Satgen 473 Ao10 Visual Inspection by GM4IHJ (BID SGEN473) 1998-04-18 In Satgen 472 mention was made of the difficulty of knowing what is happening to Ao10 Oscar 10, since it ceased to be spin stabilised. Noting that, with no telemetry , the only guides we have are the unmodulated beacon signal , and perhaps, the possibility of getting good visual information by observing it with a telescope. Reactions to the suggestion of telescope observation have been varied. One Astronomy type has even suggested that it is impossible. But several operators who regularly watch satellites have confirmed that there is no reason why we cannot do this. In fact it seems to be a case of how much experience you have of visually tracking satellites. With several operators reporting no trouble with geostationary sat watching, provided you know what you are doing, and follow the ground rules. Which are :- a. Appreciate that Ao10 carries no lights , but does reflect quite a lot of sunlight. b. Ao10 is a much smaller target than say Mir , but that is no obstacle. Very small targets such as Uosat 11 are visible in good conditions, and are trackable using binoculars even by visually limited observers such as GM4IHJ. Ao10 does of course go much further out from the earth than the LEO sats but there is no problem following sats right out to the geostationary orbit with good tracking data and a telescope of 6 to 8 inches diameter. c. You will not see Ao10 in daylight . It will be lost against the bright sky background. But you will see it at night if you wait until an hour or so after sunset and let the sky get clear and completely dark. Then you should see Ao10 reflecting sunlight, noting that even at night it rarely goes into eclipse darkness behind the earth. d. The various surfaces of Ao10 have different reflection properties, so a few minutes watching or CCD tracking should give some useful data on how it is spinning and or tumbling in space. e. Ao10 is a slow moving target , so it is much easier to acquire and track than the LEO sats which move at least 15 times faster. NASA 2 line elements are more than adequate for the task. f. Ao10 does go a long way from earth . Its distance varies by a factor of about 1 to 10 as it goes from perigee to apogee. So the amount of light it reflects can vary by 100 to 1 as it moves outwards. What sort of telescope you use depends on just what is available. It is much easier to set up a telescope with an Alt/Azimuth mounting, than it is to set up an Equatorially mounted telescope, for satellite tracking. But either can be used successfully on slow moving Ao10. You can of course help matters by finding an observation site clear of the light pollution becoming all too familiar in our cities and towns, and it does help if you live in clear dry air Arizona rather than misty overcast Scotland . Give it a try, if you can get the equipment, and pay no attention to those who say it is too difficult. Indeed far out Geosat watching has become quite a sport recently . For, contrary to some noisy "expert" opinion, geosats are never stationary in your sky. In fact they dance around in some very interesting patterns - about which more next week.