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Contains:  Little Gem, NGC 6445, NGC 6440
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NGC 6445 and NGC 6440, 


            Gary Imm
NGC 6445 and NGC 6440

NGC 6445 and NGC 6440

Technical card

Resolution: 3000x2303

Dates:April 19, 2019April 20, 2019April 21, 2019

Astrodon Blue 31mm Gen2 I-Series: 30x60" (gain: 139.00) -20C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 30x60" (gain: 139.00) -20C bin 1x1
Astrodon Ha 31mm 5nm: 24x300" (gain: 300.00) -20C bin 1x1
Astrodon OIII 31mm 3nm: 24x300" (gain: 300.00) -20C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 30x60" (gain: 139.00) -20C bin 1x1

Integration: 5.5 hours

Avg. Moon age: 15.88 days

Avg. Moon phase: 97.76% job: 2694839

RA center: 267.290 degrees

DEC center: -20.166 degrees

Pixel scale: 0.718 arcsec/pixel

Orientation: 48.714 degrees

Field radius: 0.377 degrees

Locations: Backyard (Mag 20.8 - New Moon), Onalaska, Texas, United States

Data source: Backyard


This field of view captures two objects, a planetary nebula (NGC 6445) and a globular cluster (NGC 6440), in the southern constellation of Sagittarius at a declination of -20 degrees. It is rare to be able to see a planetary nebula and a globular star cluster in the same field of view. This image combines narrowband and RGB to capture both nebula detail and star color.

The planetary nebula spans 3 arc-minutes in our apparent view. It is one of the largest PN (and therefore also one of the oldest) at a true diameter of 4 light years. It lies 4,500 light-years distant. It has two nicknames - Box Nebula and Little Gem Nebula - which both stem from its RGB projection as a rectangular box, seen in this image as the bright white outline. At least two other PN are also nicknamed the Box Nebula - NGC 6309 and NGC IC 4406.

The overall structure of this nebula is very similar to that of NGC 40. Like NGC 40, the white box is the cross-section of the torus of dense material which originally contained the bi-polar PN gas outflow. Our perspective is at 90 degrees, a side view. Also like NGC 40, the gas flow has burst through the ends and expanded into a butterfly shape. NGC 40 is a multi-polar PN and so is this one, as seen by the various axes of gas outflows. A recent scientific study has concluded that this is a quadrupolar PN, but it looks like a bit more than that to me.

The globular cluster NGC 6440 lies 6x further away, at 24,000 light-years distant. The orange tint is very interesting, presumably from a significant amount of dust in that distant direction. The outer extent of the cluster is very unsymmetric, with a void area seen on the left side of the cluster. Again, I assume that this is due to dust.



Gary Imm
License: None (All rights reserved)

Sky plot

Sky plot


NGC 6445 and NGC 6440, 


            Gary Imm