Archive | April 2012

What’s the word? Follow-ups! (and more)

We haven’t posted an update since March 25th and one volunteer pointed that out to me in a message and then asked: “What’s the word?” Well, it’s “follow-ups”… mostly.  We’re finally going to start testing live follow-ups next week. We’ll be doing the testing in the background at first and until we’re certain that it’s working properly, you won’t be able to tell that we’re doing it and the “Followups” counter on your profile will remain zero. Once we’re sure it’s working, we’ll start updating the follow-up counters and let you know anytime a follow-up gets to a certain level. Early next week, we’ll also go live with some subtle, but very important changes: We’ll improve the waterfall display processing and we’ll be adding simulated ET signals. Read on…


Being able to do follow-ups is a unique and exciting SETILive capability. If  enough users mark a signal that appears in only one waterfall diagram (and therefore a potential ET candidate), the ATA telescope can be commanded to immediately go back to collect and send us more data from that target so we see if it still looks like ET through our usual marking. If it still shows up in the same single beam, a second followup will be triggered and then basically “rinse and repeat” as long as it continues to look potentially ET. Anyone classifying signals when this happens will be getting the follow-up waterfalls for classifying as well.

When they are enabled, tested, and fully active with live notifications (hopefully next week), we expect first follow-ups to happen pretty often as you might expect since single-beam signals are not that unusual. Terrestrial signals can often appear in one beam since the amount of signal that leaks into each beam varies quite a bit and if the signal is weak, it might not be strong enough for us to see it leaking into two of the beams. The leakage can change quite a bit as the ATA adjusts its beams to track the celestial sources and as the terrestrial source (an airplane, satellite, etc. ) moves with respect to the ATA. So, if a terrestrial source happened to look ET in one set of waterfalls, it likely won’t look that way in the next set we get several minutes later when the geometry has changed between the ATA and the RFI source. So, most followups won’t go past the second level and we won’t be notifying you that a follow-up is in progress unless it survives the second set of markings. At that point you’ll know that we’re starting to track a potential ET and that will be quite exciting even though it’s very unlikely to continue to pass the following ET tests. If it does… well, now that could get very exciting.

Waterfall Changes and Simulated ET Signals

We’ll be randomly adding simulated ET signals so that we can measure our detection capabilities. As soon as you finish with a classification having an artificial signal, we’ll let you know where the signal was on the waterfall. In order to make this measurement more consistent and useful and to improve your ability to see weak signals in general, we’ll also change the waterfall processing and display to give them a more consistent brightness scale. It should improve your ability to make out very weak signals even when there’s some stronger RFI there too.

The main thing you might notice with the new waterfall processing is that the background noise pattern of random bright and dim spots will be more consistent and a bit more “filled in”. We hope this will help you pick out weak signals better and more often. It might even help reduce our tendency to see signal patterns in the noise – I’m not sure about that, though. Part of this improvement comes from keeping bright signals from causing the background to get dimmer. A side benefit is that the dark banding caused by strong signals going bright then dim should be less severe. I already know that you’ll probably see some new artifacts in the noise background that the old processing took out and we encourage you to point these and other things out in Talk as you did with the old processing, especially if it makes classification difficult. When it goes live, I’ll create a new Featured Topic on Talk for you to post any comments about these display changes and the artificial ET signals.

The statistics we collect on your classification of these artificial signals in the presence of terrestrial RFI signals will eventually become part of a peer-reviewed and published scientific paper. So, it’s important for you to continue to make your best effort at marking all signals in each waterfall as well as those that might be ET. We need to know what else was in the waterfall to properly measure our collective detection capability in the presence of a variety of RFI signals.

Thanks for your continued participation and I hope you look forward to the SETILive going to the next level with live follow-ups as much as we do.

Lou Nigra

SETILive Science Team