WEBVTT 00:00.100 --> 00:00.933 All right. 00:00.933 --> 00:02.870 - Hi everyone, my name is Dr. Rachel Mattson, 00:02.870 --> 00:04.890 and I work here at USNO, 00:04.890 --> 00:07.219 in the Celestial Reference Frame department. 00:07.219 --> 00:09.350 And I am one of the people, who gets to use 00:09.350 --> 00:13.320 the 26 inch-telescope that you just learned about. 00:13.320 --> 00:14.280 One of the projects 00:14.280 --> 00:16.450 or the main project, that we use that telescope for 00:16.450 --> 00:17.400 is double stars, 00:17.400 --> 00:18.990 observing double stars. 00:18.990 --> 00:22.680 And a double star is any star that basically when you look, 00:22.680 --> 00:24.240 and see one in the night sky, 00:24.240 --> 00:26.320 there's another one right there next to it. 00:26.320 --> 00:28.110 And some of these are just 00:28.110 --> 00:29.060 an optical illusion. 00:29.060 --> 00:31.350 They look right next to each other in the sky, 00:31.350 --> 00:32.500 but they aren't necessarily 00:32.500 --> 00:33.810 have anything to do with each other. 00:33.810 --> 00:34.700 But there are also ones 00:34.700 --> 00:35.970 that are actually physically bound. 00:35.970 --> 00:37.770 They actually orbit around each other, 00:37.770 --> 00:39.170 and those are called binaries. 00:39.170 --> 00:41.500 And so we monitor specifically 00:41.500 --> 00:43.440 either ones, but specifically binary stars, 00:43.440 --> 00:46.750 because we are looking for the motion. 00:46.750 --> 00:50.460 Because if you are using a star for navigation, 00:50.460 --> 00:52.360 for star track or something like that, 00:52.360 --> 00:54.490 if you are looking at this kind of central blob, 00:54.490 --> 00:56.820 if there's actually two stars or more in there, 00:56.820 --> 00:58.350 you are actually 00:58.350 --> 01:00.770 that blob is going to move around in a certain way. 01:00.770 --> 01:02.760 And so by observing these double stars, 01:02.760 --> 01:04.465 we can actually look and see 01:04.465 --> 01:06.760 where both of the two stars, 01:06.760 --> 01:08.000 in there are, 01:08.000 --> 01:10.490 as well as actually learn about their orbits. 01:10.490 --> 01:12.107 If they rotate around each other. 01:12.107 --> 01:14.700 And this can help with understanding motion 01:14.700 --> 01:17.280 of how that center of light of the star is going to change, 01:17.280 --> 01:20.020 and be able to predict that and measure that. 01:20.020 --> 01:21.040 And so, 01:21.040 --> 01:22.060 one of 01:22.060 --> 01:24.520 so essentially the way we take data here is 01:24.520 --> 01:26.420 we take really really fast images 01:26.420 --> 01:28.650 in this process called speckle imaging. 01:28.650 --> 01:32.700 And so this image here on the screen on the left 01:32.700 --> 01:35.440 is actually what our data actually looks like. 01:35.440 --> 01:36.470 And you can see, 01:36.470 --> 01:37.650 there are two things stars here 01:37.650 --> 01:40.120 but they're very kind of blurry and blob 01:40.120 --> 01:42.150 and that's the motion of the atmosphere. 01:42.150 --> 01:43.850 And so when there's two stars like this 01:43.850 --> 01:45.240 well we can see them 01:45.240 --> 01:46.370 in order to 01:46.370 --> 01:48.090 measure the separation between them 01:48.090 --> 01:50.210 and watch them move around each other over time, 01:50.210 --> 01:51.563 which can be decades, 01:51.563 --> 01:52.747 it can be hundreds of years, 01:52.747 --> 01:53.580 thousands of years 01:53.580 --> 01:57.070 but we can still track that motion slowly over time. 01:57.070 --> 01:57.903 But as we, 01:57.903 --> 01:59.288 so we can take this data 01:59.288 --> 02:00.970 and we 02:00.970 --> 02:02.430 kinda can use a map 02:02.430 --> 02:06.240 and various techniques to kind of overcome the atmosphere. 02:06.240 --> 02:07.670 And rather than 02:07.670 --> 02:09.210 seeing these two stars that can sometimes 02:09.210 --> 02:10.050 be blurred together 02:10.050 --> 02:12.280 we can actually measure them 02:12.280 --> 02:14.850 and be able to separate them out very clearly. 02:14.850 --> 02:16.510 And so this image over here, 02:16.510 --> 02:17.880 is once we had taken 02:17.880 --> 02:19.747 use a technique called fornia transform 02:19.747 --> 02:22.566 to actually look at the two stars 02:22.566 --> 02:25.890 essentially do some maths and then image processing 02:25.890 --> 02:28.560 and come up with this image over here on the right. 02:28.560 --> 02:30.270 And it looks like there's three stars. 02:30.270 --> 02:32.400 That's just because there's 02:32.400 --> 02:33.680 you can have the, 02:33.680 --> 02:35.900 in the map, you can have the star on either side, 02:35.900 --> 02:37.270 but you can see the central star here 02:37.270 --> 02:39.260 and very clearly one on either side. 02:39.260 --> 02:40.350 And you can use some other techniques 02:40.350 --> 02:43.073 to figure out which is the actual real companion. 02:44.010 --> 02:44.843 You can see this is 02:44.843 --> 02:47.125 and we can then measure the separation between those stars 02:47.125 --> 02:49.170 and watch them move over time. 02:49.170 --> 02:51.093 And the difference in light for them. 02:52.410 --> 02:54.290 We'll also show you 02:54.290 --> 02:55.810 here's another example. 02:55.810 --> 02:59.320 Again, here's the actual image that we would see, 02:59.320 --> 03:00.410 here on the left 03:00.410 --> 03:02.610 and this time you can still see those blurry 03:02.610 --> 03:04.460 potentially spot speckles, 03:04.460 --> 03:06.300 what the technique is named after, 03:06.300 --> 03:07.600 but you can't actually detect 03:07.600 --> 03:09.870 that there are two separate stars in there. 03:09.870 --> 03:11.060 And that's because it's a very 03:11.060 --> 03:13.200 it's an even closer double star 03:13.200 --> 03:15.180 or binary star system. 03:15.180 --> 03:17.250 But if you look over here on the right, 03:17.250 --> 03:20.330 you can see that when we collect all this data 03:20.330 --> 03:21.201 summit together 03:21.201 --> 03:22.223 and, 03:23.990 --> 03:25.550 process that you can now 03:25.550 --> 03:26.470 see that separation 03:26.470 --> 03:28.590 you can see those separate companions. 03:28.590 --> 03:29.980 And so that's essentially what we do here 03:29.980 --> 03:32.980 is try to resolve these binary stars 03:32.980 --> 03:33.870 these double stars, 03:33.870 --> 03:35.950 as well as measure 03:35.950 --> 03:37.940 ones with larger separations over time 03:37.940 --> 03:39.010 to be able to track them. 03:39.010 --> 03:40.340 And we have a catalog 03:40.340 --> 03:42.600 known as the Washington double star catalog. 03:42.600 --> 03:44.510 That is this list 03:44.510 --> 03:46.740 of hundreds of thousands of double stars 03:46.740 --> 03:48.850 that we keep track of here at the observatory. 03:48.850 --> 03:49.750 For star trackers, 03:49.750 --> 03:52.410 as well as stronger than anyone else, 03:52.410 --> 03:54.197 and the DOD needs them.