Message boards :
Nebula :
All in the timing, part deux
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David Anderson Send message Joined: 13 Feb 99 Posts: 173 Credit: 502,653 RAC: 0 |
Turns out that the changes described in my last post didn't completely work. First, the use of time entropy in the drifting RFI algorithm (see last post) was the right idea, but there were cases that actually were RFI but for which the entropy was very low, so we were failing to remove it. Dan W. pointed out some of these. I switched to a different approach where we divide each triangle into 10 time intervals; if signals are present in < 4 of these intervals, we don't count it as drifting. This fixes the cases that Dan found; hopefully it works in general. Second, there's the recurring issue of how to reward (i.e. boost the score of) multiplets whose signals are spread out across the whole range of times we observed that sky position. Or conversely how to penalize multiplets that consist of two signals a second apart. This is key to SETI@home - we're the only radio SETI project that looks for signals that recur over years and decades, and we need to maximize this advantage. The multiplet score includes a term called "nd_factor" (ND stands for "number of detections"; detections is what we used to call signals). Without going into mathematical detail:
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Tom M Send message Joined: 28 Nov 02 Posts: 5126 Credit: 276,046,078 RAC: 462 |
+1 A proud member of the OFA (Old Farts Association). |
Jon Golding Send message Joined: 20 Apr 00 Posts: 105 Credit: 841,861 RAC: 0 |
With these various iterations of Nebula, are you beginning to see consistent regions of the sky that get flagged as interesting for follow-up? |
rob smith Send message Joined: 7 Mar 03 Posts: 22539 Credit: 416,307,556 RAC: 380 |
a number of tables have been published giving the RA & DEC of areas covered and the signal found in them - one example of these tables is: https://setiathome.berkeley.edu/nebula/pixels.php?s6= Using one of the many on-line star maps you should be able to plot these locations and see hot-spot. Bob Smith Member of Seti PIPPS (Pluto is a Planet Protest Society) Somewhere in the (un)known Universe? |
Jon Golding Send message Joined: 20 Apr 00 Posts: 105 Credit: 841,861 RAC: 0 |
Thanks Bob I've seen these tables before for each new version of Nebula. However, I'd never taken the time to see if there are any regions that are consistently high scoring (which is the whole point of what Nebula does). Guess I was jumping ahead with my curiosity before any paper/announcement is made. Jon |
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