The Catalina Sky Survey:

Alerts and Event Brokering

Eric J. Christensen Catalina Sky Survey

D. C. Fuls, A. R. Gibbs, A. D. Grauer, J. A. Johnson, R. A. Kowalski, S. M. Larson, G. J. Leonard, R. G. Matheny, R. L. Seaman, F. C. Shelly

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Catalina Sky Survey

• Near-Earth object (NEO) survey • Two survey telescopes: – 1.5-m aperture, 5.0 deg2 FoV (recently upgraded from 1.2 deg2) – 0.7-m aperture, 8.2 deg2 FoV (soon to be upgraded to 19.7 deg2) • One follow-up telescope: – 1.0-m aperture, 35 arcmin. FoV

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Catalina Sky Survey

• Survey telescopes cover thousands of deg2 per night to 50% liming magnitude of V~19.7 or V~21.3 (for moving object detecon) • Automated data processing reduces these images into lists of candidate moving objects • Human observers visually validate the highest scoring candidates • New NEO candidates are immediately reported and followed up

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Alerts (Discovery)

• CSS uses a NEO-friendly cadence to make downstream processing easier • Four visits to a field; revisit mes ~10 minutes • Linking soware finds thousands of possible tracklets per field (3 or 4 observaons) • 200 fields / night * ~2,500 candidate tracklets / field = 500,000 “alerts” per night per survey telescope

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Alerts (Brokering)

• Tracklets are ranked for likelihood of being true moving objects (great circle moon, consistent SNR, magnitude, FWHM, etc.) • Best-scoring candidates are presented to the observer (~25 per field = ~5,000 per night) • Remaining low-scoring tracklets are not visually veed or reported, but are preserved • Real, unknown moving objects are assigned a digest2 score based on their likelihood of being “unusual”

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Alerts (Follow-up)

• High digest2-scoring objects are immediately reported to the Minor Planet Center (MPC) – MPC provides overall brokering and coordinaon services for all solar system observaons • Minor Planet Center tests links to known objects and posts new NEO candidates to a public webpage • New objects can be followed up by external resources (preferred), or by any CSS telescope, including survey telescopes

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Workflow: Soware vs. Humans

• Survey fields selected • Images acquired • Images processed • Moving object candidate lists – built and ranked • Known asteroids removed • False detecons removed - visual validaon • Real objects classified – is it “interesng”? • NEOs reported to Minor Planet Center • Follow-up observaons scheduled • Follow-up images acquired, processed, etc.

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Summary

• CSS generates up to 1,000,000 moving object “alerts” per night • The best ~10,000 alerts are visually validated by a human observer • An addional ~10,000 alerts are automacally idenfied with known asteroids, and are reported without visual inspecon • Immediate idenficaon of NEO candidates allows same-night follow-up by internal or external resources • 1 to 10 new NEO candidates are reported to MPC nightly; about half are eventually confirmed as new NEOs

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016 Quesons?

[email protected]

LSST Project & Community Workshop | Tucson, AZ | August 17, 2016