Open Cluster NGC 7128

NGC 7128
NGC 7128: 500 mm Cassegrain 3625 mm f/7.2; SBIG STL11K; 40x10min Lum, 11-16-13x10min RGB; Bernese Highlands; © 2025 Radek Chromik [32]

History

This open cluster was discovered by William Herschel on 14 October 1787. He classified it as seventh class (pretty much compressed clusters of large or small stars) with the designation VII-40 and the notes: «A cluster of small stars of several sizes. 3 or 4' diameter, pretty rich like a forming one.» [464] John Herschel listed it as h 2130 and noted: «A star 9-10m of a ruby red colour in an oval annulus of small stars 4' diameter.» [466]

Physical Properties

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
DesignationNGC 7128
TypeOCL (II3m)
Right Ascension (J2000.0)21h 43m 57.7s
Declination (J2000.0)+53° 42' 55"
Diameter4 arcmin
Visual magnitude9.7 mag
Metric Distance2.307 kpc
Dreyer DescriptionCl, S, pRi, has a ruby * 9.5
Identification, RemarksWH VII 40; h 2130; GC 4701; OCL 218

Finder Chart

The open cluster NGC 7128 is located in the constellation Cygnus. On 17 August it in opposition with the Sun and is therefore highest in the sky at local midnight.

Cygnus: Open Cluster NGC 7128
Finder Chart Open Cluster NGC 7128
12:03
17:30 | 36.2°
22:58
Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. Times are shown for timezone UTC, Latitude 0°, Longitude 0°, Horizon height 5°, Date 2025-11-24. [149, 160]

Objects Within a Radius of 10°

References

  • [32] Astrofotografie; Radek, Bernie and Dragan; sternwarte.ch
  • [149] SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
  • [160] The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
  • [277] Historische Deep-Sky Kataloge; Dr. Wolfgang Steinicke; klima-luft.de/steinicke; 2021-02-17
  • [464] Catalogue of a second thousand of new nebulae and clusters of stars; with a few introductory remarks on the construction of the heavens; William Herschel; Philosophical Transactions of the Royal Society of London, 1 January 1789; DOI:10.1098/rstl.1789.0021
  • [466] Observations of nebulæ and clusters of stars, made at Slough, with a twenty-feet reflector, between the years 1825 and 1833; John Frederick William Herschel; Philosophical Transactions of the Royal Society of London, 1 January 1833, Pages: 359-505; DOI:10.1098/rstl.1833.0021