Arp77
NGC 1097
30’ x 20’ | 0.3”/px | 6000 × 4000 px | full resolution
Fornax
RA 02h 46m 18s Dec -30° 16’ 33” | 0°
Arp77 is a pair of interacting galaxies. The system is composed of the larger barred spiral galaxy NGC 1097 and its smaller companion, the elliptical galaxy NGC 1097A. Located approximately 45 million light-years away in the constellation Fornax, these galaxies are engaged in a gravitational interaction that has visibly distorted their structures. NGC 1097, classified as a Seyfert galaxy, hosts an active galactic nucleus powered by a supermassive black hole, while the interaction with NGC 1097A has sparked intense starburst activity and created a striking ring of star formation around its core. The study of Arp77 provides valuable insights into the processes of galactic mergers, tidal forces, and the broader impacts of such interactions on galaxy evolution. This system is particularly useful for astronomers seeking to understand how galaxies transform over time, especially in environments where gravitational encounters are frequent. The dynamic interplay between NGC 1097 and NGC 1097A offers a glimpse into the complex mechanisms that drive star formation, black hole activity, and the eventual fate of colliding galaxies.
source: Mistral.ai
Data Acquisition
Data was collected over 12 nights during scattered periods in November 2024, January, February and September 2025, using a 14” reflector telescope with full-frame camera at the remote observatory in Spain. At this location the maximum altitude is only 22°, leaving short imaging intervals each night and thus many sessions quite far apart. Data was gathered using standard LRGB filters. A total of approximately 20 hours of data was finally combined to create the final image.
Location Remote hosting facility IC Astronomy in Oria, Spain (37°N 2°W)
Sessions
Frames
Equipment
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Planewave CDK14 (2563mm @ f/7.2), Optec Gemini Rotating focuser
10Micron GM2000HPS, custom pier
Moravian C3-61000 Pro (full frame), cooled to -10 ºC
Chroma 2” LRGB unmounted, Moravian filterwheel L, 7-position
Unguided
Compulab Tensor I-22, Dragonfly, Pegasus Ultimate Powerbox v2
Voyager Advanced, Viking, Mountwizzard4, Astroplanner, PixInsight 1.9.3
Processing
All processing was done in Pixsinsight unless stated otherwise. Default features were enhanced using scripts and tools from RC-Astro, SetiAstro, GraXpert, CosmicPhotons and others. Images were calibrated using 50 Darks, 50 Flats, and 50 Flat-Darks, registered and integrated using WeightedBatchPreProcessing (WBPP). The processing workflow diagram below outlines the steps taken to create the final image.
The nucleus of this galaxy is quite tricky. It can burn out easily and become ‘star-like’. One run of GHS using the invert mode helped to bring the dynamic range in the center of the galaxy down a touch, to keep structure in the core visible, while still showing the large dust-lanes surrounding the galaxy arms.
Given the maximum altitude of only 22° of this target, the overall quality of the data is less than if it would have been higher at the horizon. Therefore a bit more attention was placed on getting the maximum contrast, colour and sharpness out the image, using additional GHS and UnsharpMask steps toward the end.
The rest of the processing followed largely a standard processing workflow.
Processing workflow (click to enlarge)
This image has been published on Astrobin.
