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According to Simbad ( http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=3C+147 ), the parallax is 0.0471 which would put it at a distance of 69,249 Light Years by using https://www.translatorscafe.com/unit-converter/en-us/calculator/parallax-distance/

This would put it inside or outside the Milky Way but Wikipedia puts it at 5.1 Billion which seems more correct. Although the indirect page at Caltech says 5.2.

How can I calculate the distance of 3C 147 using the parallax from Simbad, by using another formula or its not possible as parallax at Simbad doesn't refer to distance.

MiscellaneousUser
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The parallax listed in Simbad is $0.0471\pm 0.1310$ milliarcseconds. i.e. The parallax is consistent with zero. You can only get a lower limit to the distance from this.

The distance might be estimated from the brightness of the galaxy and some assumption about its intrinsic luminosity. Or you could just assume it is far enough away to be part of the Hubble flow; in which case you can estimate a distance from its redshift of 0.55.

Using this cosmology calculator with the default cosmological parameters in a flat universe gives a light travel time of 5.4 billion years.

This may or not be the distance you want; there are several ways to define distance in cosmology and these are also given by the calculator referred to.

ProfRob
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  • Can I determine the value for the JS from the information displayed on the Simbad page? – MiscellaneousUser Nov 01 '21 at 00:16
  • Not totally sure what you are asking, but the redshift that @ProfRob put into the calculator is shown on the Simbad page under the Radial velocity / Redshift / cz heading where it gives z(spectroscopic) 0.55 (z is the common abbreviation/symbol for redshift) – astrosnapper Nov 02 '21 at 00:16