M 47 (NGC 2422, Lund 356) Open Cluster in Puppis

Located at: RA 07 hours 36 minutes 36 seconds, Dec -14 degrees 29 minutes 00 seconds

Size: 29' (25') Magnitude: 4.4 Class: I 3 m

North is up

West to the right

Telescope:

 8" f5 Newtonian reflector

Camera:

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

Image:

Lumicon Red filter, 230 minutes  (23 x 10 minute subs) 03/10/2010; seeing 3.2-4.9 FWHM per CCDStack

Processing:

CCDStack 1.6.1, Photoshop 7.0

Location:

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

Notes:

Shot this Messier open cluster on a night of bad seeing ... may try a re-shoot later for better seeing.

According to "Star Clusters", by Brent Archinal and Steven Hynes, the size of this open cluster is 25 arc minutes.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 2422

NGC 2422 = M47 = Cr 152
07 36 35 -14 29.0
V = 4.4;  Size 30

13.1": very bright, very large, fairly rich, impressive.  Includes double stars 
?1121 = 7.9/7.9 at 7" in the center and ?1120 = 5.7/9.6 at 20" on the W side.  
Easy naked-eye.

8": very bright, large but scattered, includes ?1121 = 8.0/8.0 at 7" near core 
and ?1120 on west side, many colored stars.

- by Steve Gottlieb

=================================================================
NGC 2478 = N2422 = M47
07 36 35 -14 29.0

See observing notes for M47 = N2422.

This is Dreyer's entry for M47!  Due to a sign error the position was 
incorrectly entered in the NGC.  The correct position was given by WH as VIII 38 
= N2422 which is now referred to as M47.  RNGC simply states "NOCL"

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 2422
NGC 2478 = M47 is probably identical to NGC 2422.  NGC 2478 is a place-holder 
for M47 in the NGC; Dreyer simply copied JH's GC entry for the missing Messier 
cluster.  He also noted Auwers's 4 minute RA difference for M47 as being a 
"clerical error", along with a reference ("V.J.S., Vol. I, p. 183" which I 
have not seen).  Precious little to go on if one were starting here to find 
the NGC object.

Glyn Jones has a story, though, in his book on the Messier objects (he repeats
it briefly in "The Search for the Nebulae").  This story apparently comes from 
Owen Gingerich's article in the October 1960 issue of Sky and Telescope (page
196) on "The Missing Messier Objects".  He claims Messier apparently switched 
the signs of his offsets from his comparison star, 2 Navis (now 2 Puppis), and 
cites articles or notes by Oswald Thomas in 1934 and T. F. Morris in 1959.

This, however, doesn't hold up very well if we precess the three positions to 
1771 when Messier found M47.  2 Pup ought to be about equidistant between the 
two positions for M47:  Messier's as recorded in the NGC for N2478 (this is 
the same as that given by Gingerich in his article), and the real position for 
N2422 (WH found that in February 1785, coincidentally using the same 
comparison star.  WH's offsets are 8m 55s preceding and 10 arcmin north of the 
star).  The differences are 8m 54s and 9.7 arcmin (close to WH's) and 9m 18s, 
41.0 arcmin, well off being identical, at least in absolute value, as they 
should be.  

So, while I can accept that Messier actually saw NGC 2422 and recorded it as
his 47th object -- his description fits and the cluster is certainly in the
right part of the sky -- I'm skeptical about the explanation that Morris,
Gingerich, and Glyn Jones have set forth. - Dr. Harold G. Corwin, Jr.