Talk:Ejnar Hertzsprung

"together with Russell"
I thought they didn't even know each other. LightSpeed (talk) 07:50, 16 December 2014 (UTC)

More detail on the measurement of Cepheid parallax?
I've been looking for more detail on how Cepheids were originally calibrated. In particular I would like to know:

1) Which Cepheids did Hertzsprung obtain a parallax for? I read it was 13, but that is the closest I have got to finding out which ones.

2) What equipment did he use? I think it was the 60 inch Hale telescope at the Mt Wilson Observatory, but I'd be interested to know if this is the case.

3) More details of his technique. The article says "statistical parallax", is that the same as Spectroscopic parallax? If so it is very different to Stellar parallax and that would explain something I have been puzzling about for some time, which is why modern space telescopes are having so much trouble with the stellar parallax of Polaris (the closest Cepheid) if Cepheids were successfully calibrated a hundred years ago!

The calibration of Cepheids was an important moment in the history of cosmology, I'd love to know more about it. Jemanuel-h (talk) 20:55, 15 October 2016 (UTC) — Preceding unsigned comment added by Jemanuel-h (talk • contribs) 20:53, 15 October 2016 (UTC)