NGC 457
From DeepSkyPedia
| NGC 457 Cr 11 << Collinder 12 >> Cr 13 Mel 6 << Melotte 7 >> Mel 8 | |
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| Position (epoch J2000) [1] | |
| Constellation | Cassiopeia |
| Position | Ra 01:19:32.6 Dec +58:17:27 |
| DSS images | |
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Appearance [1] | |
| Apparent mag. | 6.4 |
| Size | 13' |
| Class | II 3 r |
| Stars | |
| Dreyer's description | Cl B L pRi st 7 8 10 |
| Other | |
| Other designations | ET cluster, Collinder 12, Cr 12, Melotte 7, Mel 7, OCL 321 and Lund 43 |
| Notes | |
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NGC 457 is an open cluster in Cassiopeia. It forms an asterism with a few neighboring stars.
Contents |
[edit] How to find it
This cluster can be found 2° S of Ruchbah, next to 5.5-magmitude star Phi 1 Cas. The star itself doesn't belong to the cluster, but together with 7-magnitude Phi 2 Cas (at PA 250), a bright star from the cluster to the W, make "eyes" of the "ET". Eyes are actualy a double star Phi Cas. Around 15' to the N are 2 stars that make the "shoes". Neither of those 2 stars are part of the cluster. The cluster is actually between "eyes" and "shoes".
Once you recognise the "eyes" and the "shoes", it is easy to see the rest of the ET's "body", providing you have enough aperture.
[edit] Appearance
This cluster is favorite to many observers because of its resemblence to ET, Owl, Kachina doll and propably some other things.
The "eyes" (Phi Cas pair) must be up in the FOV for the illusion to work best. Beside the "eyes", that are the brightest and most striking part of the asterism, there is no other stars in the "head".
A chain of stars stretches between "eyes" and "shoes", with 2 lateral chains extending from the "chest" and forming the arms or wings (if you see this an an owl). Asterism's arms are raised at a 45° angle above its shoulder, and a little bit longer than one would expect. Bright 8th magnitude red star is in east "hand", 3' E from the center.
The stars are of mags 7 and dimmer.
Some observers compared the shape of the cluster with constellations of Gemini [2] (because of 2 pairs of bright stars at the edges) or Cygnus[3] (because of cross-like appearence of the cluster itself).
It is not visible to the naked eye, so you need at least a good finder or small binoculars to find its brightest stars and small telscope to recognise it as an ET.
[edit] Binoculars and finders
In smaller finder, like 5x10, "eyes" and "shoes" are visible. The cluster looks like a moderately bright round glow, 10' in diameter, starting from "eyes" and stretching 2/3 of the way to the "shoes".[4]
In somewhat bigger finder, like 11X80, in very good conditions, together with "eyes" and "shoes", at least 8 stars in the area next to the "eyes" are visible[5].
In bad viewing conditions, in small binoculars (like 12x45), the cluster can be seen as a moderately bright round glow, 10' in diameter, starting from "eyes" and stretching 2/3 of the way to the "shoes". [4]. Sometimes, 2 or 3 stars can be discerned from this glow[6].
[edit] Telescopes up to 4"
In 60 mm scope, like ETX60, it is hard to see anything reminiscent of the body. All you can see is a small cluster[7]. Since there are some stars of 7th magnitude, you should be able[Citation needed] to recognise the cluster at higher power.
[edit] In 4" telescopes
In 4" telescopes, at lower power (up to 20x), cluster appears well concentrated, with dozens of stars of various brightness, from quite bright to faint[8].
At moderate power (20x to 60x), around 30 stars can be seen, concentrated along a well defined central line, with stars of magnitude from 8.5 to 10+. Phi Cas double shows gold/violet-bluish color.[9].
At 22x, cluster can be recognised as "body", the way kids draw it, with the hands and legs made out of lines only. You can recognise asterism's raised arms.[10]. At 100x, nebulosity gives away to many stars. In moderate conditions, you can see "eyes", 2 hands with 3 stars in each, 2 legs and 2 shoes. On the "chest", where the "hands" connect, there are two groups of 3 to 4 *, each cramped within less than 1'[11].
[edit] In 6" telescopes
In 6" telescopes, at 48x, between 20 and 30 stars are visible[12].
[edit] In 8" telescopes
In 8" telescopes, about 40 stars with mags 6-12 are visible, concentrated towards the center. Few double stars can bee seen among those. In the center, V-shaped dark area can be seen. "Owl"-shape is easy to recognise[13]. Some have seen up to 50 stars with this aperture[14].
[edit] In telescopes above 8"
With 10" telescope, a few 'dark' red stars, like dim carbon stars, can be seen [2], like
The 13" telescope provides the view of around 80 stars (at 100x) in the 15' cluster that is bright, large, rich and compressed. At higher power (150x), ne new stars are visible, and cluster appears to be fully resolved, without fuzzy background to the grouping[5].
[edit] Notes
Phi Cas is a double star.
Closest DSO is open cluster NGC 436. Other than that, closest DSO is open cluster M 103, around 3° to the NE.
[edit] References
- ↑ 1.0 1.1 Historic NGC and IC by Wolfgang Steinicke (version Nov. 20, 2006.)
- ↑ 2.0 2.1 (IAAC) Obj: NGC 457 - Inst: 10" F/5.6 Dobsonian , Brian Carter , Dobson , d=10" , f=56" , 64x, 109x, 203x, 284x , 11/14/2004 , Charlie Elliot , LM: 5.0 , seeing: 6
- ↑ (IAAC) Obj: NGC457 - Inst: 10" f5 Dobsonian , Dr Adrian Jannetta , Dobson , d=10" , f=50" , 39 , 29-August-2005 2200UT , Hadston, UK (Lat 55.3, Elev 10) , LM: 6.0 , seeing: 7
- ↑ 4.0 4.1 NGC 457 with 12x45 binoculars by Ante Perković (SEEN, Aug 11 2004) [include this report]
- ↑ 5.0 5.1 (IAAC) Obj: NGC 457 - Inst: 13" f/5.6 "Bigfoot" German Eq. mount , Steve Coe , "Bigfoot" German Eq. mount , d=13" , f=72.8" , 100X, 150X , 24 Jan 98 , Sentinel, AZ (Lat +33, Elev 1800 ft) , SB: 8/10 , seeing: 7
- ↑ NGC 457 with 12x45 binoculars by Ante Perković (SEEN, Jan 12 2003) [include this report]
- ↑ (IAAC) Obj: NGC 457 - Inst: ETX60 , William L. Schart , ETX60 , d=60mm , 14x, 39x , 11/22/01 8:50 pm CST , Killeen, TX (Lat 31 07, Elev 600 ft) , LM: 3.5 , seeing: 8
- ↑ (IAAC) Obj: NGC 457 - Inst: Astroscan 4,1" f440mm Widefield , Martin Baur , Astroscan Widefield , d=4.1" , f=440mm , 16x, 21x , 25.01.2000 20:00 MET , clearing near Hofgeismar, Germany (Lat +51°, Elev 820ft) , LM: 5,5
- ↑ (IAAC) Obj: ngc457 - Inst: Newt 4.2" f/4.25 , Lew Gramer , Newton (AstroScan) , d=4.2" , f=17.85" , 20x, 40x, 65x , 1996-11-12, 05:30 UT , Medford, MA, USA (42N) , LM: 5.4
- ↑ (IAAC) Obj: NGC 457 - Inst: TV-102 (102mm f/8.6 APO refractor) , Ron B , TV-102 (APO refractor) , d=102mm , f=880mm , 22x, 30x, 60x , 10/13/01 , 117h 9m W (Lat 32h 43m N, Elev 2000 ft) , LM: 5 , seeing: 5
- ↑ NGC 457 with 120mm f/8.33 refractor, eq. mount (Konus, Lukrica) by Ante Perković (SEEN, Mar 15 2003)
- ↑ (IAAC) Obj: NGC 457 - Inst: Orion 6" Dob , William L. Schart , "Orion" Dob , d=6" , 48x , 8/19/98 11:44 pm CDT , Killeen, TX (Lat 31 N, Elev 600 ft) , LM: 3.5 , seeing: 6
- ↑
NGC 457 observation and sketch by Jaakko Saloranta with 8" Orion DSE @ 60x - ↑ (IAAC) Obj: NGC 457 - Inst: Celestar 8" SCT, fork mount , William L. Schart , Celestar SCT, fork mount , d=8" , f=80" , 11/22/01 , Killeen, TX (Lat 31 07, Elev 600 ft) , LM: 3.5 , seeing: 8
[edit] Links
- NGC 457 with 12x45 binoculars by Ante Perković (SEEN, Aug 15 2004) [include this report]
- NGC 457 with 20x50 spotting scope by Ante Perković (SEEN, Oct 02 2002) [include this report]
- NGC 457 observation by Paul Kemp (Southern Sentinel) with 80mm Stellarvue Refractor (22nd May & 23rd May 2004) [include this report]
- NGC 457 observation by Jeff Burton (x.astrogeek.org) with Meade ETX-90EC 90mm Maksutov [include this report]
- NGC 457 observation by Jeff Burton (x.astrogeek.org) with Orion Little Giant II 20x70mm Binoculars [include this report]
- NGC 457 observation and sketch by Rony De Laet with Skywatcher 102/500 [include this report]
- NGC 436 and NGC 457 observation and sketch by Rony De Laet with TS Marine 15x70 binoculars [include this report]
- NGC 457 with 4.5" (114mm) f/8 homemade dobson (babydob) by Ante Perković (SEEN, Dec 13 2003) [include this report]
- NGC 457 observation by Jeff Burton (x.astrogeek.org) with Orion Giant View 25x100 Binoculars [include this report]
- NGC 457 with 25x100 binoculars by Ante Perković (SEEN, Feb 04 2005) [include this report]
- NGC 457 observation by Brian Rachford with 6" f/8 Newtonian (3 Dec 2002) [include this report]
- NGC 457 observation by Olivier Van Aelst @ deepskylog.be (with Celestron Advanced 200mm) [include this report]
- NGC 457 observation and sketch by Jere Kahanpää with Newton 205/1000 [include this report]
- NGC 457 observation and sketch by Juha Ojanperä with Newton 250/1200 mm [include this report]
- NGC 457 observation and sketch by Iiro Sairanen with Newton 300/1500mm [include this report]
- NGC 457 observation and sketch by Math Heijen (starobserver.eu) with Orion Optics UK 300mm [include this report]
- NGC 457 observation by Jeff Burton (x.astrogeek.org) with Homemade 12.5" Reflector [include this report]
- Cassiopeia by Steve Coe - NGC 457 with 13" [include this report]
- NGC 457 observation by Tom Polakis with 13" and 20" [include this report]
- NGC 457 observation by Jeff Burton (x.astrogeek.org) with AstroSystems TeleKit 14.5" Reflector [include this report]
