voeventnet.caltech.edu NEAT pipeline for transients Ashish Mahabal, Joshua Dickerson, George Djorgovski and the Caltech group

Transients from NEAT data Extensible: PQ (+ other surveys) Complimentary to other approaches (e.g. catalog domain) Brief update on Solar System objects/Variables associated with VOEvent error ellipses

NEAT NEAT is a program to look for Near Earth Asteroids (Mike Brown et al.) o Palomar observatory o 48-inch Oschin Schmidt telescope o Palomar-QUEST camera CCDs o Point and shoot mode

The Palomar-Quest (PQ) and NEAT Surveys P48 done with the Yale/IU Quest CCD camera at the Palomar 48 Oschin Schmidt telescope

The NEAT mode o Triplets 20 or 90 minutes apart o Single filter (R) used o Subroutine looks for possible transients o Lot of junk ensuring real candidates are retained o Several tens per night

Process flow A NEAT tar file arrives nightly Script detects new arrival - springs in to action Valid candidates identified and transformed on to a web page - tentatively it is: Alerts sent off for most promising ones

First attempt o Take a triplet o Obtain catalogs using sextractor o Throw out extended objects o Compare seeing based object numbers o Check if central object shows big magnitude swing

Data Flow NEAT.tar Files MEFs Images IRAF SExtractor Catalog Matching Possible Transien t? FITS Files 1, 2 & 3 Catalogs 1, 2 & 3 Filter Against Documented Sources, etc. Generate Report, Send Alerts. Database Figure 1. Transient Discovery Flowchart History Extraction (010)… Filter against Seeing

Transient Criteria Object history, h i Visibility/seeing, v i Stellarity, s i Detected? D j j th Candidate is ranked by probability, p j Image 1Image 2Image 3Possible Transient (Best case)

Complicating Factors Faint stars near detection threshold CCD defects Satellites, airplanes Crowded fields Asteroids Known variables

Example artifacts o CCD defects o Reflections o Grazing CRs o Partially uncorrected bad columns o unknowns

More artifacts

Some reasons o Sextractors S/G classification is not the best o In crowded areas and with variable seeing sextractor gets easily confused

Modifications o Better statistics - sigma clipping to determine typical variation (non- intrinsic) o Use checkimage and the extent of object it defines to better estimate the magnitude o Obtain stellarity measure independently

Result o Much better clean-up o A very small fraction of possibly real candidates get thrown out o Smaller proportion of contaminants o Script now ready as a blackbox to unleash transients o Advanced cog-sci still needed to assign significance values to events

Specimen

And couple more

Complimentary work Current work is clearly extensible to other surveys, and especially our own Drift Scan data from the Palomar- QUEST survey. o Basic work based on mosaicing carried out for the Griffith Observatory picture has been started o Being extended using HyperAtlas o To be real time in the near future

Asteroids in the Big Picture Tile b Cantabia

The Big Picture A 152 ft 20 ft mural produced for Griffith Observatory from PQ survey BRI images A swath of swath through the center of the Virgo cluster, sampled at 0.4 arcsec/pixel, giving a 136,800 18,000 pixel image Computed at CACR using HyperAtlas and a custom data cleaning pipeline Reproduced on 114 steel-backed porcellain plates, expected to last many decades Will be seen by millions of visitors Associated website will include NVO outreach

The Big Picture: Tile C12 (M87) Zoom-in

Big Picture - Detail

Catalog domain Another complimentary area is the catalog domain o Started a basic program using single epoch catalogs from the Yale pipeline o Awaiting new and improved catalogs from Caltech pipeline which is now up and running o This is next day stuff …

Examples (Priya Kollipara)

Conclusions for part I We are ready to start producing events. Lots of them. It is now important to have ways to Attach significance values to different Events. (Entities like aggregators will not be intelligent unless we make them so)

Event Synthesis Engine Pairitel Palomar 60 Raptor PQ next-day pipelines catalog Palomar-Quest known Variables known asteroids SDSS 2MASS PQ Event Factory remote archives baseline sky eStar VOEventNet VOEventNet: a Rapid-Response Telescope Grid VOEvent database

Solar system objects/Variables Known asteroids and variables can masquerade as transients. These can easily be eliminated by overplotting the error ellipse with solar system objects and variables. o Get epoch, coordinates, error ellipse o Get solar system objects, variables and a sky survey image o Allow overplotting of other possibly interesting source types like X-ray and radio sources.

bin/grand_aladin3.cgi Currently uses aladin. Images from DPOSS for northern sky and DSS for southern sky could be used ent/ ent/ has the collective list

GUI (RESTful) String DateTime SIAP like

Output

Currently as cgi Directly callable Can consume feeds directly Events stored as an HTML page

Current tentative URLs NEAT VOEvents: Solar System objects/Variables: bin/grand_aladin3.cgi bin/grand_aladin3.cgi