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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MPLDDZMZCNS5PGL3J2WMK763MLNGRI2S/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "MPLDDZMZCNS5PGL3J2WMK763MLNGRI2S",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/MPLDDZMZCNS5PGL3J2WMK763MLNGRI2S/",
    "sender": {
        "address": "clivew (a) zetnet.co.uk",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Clive Wallis",
    "subject": "[amsat-bb]  OSCAR-11 Report",
    "date": "2007-10-23T13:41:51Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "\n                    OSCAR-11 REPORT\n\n                   22 October 2007\n\nDuring the period 27 September to 22 October 2007 the satellite has been\nheard from 06 October to 08 October. The beacon switched on as expected, on\n06 October, but prematurely switched OFF sometime between 08 and 09\nOctober.  Signals were weaker than usual.\n\nThe on-board clock has continued to loose time. During the ten day OFF\nperiod it lost 72 minutes, and there was a further loss of 48 minutes\nduring the last ON period. When last heard the clock error was 69.97793\ndays slow.  The day of the week counter is unchanged with 0 representing\nMonday UTC.\n\nThe premature shutdown has probably caused the watchdog timer to reset,\nand start a new 20 day cycle.  If that has occurred then the beacon should\nresume transmissions around 29 October 2007.\n\nI am indebted to John N7ZL, John N3NKC, Thomas HB9SKA, and Peter ZL3TC, for\ntheir reports. Many thanks.\n\nThe satellite is  now in continuous sunlight and this will continue until\nthe start of November, when there will be a short eclipse season, lasting\nuntil around 07 January. However the maximum duration of the eclipses will\nonly be about 12 ninutes. At this level the satelite might just survive.\n\nJohn KD2BD has noticed a descrepancy between my eclipse predictions and\nthose from his Predict program. This could explain why the beacon didn't\nswitch on until mid September.  The main cause of the problem was due to\nthe use of old Keplerian elements.  In previous years the it had been\npossible to use elements which were many months out of date, with only\nminor effects on the eclipse predictions.  This year the orbit appears to\nbe more critical.  Different software also produces slightly different\nresults.  Many thanks John for your comments.\n\nThe current status of the satellite, is that all the analogue telemetry\nchannels, 0 to 59 are zero, ie they have failed. The status channels 60 to\n67 are still working. The real time clock is showing a large accumulated\nerror, although over short periods timekeeping is accurate to a few\nseconds per month.  The day of the month has a bit stuck at 'one' so the\nday of the month may show an error of +40 days for some dates.  The time\ndisplay has switched into 12 hour mode. Unfortunately, there is no AM/PM\nindicator, since the time display format was designed for 24 hour mode.\nMore data is required to determine exactly when the date changes.\n\nThe spacecraft computer and active attitude control system have switched\nOFF, ie. the satellite' attitude is controlled only by the passive gravity\nboom gradient, and the satellite is free to spin at any speed. When\ntelemetry was last received it showed that one of the solar arrays had\nfailed, and there was a large unexplained current drain on the main 14 volt\nbus. After 23 years in orbit the battery has undergone around 100,000\npartial charge/discharge cycles, and observations suggest that it cannot\npower the satellite during eclipses, or sometimes during periods of poor\nsolar attitude.\n\nThe watchdog timer now operates on a 20 day cycle. The ON/OFF times have\ntended to be very consistent. The average of many observations show this to\nbe 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor\nsolar attitude may result may result in a low 14 volt line supply, which\nmay cause the beacon to switch OFF prematurely, and reset the watchdog\ntimer cycle. When this occurs, the beacon is OFF for 20.7 days.\n\nThe Beacon frequencies are -\n\nVHF 145.826 MHz.  AFSK FM  ASCII Telemetry\n\nUHF 435.025 MHz.  OFF\n\nS-band 2401.5 MHz. OFF\n\nListeners to OSCAR-11 may be interested in visiting my website. If you need\nto know what OSCAR-11 should sound like, there is a short audio clip for\nyou to hear. There is an example of the latest telemetry received from the\nsatellite. The website contains an archive of news & telemetry data. It\nalso contains details about using a soundcard or hardware demodulators for\ndata capture.  There is software for capturing data, and decoding ASCII\ntelemetry.  The URL is www.users.zetnet.co.uk/clivew/\n\nIf you place this bulletin on a terrestrial packet network, please\nuse the bulletin identifier $BID:U2RPT138.CWV, to prevent duplication.\n\n73 Clive G3CWV   [email protected] (please replace xxxxx by g3cwv)\n",
    "attachments": []
}