UDF 423

UDF 423
UDF 423
	Spiral galaxy UDF 423 in the Hubble Ultra Deep Field
Observation data (J2000 epoch)
Constellation	Fornax
Right ascension	03h 32m 39.16s
Declination	−27° 48′ 44.7″
Redshift	1 (or 0.46)
Distance	7.7 billion light-years (or 4.7 billion light-years); (light travel distance); ~10 billion light-years (or 5.7 billion light-years); (present comoving distance)
Apparent magnitude (V)	20
Characteristics
Apparent size (V)	0.11' x 5.04"

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]

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]

References

^ ^a ^b ^c ^d ^e ^f "UDF 423". Wikisky. Retrieved 2010-11-03.
^ ^a ^b Sangeeta Malhotra. "As far as the Hubble can see" (PDF). Arizona State University. Retrieved 2010-10-28.
^ ^a ^b ^c ^d ^e Edward L. (Ned) Wright. "Cosmology Calculator I". Astronomy @ UCLA. Retrieved 2010-10-22.

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[Wikisky-1] ^ ^a ^b ^c ^d ^e ^f "UDF 423". Wikisky. Retrieved 2010-11-03.

[Malhotra-2] Sangeeta Malhotra. "As far as the Hubble can see" (PDF). Arizona State University. Retrieved 2010-10-28.

[Calculator-3] Edward L. (Ned) Wright. "Cosmology Calculator I". Astronomy @ UCLA. Retrieved 2010-10-22.

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