NGC 5474 – Galaxy in Ursa Major: June 2022 Observer’s Challenge Report #161

Work-File: Used only for organization and editing. When all entries are received (July 8th) a final and a .pdf report will be issued by the 10th of July, and at that time will be posted on this page.

James Dire: Observer from Illinois

NGC5474 is a peculiar dwarf galaxy in Ursa Major. The galaxy is 21 million light years away and shines at magnitude 11.3. The galaxy measures 4.8 x 4.3 arcminutes in size. William Herschel discovered NGC5474 in 1788 using his 18.7-inch Newtonian telescope.

NGC5474 is a satellite galaxy of M101. Although it is classified as a dwarf galaxy, NGC5474 still contains a few billion stars. It’s roughly comparable in size to the Small Magellanic Cloud, a satellite galaxy of the Milky Way. 

NGC5474 is peculiar in that it only has visible spiral structure on one side of the galactic core. The side facing M101 seems devoid of visible matter. The galaxy has undergone some intense gravitational distortion from interactions with the massive Pinwheel Galaxy.

I viewed NGC5474 with two telescopes this month. The first was an 8-inch, f/3.9 Newtonian with a coma corrector. Using a 26mm Televue Nagler Eyepeice (31x), I was able to see both M101 and NGC5474 at the same time. M101 has a very low surface brightness. But in my highly transparent dark skies, I was able to see the pinwheel structure of this galaxy. NGC5474 has comparable surface brightness to M101. Both are difficult to see under less than ideal conditions. I could make out the core of NGC5474, as well as a fan structure on one side of the galaxy. The core was very star-like, while the fan-shaped region was just a faint glow.

Next, I observed NGC5474 with a 10-inch, f/12 Cassegrain reflector using the same eyepiece (117x). The increased magnification spread out the faint light of the galaxy. But the greater surface area of the 10-inch telescope brought more light to the eyepiece. Thus I found the view in the Cassegrain to be very similar to that of the Newtonian. The fuzzy glow of this oddly shaped galaxy was just larger.

I photographed the M101 group, including NGC5474, using an Askar 72mm f/5.6 Qunituplet Apo with a 0.7x focal reducer to yield f/3.9 and a SBIG STF-8300C CCD camera. The exposure was 100 minutes using 10-minute subframes. NGC5474 appears to be the largest and brightest of the Pinwheel’s satellite galaxies. This imaged shows the level of detail I could see of NGC5474 in my telescopes.

I next imaged NGC5474 with an 8-inch f/8 Ritchey–Chrétien Cassegrain (with a Televue 0.8x focal reducer/field flattener yielding f/6.4) using an SBIG ST-4000XCM CCD camera. The exposure was 190 minutes again using 10-minute subframes. This image shows a very star-like bright core with spiral structure on the south side of the core. The brighter blotches in the spiral arms are massive regions of ongoing star formation.

NGC5474 is a challenging object to see visually. But it is impressive to see and image this celestial oddball!

Mario Motta: Observer from Massachusetts

NGC 5474, a distorted galaxy near M101. The following image this is 90 minutes of imaging Lum filter only.

Taken with my 32-inch f/6.5 telescope, with ZWO ASI6200 camera,  stacked and processed with pixinsight. This is a “dwarf spiral satellite galaxy” of M101, distorted with an off-set center, and spiral arms.

David Rust: Observer from Indiana

Larry McHenry: Observer from Pittsburgh

Galaxy NGC 5474 in Ursa Major:

The dwarf galaxy NGC 5474 is located in the circumpolar constellation of Ursa Major, known as “The Great Bear” and most commonly called the Big Dipper. It was discovered by William Herschel on the night of May 1st 1788 using his 20-Foot reflector (18.7-inch speculum metal mirror) at Slough. Herschel described the galaxy as “considerably bright, and large”.

The 11th magnitude galaxy is about 21 million light years distant, and spans a size of 4.8 x 4.3 arc seconds. While not listed in Arp’s Peculiar Galaxy catalog,  this galaxy does exhibit a distorted appearance, due to its interaction with the much larger, and nearby galaxy M101.

Video-Capture/EAA:  

Using EAA techniques, NGC 5474 displays nicely in medium-size optics. It is a fairly bright face-on spiral, with an elongated core, and several spiral arms arranged in parabolic arcs on the south side of the nucleus, with each arm containing knots of HII star-forming regions. 

05/30/2022: from Cherry Springs State Park, PA, using an 8-inch SCT optical tube @ f/6.3 on a GEM mount, with a CMOS color camera and broadband filter @ 180-second guided exposure, live-stacked for 30 minutes.  

Mike McCabe: Observer from Massachusetts

Well, I’m happy to report that after three tries – one with the 6-inch refractor and two with my 10-inch Newtonian. I can now say that I definitively saw NGC 5474! This was a tough little guy, and although I initially focused on high power examinations of the field and actually was successful in seeing the galaxy.

However, it worked best when using medium power as I had more background sky to work with. The galaxy was invisible at low powers due to the brighter field. But, it’s fitting that this little satellite neighbor of M101, should behave much the same as its bigger brethren due to the low surface brightness, which makes it a real challenge. 

This month’s challenge brought me back to September of 2018, when at that time the challenge object was the planetary nebula NGC 6818, which is very closely situated near NGC 6822, aka Barnard’s Galaxy.

In the same vein as Barnard’s Galaxy, NGC 5474 was seen but no significant detail could be discerned. Rather what was seen was nothing more than a very faint and fuzzy patch with no definable shape or structure. A dark sky would probably change this, but most of the time we work with what we have.

My sketch and summary as following from my photo file.

Phil Orbanes: Observer from Massachusetts

Attached is my photo of galaxy NGC 5474 (and nearby  M101).

I decided to do something different. Initially,  I took a wide field shot that includes both 5474 and its parent galaxy M101.

Recently, I took a close-up of NGC 5474. I included them both in the attached image.

NGC 5474 is the most notable of M101’s companion galaxies. It lies 21 million light years away. It it a “peculiar” galaxy because the gravitation interaction between the two galaxies has distorted the disc of 5474, causing its core to be far off-center, and its sitar-forming arms to be thrust to one side..

A total of 22 hours of imaging was made in 2018, 2020 and 2022. 

I used my 5-inch Takahashi refractor/FLI camera for the wide field image and my 14-inch Planewave reflector/ FLI camera for the close-up.

The total exposure time was divided evenly between R, G and B, Ha filters.

Rony De Laet: Observer from Belgium

NGC 5474 is an elusive object. At first only the core is visible, a dim smudge of light near a small mag 14.5 star. The core is brighter in the centre without a stellar nucleus. The core seems elongated in a SW to NE direction. An extended examination of the galaxy, reveals traces of its halo which is offset to the SW of the core. Brightening’s in the halo appear to connect to the elongated edges of the core, making the whole look like a deformed torus.

Site : Bekkevoort, Belgium (51° N)

Date : May 28, 2022
Time : around 23:30 UT

Telescope : Taurus 16-inch
EP: Morpheus 9mm 76°, 200x
Filter : none
Seeing : 4/5
Sky brightness : 20.1 magnitudes per square arc second near zenith (SQM reading).
Sketch Orientation: N up, W right.
Digital sketch made with Corel Paint Shop Pro X2, based on a raw pencil sketch.

John Bishop: Observer from Massachusetts

This month’s Challenge object is NGC 5474, a peculiar dwarf galaxy in Ursa Major.  It is relatively close to galaxy M101, and is thought to be distorted by gravitational interaction between the two galaxies.  Images of NGC 5474 would seem to support that view.  They show an unusual, face-on galaxy with some spiral structure, and a nucleus offset from the center of the disc    

This object was new to me.  I observed it twice for this report, first on May 21, and again on May 29, 2022, both times from the ATMoB Clubhouse in Westford, Massachusetts.  Observing was accomplished using an 8.25-inch f/11.5 Dall-Kirkham reflector at magnification of 48x to 192x, on a motor driven equatorial mount without go-to.  Skies were clear on both nights.  Contrast was fair to start, but then deteriorated, especially on May 21.

The entry for NGC 5474 in Luginbuhl and Skiff is one of the most meagre, uninviting descriptions in their entire Catalogue.  Citing only 10-inch and 12-inch telescope views, L&S describe NGC 5474 as “…diffuse, poorly concentrated, and without any distinct detail.”  Surely this neglected stepchild deserved some attention.

First, we would have to find it.  Starting at Mizar/Alkor, a string of four 5th and 6th magnitude stars lead to two faint pointer stars, directed just south of M101, which was a faint glow in the finder.  NGC 5474 lies less than a degree south of M101, just west of a line between M101 and an 8th magnitude star.

Seeing NGC 5474 required averted vision, and time spent on the FOV.  A slight brightening in the FOV built up to a faint glow, and then become a definite object, although still quite faint.  Unfortunately, Luginbuhl and Skiff were correct.  At least for this smaller aperture visual observer, NGC 5474 was a dim, nebulous  patch, with no obvious detail or structure.  My notes say, “faint, shapeless blob, no core or nucleus, more round than long, smaller than M101, but not small”.  It was especially helpful to have a polar aligned tracking mount when sharing the view with other observers.  I was able to hand off the eyepiece to others, confident that the object was centered, although it was not immediately visible to any observer.

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