[Dennis]

Originally Posted by bojan

How far apart (in time) are the shots?

From Wiki:
Radial velocity (Rv)−3.2[8] km/s


Proper motion (μ)
RA: −714.590[2] mas/yr
Dec.: −1036.80[2] mas/yr

Hi Bojan

Thanks for that.

I do not know the source details for DSS images downloaded via Sky Safari Pro on my wife’s iMac but Wiki writes:

“The term Digitized Sky Survey originally referred to the publication in 1994 of a digital version of an all-sky photographic atlas used to produce the first version of the Guide Star Catalog”

See also:

https://irsa.ipac.caltech.edu/data/DSS/

Which indicates that the source data for the digitisation program are either from the UK Schmidt or the Oschin Schmidt (Palomar) telescopes.

My Mewlon image was taken on 7th April 2019, so assuming 1994 for the DSS Plates, the gap is around 25 years, although some of the original photographic plates come from Palomar Surveys in the 1950's.

Cheers

Dennis