Arp 38: not that peculiar

2026-06-27 [Photo]

Data is from 2026-06-20.

North is right. 0.53"/pixel (27'x27' field). FWHM=4'

A nice, if rather small (~100") edge on spiral galaxy. Arp filed this one under "low surface brightness companions", but the companion doesn't seem to exist.

There's a bright spot to the north (right) of the core, but hubble data shows it's just a bright HII region and star cluster. This part of the sky isn't covered by SDSS, so I don't have widefield reference data.

Total exposure time:

327 * 30 seconds = 2.7 hours.

Telescope:

C9.25 (230mm, f/10, fl=2300mm) + 0.63 Starizona reducer

Camera:

IMX533 (16mm diagonal, square, color)

Processing:

1. Callibration (dark + flat)
2. Stacking (average w/ outlier rejection)
3. White balance and background subtraction (no gradient removal)
4. Asinh stretch (color preserving)

Again with the walking noise!

I'll try to check my callibration frames and restack this one.

Related:

• https://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp38.jpeg: Arp's image.
• /astro/arp38/arp38.fits.fz: raw stacks