Celestial hemisphere:  Southern  ·  Constellation: Sagittarius (Sgr)  ·  Contains:  11 Sgr  ·  4 Sgr  ·  7 Sgr  ·  9 Sgr  ·  B296  ·  B302  ·  B303  ·  B85  ·  B88  ·  B89  ·  B91  ·  HD163118  ·  HD163179  ·  HD163298  ·  HD163317  ·  HD163369  ·  HD163391  ·  HD163428  ·  HD163429  ·  HD163451  ·  HD163479  ·  HD163516  ·  HD163537  ·  HD163554  ·  HD163575  ·  HD163647  ·  HD163665  ·  HD163703  ·  HD163721  ·  HD163752  ·  And 740 more.
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The Sagittarius Triplet, Aleix Roig
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The Sagittarius Triplet, Aleix Roig
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Acquisition details



Close to the Galactic Center of our Milky Way we can find an interesting trio of nebulae. Well known since the 17th century these nebulae are one of the most popular deep sky targets. Located some 4,100 light-years away from planet Earth, this trio is composed of the Lagoon nebula, Messier 8, the Trifid nebula, Messier 20, and NGC 6559. 

Together with the three main nebulae we can distinguish some other faint nebulae such as IC 4684, IC 4685, IC 274 and IC 275. Some of those nebulae are emission ones while others reflect the light from the closer stars (that's the case of the blueish part of M20).

In the image we can also see two star clusters as follows.

Close to M8, at the bottom of the image, we can see NGC 6544, a globular cluster located at a distance of 9,500 light-years. This group of stars was firstly discovered by Willian Herschel back in 1784. It only covers a diameter of 1 arcminute. Within this globular cluster, in 1999 was discovered a millisecond pulsar in a binary system catalogued as PSR J1807-2459.

Another cluster of stars can be found in this field, close to M20, at the top of the image. This open cluster is catalogued as Messier 21, NGC 6531, and popularly known as the Webb's Cross. It's located some 3,900 light-years away from Earth and was discovered by Charles Messier back in 1764. 

This image was acquired last Agust during my trip to Tivoli Astrofarm in Namibia. I captured a bit more than 2 hours of data using my monochrome camera, ASI2600MM on the small refractor FRA300. 

The full image shown above covers an area of 4º28' x 2º58' at a resolution of 2.59"/pixel. 

Image details:

L: 12x300" (1h)
RGB: 12x 60" each channel (36')
Ha: 6x300" (30')
[OIII]: 6x300" (30') 
Calibrated with darks, flats. dark-flats. 

Total exposure: 2h 36'

Moon at 6%Sky darkness: 22,05 mag/arcsec2
Image resolution: 2.59”/pixelFOV (full image): 4º28' x 2º58'


FRA300 + ASI2600MM + LRGB ZWO filters + ZWO EFW 7 pos + ZWO EAFZWO AM5 mountASI AIR PlusGuiding with ASI120MM and ZWO Mini Guide Scope  

Aleix Roig, November 2022
Tivoli Astrofarm (Namibia).


Sky plot

Sky plot


The Sagittarius Triplet, Aleix Roig

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