NGC 3521 - wonderfuluniverse.de

NGC 3521 from Telescope Live CHI-1-CMOS and Insight Observatory

In 2024, I received a high-quality dataset of the spiral galaxy NGC 3521 from Telescope Live, acquired with professional equipment in Chile. This was not my first encounter with the galaxy, however. Some years earlier, I had already received another dataset of NGC 3521 from the Insight Observatory, recorded with a telescope in New Mexico. Having access to data from two different observatories provided an excellent opportunity to compare imaging systems, observing conditions, and processing techniques while studying one of the most interesting spiral galaxies in the northern sky.

NGC 3521 is located in the constellation Leo at a distance of approximately 35 million light-years. It is classified as a flocculent spiral galaxy, meaning that its spiral structure is not organized into a few well-defined grand-design arms but instead consists of numerous fragmented and patchy spiral segments. This gives the galaxy a highly textured and somewhat chaotic appearance that becomes increasingly impressive in deep images.

One of the most striking features of NGC 3521 is its rich network of dark dust lanes that weave through the disk and partially obscure the bright stellar background. These dust structures create a remarkable three-dimensional appearance, especially where they overlap with luminous star-forming regions. The galaxy is also known for its extensive stellar halo and faint tidal debris, suggesting that it has undergone gravitational interactions or minor mergers in the past.

Deep observations reveal countless star-forming knots distributed throughout the spiral arms, along with subtle streams and shells surrounding the galaxy. These faint outer structures are of particular scientific interest because they preserve evidence of the galaxy’s evolutionary history and past interactions with smaller companions. Studies have shown that NGC 3521 possesses a complex stellar population, containing both very old stars and younger generations formed in more recent epochs.

Because of its combination of bright structure, intricate dust patterns, and faint outer features, NGC 3521 is considered one of the finest spiral galaxies for deep imaging. The datasets from Insight Observatory and Telescope Live allowed the galaxy to be explored in exceptional detail, revealing everything from the bright central bulge and fragmented spiral arms to the delicate halo structures extending far beyond the visible disk. The result showcases a galaxy whose seemingly chaotic appearance hides a rich and fascinating evolutionary history.

Data calibration and registration and the final processing was done with PixInsight. The result was as follows:

NGC 3521 - Telescope Live — NGC 3521 – Telescope Live, 2024

The faintest star in this image has an apparent magnitude of 23.5 mag_v (SDSS DR17).

Beside NGC 3521 there are a lot of background galaxies in the image.

The two highest redshift quasars [Flesh 2015] in the image are:
SDSS J110624.62-000233.7 z=2.5 mag_v=22.2 (SDSS DR17)
SDSS J110531.99+000653.6 z=2.22 mag_v=21.4 (SDSS DR17)

The images were taken with the following equipment:

Date: 2024
Location: El Sauce Observatory, Chile
Telescope/Lens: Planwave CDK 24
Focal length [mm]: 3962
Focal Ratio: 6.5
Mount: Mathis MI-1000/1250
Camera: QHY 600M Pro
Filter: LRGB
Exposure time [min]: 120:120:130:145
Resolution: 0,39″/px (bin 2)

For the 2021 data the calibration and registration and the final processing was done with PixInsight. The result was as follows:

The faintest star in this image has an apparent magnitude of 22.4 mag_G (SDSS DR15).

Beside NGC 3521 there are a lot of background galaxies in the image. Furthermore I marked the two most distant quasars:

The two highest redshift quasars [Flesh 2015] in the image are:
SDSS J110605.31+001032.6 z=2.79 mag_G=21.1 (SDSS DR9)
2QZ J110715.4-001532 z=2.79 mag_G=20.2 (SDSS DR9)

The galaxy is close to the ecliptic, so some asteroids are visible in the image. The most prominent one is 2629 Rudra.