Arp 114:

North is left. (mirrored). 26x18 arcmin (0.3 arcsec/pixel)

Total exposure time: 393 * 30 seconds = 3.2 hours. (across 2 nights)

Exposure used in stack: 241 * 30 seconds = 2 hours.

Telescope: C9.25 (230mm, f/10, fl=2300mm)

Camera: IMX533 (16mm diagonal, square, color)

Processing: (no software sharpening used)

1. Callibration (dark + flats)

2. Stacking (average w/ rejection)

3. White balance and background subtraction

4. Asinh stretch

5. Light denoising

6. Tone curve

7. Crop

This one has two entries in the Altas of Peculiar Galaxies:

Once as Arp 25 under "one heavy arm" and again as Arp 114 under "ellipticals close to and perturbing spirals". The spiral structure of NGC 2276 is somewhat unusual looking, although it's not an obvious case of tidal interaction.

Hubble data suggests it's actually moving quite fast (950 km/sec) through space, which causes the lob-sided arms as it interacts with sparse gas clouds. If this is correct, the galaxy is not actually head-on as seen from earth: It tilts toward us on the eastern (top) side and away on the western (bottom) edge.

This would require the galaxy to be stretched by the gravity of NGC 2300, so it's still an interacting galaxy, but in a different way.

The origin of spiral structures in galaxies is somewhat debated because the arms are unstable:

The inner regions of the galaxy orbit the core faster, which should mix them together into a uniform disk. It's generally believed that — instead of being physical structures — the arms are density waves traveling through interstellar gas and triggering rapid star formation, making those regions much brighter.

The galaxy at the top (NGC 2300) doesn't have very much gas so it's glow is mostly composed of long-lived red stars. Elliptical galaxies like this are the majority in the universe, but are quite rare in our part of it: this is the first time I've intentionally imaged one instead of having it sneak into the background.

... although spiral galaxies have an elliptical-style halo around them. It's usually much dimmer than the spiral arms, but it is there.

As for imaging, both are less than 5 degrees from the north pole, so it's one of the few galaxies that could work well with untracked photography: using a normal tripod and telephoto lens.

Some of my data came from a night with really poor transparency and the rest was taken during the full moon. This was not ideal for the low surface brightness of the elliptical galaxy.

The spiral galaxy is around 100 arcseconds wide (~2 jupiters) so it's not really a good match for my perpetually bad seeing: the image FWHM is around 4 arcseconds.

... but I'm not convinced clear nights with no moon or/and good seeing even exist at my place.

• stack.fits.fz: 32-bit compressed FITs image

• esahubble.org/images/heic2106a: High-resolution hubble image.

• arxiv.org/pdf/2512.17486: Ram pressure write up.