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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/2HH56ULYEZ7UT5DEA3RKTUWV6ZUE6PG7/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "2HH56ULYEZ7UT5DEA3RKTUWV6ZUE6PG7",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/2HH56ULYEZ7UT5DEA3RKTUWV6ZUE6PG7/",
    "sender": {
        "address": "ok2gz (a) seznam.cz",
        "mailman_id": "0f843deae0134ca2951f3a00495168cd",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/0f843deae0134ca2951f3a00495168cd/emails/"
    },
    "sender_name": "ok2gz",
    "subject": "[amsat-bb] RS-44 orbit",
    "date": "2020-07-25T11:17:25Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Bob and Nico,\n\n  I want to add some info about this problem.\n\nIf You have the ARRL Satellite Handbook, see  page A-8 (Appendix A - \nSatellite Orbits).\n\nThere is Equation 13a, which give us the value - rate of change of \nargument of perigee in degrees per day.\n\nThe value for RS-44 with  current TLE data is   -2.3331333 degrees per day.\n\nA negative value means that the ARGP angle will be smaller tomorrow.\n\nFor example 180  degrees divided by -2.3331333 is approx. -77.1495471 days.\n\nSo, in 77.15 days the positions of the apogee and perigee will be swaped.\nAnd yet, if we have apogee in the best position for some rare qso with \nRS-44 transponder,  this situation will be repeated 2.366 times per year.\n\nMy calculation:\n360/2.3331333 = 154.2989\nand 365 days / 154.2989 is 2.366\n\nWith the same equation 13a  we can calculate the famous angle of 63.435 \ndegrees of inclination with zero drift as Nico says. This angle was used \nby the old Russian Molnia satellites at a time when it was still \ndifficult to reach a geostationary orbit.\n\nMy favorite FO-29 (now probably nice history) has Rate of change ARGP \n-2.573348 deg/day.\nYet, AO-91 with elliptical orbit (apogee 811.8 km /perigee 453.6 km) has \nRate of change ARGP  = -3.251476 degrees/day, so it takes -55.359 days \nfor exchange apogee and perigee positions..\n\nIt is very good to check the ARGP angle in the TLE data when working via \nelliptical orbiting satellites.\nFor example, for the qso between the eastern costs of the USA and \nEurope, we need an orbit height of approximately 950 km (for OK \nstations). FO-29has an apogee height of 1320.8 km, perigee 801.2 km. It \nwas not possible to make with the apogee in the wrong position\nQSO  USA-Europe...\n\n73\nJarda ok2gz\n\n\n\n\n\n-- \nThis email has been checked for viruses by AVG.\nhttps://www.avg.com\n",
    "attachments": []
}