Comments on: Meteor Dreams http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/ Astronomers look up meteorite hunters look down Thu, 09 Feb 2012 04:41:12 +0000 hourly 1 http://wordpress.org/?v=3.0.4 By: Marc Fries http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-414 Marc Fries Thu, 13 Aug 2009 18:01:12 +0000 http://www.mikesastrophotos.com/?p=633#comment-414 No worries; tongue-in-cheek doesn't show up well in email and blog comments. The reason I haven't assigned a probability ellipse or what-not to the fall location is that the uncertainties themselves aren't very well quantifiable. Assessing all the variations in pointing direction, video image distortion, eyewitness account variation, etc etc etc would probably be more time consuming than just searching the ground itself. Plus, I wouldn't put much stake in the result just because it is so complex. The important point to take from the wind-drift model is this - winds at the time tend to "push" any meteorites to the east of the fall line, apparently by about a half-mile (almost a km) for the 100-1,000g masses. The actual point on the map is a guideline only, not some sort of pirate-map X. No worries; tongue-in-cheek doesn’t show up well in email and blog comments. The reason I haven’t assigned a probability ellipse or what-not to the fall location is that the uncertainties themselves aren’t very well quantifiable. Assessing all the variations in pointing direction, video image distortion, eyewitness account variation, etc etc etc would probably be more time consuming than just searching the ground itself. Plus, I wouldn’t put much stake in the result just because it is so complex. The important point to take from the wind-drift model is this – winds at the time tend to “push” any meteorites to the east of the fall line, apparently by about a half-mile (almost a km) for the 100-1,000g masses. The actual point on the map is a guideline only, not some sort of pirate-map X.

]]> By: Mark http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-402 Mark Wed, 12 Aug 2009 15:23:18 +0000 http://www.mikesastrophotos.com/?p=633#comment-402 ...search regions rather than trying to search in a more "statistical" way - searching more widely along sample routes, for example. I'm not faulting your computer program, but it would be nice to see a list of assumptions that have helped make your predictions and to know that, for example, if one input is tweeked, say, one degree, how will that affect the outcome of the prediction? Is the error circle a matter of feet, miles, or tens of miles? Is the error zone shaped like an ellipse, a circle, or what? What happens to the outcome, for example, if Hankey's photo is not of the main body but is a large chunk that has broken off on its own? How sensitive are your models to, say, a 5 or 10 percent change in aerodynamic drag coefficients? The corn belt around Lancaster is vast, littered with iron, and what is not an impenetrable sea of crops, dairy cows, and dung is a dense craggy forest littered with slag piles and spent shotgun shells. Not counting Antarctica, I'm going to bet Lancaster county is one of the most difficult places in the world to find a meteorite, so your computer model is essential - and I thank you for your stellar efforts on this. My only gripe is that the fundamental nature of the data needs to be explained to the general public so they understand what these lines and map points really mean. Because of your familiarity with scientific data, you know instinctively that these lines only represent the center of a blob, etc., but the rest of us are prone to thinking they are really, truly the end of a rainbow. I think it would help the situation if we had a error bar here and there. Thanks again, and my apologies if I sounded too harsh about your being off by a couple inches. :-) …search regions rather than trying to search in a more “statistical” way – searching more widely along sample routes, for example. I’m not faulting your computer program, but it would be nice to see a list of assumptions that have helped make your predictions and to know that, for example, if one input is tweeked, say, one degree, how will that affect the outcome of the prediction? Is the error circle a matter of feet, miles, or tens of miles? Is the error zone shaped like an ellipse, a circle, or what? What happens to the outcome, for example, if Hankey’s photo is not of the main body but is a large chunk that has broken off on its own? How sensitive are your models to, say, a 5 or 10 percent change in aerodynamic drag coefficients? The corn belt around Lancaster is vast, littered with iron, and what is not an impenetrable sea of crops, dairy cows, and dung is a dense craggy forest littered with slag piles and spent shotgun shells. Not counting Antarctica, I’m going to bet Lancaster county is one of the most difficult places in the world to find a meteorite, so your computer model is essential – and I thank you for your stellar efforts on this. My only gripe is that the fundamental nature of the data needs to be explained to the general public so they understand what these lines and map points really mean. Because of your familiarity with scientific data, you know instinctively that these lines only represent the center of a blob, etc., but the rest of us are prone to thinking they are really, truly the end of a rainbow. I think it would help the situation if we had a error bar here and there. Thanks again, and my apologies if I sounded too harsh about your being off by a couple inches. :-)

]]> By: Mark http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-401 Mark Wed, 12 Aug 2009 14:35:12 +0000 http://www.mikesastrophotos.com/?p=633#comment-401 Marc, no disrespect intended here. Just kidding around about the rocker. But it would be nice if we had an error estimation along with your predictions. The general public, with whom you and Hankey are generously sharing your data, have no idea that computer models usually come with a disclaimer of some kind, "this data is good plus or minus X number of feet or miles or whatever". I think many people have been treating the results of these computer models as though they are more accurate than they really are and it's possible that this kind of confusion is translating into field workers focusing too narrowly upon small sear Marc, no disrespect intended here. Just kidding around about the rocker. But it would be nice if we had an error estimation along with your predictions. The general public, with whom you and Hankey are generously sharing your data, have no idea that computer models usually come with a disclaimer of some kind, “this data is good plus or minus X number of feet or miles or whatever”. I think many people have been treating the results of these computer models as though they are more accurate than they really are and it’s possible that this kind of confusion is translating into field workers focusing too narrowly upon small sear

]]> By: Marc Fries http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-398 Marc Fries Wed, 12 Aug 2009 05:21:24 +0000 http://www.mikesastrophotos.com/?p=633#comment-398 Care to elaborate? Care to elaborate?

]]> By: Mark http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-397 Mark Wed, 12 Aug 2009 03:04:27 +0000 http://www.mikesastrophotos.com/?p=633#comment-397 My rocker comment was aimed at Fries. Oops, guess I missed. Maybe I'm using the same software he's using to pinpoint this meteorite. Ha! :-) My rocker comment was aimed at Fries. Oops, guess I missed. Maybe I’m using the same software he’s using to pinpoint this meteorite. Ha! :-)

]]> By: Mike Hankey http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-396 Mike Hankey Wed, 12 Aug 2009 02:41:16 +0000 http://www.mikesastrophotos.com/?p=633#comment-396 people have been telling me that my whole life. its worked out pretty good so far. :) people have been telling me that my whole life. its worked out pretty good so far. :)

]]> By: Mark http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-393 Mark Tue, 11 Aug 2009 22:05:29 +0000 http://www.mikesastrophotos.com/?p=633#comment-393 I think you're off by a couple inches. Your rocker, that is. :-) I think you’re off by a couple inches.

Your rocker, that is. :-)

]]> By: Marc Fries http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-392 Marc Fries Tue, 11 Aug 2009 15:24:34 +0000 http://www.mikesastrophotos.com/?p=633#comment-392 That tree does look like it needs the attention of a bulldozer, though - a 10 kg meteorite at terminal velocity would have done the trick pretty thoroughly! That tree does look like it needs the attention of a bulldozer, though – a 10 kg meteorite at terminal velocity would have done the trick pretty thoroughly!

]]> By: Marc Fries http://www.mikesastrophotos.com/baltimore-pa-meteor/meteor-dreams/comment-page-1/#comment-391 Marc Fries Tue, 11 Aug 2009 15:21:53 +0000 http://www.mikesastrophotos.com/?p=633#comment-391 Ugh - I did NOT say there was a 10kg meteorite right there! I plotted the fall locations due to wind deflection of a range of meteorite masses from 0.1g up to 10,000g in 10x steps. That defines the expected shape of the strewn field and makes a guess at the location, but it doesn't necessarily mean that there is a 10kg meteorite in there. (I don't think hunting for 0.1g meteorites is a good use of time, either!). The important point is how far off the ballistic fall line the ~1,000 down to 10g fragments should fall - knowing this simplifies the search quite a bit. Good luck and keep us posted! Ugh – I did NOT say there was a 10kg meteorite right there! I plotted the fall locations due to wind deflection of a range of meteorite masses from 0.1g up to 10,000g in 10x steps. That defines the expected shape of the strewn field and makes a guess at the location, but it doesn’t necessarily mean that there is a 10kg meteorite in there. (I don’t think hunting for 0.1g meteorites is a good use of time, either!). The important point is how far off the ballistic fall line the ~1,000 down to 10g fragments should fall – knowing this simplifies the search quite a bit. Good luck and keep us posted!

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