Saturday, 11 March 2006

Lacrosse 5 disappearance trick & timing problem gone?

I observed Lacrosse 5 doing its disappearance trick this evening. I think this explains my non-observation of March 6th in combination with Peter Wakelin seeing it easily only minutes before.

Saw it making a nice pass here around 19:11-19:15 UTC (obtained two good trail photographs during this pass), easily visible at mag. +1.5 to +1.0 or so. Just after the last of my two exposures ended (19:14:51 UTC), and well before it should get into eclipse, it suddenly disappeared from naked eye view, within maybe 3-5 seconds so very fast. This was at about 19:15:00-19:15:10 UTC or so.

I think this might happened at March 6th as well, just before I started to look for it.

I obtained two pictures during this pass, hence 4 points. One point (point two of photograph 1) was clearly anomalous (delta T +0.35), the other three are very consistent both internally and with Mike Mccant's latest elset for Lacrosse 5. The -0.3s delta T deviation of the previous week (see the previous post) has gone, even though I did not make an extra time correction!

Pierre Neirinck noted that Lutz Schindler, who also used the DCF77 time signals, had a similar time deviation last week. So I am now starting to believe that the problem was not with the camera at all: but with the Frankfurt time signals!

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