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IC 5350 - 5386 ← NGC Objects: NGC 1 - 49 → NGC 50 - 99
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Page last updated Aug 12, 2017

NGC 17 (=
NGC 34 = PGC 781)
Discovered (1886) by Frank Muller (and later listed as NGC 17)
Discovered (Nov 21, 1886) by Lewis Swift (and later listed as NGC 34)
Also observed (Jul 1, 1899 to Jun 30, 1900) by Herbert Howe (proving NGC 17 = NGC 34)
A magnitude 14.4 spiral galaxy (type S? pec) in Cetus (RA 00 11 06.6, Dec -12 06 28)
Historical Identification: Per Dreyer, NGC 17 (Muller list II (#276), 1860 RA 00 01 58, NPD 102 54.0) is "very faint, extremely small, irregularly round, double star 2 arcmin to west". The position precesses to RA 00 09 07.3, Dec -12 07 14, which is 2 minutes of right ascension (about half a degree) west and nearly an arcmin south of the galaxy listed above, but (per Howe) the double star two arcmin west of the galaxy firmly establishes its identity with NGC 34 (which see for a discussion of the double listing).
Note About A Supposed Companion: In lower-quality images the northwestern cloud of stars torn away from the galaxy looks like it might be a faint companion, and it is listed as such in Corwin's table of positions for NGC objects; but as the HST images below show, the "companion" is only an extended cloud.
Physical Information: Based on a recessional velocity of 5880 km/sec (and H0 = 70 km/sec/Mpc), NGC 17 is about 270 to 275 million light years away. Given that and its apparent size of about 0.75 by 0.6 arcmin for the central galaxy and its northwestern extension, about 1.7 by 0.6 arcmin including its bright northern tail and about 2.5 by 0.7 arcmin including the much fainter southern tail (all sizes from the images below), the central region is about 60 thousand light years across, the northern tail is about 85 to 90 thousand light years long, the southern tail is about 60 to 65 thousand light years long, and the entire structure spans about 200 thousand light years. NGC 17 is the result of a collision between two (presumably) spiral galaxies. The galaxies appear to have nearly completed their merger, as the central region contains only one nucleus, but long tails of stars scattered into intergalactic space and moderate starburst activity near the center of the merged galaxy give ample testament to the collision. Note: NGC 17 and 35 are only a few arcmin apart, and given their apparently common distance may be less than half a million light years apart. If so, they could be gravitationally bound.
HST image of region near spiral galaxy NGC 17, overlaid on a DSS background to fill in missing areas, also showing NGC 35
Above, a 12 arcmin wide DSS image centered on NGC 17, also showing NGC 35
(NGC 17 is shown by an overlay of the HST images below, which see for credits)
Below, a 1.8 by 2.6 arcmin wide exaggerated-contrast HST image of NGC 17 and its tails
HST mosaic of spiral galaxy NGC 17 and its tails
Below, a 1 by 2 arcmin wide image of the bright tail and core of the galaxy, rotated to show greater detail
(Credit for all versions of the HST image: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration,
and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University), HubbleSite)

HST mosaic of brighter tail and central portion of spiral galaxy NGC 17
Below, a 0.75 arcmin wide HST view of the central galaxy, with normal orientation (Image Credit as above)
HST mosaic of central portion of spiral galaxy NGC 17
Below, a 12 arcmin wide DSS image centered on NGC 17, overlaid by an HST image of the galaxy
Also shown are NGC 35 and PGC 956278, 958282, and 958866
HST image of region near spiral galaxy NGC 17, overlaid on a DSS background to fill in missing areas, also showing NGC 35

NGC 34 (=
NGC 17 = PGC 781)
Discovered (Nov 21, 1886) by Lewis Swift (and later listed as NGC 34)
Also discovered (1886) by Frank Muller (and later listed as NGC 17)
Also observed (Jul 1, 1899 to Jun 30, 1900) by Herbert Howe (proving NGC 17 = NGC 34)
A magnitude 14.4 spiral galaxy (type S? pec) in Cetus (RA 00 11 06.6, Dec -12 06 28)
Historical Identification: Per Dreyer, NGC 34 (Swift list VI (#1), 1860 RA 00 03 53, NPD 102 53.2) is "pretty faint, small, round, 2 stars near". The position precesses to RA 00 11 01.9, Dec -12 06 27, about 5 seconds of time west of the galaxy listed above, but there is nothing comparable nearby and the double star west of the galaxy makes the identification certain. The double listing is due to the fact that Muller's and Swift's positions differ by nearly half a degree (being 5 seconds off for Swift and 2 minutes for Muller), so Dreyer had no reason to suspect the identity of the two nebulae. However, on the basis of the nearby stars mentioned by both observers, Howe discovered the equality of the two observations in 1899/1900, causing Dreyer to state "NGC 17 = 34 (Howe)" in the corrections for NGC objects published in the Second Index Catalog; so the duplicate entry has been known about for more than a century.
Physical Information: Although Swift had the far better position, tradition assigns the numerically earlier designation to duplicate entries, so see NGC 17 for anything else.

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IC 5350 - 5386 ← NGC Objects: NGC 1 - 49 → NGC 50 - 99