Lagoon Nebula, M8

Burnham’s Celestial Handbook (forty years old and still available) describes M8 as “One of the finest of the diffuse nebulae….seen to consist of a fine irregular nebulosity enveloping the scattered open cluster NGC 6530”.

It goes on to say that “One of the remarkable features of the Lagoon Nebula is the presence of very tiny circular dark nebulae, known as globules, appearing as so many little black dots on the luminous background”.

These are now known as Bok Globules and they are believed be regions of gravitational collapse from whence new born stars will emerge. I’m not sure if I would describe them as circular but there are several Bok Globules visible on the above image.

The star cluster includes about fifty stars. The nebula is large, about three lunar diameters in apparent width, whilst the “lagoon” itself is the dark strip which is located just to the left of centre.

My previous attempt  at imaging this object, taken in 2017 with a DSLR camera, shows the nebula as a bluish-purple colour.

Object Details:

Designation: Messier 8, M8, NGC 6523 (nebula), NGC 6530 (cluster).
Constellation: Sagittarius.
Visual magnitude:  +6.0
Apparent size:  90′ x 40′
Diameter:  114 light years.
Distance:  4,300 light years.
Altitude during exposure:  42° above W horizon.

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Please feel free to ignore the technical stuff:

Image: Exposure:   240 x 30  sec = 120 min. Gain: 260 Date:  2019-08-23 Location:  outer suburban. Conditions:  clear. Moon: No

Processing: Image acquisition:  SharpCap. Method: Live stacked. Darks: 10x Image post-processing:  GIMP. Cropping:   No Sky:  0.63 e/pixel/sec.

Gear:

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:	01’ 09”

Geek Log:

[ZWO ASI071MC Pro] Debayer Preview=On Pan=0 Tilt=0 Output Format=FITS files (*.fits) Binning=1 Capture Area=4944×3284 Colour Space=RAW16 Hardware Binning=Off Turbo USB=40 Flip=None Frame Rate Limit=1 every 4 seconds Gain=260 Exposure=30 Timestamp Frames=Off White Bal (B)=50 White Bal (R)=53 Brightness=40 Temperature=-14.8 Cooler Power=53 Target Temperature=-15 Cooler=On Auto Exp Max Gain=300 Auto Exp Max Exp M S=30000

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\30.0s\gain_260\dark_10_frames_-14.8C_2019-08-23T11_25_55.fits #Black Point Display Black Point=0.14572864321608 #MidTone Point Display MidTone Point=0.741206030150754 #White Point Display White Point=1 TimeStamp=2019-08-23T13:29:48.4773617Z SharpCapVersion=3.2.6086.0 TotalExposure(s)=7200 StackedFrames=240

Image © Roger Powell

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