The Eagle Nebula

Messier 16, generally known as the Eagle Nebula, in Serpens is simply one of the best nebulae in the sky.

Technically, M16 consists of two objects: the emission nebula IC 4703 and a cluster of around fifty stars, NGC 6611.

The brightest stars in the cluster are emitting ultra-violet radiation which cause the gas in the nebula to fluoresce. The nebula seems to be associated with its near neighbour, M17, the Omega Nebula.

At the heart of M16 is the subject of the famous “Pillars of Creation” photograph produced by the Hubble Space Telescope.

I was planning to stay out late to get at least a couple of hours of data for this image but –  well , you can probably guess what cut my session short. 


Fortunately, the SharpCap image acquisition software has a brightness filter as part of its live stacking feature, so the bad frames do not get included in the stack. At first the good frames were winning 19-0 but I felt the urge to quit by the time the baddies were winning 19-43.

I know this image could still be improved, especially with more exposures and better polar alignment but it is better than the last shot I took of M16 two years ago.  I’m not a person who perseveres with the same object over and over until it’s perfect, I just prefer to move on to the next target and maybe have another go at it at some future date.

Object Details:

Designation:  M16, The Eagle Nebula, Star Queen Nebula, NGC 6611, IC4703.
Constellation: Serpens.
Visual magnitude:  +6.4
Apparent size:  35′ x 28′
Diameter:  58 light years.
Distance:   5,700 light years.
Altitude during exposure:  63° above N horizon.
Also in image:  Trumpler 32, a nice star cluster with 30 stars no brighter than 12th magnitude, about 6′ diameter. Located on the right.

Technical stuff below.
Please feel free to jump to the end and like or comment.



Exposure:  19 x 45 sec = 14.25 min.
Gain:  290.
Date:  2019-07-31.
Location:  outer suburban.
Conditions:  initially clear.
Moon: no.


Image acquisition:  SharpCap.
Method: Live stacked.
Darks: 10 applied.
Image post-processing:  GIMP.
Cropping:   no.
Sky:  0.54 e/pixel/s .


Telescope: SkyWatcher Esprit  Type: 120ED triplet refractor
Focal: 840 mm F/7 Mount: SkyWatcher EQ6-R Pro
Camera: ZWO ASI 071 MC Pro
Type: CMOS 28.4mm 16 Mpx
Optical aids: Flattener: Y; filter: LP Guiding: No
Polar aligning: QHYCCD PoleMaster Polar Error: 06’ 34”

Geek Log:

[ZWO ASI071MC Pro]
Debayer Preview=On
Output Format=FITS files (*.fits)
Capture Area=4944×3284
Colour Space=RAW16
Hardware Binning=Off
Turbo USB=40
Frame Rate Limit=1 every 4 seconds
Timestamp Frames=Off
White Bal (B)=50
White Bal (R)=53
Cooler Power=100
Target Temperature=-15
Auto Exp Max Gain=300
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Anti Dew Heater=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=C:\Users\Roger\Desktop\SharpCap Captures\darks\ZWO ASI071MC Pro\RAW16@4944×3284\45.0s\gain_290\dark_10_frames_6.4C_2019-07-31T12_34_51.fits
#Black Point
Display Black Point=0.165829145728643
#MidTone Point
Display MidTone Point=0.57035175879397
#White Point
Display White Point=1

Images © Roger Powell


  1. I like it. I followed your links and found this image putting a few things into context for me.

    Our skies were dry and clear all day yesterday. I put the telescope equipment into the car trunk for later views of Jupiter etc. Guess what. Clouds rolled in here, too. Maybe tonight.

    Liked by 1 person

      1. There was no intention to compare Hubble with you. I remember in the days following their release of the Pillars, I zoomed in on that image and found many fascinating structures. Your image, in many ways, puts their Pillars into context. I get the overall view.

        Liked by 1 person

    1. Hi Paul, thanks for checking out both images. They were taken with different cameras and processed differently and I guess it’s natural to notice the flaws in one’s own work.

      Liked by 1 person

  2. Low and behold, a check of my records during the summer of 1961, shows me logging in M-16 as an open cluster, with no mention of the nebula. I would need to say that, back then, I was quickly noting the visual seeing of NGC 6611, the cluster, and not M 16, the nebula. This could be very distressful, as I now need to subtract one Messier object from my “have seen” list. 😦 But maybe this will give me the impetus to find a dark location one more time, (easier said than done,) drag a telescope or good binnocular out there and regain my “find!” M 🙂

    Liked by 1 person

    1. I’m not sure who is the final authority on this but my reading is that M16 covers both the cluster NGC 6611 and the nebula IC 4703 – especially as the stars are embedded in the nebula. So technically at least, you spotted part of M16 on that occasion, in my opinion.

      I hope you get the opportunity to spot the nebula.

      I have to congratulate you on your historical observing records. I know of at least one other person who has kept such meticulous observing records. My own participation in this hobby would be far richer if I had been more prolific in the past with my own records – but I hope this website is making up for it.


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