Hemisphere:  Southern  ·  Constellation: Sagittarius (Sgr)  ·  Contains:  IC 4715  ·  M 24  ·  NGC 6603  ·  Small Sgr Star Cloud
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Objects in the Sagittarius Star Cloud M24 - EAA, 



    
        

            DavidLJ
Objects in the Sagittarius Star Cloud M24 - EAA
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Objects in the Sagittarius Star Cloud M24 - EAA

Acquisition type: Electronically-Assisted Astronomy (EAA, e.g. based on a live video feed)
Getting plate-solving status, please wait...
Objects in the Sagittarius Star Cloud M24 - EAA, 



    
        

            DavidLJ
Objects in the Sagittarius Star Cloud M24 - EAA
Powered byPixInsight

Objects in the Sagittarius Star Cloud M24 - EAA

Acquisition type: Electronically-Assisted Astronomy (EAA, e.g. based on a live video feed)

Acquisition details

Dates:
July 16, 2021
Frames:
30×8(4′)
Integration:
4′
Avg. Moon age:
6.40 days
Avg. Moon phase:
39.64%

Basic astrometry details

Astrometry.net job: 4752994

RA center: 18h16m39s.8

DEC center: -18°1525

Pixel scale: 1.188 arcsec/pixel

Orientation: 180.023 degrees

Field radius: 0.827 degrees

Resolution: 4144x2822

File size: 23.8 MB

Locations: Home observatory, Glenorie, NSW, Australia

Data source: Backyard

Description

This image is dominated by dark nebulae silhouetted against the background of the Sagittarius Star Cloud Messier 24. The two most prominent dark nebulae are Barnard 92 (just to left of centre) and Barnard 93 (further over to the left). But many other wisps of dark nebulosity are visible as well. Over to the upper right is the open cluster NGC 6603.

The Sagittarius Star Cloud is presumably so named because it is located in the constellation Sagittarius. However, for the most part it does not seem to be part of the Sagittarius arm of the Milky Way, the next arm in from us towards the galactic core. Rather, it seems to be further away belonging to the Scutum/Centaurus arm which is closer still to the galactic core. The Wikipedia article on M24 states that it “fills a space of significant volume to a depth of 10,000 to 16,000 light years”. It contains components in the range of 200 to 600Myr or more. The golden hue stretching right to left across the image is caused by the faint foreground diffuse emission nebula Sharpless 41.

The dark nebulae clearly lie between us and the star cloud but it is not clear if they are all at approximately the same distance. Searching the internet for the distances to B92 and B93 turned up only one reference, ~10,000 light years for B92. On that basis I measure the longest axis of the darkest part of B92 to be 43 light years.

The open cluster NGC 6603 appears to be at a similar distance. At an age of 200Myr +/- 100Myr it is thought to be a younger component of the star cloud. Said to contain about 30 stars, this image suggests that there are in fact many more. I measure its diameter at about 20 light years.

Image B of the actual EAA experience shows that the later Photoshop adjustments to arrive at the main image were minimal.

Comments

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  • Final
    Objects in the Sagittarius Star Cloud M24 - EAA, 



    
        

            DavidLJ
    Original
  • Objects in the Sagittarius Star Cloud M24 - EAA, 



    
        

            DavidLJ
    B

B

Description: Screenshot of on-screen display during SharpCap livestack.

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Objects in the Sagittarius Star Cloud M24 - EAA, 



    
        

            DavidLJ

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