Waid Observatory

Object: NGC 6940
Aug. 6-7, 2022    -    Location: Davis Mountains west of Fort Davis, TX
Telescope: 10 in. RC   Mount: Paramount MX   Camera: Apogee Alta F8300M
Exposure: Lum = 90 min. Bin 1x1   R G & B = 60 min. each Bin 2x2  -  All 3 min. sub-exposures
Click on the image below to view at higher resolution.

NGC 6940


NGC 6940 1

NGC 69401 is an open cluster in the constellation Vulpecula1 approximately 2,500 light-years1 distant.  The age of the cluster has been estimated to be 770 million years3.  The cluster spans1 about 25 arc-minutes which is almost the size of the full Moon.  The stars of the cluster are somewhat scattered with non-member field stars visible between cluster stars.  Using the planetarium program The Sky X, I identified the bright "red" star near the center of the image as HIP 101527.  (FG Vulpeculae)5 The distance to this star is almost 8,000 light years6 which makes it a background star not associated as a cluster member.  The bright blue stars in the image also are probably either foreground or background stars.  A wide field image of the cluster may be viewed here.

Soft X-ray sources in the cluster have been studied2 using the ROSAT4 space telescope.  Four sources of these X-rays have been associated with the cluster.  One additional source was associated with a K0 giant star which is a possible cluster member.

1Wikipedia - https://en.wikipedia.org/wiki/NGC_6940
2Soft Xrays - https://adsabs.harvard.edu/full/1997A%26A...326..608B
3Cluster Age -https://eddb.io/body/5702788
4ROSAT - https://heasarc.gsfc.nasa.gov/docs/rosat/rosat3.html
5FG Vulpeculae - https://www.universeguide.com/star/101527/fgvulpeculae
6 FG Vulpeculae Distance- https://www.universeguide.com/star/101527/fgvulpeculae#distance

Copyright Donald P. Waid