Object of the Week April 13th, 2025 – NGC 4536 & NGC 4527

[Dragan]

Object of the Week April 13^th, 2025 – NGC 4536 & NGC 4527


NGC4536
UGC7732

Galaxy

Constellation: Virgo

RA: 12 34 26.9
DEC: +02 11 19
Class: SAB(rs)bc)
Mag: 10.7
Size: 8.4’x3.2’

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NGC4527
UG7721

Galaxy

Constellation: Virgo

RA: 12 34 08.8
DEC: 02 39 13
Class: SAB(s)bc
Mag: 10.5
Size: 6.9’x2.4’

Today I offer up 2 beautiful spiral galaxies in Virgo.

NGC 4536
Discovered by William Herschel on January 24^th, 1784, NGC 4536 is an intriguing barred spiral galaxy tucked away in the constellation Virgo, approximately 50 million light-years distant as a member of the M61 subgroup within the Virgo Supercluster. NGC 4536 stands apart from many of its Virgo Cluster counterparts due to its robust star-forming, AGN-type activity. Classified as a starburst galaxy, it is actively creating new stars, primarily observed in infrared wavelengths due to substantial amounts of interstellar dust and gas. This galaxy was notably the host of the Type Ia supernova SN 1981B, providing astronomers valuable data to help calibrate cosmic distances. This galaxy gracefully presents itself with a tilt that provides observers with a satisfying view of its structure—not fully edge-on nor entirely face-on. Although there are observing reports online in scopes as small as 8", moderate aperture telescopes (around 12” to 16”), observers under decent suburban skies will detect an elongated mottled glow, nearly stellar core and hints of its bar and arms. To truly resolve its arms, you’ll need darker skies and scopes approaching 20” with moderate power. In large scopes, NGC 4536 reveals itself as a bright spiral with apparent arms extending NW to SE and an apparent bar..


While NGC 4536 may not stun immediately like brighter, more renowned spiral galaxies, it offers an understated yet profoundly rewarding observational experience. Its subtle elegance combined with an intriguing astrophysical backstory makes it an excellent addition to spring observing lists. Take your time with this cosmic whisper—it rewards patience and thoughtful observation.

NGC 4527
Inexplicably discovered a month after NGC 4536 on February 23, 1784 by Herschel, NGC 4527 is another captivating spiral galaxy in Virgo approximately 46 million light-years away. This intermediate spiral galaxy presents a subtly elongated appearance, offering observers a pleasing view of its form, partially tilted to our line of sight. With a visual magnitude of about 10.5, it is slightly brighter and easier to detect compared to its neighbor NGC 4536. NGC 4527 is also recognized for its notable star-forming activity. The galaxy features abundant molecular gas and dust, fueling active star formation. Interestingly, NGC 4527 hosted the Type Ia supernova SN 1991T, a highly luminous event used extensively to refine distance measurements within our universe.
Like other spirals located within densely populated clusters, NGC 4527's well-maintained structure and robust star formation stand out as noteworthy, suggesting it has thus far avoided the severe gravitational interactions typically observed in cluster environments.


Through telescopes of modest to moderate aperture (10” to 16”), observers from suburban skies can appreciate its diffuse glow with a distinctly elongated shape. At magnifications around 150x, the galaxy reveals its brighter, elongated central region and soft extensions indicative of spiral arms. Under optimal conditions in larger telescopes, dust lanes and mottled structure may be observed. The galaxy is oriented SW-NE with a bright elongated core.


Next time you’re out, don’t forget to give these two spirals a try. Situated only 28 minutes apart, it is completely doable to observe the pair in a single view. And as a challenge, be sure to try for magnitude 13.7 NGC 4533 lying in between the two 103Mly further away!


And as always, give it a go and let us know!

N4536s-crop.jpg
NGC4536

NGC4527_-_SDSS_DR14_(panorama).jpg
NGC4527

4537_4527 pair MS.jpg

NGC4536 & 4527 pair

[kisspeter]

I can contribute a 16" drawing of NGC 4536 from 2009 (196x, 23' field). I didn't find the spiral structure to be difficult in the 16" scope. I'm sure it can be seen with smaller apertures as well. But I've not tried yet.
Unfortunately I didn't pay too much attention to NGC 4533 and I could probaly only see the core region and missed the elongation. Time to revisit the field. I totally agree, NGC 4536 is a gem among the Virgo galaxies.
ngc4536_kisspeter.jpg

[Steve Gottlieb]

This observation of NGC 4536 with my 24" was made at my local observing site on a better than average night (SQM-L = 21.5):

Bright, very large, very elongated at least 3:1 NW-SE with two long slightly arched arms, ~6.5'x2'. The galaxy is strongly concentrated with a bright elongated core that increases to a very small but non-stellar nucleus. The long eastern arm is attached on the north side of the core and is brightest in a 1.5'-2' section angling to the SE. The arm dims with a diffuse, lower surface brightness extension out to 3.5' SE of center, spreading further south at the eastern end. The western arm is also brightest in the initial 1' section on the west side of the core. The arm dims and narrows but stretches northwest for ~3' from center, where is seems to bend north and fade out.

R.J. Mitchell, an observing assistant to Lord Rosse, sketched the galaxy in late May 1856 with the 72" (speculum) as a stretched Z-shape, with a short, prominent bar. The second image is the central portion of the galaxy, rotated to match orientation, on the blue DSS2. Mitchell's sketch seems a pretty good match.

NGC 4536.jpg

NGC 4536_Mitchell.jpg

Spiral structure was more subtle in NGC 4527 from the same site on an average night (SQM 21.3).

Bright; very large; very elongated ~4:1 WSW-ENE, ~4'x1', well concentrated with a very bright elongated core that contains a fairly intense nucleus. The galaxy appears to brighten slightly on the western end, curl south, and spread out. Similarly, an enhancement curls a bit north on the eastern end, like the beginning of spiral arms [verified later on the DSS].

I viewed the type Ia SN 1991T (Type Ia) on May 10th, nearly a month after discovery, and it was still quite bright! It appeared as a mag 11.0-11.5 star less than 1' NE of the nucleus of NGC 4527.