Object of the Week May 26, 2013 - NGC4535 Lost in Virgo

[Dragan]

NGC 4535

Lost Galaxy, UGC 7727

Virgo

RA: 12 34 20
DEC: +08 11 53

Size: 7.1’ x 5.0’

Mag: 9.9

Class: SAB(s)c



Originally discovered by William Herschel in 1785, NGC 4535 is a gorgeous, albeit low surface brightness barred spiral in Virgo. The moniker "Lost Galaxy" was given it by Leland S. Copeland in his 1955 S&T article Adventuring in the Virgo Cloud. In his article, Copeland refers to the galaxy as he describes his jaunt thru the Virgo Cluster using his 8" Cave reflector. He states, "North of the Diamond is a very dim spiral, here called the Lost Galaxy, NGC 4535." Leland was probably referring to NGC4535s difficulty to locate due to its inherently low surface brightness. Copeland also claims that NGC4535's "delicate structure shows only on long exposure photographs". Probably limited by the equipment he had during his time, today we know this to not be entirely true, especially when it comes to today's monster dobs. But please don't be discouraged by what Copeland saw. Go out and give it a shot. There are reports of observers with scopes as modest as 15" seeing the famous "S" shape.

On an interested side note, published in 1999 and detailed in the paper The Extra-galactic Distance Scale Key Project. XVIII. The Discovery of Cepheids and a New Distance to NGC 4535 Using the Hubble Space Telescope, L. M. Macri et al (http://iopscience.iop.org/0004-637X/521/1/155/fulltext/), a study with the intent to measure the Hubble constant to an accuracy of 10% was conducted. During the summer of 1996 while using the WFPC2 camera of the HST measurements of 18 galaxies was conducted, one of which was NGC 4535. 50 Cepheid Variables were discovered in NGC4535 which were then measured to place the distance to NGC4535 from us at 16.0 +/- 1.9Mpc or 52,186,135.1 light years. This distance places NGC4535 squarely in agreement with other Virgo Cluster members.

NGC4535 can be a relatively difficult object to discern detail out of. Not unlike M101, where the objects magnitude can be misleading, NGC4535 really does need some decent enough sky conditions with moderate aperture to eek out the most possible detail. Below are some of my past, albeit inadequate, notes:

25" f/5
April 30th 2011 S 3/5 T 4/5 At 350x S shape visible direct. pops for me with averted vision. Many foreground stars are visible giving the view a slight 3D effect. Great object! 2 prominent arms visible

I most recently looked at NGC4535 this year at TSP with Jimi and German forum members, Uwe, Marc and Frank.
48" f/4 488x S shape direct vision 100% of the time. Looks fantastic! Can make out a small segment of a 3rd arm that comes off the core. Everybody else confirmed.

I've included an image below with that 3rd 'arm' highlighted. I'll definitely have to revisit this object now to see if it would be visible in my scope. My previous notes don't refer to this 3rd 'arm'.

If you've never before seen NGC4535, it is a fantastic object that should be on your agenda this spring. Don't let the low surface brightness deter you. If you have seen it before, please be sure to revisit it the next time you're out. I know you won't be disappointed.


And remember,

"Give it a go and let us know!"

Good luck and great viewing!

677 678

[Jimi Lowrey]

This with out a doubt is my most favorite Virgo cluster galaxy. I have wondered for years why it is not better known among amateurs.

I recently spent 3 1/2 hours over 2 nights observing and drawing the "Lost Galaxy" with my 48" reflector. It is amazing how much detail you can see when you spend that much time observing a object with your head covered in total darkness. The longer you look the more you see. I have heard this for years and it is so true!

Be sure to add this to your list and if you are like me you will return year after year to revisit NGC 4535 the "Lost Galaxy of the Virgo Cloud".

NGC4535
679

[Uwe Glahn]

Dragan,

thanks for pointing this overlooked galaxy out. Jimi is right when he wondered why the galaxy is not known.

I dig up an old observation and sketch with an 20" at the observatory I often used in the past. Under exceptionally skies the "S" was very prominent. Beside the "third arm" I could pick up a brighter HII region to the north in direction to NGC 4535A.

20", 293x, NELM 6m5+
680

[Dragan]

Beside the "third arm" I could pick up a brighter HII region to the north in direction to NGC 4535A.

Uwe, which object are you referring to when you say 4535A?

[Steve Gottlieb]

I dig up an old observation and sketch with an 20" at the observatory I often used in the past. Under exceptionally skies the "S" was very prominent. Beside the "third arm" I could pick up a brighter HII region to the north in direction to NGC 4535A.

Excellent sketch, Uwe. It captures much of the detail I saw in early April in Jimi's 48-inch. Here are my notes from a pretty quick look as well as the HII regions I noted in central region.

4/4/13: gorgeous face-on Sc spiral with two, long, very prominent arms extending from a small, very bright central region. The small, very bright core is elongated SSW-NNE and punctuated by an intense, stellar nucleus. The two main arms are clearly attached right at opposite ends of the core. At the NE end, a beautiful thin arm winds clockwise to the west with a mag 13.5 star pinned on the outer north edge. The arm contains #141/145/157 (from Hodge & Kennicutt's "Atlas of HII regions in 125 galaxies"), a small, bright, 15" knot and then dims as it wraps to the south. A mag 14.5 star is situated midway between the nucleus and southern end of this arm [47" SW of the nucleus].

The second main arm is attached at the SW end of the core and curves clockwise to the SE, where the arm brightens in an elongated 30" patch (#51/52/72/78), which is symmetrically positioned opposite #141/145/157. A fainter arm segment, extending WNW to ESE is visible on the south side, containing #84/90, a small, fairly faint 12" patch, located 1.5' SSE of center. This knot forms the vertex of a flat isosceles triangle with a mag 15 star 0.5' NW and a mag 14 star 0.7' S. The arms are etched on the slightly fainter and larger background glow of the disc, which extends 5.5'x4.0' N-S.

681

[Jimi Lowrey]

I can not find the Galaxy NGC 4535A in SIMBAD??? It also is not in the NGC IC project data base??? Any one have information on this galaxy????

[Uwe Glahn]

Dragan, Jimi,

I refer to PGC 1343342 which is 4,8' NNW of NGC 4535. Wolfgang Steinicke has this galaxy in his actual RNGC and NED also displays a "NGC 4535A" at the position of the PGC.

[Steve Gottlieb]

NGC 4535A here (http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC+4535A&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES) and here (http://leda.univ-lyon1.fr/ledacat.cgi?PGC1343342&ob=ra). I believe the designation first appeared in RNGC.

[Jimi Lowrey]

Steve it is not in the historical data of Wolfgang. Do you know who found it???

[Steve Gottlieb]

Steve it is not in the historical data of Wolfgang. Do you know who found it???

Here's the page from the RNGC that shows NGC 4535A. This galaxy was not discovered visually -- I believe the first reference is Holmberg's 1937 "A Study of Double and Multiple Galaxies"

682

Sorry my cell phone photo is not sharp, but I think you have the RNGC anyways