On 2/25 Robert Fenske, Jr. posted the following URL http://spaceflightnow.com/shuttle/sts107/030225amos/visible.html which shows a remarkable image of the Columbia taken on Jan 28. The telescope that took the picture was on Maui at an observatory with a geodetic altitude of 3,058 meters. After much searching I finally located the observatory's coordinates. They are 156:15:29 West and 20:42:31 North. The UTC offset is -10 hours. I looked at the pictures and noticed what looked like low angle direct sunlight on the nose and other places and what appeared to be a low contrast illumination that looked like what would be caused by "earth shine" on the rest of the craft. That made me wonder if this picture was shot during daylight in what would have been, as seen from that observatory's altitude, a deep blue sky. On the picture itself is the following information: STS-107 28 Jan 2003 21:49Z. If the 21:49Z means 21:49 UTC the photograph was taken at 11:49 AM local time, right?? That time I do not think would not provide the correct angle of direct sunlight. In an attempt to double check the time that the picture could have been taken I looked up an archived TLE for the Shuttle that day and plugged it into my planetarium software. The TLE I used follows: 1 27647U 03003A 03028.25000000 .00065526 72042-5 11773-3 0 506 2 27647 39.0185 151.7164 0008975 103.0922 196.3708 16.00992267 1855 I ran a check and determined that the best possible pass over Maui was around 16:46:00 local time. At that time the shuttle was generally SE and was about 57 degrees in altitude; the sun was also at the proper angle for producing the glare that the image shows and the earth below would have been well illuminated. I welcome comments on my analysis. I may have made a serious error because this type of analysis is quite new to me. In doing the research I have learned much about the satellite tracking systems at the Maui site. They are impressive to say the least. If you are interested you can begin by doing a Google search for "MAUI SPACE SURVEILLANCE SYSTEM (MSSS) SENSORS" then click on "cache" otherwise you will get an error message. A system called GEMINI can produce images of satellites even in daylight conditions. There you have it! That must be what they did when photographing the Shuttle. Some of the telescopes are even fitted with lasers that can illuminate LEO satellites during the time they are in shadow! There is also a telescopic setup called the, "Contrast Mode Photometer (CMP)" that is very impressive. The article reads, "because of its large, twenty stellar magnitude dynamic range, the CMP is particularly useful for observing specular glint measurements from artificial satellites illuminated by the sun. An example of a photometric signature obtained from a geostationary satellite is shown in Figure 5. Much can be learned about the configuration and dynamics of an unknown satellite by studying the glints in CMP signatures. Uniform repetition of glints might indicate rotation of the object which can indicate that it is spin stabilized or has gone unstable. Motions and configuration can also be determined through analysis of the more slowly varying diffuse component of an optical signature." The manual for the AMOS telescope system is very informative too. It can be obtained here: http://www.maui.afmc.af.mil/AMOS/AMOS_UsersManual_02.pdf It's only 16MB and 117 pages long! :~) One last thing for any stereo enthusiasts. The last of the three visible light pictures of the shuttle can be stereofused with the first or second image to produce a crude 3D image. I placed the last image to the right of the other ones and used the cross-eyed method to see the third dimension. Clear skies! Tom Iowa USA ..... ----------------------------------------------------------------- To unsubscribe from SeeSat-L, send a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@satobs.org List archived at http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sat Mar 01 2003 - 02:29:23 EST