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Chris,

I’m only a newbie on this board, but might I be allowed to comment on the specific ISS suggestion please?

It looks from the data on the Heavens-Above site that ISS can reach a maximum altitude of about 69 degrees when seen from central England so could fit the “high in the sky” description.  However I think from there it would always appear to be moving right to left in the sky rather than left to right.  I’m to the North of the maximum latitude that ISS reaches (about 51.64 degrees) and I know David is as well.

If ISS data was to be compared from one day to another I believe that – at the moment -comparing ISS data for April 10^th would be more useful than data for the 9^th, assuming David saw the object on the 8^th. In general a given day’s ground track of a satellite can be different to the next day. I think it’s because a satellite doesn’t necessarily make an integer number of orbits in the 24 hours.

At the moment, the ISS’s ground tracks seem to be fairly similar at 48 hour intervals. From where I live there are ISS passes predicted on Heavens-Above for 15:20:05 on the 9^th April, at 15:22:28 on the 11^th, and 15:24:47 on the 13^th but nothing around those times on the intermediate 10^th and 12^th.  I’m guessing the approximately “48-hour cycle” at the moment may come from the number of orbits ISS makes in 24 hours being close to a “half-number”, 15.4872 orbits at present.

Regards,

Adrian