Galaxy Triplet NGC 6769-71

This is another image from telescope live, of an interacting galaxy triplet plus some friends in the background. It was a really tough dataset to process – the data was badly undersampled and slighly out of focus. Very careful work with GHS and MMT helped a lot with this image, and I’m pretty happy with the amount of detail I got out considering the lack of data.

Galaxy Triplet NGC 6769-71 is a gravitational interacting triplet of galaxies, located about 190 million light years away in the southern constellation of Pavo (the Peacock).

Most galaxies are members of clusters of galaxies. In these, they move around among each other in a mostly slow and graceful ballet. But every now and then, two or more of the members may get too close for comfort – the movements become hectic, sometimes indeed dramatic, as when galaxies end up colliding. This image shows an example of such a cosmic tango.

As dramatic and destructive as this may seem, such an interaction event is also an enrichment, a true baby-star boom. A cosmic catastrophe like this one normally results in the formation of many new stars. This is obvious from the blueish nature of the spiral arms in NGC 6769 (upper right) and NGC 6770 (upper left) and the presence of many sites of star forming regions.

Image:

Full-quality PNG here: https://live.staticflickr.com/65535/52850936230_ffe3af7b4b_o.png

Closeups:

Annotated Image:

Full-quality image here: https://theastroenthusiast.com/wp-content/uploads/2023/04/NGC6769_annotated.jpg

Details:

Telescope: Planewave CDK24
Camera: FLI PL 9000 
Filters: Astrodon LRGB 2GEN
Location: El Sauce Observatory, Río Hurtado, Coquimbo Region, Chile
Date of Observations: 8/28/2022, 8/29/2022, 9/1/2022, 9/14/2022
L: 10 x 600s (1h 40min)
R: 10 x 600s (1h 40min)
G: 10 x 600s (1h 40min)
B: 10 x 600s (1h 40min)
Processing: Pixinsight
Credits: Data: Telescope Live; Processing: William Ostling

Processing:

Pre-processing and Stacking
- Images were cosmetic corrected for hot pixels
- The subframes were weighted, registered, normalized, integrated, and drizzled in WBPP
Preparation of all frames:
- Stacking artifacts were cropped
- RGB Channels were combined to create an RGB image
- RGB image was plate solved
- Starless DBE was applied to L, RGB as follows:
      - Starnet 2 was applied to a clone of the target image, creating an image with stars and an image without stars
      - DBE was applied on the starless image to create a background model
      - The background model was subtracted from the stars image
- the RGB image was photometrically color calibrated using SPCC and clipped H values were fixed with the repaired HSV separation script
Deconvolution of the luminance
- a PSF was created using the dynamic PSF process
- Linear starnet was applied to create a starless image and a star mask
- the linear image was duplicated, stretched, clipped, and convoluted to create a mask
- The starless image was deconvoluted using the RVC algorithm
- the stars were added back in
- A low contrast mask was created and applied to the luminance image
- Noise Xterminator was applied with strength 73 and detail 0
- DeepSNR noise reduction was applied to RGB
Stretching
- The Luminance image was stretched using MMT and GHS
- The RGB image was stretched using ArcsinH and GHS
Non-linear adjustments
- LRGB combination
- Star reduction