NGC 7789

From DeepSkyPedia

Share/Save/Bookmark
Jump to:navigation, search
This article has reached satisfactory level of qualityQuality article
open cluster
NGC 7789
Cr 459 <<  Collinder 460  >> Cr 461 

Please, help us find free binocular or telescope sketch of this object

Position (epoch J2000) [1]
Constellation Cassiopeia
Position Ra 23:57:24.0
Dec +56:42:30
DSS images

10' · 20' · 30' · 45' · 1°

Appearance [1]

Apparent mag. 6.7
Size 25'
Class II 2 r
Stars
Dreyer's description  Cl vL vRi vmC st 11...18
Other
Other designations Caroline's Cluster, Collinder 460, Cr 460, Lund 1053, OCL 269, H VI-30, h 2284 and GC 5031[2]
Notes
Edit this infobox

NGC 7789 (Caroline's Cluster) is an open cluster in Cassiopeia.

Contents

[edit] How to find it

It can be found 3° SE of the star Caph (Beta Cassiopeia), on the west side od the Cassiopeia's "W" asterism.

[edit] Appearance

NGC 7789 is famous for its dim but numerous stars. Sometimes a small increase in aperture or improvement of observing conditions can make a great difference, with cluster changing from faint fuzzy to rich cluster of tens of stars. If You do see the stars, it will propably be hard to count them since there will always be many stars just barely visible.

All the stars are white or very light yellow, little color can be seen, even with big telescopes[3].

[edit] Binoculars and finders

In good conditions (lm=6.7), this object is easily recogniseable as a cluster, even in a good finder (like 11x80). Only 2 stars can be resolved but the cluster is bright, large and little brighter in the middle. [3][4]

In small binoculars (like 12x45), it looks like very faint 10' fuzzy, visible with direct vision. With averted vision, it may grow about 20% in diameter, but this "halo" is visibly fainter[5] No stars are resolved with this kind of instrument[6].

[edit] In 4" to 8" telescopes

In 4" telescope (like TV-102), the view depends on power used. At smaller power (30x), it as large dense nebulosity with grained appearance, giving the impression of an open cluster embedded inside a nebula. At 60x, nebulosity gives away to many dim stars, and at 110x some 50 tiny stars can be resolved[7].

In 6" telescope, at 30x, about 15 fairly bright stars can be seen scatted over fainter ones. It is hard to say where the cluster ends and stary backgorund of Milky Way begins. Near the center, a small rectangular asterism of medium bright stars can be seen just of a triangle of brighter stars[8]. Higher power (104X), makes around 33 stars visible, sparkling on a huge, fuzzy background. Cluster looks bright, large, not brighter in the middle, very compressed, and rich.[4]

In medium sized telescopes (like 8"), cluster can give the impression of clumpyness [9]. In bigger telescopes, clumpines gives away to dark lanes and star "islands".

[edit] In 10" telescopes

In 10" telescopes, at 65X, some 120 stars can be resolved, with lots of beautiful dark lanes within the cluster and a few wind their way out into the Milky Way. Going to 158X (9mm) shows a dark marking right in the center of the cluster.[4]

[edit] In 13" telescopes

A 13" telescope provides wonderful view.

At 60X it is bright, very large, rich and much compressed, with around 30 (at lm=6.7) stars resolved, with 2 dark lanes winding through the cluster[4][3].

Raising the power to 100X resolves over 70 (at lm=6.7) of magnitudes 10 and less, with lots of beautiful chains of stars, spread over 1/3 of FOV[4][10], and some estimates of number of stars visible in at this power go as high as 160, many of them dim.[4] There are lots of curved chains of stars can be seen within the cluster [3]. The cluster might look bright, large to very large, very rich, (very) much compressed and much brighter in the middle.[10][4]. Dark lanes wind through this group from edge to edge and give the impression of spiral structure.[4]

At 117X (with SCT, LX200), estimated 100-150 stars are resolvable under good skies. The cluster resembles a sparse globular cluster with irregular boundry. It gradually brightens toward the center, but without a real nucleus. The brighter 75-100 stars stand out well against the fainter stars[4][11].

Raising the power to 150X can bring up to 250 stars visible, filling about half of the field. This power seams to be the best for this aperture. The chains of stars are very prominent at this power. Dark lanes look best at power of around 150X[4].

At even higher powers (165X)[4], many lovely faint pairs and delicate asterisms begin to appear, so power of 220X might bring 8 to 10 faint binaries within the cluster.[10][3].

Higher power (like 300X) is too much for this cluster. [4]

[edit] In 36" telescopes

In really big telescopes, like 36", at 169X (27 mm), 75 stars is visible just in SW quadrant (estimated total: 300!), with some dark yellow (20 of total 75 counted) and orange stars (4/75). Dark lanes can be seen cuting through the cluster, and winding their way out into Milky Way. Lots of stars are just beginning to be resolved form a milky background.[4]

[edit] Notes

[edit] References

  1. ↑ 1.0 1.1 Historic NGC and IC by Wolfgang Steinicke (version Nov. 20, 2006.)
  2. ↑ NGC 7789 page @ x.astrogeek.org
  3. ↑ 3.0 3.1 3.2 3.3 3.4 (IAAC) NGC 7789 in Cassiopeia using 13", AZ , Steve Coe , 13" f/5.6 on Bigfoot German EQ. with 11X80 finder , d=13" , f=72.8" , 60X, 100X, 150X, 220X , 28 Nov 97 , 100 miles SW of Phoenix, AZ , LM: 6.7 , seeing: 7
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 Cassiopeia by Steve Coe - NGC 7789 with finder 11x80, 6", 10", 13", 36" f/5
  5. ↑ NGC 7789 with 12x45 binoculars by Ante Perković (SEEN, Aug 11 2004)
  6. ↑ NGC 7789 with 12x45 binoculars by Ante Perković (SEEN, Jan 12 2003)
  7. ↑ (IAAC) Obj: NGC 7789 - Inst: TV-102 (102mm f/8.6 APO refractor) , Ron B , TV-102 (APO refractor) , d=102mm , f=883mm , 30x, 60x, 110x , 10/12/01 , 117h 9m W (Lat 32h 43m N, Elev 2000 ft) , LM: 5.0
  8. ↑ (IAAC) Obj: NGC7789 - Inst: Orion 6" Dob , William L. SChart , Orion Dob , d=6" , 32x , 10/10/99 10:48 pm CDT , Killeen, TX (Lat 31d, Elev 600') , LM: 4 , seeing: 8
  9. ↑ (IAAC) Obj: NGC 7789 - Inst: 10" F/10 SCT (Meade LX200) , Gary A. Weston , SCT (Meade LX200) , d=10" , f=100" , 71.4x, 78.1x, 96.15x, 131.6x (+2x barlow) , 8/10/02 10:15pm EST , Stellafane - Springfield Vt. , seeing: 8
  10. ↑ 10.0 10.1 10.2 (IAAC) Obj: NGC 7789 - Inst: 13" f/5.6 "Bigfoot" German Eq. mount , Steve Coe , 13" f/5.6 on Bigfoot German EQ. with 11X80 finder , d=13" , f=72.8" , 100X, 150X, 220X , 24 Jan 98 , Sentinel, AZ (Lat +33, Elev 1800 ft) , seeing: 8
  11. ↑ (IAAC) Obj: NGC7789 - Inst: 30cm, f:10, SCT, LX200 , Jim Anderson , SCT, LX200 , d=300mm , f=3000mm , 117X , 10052000-00:40EST , Bigwoods, NC (Lat 35:46, Elev 250') , seeing: 5

[edit] Links

W.pngikipedia has an article on NGC 7789   

Retrieved from "http://deepskypedia.com/wiki/NGC_7789"
Navigation
Toolbox
Google AdSense