Eyeballs and automation in pursuit of moons (and limiting magnitudes)

Max MutchlerResearch & Instrument Scientist

Space Telescope Science Institute

Nix & Hydra 5th Anniversary WorkshopMay 11-12, 2010

Overview• Currently have HST moon search data for Pluto, Ceres,

Vesta, Pallas, and Lutetia. • Would like to further define methods to enable efficient

moon searches and limiting magnitude studies for archival data sets, and to help justify future HST and JWST observations

• Ideas for turbo-charged “Steffl et al. on steroids” moon searches, and limiting magnitudes:– Monte Carlo method: thousands of software iterations– Zoo method: thousands of human eyeballs

• What are the optimal roles and usage for eyeballs and software for setting limiting magnitudes?

• The time is ripe: what other planetary data analysis tasks could benefit from the “Zoo” approach?

Eyeballs: pros and cons• Eye-brain can quickly

parse a messy image • Very reliable for short

periods of time, but can become fatigued

• Small-number statistics: can only get a few colleagues to do it

• Best as spot check and tuning for a more automated approach?

Automation: pros and cons• Hardware/software can work

tirelessly with consistency• Can consistently miss

candidates in complex images• Monte Carlo: relentless

iteration can sample entire field with better statistics

• Visual inspections still needed for spot checks, tuning, verification

• Certain tasks may never fully lend themselves to automation: is this one?

Nix & Hydra discovery observations

• ACS Wide Field Channel (WFC) covers entire orbital stability zone

• Pluto-Charon near chip gap

• 4 long exposures on May 15 and again on May 18, 2005

• Nix & Hydra playing peek-a-boo throughout the observing sequence

• Many pixels to inspect, even for this relatively small data set

• Limiting magnitude data is inherently noisy and messy: complicated images

Quite a few different artifacts to contend with…

15 May 2005sum 4 frames

15 May 2005median 4 frame

Even cleaned-up images are not necessarily ideal

“clean” implanted software detections truth

Implanting and automatically detecting simulated moons

Can Monte Carlo iterations (better statistics) overcome software detection limitations?

Deep (saturated and bleeding) image implanted with simulated moons

Software detections marked with red boxes Truth marked with blue boxes

Can iterate endlessly to test every pixel in the field with simulated moons of varying magnitudes, and build up a hi-resolution limiting magnitude map...

Can iterate endlessly to test every pixel in the field with simulated moons of varying magnitudes, and build up a hi-resolution limiting magnitude map...

Can iterate endlessly to test every pixel in the field with simulated moons of varying magnitudes, and build up a hi-resolution limiting magnitude map...

Then again, imagine if we could have thousands of people making millions of independent visual searches?

Welcome to the Zooniverse, where you can help astronomers explore the Universe

We need your help to classify… a task at which your brain is better than even the most advanced computer… you may even be the first person in history to see…

More than 250,000 people have taken part … within 24 hours of launch, the site was receiving 70,000 classifications an hour, and more than 50 million classifications were received by the project during its first year.

Having multiple classifications of the same object is important… we were able to prove that the classifications are as good as those completed by professional astronomers.

Thanks to the overwhelming response we realized we could ask much more. In the 14 months the site was up, Galaxy Zoo 2 users helped us make over 60,000,000 classifications.

Next “Zoo” ?

• Find-a-moon online activity; not a gimmick• Helps set limiting magnitudes• Small but enticing chance of discovery, e.g.

“Hanny’s Voorwerp”…the next Nix or Hydra… a post-Pluto KBO for New Horizons to visit?

• Best of both worlds: versatility of human eyeballs, with good statistics via brute force (many people instead of many CPU cycles)

• The tools and “standing army of thousands” already exists. They are hungry for a wider range of projects to do, thanks to the “Zooniverse”

NEXT ZOO ?

full frame sum clean