Sunday, February 03, 2008

NOSS 3-4, Lacrosse 5 oddity, and not every DCF-77 clock is the same... (updated)

This morning, unlike yesterday evening, it was reasonably clear. There was some haze in the sky, but conditions were good enough for decent observations. Targets were the ELINT sat USA 32 (88-078A), two of the NOSS 2-3 components (96-029C & E) and the NOSS 3-4 duo (07-027A & C). USA 193 (060-57A) stayed too low in the sky for my location this morning.

The NOSS 3-4 duo (07-027A & C) is still actively manoeuvering. I observed them on two consecutive passes this morning. Compared to their 08031.475 elsets they were 46-50 seconds late, indicating that they have moved up again between Jan 31 and early Feb 3.

The reason for this manoeuvering is that during their launch last year, the final stage of their rocket booster quit too early, and the payloads as a result entered into a too low orbit. Since that moment, they are gradually working themselves upward to their intended orbits, using their own onboard engines.

In my previous post I noted the purchase of a new DCF-77 clock, following the failure of my old trusted Oregon Scientific DCF-77 clock. Careful comparison to several other DCF-77 clocks however, reveiled that the new clock is 0.40 seconds early to other DCF-77 clocks. That was an unpleasant surprise. I ditched the clock and purchased yet a new one, which runs synchronous with other DCF-77 clocks I compared it too. Interestingly, this new clock was a cheap 7 euro one purchased in a large store chain here in Leiden (HEMA: clock name is "Portland"). The clock that runs 0.40s early (brand: Cresta) was much more expensive. So more expensive evidently not always translates to "more reliable".

As a result, my observations on the evening of Feb 1 need to be corrected by 0.40 seconds.

Those observations concern USA 32 again, and Lacrosse 5 (05-016A). I have the latter 2 seconds early and 0.6 degree off-track compared to elset 08027.73865531. However, this was a difficult observation during a short clearing, with clouds moving into the FOV almost right after the sat passed it, so I cannot rule out I made a mistake in the reference stars used.

Update: an 05-016A observation I made on the evening of Feb 3rd is in-line with elset 08027.73865531 again (delta T only 0.07s, x-track 4 arcminutes), so the Feb 1st result indeed must be the result of a mistake in reference stars used.

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