Sh2-223, Sh2-224, Sh2-225, Sh2-227 widefield

Sh2-224 is a supernova remnant visible in the constellation of Auriga. It is situated 3.5 ° to SSE of the bright star Capella, the dominant star of the constellation. It is formed by two soft nebulous filaments, the most conspicuous of which is that of the northwest and extends for 20 ‘x 30’ towards the center of the source of radio waves, which has dimensions of 70 ‘x 75’. The object has an unusual shape, with a shell structure with a radius of about 25 parsec, and is in interaction with a cavity of the interstellar medium at a higher temperature than the surrounding environment, located in the south-western part and of the arch. This conformation suggests that the rest of the supernova in the southwest direction has come into contact with the cavity, first deforming and entering into interaction with this structure, then expanding inside it and creating a wider propagation wave that has emerged from the opposite part, thus creating the arch structure visible in the westernmost part, ie beyond the cavity. The distance of the structure is estimated at about 14,700 light years from the solar system, in a peripheral region of the Arm of Perseus. The X-ray study determined an age of the structure between 13,000 and 24,000 years.

This is another image from telescope live. The Oiii data in particular was really hard to work with – There wasn’t much signal at all, and the star halos were very tricky to work around. However, the Ha data was incredibly good, so using some processing tricks I was able to make the whole image a lot better. Though there was Sii data included, I decided not to use it as it didn’t really add anything.

Image:

You can access the full quality PNG here: https://live.staticflickr.com/65535/52704715609_dd6b82c402_o.png

Annotated Image:

Details:

Telescope: Takahashi FSQ-106EDX4 with 0.73x focal reducer
Camera: FLI PL16803
Filters: Astrodon Ha (3nm), SII (3nm), OIII (3nm)
Location: Telescope Live's IC Astronomy Observatory, Spain
Date of Observations: 11/2/2022, 11/4/2022, 11/6/2022, 11/6/2022, 11/7/2022, 11/25/2022, 12/19/2022, 12/26/2022, 1/11/2023
Ha: 26 x 600s (4hr 20m)
Oiii: 26 x 600s (4hr 20m)
Processing: Pixinsight
Credits: Data: Telescope Live; Processing: William Ostling

Processing:

Pre-processing and Stacking
- Linear defects from the CCD were removed using pixinisight's lineardefectdetection and lineardefectremoval script
- The subframes were weighted and registered in WBPP
- Ha and Oiii were individually integrated and drizzled
- Ha and Oiii were drizzled
Linear preparation of all frames:
- Stacking artifacts were cropped
- Starless DBE was applied to Ha, Oiii 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
- Ha, Oiii were made starlesss using Starnet 2
- A low contrast mask was created and applied to Ha and Oiii
- Noise Xterminator was applied with strength 81 and detail 0
- The denoised starless Ha and Oiii images were combined to create and HOO image
- the HOO image was color calibrated
Stretching:
- The Ha image was stretched using GHS
- The HOO image was stretched using GHS
Non-linear adjustments
- Ha and HOO image were combined through LRGB combination
- Curves Transformation
- Background level was set to .115
- A psuedo-RGB image was created, and the stars were extracted
- the HHOO image and stars image were re-linearized and added together
- Curves transformation
- Adam block-style star reduction
- Starless enhancement
- Slight non-linear noise reduction
- Exponential transformation