UDF 423

UDF 423 is the Hubble Ultra Deep Field (UDF) identifier for a distant spiral galaxy. With an apparent magnitude of 20,[1] UDF 423 is one of the brightest galaxies in the HUDF and also has one of the largest apparent sizes in the HUDF.[1]

UDF 423
Observation data (J2000 epoch)
ConstellationFornax
Right ascension03h 32m 39.16s[1]
Declination−27° 48′ 44.7″[1]
Redshift1 (or 0.46)[2]
Distance7.7 billion light-years (or 4.7 billion light-years)
(light travel distance)[3]
~10 billion light-years (or 5.7 billion light-years)
(present comoving distance)[3]
Apparent magnitude (V)20[1]
Characteristics
Apparent size (V)0.11' x 5.04"[1] or 0.0027' x 0.0027'
UDF 423 is the spiral galaxy in the lower right quadrant of the Hubble Ultra Deep Field.

Distance measurements

The "distance" of a far away galaxy depends on how it is measured. With a redshift of 1,[2] light from this galaxy is estimated to have taken around 7.7 billion years to reach Earth.[3] However, since this galaxy is receding from Earth, the present comoving distance is estimated to be around 10 billion light-years away.[3] In context, Hubble is observing this galaxy as it appeared when the Universe was around 5.9 billion years old.[3]

See also

References
  1. "UDF 423". Wikisky. Retrieved 2010-11-03.
  2. Sangeeta Malhotra. "As far as the Hubble can see" (PDF). Arizona State University. Retrieved 2010-10-28.
  3. Edward L. (Ned) Wright. "Cosmology Calculator I". Astronomy @ UCLA. Retrieved 2010-10-22.


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