The NGC/IC Project

NGC 6946

DSS Image annotation ©Copyright 1996 through 2008 by Robert E. Erdmann, Jr. - All rights reserved.
Commercial use of these images (books, software, etc.) is strictly prohibited without written permission.

Digitized Sky Survey (DSS) Image Information for  NGC 6946
DSS Acknowledgement ,  DSS Copyright Notice DSS Image Generation:  1st Generation DSS Image
Image Center (2000):  20h 34m 52.7s; +60º 09' 11"Image File Name:  n6946.jpg
Image Size (arcminutes):  20' x 20'Image Size (pixels):  353 x 353
Original NGC Catalogue Data for  NGC 6946
General Catalogue Designation:  4594William Herschel Designation:  IV 76
John Herschel Designation:  2084Other Observers:  ...
Right Ascension (Equinox 1860):  20h 31m 57sAnnual RA Precession (Equinox 1880):  +1.27s
North Polar Declination (Equinox 1860):  30° 20.3'Annual DEC Precession (Equinox 1880):  -12.4"
Summary Description:  vF, vL, vg, vsbM, rr
Notes:  Comments:  
Discovered by:  Friedrich Wilhelm Herschel (1738 - 1822)Year of Discovery:  1798
Telescope Aperture (Inches):  18.7Telescope Type:  Reflector
Understanding the 'Summary Description':  Summary Description Abbreviations List
Contemporary/Current Data for  NGC 6946
Right Ascension (2000):  20h 34m 52.7sDeclination (2000):  +60º 09' 11"
Object Type:  GalaxyObject Classification:  Sc I
Constellation:  CygnusPosition Angle:  … °
Visual Magnitude:  9.1Surface Brightness:  14.1
Blue Magnitude:  9.6Object Size:  11.5'X9.8'
Also Cataloged As:  UGC 11597, MCG+10-29-006, PGC 65001, H IV-76, h 2084,
GC 4594, CGCG 304.006, ARP 29, IRAS 20338+5958
Catalogue Notes:  ---------------
Book / Chart References for NGC 6946
Luginbuhl & Skiff (Page):  99Burnham's (Volume : Page):  1:615
Uranometria 2000:  32,56Herald-Bobroff Astroatlas:  C-05,C-06
Microsky:  145GSC Small Region Number:  4246
POSS Blue Plate #:  598POSS Red Plate #:  598
Database Update Level: 2 (Complete)
Contemporary Visual Observation(s) for NGC 6946
NGC 6946 = UGC 11597 = MCG +10-29-006 = CGCG 304-006 = Arp 29
20 34 52.3 +60 09 14
V = 08.8;  Size 11.5x9.8;  SB = 13.8

18" (10/9/04): viewed type II supernova 2004e, discovered 9/27/04 (13 days ago) 
and appeared at approximately mag 12.8.  It was easily identified using a 
photographic finder chart.  The supernova is located 4.1' E and 1.9' S of the 
nucleus, just west of a pair of mag 13/13.5 stars at 12" separation and was 
comparable to the brighter star of this pair.  A fainter mag 14.4 star is close 
WSW and the three stars plus supernova form a small wedge of Sagitta shaped 
group.  This is the 8th supernova discovered in N6946 since 1917.

17.5" (8/29/92): bright, very large, 6' diameter to main body, elongated 3:2 ~E-
W.  Three arms are visible.  A long bright arm is attached at the north side of 
the core and trails to the east.  This eastern arm splits; a short fainter 
branch bends south following the core and a long curving bright arm terminates 
with a very faint, very small HII knot.  On the west side a fainter arm shoots 
sharply to the north from the core.  These outer arms significantly increase the 
diameter of the main body.  The galaxy has a very large brighter middle but the 
core is just a very small brighter region close SW of the geometric center.  A 
very faint stellar nucleus was seen with direct vision.  Observation from 
12,000' in the White Mountains.

17.5" (8/13/88): main spiral arm very prominent and easily seen to split.

17.5" (9/14/85): bright, large, brighter central core.  A prominent arm attached 
on the NE side of the core and trailing to the east.  This arms splits - the 
shorter arm is close to the core and a brighter region or arm to the west.

13" (7/27/84): bright arm on the east side highly suspected to branch or split 
into two arms.  Also an arm or brigter region seen on the opposite side of the 
galaxy pointing W a short way.

- by Steve Gottlieb

Data Sources Used to research NGC 6946
[NGC] New General Catalogue / [IC] Index Catalogue (Dreyer - 1888, 1895, 1908)
[OHCDSO] Observing Handbook and Catalog of Deep-Sky Objects (Luginbuhl & Skiff - 1990)
[RE-NGCDDB] NGC Discoverer's Database (Erdmann 1990 - 2006)
[UGC] Uppsala General Catalog of Galaxies (Nilson - 1973)
[ARP] Atlas of Peculiar Galaxies (H. Arp)
[CGCG] Catalog of Galaxies & Clusters of Galaxies (Zwicky - 1968)
[MCG] Morphological Catalog of Galaxies (Vorontsov-Velyaminov et al - 1962 thru 1968)
[RE-AZDB] The Arizona Database®, V15.5 (Erdmann - 1987 thru 2006)
[HC-PPL] NGC/IC Accurate Positions List Database (Corwin - 1996 thru 2006)
[SG-NGCO] NGC/IC Observations Database (Gottlieb - 1998 thru 2006)
[PGC] Principle Galaxy Catalog (Paturel et al. - 1989, 2003)
[DSS] Digitized Sky Survey - 1st (102 CD-ROM) and 2nd (Web Site) Generation (STScI - 1994)
[NED] NASA's Extragalactic Database (NED) located at http://nedwww.ipac.caltech.edu/

Additional Notes
1st generation images were generated from the 102 CD-ROM version of the Digitized Sky Survey (DSS)
2nd generation images were generated at the DSS web site located at http://archive.stsci.edu/cgi-bin/dsswin
Luginbuhl & Skiff page numbers are from 'Observing Handbook and Catalogue of Deep-Sky Objects' by Christian B. Luginbuhl and Brian A. Skiff, produced by Cambridge University Press
Burnham's refers to 'Burnham's Celestial Handbook' in three volumes produced by Dover Publications, Inc.
Uranometria 2000 chart numbers are for those printings authored by Tirion, Rappaport & Lovi, and are not for the most recent printings authored by Tirion, Rappaport & Remaklus in which the charts were re-numbered, all of which were and/or are produced by Willmann-Bell, Inc.
The Herald-Bobroff Astroatlas is by D. Herald and P. Bobroff of Canberra, Australia and is produced by HB2000 Publications
Microsky® is the microfiche rendition of the Palomar Observatory Sky Survey (POSS) produced by Deen Publications (P.O. Box 867088; Plano Texas 75086)
POSS refers to the Palomar Observatory Sky Survey produced by The National Geographic Society in conjunction with The California Institute of Technology
All DSS image annotation was performed by Robert E. Erdmann, Jr., and is ©Copyright 1996 through 2008 by Robert E. Erdmann, Jr. - All rights reserved
All product names, trademarks, and copyrights are the property of their respective owners
Contemporary/Current Data for this object was hand collected and entered from the data sources listed in the "Data Sources Used" section of this table above.- Robert E. Erdmann, Jr.


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