARdevelopmentrole.Secondly,wepresentourpub-
licnewEURONEARdataminingserviceMega-Precovery, Owned by the Isaac Newton Group (ING), the 2.5m Isaac
togetherwithitsassociatedMega-Archive.Throughoutthis Newton Telescope (INT) is installed in the Northern Eu-
paper and conform with our two previous papers, we de- ropean Observatory of Roque de los Muchachos (ORM)
fine “precoveries” as apparitions before discovery date in La Palma, Canary Islands. Since 1998 the prime focus
(Steel,1997). of the INT houses the Wide Field Camera (WFC) which
2
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
δ ∼ −30◦ and δ ∼ +90◦ and clearly some 10◦ wide
band around the galactic plane which represents the two
major galactic INT surveys,namely The INT/WFC Photo-
metricHαSurveyoftheNorthernGalacticPlane(IPHAS,
Drewetal.,2005)andTheUV-ExcessSurveyoftheNorth-
ern Galactic Plane(UVEX,Grootetal.,2009) to be com-
pletedsoon.Wedrawwithmagentatheecliptic,whichhas
beenfollowedsporadicallybyfewSolarsystemrunsledby
A.Fitzsimmons(NEAsandcomets),J.L.Ortiz(TNOs),J.
Licandro(MBCs),O.Vaduvescu(NEAs)andpossiblyother
PIs.
2.3 ExposureTimeandFilters
Figure2 plotsthe histogramofthe exposuretimesused in
the ESO WFI archive(above)andthe INT WFC (bellow).
Most images were taken with exposuresshorterthan 200s
in both archives,thereforetheyare suitable forfindingsof
NEAs affected by a small trail effect caused by their fast
propermotion (µ > 1′′/min). Few other maxima in expo-
sure times are visible on both histogramsfor longerexpo-
sures,upto2500sinbotharchives.
Wealsostudiedtheusageoffiltersinthetwoarchives.
The ESO WFI archive counts 44 filters, while INT WFC
counts20filters(bothbroadandnarrowband).FortheESO
WFI archive, 93% represent 13 broad band filters (led by
Rc,I,B,V andnofilter),while30otherfiltersrepresent-
ingnarrowbandandotherscountforonly7%.FortheINT
WFC archive, 73% represent14 broad band filters (led by
r,i,g,V andnofilter)while6narrowbandfilterscountfor
27%.Inconclusion,bothESOWFIandINTWFCarchives
areappropriateforasteroiddetectioninmostoftheirbroad
bandimages.
3 Results
Fig.1 TheskycoverageoftheESOWFIandINTWFC
3.1 FoundObjects
archiveswhoseobservedfieldsareplottedascyan(fainter)
dots.Bothhemipheresarecoveredrandomly,includingfew
Run with the two archives and assuming a safe limiting
skypatchesandthegalacticplanecoveredbyafewsurveys. magnitudeV =23,PRECOVERYreportedatotalof7,123
Weoverlaywithblue(larger)dotstheNEAsandPHAsen-
candidateimages(1,535fortheESOWFIarchiveand5,588
counteredinthisworkandwithmagenta(faintercurve)the
for the INT WFC archive). These images were inspected,
ecliptic.
thenastrometricallyresolvedandmeasuredbyourteamin
adistributedbuthomogenousmanner.Afterinspectionand
search,only761imagesfromtheinitialcandidatesresulted
inreportedpositions,whichrepresentsonly11%.Thisdra-
consists of 4 CCDs 2K ×4K pixelseach, coveringan L- matic decreasecouldbe explainedbysome factors,led by
shape34′×34′ (0.28squaredegrees)withapixelscaleof the optimisticlimitingsafermagnitudeV = 23,theexpo-
0.33′′/pix. suretime,propermotion,Moonphase,weatherconditions,
In this paper we studied the INT WFC during the pe- airmass,uncertaintyinsomeephemeridesandmagnitudes,
riod20-06-1998(firstlight)to10-07-2009(whenwestarted usedfilters,etc.
the INT project), although WFC is continuing to be of- InFigure1weoverlaywithblue(larger)dotstheNEA
fered by the ING beyond this date. During the above pe- and PHA fields measured in the two archives (ESO WFC
riod, the WFC acquired 237,768 science images. Figure 1 above and INT WFC bellow). In both archives the NEA
(bottom) plots the sky coverage of the WFC archive dur- findings are spread randomly with respect to the eclip-
ingthisperiod.Theplotshowsrandomdistributionbetween tic up to high ecliptic latitudes (β ∼ 40◦), in agreement
3
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
Fig.2 Histogramsshowingtheexposuretimeusedinthe Fig.3 HistogramsshowingthepredictedV magnitudeof
ESO/MPGWFIarchive(above)andtheINTWFCarchive theencounteredNEAsandPHAsinthetwosurveys(ESO
(bellow).Relativelyshortexposures(lessthan1-2minutes) WFC top and INT WFC bottom).A limit aroundV ∼ 22
were mostly used, making the two archives suitable for wasreachedinbotharchives,consistentwith2mfacilities.
searchingNEAsaffectedbythetraillosseffect.
Figure3 showsthe histogramof the predicted V mag-
withtheknowndistributionoftheinclinationsoftheNEA nitudefortheencounteredobjectsinthetwoarchives(ESO
population. In total, 152 objects were measured and re- WFI above and INT WFC bellow). Both datasets show
ported,namely44PHAs(15intheESOand29intheINT fainter objects around V ∼ 22, according to the limiting
archive)and108otherNEAs(40intheESOand68inthe magnitudeof2m-classtelescopesimagingmovingasteroids
INTarchive).124objectshavedatasetsincludedwithinthe withrelativelyshortexposures(lessthan∼oneminute).
timespanoftheirexistingarcs.Foratotalof28objectswe
wereabletoprolongtheexistingarcsbyneworlastoppo- UsingPRECOVERYandMega-Precovery(presentedin
sitiondatasets.Fromthese,18objectsrepresentprecoveries Section4),onecouldsearchthetwoarchivesforapparitions
(8 in the ESO archive and 10 objects in the INT one) and ofanyothergivenasteroid(s),includingprecoveriesofnew
10objectsrepresentrecoveriesatanewoppositionorpro- NEAsandPHAscataloguedafterAugust2009(theendof
longedarcsatthelastopposition(6intheESOand4inthe ourwork).We plantoupdatesoonthesearchivesbeyound
INTarchive). 2009.
4
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
3.2 Astrometry
Likeinourpreviousdistributedworkinvolvingstudentsand
amateurs,we usedthe Astrometrica software(Raab,2012)
to resolve the astrometryof the fields. Afterresolving and
aligningthemultipleimagesofthesamefield,wesearched
for the asteroids in the candidate images by blinking the
images, finally measuring manually the asteroid positions.
Weusedquadraticsky-platetransformationandtheUSNO-
B1 catalog that allowed in average identification of about
50-100referencestarsineachCCDwhichwasresolvedin-
dividually.
Figure4plotstheO-Cresiduals(observedminuscalcu-
lated positions) of the objects measured by us in the ESO
WFI archive (above) and the INT WFC archive (bellow).
Residuals are mostly clustered around origin for the ESO
WFI archive (standard deviation 0.56′′ and average devia-
tion0.34′′),thesebeingmostlydominatedbycatalogerrors
andmeasurements.TheINTWFCresiduals(right)showa
largerspread(standarddeviation 0.72′′ andaveragedevia-
tion0.53′′)mostlyduetothelargerknownWFC fielddis-
tortion in the prime focus of the INT which is larger than
thatoftheESOWFICassegraincamera.
Becausemostexposuretimeswerequiteshort(lessthan
one-twominutes)mostasteroidapparitionsshowstellaror
small elliptical aspect easily fitted by Astrometrica which
measurestheircentresinrespecttomid-exposuretime.We
encountered also few longer trails caused by longer expo-
sures for which we measured in the same manner the two
ends,thenwemeasuredtheaveragepositioncorresponding
tothemid-timeexposure.
Using FITSBLINK asteroid residual server calculator
(Skvarc,2012) we checked the astrometry for possible er-
rorswhichcouldincludebadmeasurementoffewfainttar-
gets, faint objects affected by nearby bright stars, possi-
bleconfusioncausedbylargerskyuncertainties,etc.Then
we reportedthe two datasets(oneforeacharchive)to Mi-
Fig.4 O-Cresiduals(observedminuscalculated)forthe
nor Planet Center (MPC). These include 316 positions of
NEAsandPHAs foundin thethe ESO/MPG WFI (above)
55 objectsfoundin the ESO archiveand445positionsfor
and INT WFC archives (bellow). For the ESO WFI, the
97 objects found in the INT archive. After minor revision standarddeviationis0.56′′andtheaveragedeviation0.34′′,
from the MPC (Spahr&Williams,2011) and our careful
mostly due by catalog errors. For the INT WFC, the stan-
re-measurementof fiveobjects(3%of the total),MPC ac- dard deviation is 0.72′′ and the average deviation 0.53′′,
cepted and published the astrometry (Elstetal.,2011 for
mostly dominated by astrometric errors due to the uncor-
the ESO archive and Fitzsimmonsetal.,2011 for the INT
rectedfieldofthecameramountedintheprimefocusofthe
archive).
INT.
3.3 OrbitalImprovement
Themineddataforthe152foundobjectswasusedtoame-
liorateorbitsoftheencounteredNEAsandPHAs.Mostof
the data improvedthe density within the existing arcs, the position. Four of these objects (2005 CG41, 1996 XX14,
observing date being contained in the existing orbital arc 2003 MK4 and 2002 DH2) were previously reported to
timeframe.For28objectsweprolongedtheexistingorbital MPCin2005,beingobservedbyotherPIs.Wemarkthese
arcsbynewoppositionsorlastoppositiondatasets,adding objects with an asterix in Table A1 and Table A2. In the
18precoveriesand10recoveries.IntheApendixTableA1 third columnwe list the orbitalarc lengthbeforeandafter
we list these 28 cases of NEA and PHA encountersrepre- ourdataminingwork.Afewcasesrepresentmajorencoun-
senting precoveriesand recoveriesat a new orthe last op- ters,namely:
5
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
– precoveriesatthefirstopposition:2005TU45(arcpro- – theMega-PrecoverysoftwarefordataminingtheMega-
longed by 5 years), 2005 MB (extended by 2 years), Archivefortheimagescontainingoneoramoredesired
2009 TG10 (extended by 6 years), 2009 NA (from 5 cataloguedobjects(NEAs,PHAsorotherasteroids)in-
monthsto 9 years),2006PW (from1 yearto 5 years), cludedinalocaldailyupdatedMPCdatabase;
2009 HW2 (from 3 days to 2 months), 2009 SP171
TheinputofMega-Precoveryconsistsof:1.aselection
(from 2 months to 2 years), 2009 FU23 (a very desir-
oftheinstrumentarchivestobesearched(includingtheop-
ablePHAwhosearcwasprolongedfrom2monthsto7
tion to search either one or all the existing archives in the
years)and2006KA(from2yearsto6years);
same time) and 2. the specified asteroid or list of few as-
– recoveriesat the last opposition: 1996 XX14 (arc pro-
teroidsgivenbytheirnames,numbersorprovisionaldesig-
longed from 2 months to 8 years), 2003 MK4 (PHA
nations.TheoutputofMega-Precoveryconsistsofalistof
verydesirable,extendedarcfrom2monthsto2years),
candidateimagesin whichthe searchedobjectisexpected
2002DH2(from4monthsto3years)and1994JX(arc
tobevisiblebasedontwomainthresholds,namelytheex-
increasedby5years).
pected limiting magnitudeof the archive and the expected
We compare the orbits of the precovered and recov- positional uncertainty of the searched object (provided by
ered objects fitted with FIND ORB software (Gray,2012) theuserbasedonthecurrentlyknownorbit).
using their published positions (full orbital arc) available Thedefinitionfilecontainingtheinstrumentarchivesin-
viaMPC.IntheAppendixTableA2welisttheorbitalele- cludes the following data: the filename keeping the tele-
mentsobtainedexcludingourdata(firstline)andincluding scope observing logs, the observatorycode, the width and
our data (second line). Orbits of most asteroids were im- height of the field (both in degrees, in the direction of α
provedusingourmineddata,namelytheσresidualsinlast and δ, respectively),the start and end Julian Date defining
columndecreasedformost.Inonly3cases σ residualsin- the timespan of the archive and the limiting magnitude V
creased, namely: 2009 HW2 (from the INT archive, from expectedfromthegiventelescopeandinstrument.
σ = 0.43′′ to σ = 0.48′′), extended arc from 3 days to 2
months), 2001 XK105 (ESO archive, from σ = 0.61′′ to
4.1 Mega-PrecoveryArchive
σ = 0.63′′,forwhichonlytwoimageswereencountered),
and2006KA(ESOarchive,fromσ =0.49′′toσ =0.53′′, Foreasieridentificationoftheimages,theMega-Archiveis
forwhichonlyoneimagewasavailableshowingalongtrail split into more instrument archives, each correspondingto
forwhich we reportedthe middle and the two endstaking a given telescope and camera. Table A3 lists the available
intoaccountthepredictedpropermotion). instrumentarchivesandtheirbasiccharacteristics.Besides
thesestandardarchives,Mega-Precoveryleavestheuserthe
flexibilitytoaddhis/herowninstrumentarchivegiveninthe
4 Mega-Precovery
same standard format, by loading the file to be run by the
server.AsofAugust2012,the Mega-Archivecountsabout
Despite some recent data mining efforts, the vast collec-
2.5 million images from 28 instrument archives available
tionofCCDimagesandphotographicplatearchivesstillre-
for search via Mega-Precovery. This collection includes
mainsinsufficientlyexploited.PRECOVERYcoversallcat-
all archived ESO imaging instruments1, most archived
alogued asteroids (including all known NEAs and PHAs),
NVO imaging instruments (National Virtual Observatory
but the search of an entire archive could take quite a long
of the United States2), the INT WFC3, CFHTLS4, Subaru
time, typically about10 hoursforsome 10,000square de-
SuprimeCam5andtheAATWFI6archives.
greesskycoverageofasinglearchive.Therefore,someded-
icatedtooltotargetoneorveryfewselectedobjectsisnec-
essary to speed up data mining of asteroids, includingim- 4.2 Mega-PrecoverySoftware
portantNEAsandPHAs.
TheMega-PrecoverysoftwareiswritteninPHP,beingem-
InthissensewedesignedMega-Precovery,withtheaim
bedded on the EURONEAR website (EURONEAR,2012)
to fasten and target the search of one or some few impor-
as a public access application under the Observing Tools
tantobjects,suchasPHAsorVirtualImpactors(VIs).Given
section.Figure5presentstheflowchartofthissoftware.To
this,weproposetosearchverylargecollectionsofarchives
runMega-Precoveryapplication,theuserneedstoloadthe
forimageswhichincludeoneorafewselectedknownaster-
webpage using any internet browser (block User input in-
oidsintheirfield.Therearetwocomponentsofthisproject:
terfaceinFigure5).Inordertocreatethequery,oneneeds
– thedatabase(namedMega-Archive)whichincludesthe toprovidethefollowinginformationtothewebinterface:
individual instrument archives, namely the observing
1 http://archive.eso.org/eso/eso archive main.html
logs for their science CCD images or plates available
2 http://portal-nvo.noao.edu
from a collection of instruments and telescope around
3 http://casu.ast.cam.ac.uk/casuadc/archives/ingarch/@@query.html
the globe.The Mega-Archiveis an open projectallow- 4 http://www3.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/cadcbin/cfht/wdbi.cgi/cfht/quick/form
ing other instrument archives to be added later for ex- 5 http://smoka.nao.ac.jp/search.jsp
plorationbyanybodywhowouldliketocontribute; 6 http://apm5.ast.cam.ac.uk/arc-bin/wdb/aat database/observation log/make
6
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
– Alistofnames,numbersorprovisionaldesignationsof comment(whichcouldincludethefilter,etc),allseparated
theasteroid(s)tosearch; by”|”.
– Theselectionoftheinstrumentarchivestobesearched TheoutputofMega-Precoveryconsistsinalistinclud-
for (the first default option ALL allowing to search the ing the images and the corresponding CCD number pre-
entireMega-Archive); dictedto containthequeriedobject(s).Theresultsare dis-
– ThefieldUncertaintyusedtoaccommodatefortheun- playedbothinthewebinterface(visibleonlyattheendof
certainty in telescope pointing plus the uncertainty in therun)andsentviae-mailtotheuser(incase thisoption
position of the searched object due to its (sometime wasselected).Theusercansearchtheimagesintheonline
moreunsecure)orbit. Based on extendedtests, forthis instrumental archive, then download, inspect and measure
parameter we recommend the default value 0.02◦ but thedatarelatedtothisasteroidbasedonhis/herownscien-
this should be increased in case of poorly known ob- tificinterest(astrometry,photometry,etc).
jectsorlessaccuratepointing.Increasingtoomuchthis
parameter(morethan∼1◦)wouldresultinselectionof
5 Conclusions andFuture Work
falsecandidateimages(falsedetections);
– The email address where Mega-Precovery could an-
Twowidefield2mclasstelescopearchives,ESO/MPGWFI
nouncetheuserabouttheendoflongrunsandtheFTP
and INT WFC, comprising about 330,000 images were
spacewheretheusershoulddownloadthedata;thisin-
mined to search for serendipitous encounters of known
cludes the same informationgiven in the web browser
NEAsandPHAs.Twomasterarchiveswerebuiltbasedon
aftertheendoftherun.
theobservinglogsofthetwofacilities.UsingthePRECOV-
After the user submits the query, this is processed by ERY software, a total of 152 asteroids (44 PHAs and 108
Mega-Precovery in the block Processor of the input, then other NEAs) were identified and measured on 761 images
the accurate ephemerides for each archive dates and the and their astrometry was reported to Minor Planet Centre
givenbody(bodies)arecalculatedintheEphemeridesquery (MPC).Bothrecoveriesandprecoverieswerereported,in-
block.ThisstepusestheIMCCE’sephemerisserviceMiri- cluding prolonged orbital arcs for 18 precoveredasteroids
ade(Berthieretal.,2009;IMCCE,2012a)whichisqueried and10recoveries,plusother124recoveries.Weanalyzeall
for some discrete times covering the entire queried tele- precoveries and recoveries at a new or last opposition by
scope archive(s),then accuratelyinterpolatedthe positions comparing the orbits fitted before and after including our
fortheobservingdatesgiveninthearchive(theblockInter- datasets. Following the PRECOVERY project, we present
polator). Mega-Precovery,anewsearchenginefocusedondatamin-
We used a five order Bessel interpolation model ingofmanyinstrumentarchivessimultaneouslyforoneor
(IMCCE,2012b), choosingfor the Miriade ephemeridesa fewgivenasteroids.Atotalof28instrumentarchiveshave
stepbasedontheasteroidpropermotion,namely1dayfor beenmadeavailableformining,addingtogetherabout2.5
objectsmovingslowerthan2degreesdailyand1hrforob- millionimagesformingtheMega-Archive.
jectsfasterthanthislimit.Usingthisfinetimestepwe en- Few otherprojectsarein planwithintheframeofEU-
sure sufficient accuracy (< 1′) for most NEAs and PHAs RONEARdataminingofNEAs.Fewmonthsagowestarted
passingcloseto Earthaffectedbyveryfastpropermotion. dataminingoftheSubaruSuprimeCamarchiveusingPRE-
ForNEAsandPHAsawayfromcloseencounterswiththe COVERY. Anotherimportantprojectwill be to extend the
Earth,andalsoforMBAs,theinterpolatorprecisionisvery miningcapabilitiesoftheMega-Precovery.Anotherproject
accurate (about 1′′). The parameters for the interpolation plans to apply Mega-Precoveryto search the entire Mega-
whereestablishedasatradeoffbetweenprocessingtimeand Archive in order to recover and improve orbits of some
predicted position accuraccy and were validated by exten- important VIs, PHAs and NEAs. Finally, we plan to con-
sivetests. tinue to enlarge the Mega-Archive,adding new instrument
Each image of the archive is defined by a rectangular archives,includingCCD camerasandphotographicplates.
box given by the telescope pointing, the width and height In this sense, any observatories, especially those endowed
field of view stored with each instrument archive entry. If withlargefieldimaginginstruments,arewelcomedtocon-
the predicted position falls within the field of the current tributetothisopensourceproject.
image bounded by the Uncertainty area, then the current
entry is selected as a candidate image to hold the queried Acknowledgements. Thisprojectincludesobservationsmadewith
asteroid.ThisstepisdoneintheSelectorblock. theESO/MPGtelescopeofEuropeanSouthernObservatory(ESO)
in La Silla Observatory, Chile and the Isaac Newton Telescope
Like in PRECOVERY, the format of each instrument
(INT) owned by the Isaac Newton Group (ING) in La Palma,
archivesfollowsthesamestandardformatlistingoneobser-
Canary Islands. This work used images retrieved from the ESO
vation(telescopepointing)oneachlinewhichincludesthe
Science Archive Facility and from the Isaac Newton Group
imageID(nameoftheimagefile),theJuliandate(startof
Archive maintained by the CASU Astronomical Data Centre at
observation),exposuretime(sec),telescopepointing(αand theInstituteofAstronomy, Cambridge. Weacknowledge Jerome
δatJ2000epoch),widthandheightofthefieldofview(to- Berthier for his continuous support provided with the SkyBoT
wardsαandδaxisframe,bothindegrees),andaeventually (Berthieretal.,2006) and Miriade (Berthieretal.,2009) servers
7
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
F developed at IMCCEand accessed byPRECOVERYandMega-
ig
. Precovery, respectively. Acknowledgements are also due to Bill
5
Gray,theauthorofFIND ORBsoftware,forhisverypromptas-
T sistanceinordertoupgradehisveryrobustanduserfriendlycode
h
e for fitting orbits. Mega-Precovery archive is based on data ob-
fl
o tained from the ESO Science Archive Facility, the NOAO Sci-
w
c ence Archive served by the National Virtual Observatory of the
h
a UnitedStates,Subaru-Mitaka-Okayama-KisoArchive(SMOKA),
r
to theCanadianAstronomyDataCentre(CADC)andCASUAstro-
f
M nomicalDataCentre(UnitedKingdom).Thisworkhasmadeuse
e ofSAOImageDS9developedbySmithsonianAstrophysicalOb-
g
a- servatory.WearethankfultoMinorPlanetCentre,specificallyto
P
r TimSpahrwhopointedoutafewerrorsinthereportedpositions.
e
co Final acknowledgements are due to the referee David Asher for
v
e carefulreadingandadvicetoimproveourpaper.
r
y
s
o
ftw References
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A Appendix: Data Tables
9
O.Vaduvescuetal:MiningtheESOWFIandINTWFCarchivesforknownNEAs.Mega-Precovery.
Astron.Nachr./AN(0000)
TableA1 28objectsfoundintheESOandINTarchivesinclude18precoveredasteroidsand10recoveredobjectswhose
arcswereprolongedbyanewoppositionoratthelastopposition.BesidestheasteroidnamewegiveitsMPCclassification
(acc.toJan2012database),thenumberofpositions,thelengthoftheorbitalarc(beforeandafterourastrometry)andthe
archive.FourobjectsmarkedwithanasterixwerereportedalsobyotherPIsin2005.
Asteroid Classification Nr.pos. Arc(before/after) Archive
ExtendedArcsatFirstOpposition(Precoveries):
2005CG41* NEAdesirable 12 3d/4d ESO
2005TU45(231134) NEAdesirable 4 3y/8y ESO
2005MB NEAverydesirable 3 3y/5y ESO
2004XP164(216707) NEAdesirable 5 4y/5y ESO
2009TG10 NEAverydesirable 6 3y/9y ESO
2009NA NEAverydesirable 3 5m/9y ESO
2002HQ11(159677) NEAdesirable 2 5y/6y ESO
2001XK105 NEAextremelydesirable 2 2m+10d ESO
2006WT1 PHAverydesirable 6 4m/5m INT
2002TY57(250162) NEAdesirable 7 5y+2m INT
2006PW NEAverydesirable 2 1y/5y INT
2009HW2 NEAextremelydesirable 8 3d/2m INT
2009SP171 NEAverydesirable 2 2m/2y INT
2005BY1 NEAverydesirable 12 10m/11m INT
2009FU23 PHAverydesirable 2 2m/7y INT
2005VC2 NEAverydesirable 5 3m/4m INT
2006KA NEAverydesirable 3 2y/6y INT
2000FL10(86666) NEAdesirable 3 8y/9y INT
ExtendedArcsatLastOpposition(Recoveries):
1996XX14* NEAverydesirable 7 2m/8y ESO
2003MK4* PHAverydesirable 7 2m/2y ESO
2002DH2* NEAverydesirable 8 4m/3y ESO
1994JX NEAverydesirable 8 9y/14y ESO
2004RS25 NEAverydesirable 2 3y+1m ESO
1999WK11(102873) NEAdesirable 6 28y+1m ESO
2005GN59(164400) PHAdesirable 2 31y+3m INT
2002EQ9(163191) NEAverydesirable 2 5y+10d INT
2007DK NEAverydesirable 4 5y+7m INT
2005CA(189263) NEAdesirable 4 30y+4d INT
10