M33 - The Pinwheel Galaxy (LRGB)

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An earlier LLRGB attempt at M33, the Pinwheel Galaxy, imaged over three nights at Comanche Springs — see the more recent HaRGB version for my current best image. A second, even earlier attempt from 2003 is further down this page.

Location: Comanche Springs, 3RF dark sky site near Crowell, Texas

Date: August 1-3, 2005

Seeing: 9/10

Transparency: 8/10 (mag. 7 skies)

Temperature: 72 degrees F (-15 degrees C on camera)

Scope/Mount: 12.5" RCOS RC @ f/9 and Paramount ME

Camera: SBIG STL-11000M astro CCD camera

Exposure Info: LLRGB image; 150:40:30:40 RGB (10 minute subexposures, all unbinned)

Processing Information: Calibration (darks/flats), registration, gradient removal, and RGB channel combine in MaxIm DL 4 (average combine). LRGB and LLRGB combine, color balance, levels/curves, high pass sharpening, and noise removal (Noel Carboni's DLR Tools) in Photoshop CS.

Exposure Notes: This one was tough to put together because of the many brighter regions within the galaxy itself. Could have used a little more luminance, but this will do. Seeing was exceptional during this stretch. Imaged over three nights in the late morning hours.

About this Object

The Andromeda Galaxy (M31) gets tons of attention, as it should. It's huge, bright and easily seen in even light polluted skies. But just on the other side of Mirach on a line extending from M31 is the Pinwheel Galaxy in Triangulum, known as M33. This is a magnificent object in its own right and, in my opinion, is a better telescopic sight than M31, as are several face-on spirals. Under dark skies, the spiral arms are evident in many scopes. In fact, little do people realize that this is sometimes a naked eye object in those same dark skies. The pinkish areas in the photo are very active star-forming regions, known as hydrogen-alpha regions, and they really stand out in many photographs. This galaxy is quite large as well, a stunning site in a big scope and even in binoculars. Don't neglect this spiral galaxy!

Previous Attempt

An earlier attempt at M33 with an SBIG ST-7e, December 2003

Location: Ballauer Observatory in Azle, Texas
Date: December 26, 2003
Seeing: 9/10 (1.3 FWHM)
Transparency: 5/10
Equipment: Tak FSQ-106 on Celestron CGE mount
Camera: SBIG ST-7e with CFW8a color filter wheel, unguided
Exposure Info: LRGB image (L = 5 x 10 min & 30 x 1 minutes, R = 3 x 10 minutes, G = 3 x 10 minutes, B = 2 x 10 minutes) binned 1x1.
Processing Info: Color channels and Luminance with darks, alignment and Sigma combine in MaxIm 3.0. RGB image combined in MaxIm. Luminance and RGB aligned and combined in Photoshop 7. Levels, Curves, and Unsharp mask in Photoshop 7 on the Luminance channel. Levels, Curves, and color balance performed on the RGB channel in Photoshop. Image cropped and resized for web.

Note: If you image this object, you might try to do a better job of focusing than I did!

🤖 AI-drafted · unverified

What it is: M33, often called the Pinwheel Galaxy (or the Triangulum Galaxy), is a face-on spiral and the third-largest member of the Local Group.
Constellation: Triangulum
Distance: ~2.73 million light-years
Apparent magnitude: 5.7
Angular size: ~70.8 × 41.7 arcminutes
Coordinates: RA 01h 33m 50s, Dec +30° 39′

This summary was generated by an AI assistant from general astronomical references, not from Jay's own notes on this specific image. Treat every detail above as a starting point for research, not settled fact.