M90, also known as NGC 4548, is a intermediate spiral galaxy located about 60 million light-years away in the Virgo Constellation. This galaxy is a member of the Virgo Cluster of galaxies, a dense region of space containing thousands of galaxies. M90 stands out for its large size, approximately 120,000 light-years in diameter, and its distinctive orientation, which makes it appear almost edge-on from Earth.
M90 is an intermediate spiral galaxy, which places it between a normal spiral galaxy and a barred spiral galaxy. It has a weak or intermediate bar structure with loosely wound spiral arms and moderate star formation activity.
One of the intriguing aspects of M90 is its close interaction with nearby galaxies, particularly IC 3583. IC 3583 is a smaller galaxy that lies just a few million light-years from M90. The two galaxies are in the process of interacting gravitationally, which is significant because their close proximity suggests that they could be exchanging gas, triggering star formation, or even on a collision course that could eventually result in a merger. This interaction is typical in galaxy clusters, where galaxies are packed closely together, and their gravitational forces can lead to complex tidal interactions.
Imaging Details
- Workflow: Broadband workflow for Galaxies
- Red: 60*300 seconds
- Green: 60*300 seconds
- Blue: 60*300 seconds
- Total Imaging Time: 15 hours
- Imaging Dates (7 nights)
- 5/5/2024
- 5/9/2024
- 5/10/2024
- 5/13/2024
- 5/14/2024
- 5/29/2024
Imaging Workflow
This image followed the Broadband workflow for Galaxies
Integrated Image
I started off with three images for red, green, and blue filters. I did my normal integration process using the PixInsight Weighted Batch Preprocessing Script.
Dynamic Crop
The Dynamic Crop process was used to clean up the edges of the 3 images.
Gradient Correction
The Gradient Correction process made it easy to remove the extreme darkness/brightness around the edges.
Deconvolution
BlurXTerminator is applied two times. The first time is for Correction only. This takes care of the coma (blurring of stars along the edges).
The second application of BlurXTerminator handles deconvolution, which improves the sharpness and details of the nebula while removing the blur from the image.
Noise Reduction
With the blurring corrected, it is time to do noise reduction. This time I used the new NoiseXTerminator add on.
Channel Combination for RGB
The next step is to do a Linear Fit across the Red, Green, and Blue channels.
Spectro-Photometric Color Calibration
The Gaia dataset was used to apply color calibration by using the Spectro-Photometric Color Calibration process.
Star Removal
To ensure the hydrogen-alpha image does not influence the star color, StarNet+ was applied to remove the stars.
Histogram Stretch
Histogram transformation was used to stretch the image. Although the image appears dark, the entire image will get brighter when the synthetic luminance is added.
SCNR
The green hue was lowered by using SCNR
Color Saturation
PixInsight Curves Transformation increased the overall color saturation.
Luminance Workflow
Before doing anything more to the color image, it is time to go through the Luminance Workflow.
Luminance Integration (LRGB)
With the luminance image processed, it can get integrated with the color image with LRGB Combination process. This used 45% for lightness and 35% for saturation.
Saturation
PixInsight Curves Transformation increased the overall color saturation.
Brightness
PixInsight Curves Transformation increased the overall brightness.
Stars
The stars were added back in. Curves Transformation was used to increase the brightness and saturation of the stars.
ACDNR for Chrominance
Although NoiseXTerminator did a great job in removing the noise from the image early on in the workflow, some of the processing might have added noise in the color. Applying ACDNR for only chrominance helps correct this without losing details.
Final Adjustments
To finish the image, I make a few minor tweaks to the brightness and colors of the stars using Curves Transformation.
