Arp 25, Arp 114
NGC 2276, NGC 2300
20’ x 15’ | 0.3”/px | 4000 × 3000 px
Cepheus
RA 07h 29m Dec +85° 44’ | 178°
Arp 25 and Arp 114 are notable entries in Halton Arp's Atlas of Peculiar Galaxies. Arp 25 is associated with the galaxy NGC 2276, a spiral galaxy located in the constellation Cepheus. NGC 2276 exhibits a distorted structure, likely due to gravitational interactions with its neighboring elliptical galaxy, NGC 2300. This interaction has led to an asymmetric spiral arm and enhanced star formation on one side of the galaxy, making it a compelling subject for studying the effects of galactic encounters. Arp 114 is actually the combination of NGC 2276 and NGC 2300. This pair exemplifies the gravitational interplay between a spiral and an elliptical galaxy, with NGC 2276's distorted morphology attributed to the tidal forces exerted by NGC 2300.
source: ChatGPT
Arp 25 details
Halton Arp classified all objects based on their peculiarity. He used 5 major classifications and 39 subclassifications. Halton Arp also wrote a short note describing each object, and a challenge, a feature that can be somewhat difficult to identify. Arp 25 (NGC 2276) is part of Arp 114 (NGC 2276 + NGC 2300).
| Number | Arp 25 |
| Common galaxy names | NGC 2276 |
| Main Classification | Spiral Galaxies (1-36) |
| Subclassification | One heavy arm (25-30) |
| Arp's note | Tubular arm, straight at first, then bent. Secondary arm from straight portion |
| Challenge | Mottling and tubular arm in NGC 2276 |
| Source: The Arp Atlas of Peculiar Galaxies: A Chronicle and Observer's Guide by Jeff Kanipe and Dennis Webb. | |
Arp 114 details
As mentioned above, Arp 114 is the bigger object that includes both Arp 25 and NGC 2300. There are four objects where one Arp object is part of a bigger Arp object. Besides the Arp 25/114 combo, the other examples are: Arp 310 is part of Arp 311, Arp 16 is part of Arp 317 and Arp 33 is part of Arp 326.
| Number | Arp 114 |
| Common galaxy names | NGC 2300 and NGC 2276 |
| Main Classification | Elliptical and elliptical-like galaxies (102-145) |
| Subclassification | Close to and perturbing spirals (113-132) |
| Arp's note | Spiral somewhat peculiar. May be perturbed. |
| Challenge | Mottling and tubular arm in NGC 2276 |
| Source: The Arp Atlas of Peculiar Galaxies: A Chronicle and Observer's Guide by Jeff Kanipe and Dennis Webb. | |
Data Acquisition
Data was collected over 9 nights, from January until March 2025, using a 14” reflector telescope with full-frame camera at the remote observatory in Spain. Data was gathered using standrad LRGB filters. A total of about 19 hours of data was combined to create the final image. These galaxies have a very high declination of 85°. This makes them circumpolar, with an altitude that is nearly constant.
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.
For the stretching, the SmartStretch scriplet from the PixelMathUI script has been used. This scriplet includes a slider called ‘Saturation Protection’, which was set all the way to 1 for the RGB image, with good results. Stretching RGB data always bears the risk of loosing colour. Therefore, I typically revert to the Colour mode in GHS or ArcSinhStretch. Both are designed to keep colours natural during the stretching process. The Saturation option in SmartStretch appears like a suitable alternative to the earlier mentioned methods.
The rest of the processing followed a standard processing workflow.
Processing workflow (click to enlarge)
This image has been published on Astrobin.
