NGC 6840 (HVII-19) and NGC 6843 Open Clusters in Aquila

Center of field at approximately: RA 19 hours 56 minutes 06 seconds, Dec +12 degrees 09 minutes 00 seconds

Size: 4.0' and 4.0' Magnitude: -- and -- Class: cluster? and cluster?

North is up

West to the right

Telescope:

8" f5 Newtonian reflector

Camera:

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

Image:

Lumicon Red filter, 200 minutes (20 x 10 minute subs), 08/8/9/2008; seeing 2.0-2.4 FWHM per CCDStack

Processing:

CCDStack 1.3.7, Photoshop 7.0

Location:

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

Notes:

Shot this pair of open clusters (?) on the same night, and immediately following, Dolidze 3. Not much to look at, but there does seem to be two concentrations of stars. "Star Clusters", by Brent Archinal and Steven Hynes, has no Comments or Aliases information on these two.

However, the NGC / IC Project has this information ... NGC 6840 is first, just west (right) of center:

Contemporary Visual Observation(s) for NGC 6840 ... see the CDS information for NGC 6840

NGC 6840
19 55 14 +12 07.1

17.5": fairly poor group of 20-25 mag 11-15 stars in a 6'x4' rectangular group.  
Includes about 10 brighter mag 11 stars.  There are no rich groupings but a very 
distinctive 3' string or stars oriented NW-SE marks the NE side of the group.  
Stands out reasonably well at 80x but not distinguishable at 220x.  Located 11' 
N of mag 8.1 SAO 105419.  In field with N6843 about 12' ENE.  Listed as 
nonexistent in RNGC.

Discovered by WH (VIII 19).  JH (h2058): "a small, poor cluster; the preceding 
of two distinct clusters.  The stars 11m."  "Is a coarsely clustering part of 
the milky way."  Reinmuth describes "a very loose clustering of a few st 
12...15."

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 6840
NGC 6840 and NGC 6843 are two sparse clusters found by JH.  N6840 has two 
groups of seven stars (separated by about 5 arcmin) in its core, surrounded by
about 5-6 others.  The stars are of fairly equal brightness, all being around
11th to 12th magnitude, and cover an area of 10 arcmin by 8 arcmin.  N6843 is 
poorer with only around a dozen stars, again 11th to 12th magnitude, scattered
over a smaller area.  

Both are superposed on rich Milky Way backgrounds, so I'm not surprised that
they did not stand out enough to be identified for RNGC.  In fact, neither may
be a real cluster, but proper motions and photometry could tell us that.
 - Dr. Harold G. Corwin, Jr.

Contemporary Visual Observation(s) for NGC 6843 ... see the CDS information on NGC 6843

NGC 6843
19 56 06.1 +12 09 49

17.5": A very unimpressive scattered group of about two dozen stars mag 11-14 in 
a 8' region.  Generally elongated N-S in a string with a separate line of six 
stars at the N end oriented E-W.  There is one close isolated double star and 
the fainter stars are at the S end of the string.  Appears to be a very weak 
asterism of no special interest except follows in the same field another 
(better) asterism N6840 by ~10'.  Listed as nonexistent in RNGC.

Discovered by JH (h2059): "A poor, small cluster. The following of two [N6840], 
just alike."  Reinmuth states "no distinct Cl, milky way."  Listed as 
nonexistent in RNGC. See visual description.

- by Steve Gottlieb