>But IMHO the most pronounced effect on BSTAR change is with the switch >between XPOP and LVLH orientation of ISS!? Try to correlate the BSTAR >changes with those orientation changes. From the April 2 report: >For the proper pointing of the GFI-1 Relaksatsiya spectrometer, station >attitude, still in LVLH (local vertical/local horizontal), was commanded >to experiment attitude at 3:35am, after control handover to the Russian >segment (RS) at 3:25am. Later, at 4:05am, the station was maneuvered to >XPOP (x-axis perpendicular to orbit plane) attitude, where it will remain >until 4/21 (after Soyuz 8S docking). So the station has been in XPOP attitude for the last 18 days. During this time there have been relatively large changes in drag. Solar data from http://www.sec.noaa.gov/ftpdir/indices/DSD.txt Product: Daily Solar Data DSD.txt Issued: 1425 UT 20 Apr 2004 # # Prepared by the U.S. Dept. of Commerce, NOAA, Space Environment Center. # Please send comments and suggestions to SEC.Webmaster@noaa.gov # # Last 30 Days Daily Solar Data # # Sunspot Stanford GOES12 # Radio SESC Area Solar X-Ray ------ Flares ------ # Flux Sunspot 10E-6 New Mean Bkgd X-Ray Optical # Date 10.7cm Number Hemis. Regions Field Flux C M X S 1 2 3 #--------------------------------------------------------------------------- 2004 03 21 111 65 320 0 -999 B1.6 4 0 0 3 0 0 0 2004 03 22 116 87 260 1 -999 B2.0 2 0 0 1 1 0 0 2004 03 23 118 110 380 0 -999 B2.1 2 0 0 2 0 0 0 2004 03 24 120 109 450 2 -999 B2.7 4 1 0 2 0 0 0 2004 03 25 127 128 650 1 -999 B3.8 5 1 0 3 0 0 0 2004 03 26 124 100 670 0 -999 B2.2 0 0 0 0 0 0 0 2004 03 27 128 129 690 4 -999 B3.4 5 0 0 1 0 0 0 2004 03 28 129 125 800 1 -999 B3.8 4 0 0 1 0 0 0 2004 03 29 129 169 750 0 -999 B3.4 8 0 0 6 0 0 0 2004 03 30 127 121 540 0 -999 B3.1 12 0 0 9 0 0 0 2004 03 31 121 95 560 0 -999 B3.2 6 0 0 5 1 0 0 2004 04 01 113 100 540 1 -999 B2.1 1 0 0 0 0 0 0 2004 04 02 108 99 470 0 -999 B1.7 0 0 0 0 0 0 0 2004 04 03 107 68 440 0 -999 B1.5 0 0 0 0 0 0 0 2004 04 04 109 69 490 0 -999 B1.5 1 0 0 1 0 0 0 2004 04 05 109 85 520 1 -999 B1.7 0 1 0 0 1 0 0 2004 04 06 101 66 280 0 -999 B1.4 1 1 0 3 0 0 0 2004 04 07 98 57 210 1 -999 B1.1 0 0 0 0 0 0 0 2004 04 08 94 33 160 0 -999 B1.3 3 0 0 1 0 0 0 2004 04 09 90 18 120 0 -999 A6.9 1 0 0 1 0 0 0 2004 04 10 88 20 150 0 -999 A7.5 0 0 0 1 0 0 0 2004 04 11 90 16 90 0 -999 A6.5 3 0 0 0 1 0 0 2004 04 12 91 37 140 1 -999 A8.9 3 0 0 1 0 0 0 2004 04 13 93 41 130 1 -999 A8.6 0 0 0 0 0 0 0 2004 04 14 95 69 230 2 -999 B1.0 0 0 0 1 0 0 0 2004 04 15 97 60 180 0 -999 B1.1 0 1 0 2 0 0 0 2004 04 16 97 53 200 1 -999 B1.0 0 0 0 0 0 0 0 2004 04 17 98 55 130 0 -999 B1.0 1 0 0 0 0 0 0 2004 04 18 109 92 310 1 -999 B1.3 0 0 0 0 0 0 0 2004 04 19 113 108 440 0 -999 B1.7 2 0 0 2 0 0 0 The solar flux data shows a strong maximum for about 20 days ago and increasing activity recently. >'Also called the radiation pressure coefficient (or BSTAR), the parameter is >another drag term in the SGP4 predictor.' BStar is directly related to the drag term. Since the SGP4 model assumes a static atmospheric model and a definition of perigee height that does not depend on the actual argument of perigee, whenever the real drag term changes, the BStar term changes by the same factor. Mike McCants ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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