Last Saturday I followed through with an idea I've had for a long time. That is, coordinate with someone else the observing of one bright iridium flare across a large distance. To determine where a specific flare would go after it passed my place (moving south in the case) I used Heavens-Above and Google Earth. The ground track was positioned through the Midwest US. The flare I was interested in would occur off iridium 13 at 18:32:40 my local time on Nov 22, 2006. The ground track for the satellite itself and the light beam are not in the same place (obviously) and are not parallel (at least at this time), I discovered. My technique was crude but it worked. [I would appreciate input as to a service that provides the flare ground track ready made.] I used the Heavens-Above satellite ground track to determine how far over my observing position was from it. Using that information I determined a position equally west of the ground track but near the Gulf of Mexico, more than 800 miles south of me. I used Google Earth to get a coordinate for that area then used Heavens-Above to see if the same flare was visible down there. The position was too far west so, using Heavens-Above I manually moved over in longitude step by step. After a few adjustments I found a coordinate which would see the maximum brightness of the same flare as I would see more than three minutes before. Using the two exact coordinates I drew a line through each on Google Earth and upon close inspection I found that the line crossed through the east side of Baton Rouge, LA. A jpg showing the two ground tracks for this event can be found here: http://img.geocaching.com/cache/log/d15a4bbf-177b-4e36-8c3f-8048b509b430.jpg The challenge was to contact someone in Baton Rouge there that would be willing to watch for the same flare some 3 minutes 41 seconds after I saw it. Alas, I knew of a way. I belong to a large organization of people that use GPS receivers to play a game called geocaching. Most players hide what are called geocaches. Each cache is listed at geocaching.com: http://www.geocaching.com/ I only needed to look for geocaches in the Baton Rouge area. There are plenty! Once I found the large list I perused the profiles of the geocache owners. With that done I sent out an e-mail to at least six people. I got all positive responses, one from a high school physics teacher that got my invitation as a forward from one of the geocachers. I know of two that watched last night with me; one was the teacher. [Most of the others were traveling of turkey eve.] This was a new experience for both participants. As the time approached for me last night, I got on my cell phone and called both guys in Louisiana. But beginning about a minute before maximum for me I talked to only one. I began a blow by blow account telling him what I was seeing. Then after I saw it, more than 3.5 minutes later him I gave him a heads up. He accidentally missed it but his son and others saw it. He looked up trying to see it ahead of the flare but the light shone about 34 degrees above his south horizon. He knows what to do next time however. Next Monday we (and even more participants) hope to repeat this scenario with Iridium 52. Here is a quote of what the physics teacher saw. "WE SAW IT! It was right on schedule; I clocked max brightness at 18:36:20. According to HA, we were 7.4 km to the east of the track with an estimated -5 magnitude and one second ahead of the predicted time. It was plenty bright. My kids loved it and now my son is Googling Iridium on his own to find out more. Cool. Our position tonight was approx. 30.405°N, 90.913°W. Now that I understand it better, we'll get dead on the track next time for max brightness. Thanks for sharing this with us. Also, I'd love to hear more about your satellite tracking curriculum some time. Thanks, Bruce" One thing I didn't mention was that I followed the ground track of the flare northward from Baton Rouge looking for another town that it crossed. I saw one in Missouri. When I zoomed in I discovered, to my surprise, that it passed within a mile of my niece's place in Rolla!!!! What are the odds? She would have participated in this event too had she not been on her way to Waterloo for turkey dinner. Maybe next time. Here is a jpg showing the flare. I added important information to it to help those that are going to look at another one next Monday to know what to expect. http://img.geocaching.com/cache/log/4160281f-3236-47f0-bc21-3c9c97e5ac56.jpg ****I have a question; will the same flare that occurs for me occur for Baton Rouge off and on in the future? I am thinking that because of the inclination of the orbital plane and our coordinates on the Earth that this will occur regularly. The details of the flare for me and Baton Rouge follows. Iridium 13 1 24840U 97030E 06325.11076316 .00000026 00000-0 21253-5 0 4797 2 24840 086.3965 163.8844 0002235 080.0002 280.1456 14.34219711493536 Approximate distance between the two locations: 830 miles. Approximate time between the two locations: 3 min 41 sec My Location: My computer [Waterloo, IA] (42.4736°N, 92.3603°W) Local Time: Central Standard Time (GMT - 6:00) Date * Local Time * Intensity * Alt. * Azimuth * Satellite 22 Nov * 18:32:40 * -7 * 34° * 163° (SSE) * Iridium 13 Their Location: East side of Baton Rouge, LA (30.4510°N, 91.0000°W) Local Time: Central Standard Time (GMT - 6:00) Date * Local Time * Intensity * Alt. * Azimuth * Satellite 22 Nov * 18:36:21 * -7 * 31° * 170° (S )/Iridium 13 The next flare that I will try to share with them (from Iridium 52) will be on 7t Nov at 18:15:07 their time. Happy Turkey day all those in the US! Tom Iowa USA PS I am currently teaching the satellite observing curriculum I created. One of my students showed up and observed the event with me. He will be getting some extra credit! ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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