Messier 8, Messier 20 and IC 4685


Click here for full resolution image

Messier 8, the Lagoon Nebula, is immersed in a large HII emission region. This wide field image (3×3 degrees) captures the three large nebulae that are visually very close (I call this region the “Sagittarius Bouquet”). Messier 8 spans more than  one degree of arc and lies about 4,300 light years away. Messier 20, bottom, left of center, has a larger distance from us, 5,200 light years. IC 4685, usually disregarded due to its much more famous neighbors, lies about 4,000 light years away from us. To get a higher resolution, this wide field image has been combined with high resolution images of the three nebulae, taken separately with a 20 inch telescope in three consecutive years. The image has been taken with narrowband filters (mapped for natural color, Ha (Red and Blue), SII (Red) and OIII (Green and Blue), broadband Blue to catch the reflection nebulae in M20 and IC4685. Shorter exposure times were taken for the stars in RGB. Here you can find the high resolution images of M8, M20 and IC4685, used for this wide field image.

This image has been selected as APOD (Astronomy Picture Of the Day) on July 27th, 2017.

Additional Information


Name(s): Messier 8, Messier 20 and IC 4685

Type: Emission/Reflection/Dark Nebulae

RA:  18h 05m 10s

Dec: -23º 52’ 53”

Constellation: Sagittarius

Size (arcmin): 90×40, 30×27 and 30×25 respectively

Magnitude: +6.0, +6.3, +10.0 resp.

Distance: All around 4,500 ly


Date: Wide field: June 2017; High Resolution 2015 and 2016.

Location:, SSO near Coonabarabran, NSW Australia

Size: 2.7×2.6 degrees

Telescope: TOA 130mm f/5.7 and Planewave CDK 20” f/6.8

Camera: SBIG STX16803 (4096x4096pix) in both cases

Guiding: Astrodon MonsterMOAG off-axis guider

Total exposure: 44.5 hours (Wide field: Ha: 2h; OIII 2h; SII: 1h40m) (High Resolution: a total of 37 hours Narrowband, used only as Luminance) (Stars wide field: RGB: 54 min) (Broadband Blue 1 hour).

Processing: CCDStack, Photoshop CC 2017

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