NGC 4147 (GCL 18) / UGC 7170 (CGCG 98-78) Globular Cluster / Galaxy in Coma Berenices

Center of field at approximately: RA 12 hours 10 minutes 10 seconds, Dec +18 degrees 40 minutes 06 seconds

Size: 4.4' / 3.0' x 0.2' Magnitude: 10.4 / 15.0 photographic Class: 6 / Scd

North is up

West to the right

Telescope:

 8" f5 Newtonian reflector

Camera:

 ST-8XME, self-guided, binned 1x1, temp -20c & -25c, camera control MaxIm DL 4.56

Image:

Lumicon Red filter, 840 minutes (84 x 10 minute subs), 05/23/24/25/26/27/2011; seeing 2.5-3.8 FWHM per CCDStack

Processing:

CCDStack 2.24.4110.20701, Photoshop 7.0

Location:

 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)

Notes: From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 4147

NGC 4147 = N4153?
12 10 06.2 +18 32 32
V = 10.2;  Size 4.7

17.5" (4/13/96): moderately bright, fairly small, irregular 2'-2.5' diameter, 
very small bright core.  A few faint stars are resolved at 220x including one 
brighter star at the south edge.  Appears on the verge on more extensive 
resolution.  At 280x, the halo clearly has an irregular outline and several 
stars are resolved in extensions or star lanes.  The core is mottled and intense 
but not resolved.

17.5" (3/20/93): fairly bright, moderately large, round, 2.5' diameter.  
Approximately six faint stars are just resolved around the edges of the halo 
including a single easy mag 14 star at the SSW edge.  The compact core is 
mottled and clumpy but has no clean resolution.  There is an impression of 
several star lanes in the halo just below the limit of resolution.

- by Steve Gottlieb

NGC 4153 = N4147?
12 10 06.2 +18 32 32

See observing notes for N4147.  Identification uncertain.

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 4147
NGC 4153 is probably NGC 4147.  This was found by WH on 15 Feb 1784, only two 
months after he started observing with his first "20-feet" telescope.  He put
the nebula 1m 30s preceding, 2d 11m south of 5 Comae.  This gives 12 08.1 +18 
38 (1950) for the nebula.  Herschel described it as "B, pL, lE, bM, m[ilky]."
It has not been seen since at this position.

The closest reasonable object that might be the missing nebula is another
early discovery of WH's, NGC 4147 = H I 19, the bright globular northwest of
the Virgo Cluster.  Herschel found this just a month after N4153 (14 March
1784), and placed it at 10m 30s preceding, 0d 46m north of 11 Comae.  This
becomes 12 07.7, +18 50 (1950), in pretty good agreement with modern positions
for the cluster.  WH's description is very much the same as that for N4153: 
"vB, pL, gbM."

At the time WH found N4153, he was still improving his method of determining
positions.  So, I suspect that the February observation, earlier on the
"learning curve," actually refers to NGC 4147.

I also recall a Sky and Telescope article on this mystery object.  It appeared 
many years ago, perhaps in the late 50s or early 60s.  Someone whose S&T's are 
not buried in the storeroom might want to dig it out.  It is not a "Deep Sky
Wonders" article, since Walter Scott Houston's article -- at least as printed
in the book edited by Stephen James O'Meara -- that mentions N4153 calls it a 
"true faint external galaxy ... about 13' south and about 8' east of NGC 
4147."  The declination would be close to WH's, but the RA is well off.  And
there is nothing in this position, either. - Dr. Harold G. Corwin, Jr.