3 ms·

The SR-71 carried a clock accurate to a hundredth of a second [1]. It used that, combined with current observed locations of the brightest stars in the field of

• DoctorOetker 8y ago
  it is possible to deduce location of the earth on its orbit around the sun, and hence the time by star transits: https://en.wikipedia.org/wiki/Transit_instrument https://en.wikipedia.org/wiki/Transit_instrument consider for example 2 very distant stars, and a closer star in the middle, and all of them in a plane perpendicular to the ecliptic. as the earth rotates, the closest star seems to move left/right with respect to the "vertical" defined by the more distant stars. from such a star transit you know the earth has just passed through the plane defined by these stars, and hence know the earth's position, hence the time. in the past catalogues for transits were optimized for human use, i.e. close to each other, ... but a modernized i.e. software solution should not need such proximity, and could make use of all the visible stars to make a more accurate assessment. I was kind of asking if there were any free open source software, it would be kind of neat to have an emergency laptop (with some optics) loaded with openstreetmap and astronomical positioning software, ...
  • rocqua 8y ago
    I might be off here, but it seems like resolution would be a real issue. The variation you are looking for has a period of 1 year. To get hour accuracy out of that you'd need to be able to distinguish 356*24 different relative positions of these stars. It seems to me like camera's aren't going to be supplying that kind of data.