Mega-Precovery, a dedicated project for

data mining worldwide image archives for poorly known asteroids

Marcel PopescuMarcel PopescuMembru Astroclub BucurestiMembru Astroclub Bucuresti

Colaborator EURONEARColaborator EURONEAR

Abstract.We describe our software which perform a search for images that

contains asteroids in a Mega-Archive – a database containing observations logs from world wide. This database is flexible allowing other observations logs from different archives to be added.

Both "precoveries" (apparitions before discovery date) and "recoveries" (apparitions after discovery date) are reported.

Using the Internet, this facility will be available to the whole astronomical community willing to study image archives that contain information about different asteroids of interests.

This presentation is organized as fallow: -> Introduction ->The idea behind Mega-Precovery; -> The format of the Mega-Archive; -> Schematic of the algorithm; -> Performances and test runs; -> Conclusions and further improvements

Introduction

The vast collection of image archives stored worldwide is still insufficiently explored and could be mined for asteroids appearing occasionally in their fields.

Both precovered and recovered objects can be measured, allowing an improve of orbit calculation and other studies like dynamical investigations or predictions of future close approach to the Earth.

Searches of this image archives for this objects is therefore highly desirable and are important resources in studies of asteroids.

Basically, intended to be used for poorly known asteroids or newly discovered asteroids, but can be used for any asteroid.

We start the database called – Mega-Archive with the observations logs from ESO/WFI, ING/INT, CFHTLS.

For this purpose we designed Mega–Precovery, a PHP software, which continues some of the ideas of Precovery. The search is performed over a very-large database of pointings logs.

The Mega-Archive want to become “open project” allowing other observations logs to be added for exploration.

The ideas behind Mega-Precovery

Basically we continue the ideas of Precovery: search for asteroids imaged in a archive of images or photographic plates.

The main differences are:

-> the size of the database: Mega-Archive contain until now ~ 350000 pointings logs.

-> this software is focused on the asteroid of interest and basically intended to be used for poorly know asteroids and for important asteroids like PHA (potentially hazardous asteroids) and (VI) Virtual Impactors.

->Mega-Archive will be flexible allowing other archives to be added(we hope to reach 1M of logs for justifying the name).

->the software receive as input a list of the name of the asteroids for which a precovery/recovery is desired. At the output the software will return a list with the name of images found in Mega-Archive (or just in selected archives) with the required asteroids in the field.

The format of the Mega-Archive

In order to perform the search we need the following information stored in Mega-Archive for each available image:-> name of the image in the specific archive;-> center of the field:

* RA[h]* DEC[°]

-> Julian Day for observation;-> Field Magnification;

We chose the format of INT observations logs for this database:“Image name|Julian Day|Exposure time|RA|DEC|Field Magnification| Field Magnification| Filter”

*The archives with different observations logs were in different format. For this, additional software was made to transform them in format described above.

Archives included until now in the MegaArchive:- ING/INT(~230.000 imags);- ESO/MPG(~100.000 imags);- CFHTLS(~20.000 imags):

*CFHTLS-Deep;*CFHTLS-Wide;*CFHTLS-VeryWide;

Archives that we hope to include soon in MegaArchive :- WFPDB – Sofia;- AIRA;- Subaru

Schematic of the project

Input: File with names of the asteroids, one per raw;

Output: File with the names of the images (pointings) that contain in the field the desired asteroid;

Additional files used (files stored on server): → astorb.dat (downloaded from http://www.naic.edu/~nolan/astorb.html)→ Mega - Archive Files:

Schematic of the project: - the main components are: Mega-Archive, astorb.dat, MegaPrecovery, query to Ephemerides Server (IMCCE);

Performances and test runs

Test version, running on a PC with a processor with frequency 1.8GHz, and Internet connection speed 54 Mbps;

25~45s for images searched in ESO logs archive (~0.1M pointings), for one input object.

The time to run the program, depends on the number of the inputs.Desirable to submit small files (5-50 objects);The time of run for one object depends on the number of occurrences found;

ConclusionsThere is a huge amount of information stored in images and

wide field plates archives around the world, insufficiently explored. This information could be very useful when computing the orbits and dynamical characteristics of poorly known asteroids or newly discovered asteroids.

With the purpose to explore this information we created Mega-Precovery, a public facility which will be integrated in the EURONEAR project.

The software, which can be launch from the EURONEAR website requires as input the name of the object/objects and performs a search in the entire Mega-Archive(or in selected archives) and gives as output the observation logs for the images that have in the field asteroid/asteroids.

This presentation described the Mega-Precovery facility which include the software and database.