The Faintest Galaxy

[glenc]

What is the faintest galaxy in the NGC and IC catalogues that was found visually, not photographically?
There are 23 NGC and IC galaxies fainter than mag 16 that were found visually. The faintest is IC 1484.
IC 1484 was discovered on 2 Dec 1893 by Stephane Javelle (https://cseligman.com/text/atlas/discoverers.htm#stephanejavelle) (1864-1917)
It is a magnitude 17.0 elliptical galaxy in Pegasus (https://cseligman.com/text/atlas/pegasus.htm#ic1484) at RA 23 22 39.9, Dec +11 23 04. Javelle found it with a 30" refractor at Nice, France. He described it as "very faint, very small." Its size is 0.4' by 0.2'.

The images show the galaxy, the 30" telescope and Javelle.
See also https://cseligman.com/text/atlas/ic14a.htm

[glenc]

Nice, France
The 77 cm (30 in) refractor telescope (https://en.wikipedia.org/wiki/Refractor_telescope) made by Henry and Gautier became operational around 1886–1887 was the largest in a privately funded observatory, and the first at such high altitude (325 m or 1,066 ft above sea level). It was slightly bigger in aperture, several metres longer, and located at a higher altitude than the new (1895) 76 cm (30 in) at Pulkovo observatory (https://en.wikipedia.org/wiki/Pulkovo_observatory) in the Russian Empire (https://en.wikipedia.org/wiki/Russian_Empire), and the 68 cm (27 in) at Vienna Observatory (https://en.wikipedia.org/wiki/Vienna_Observatory) (completed early 1880s). In the records for the largest refracting telescopes all three were outperformed by the 91 cm (36 in) refractor installed at the Lick Observatory (https://en.wikipedia.org/wiki/Lick_Observatory) at 1,283 m altitude in 1889.

https://en.wikipedia.org/wiki/Nice_Observatory

[astroron]

Sinbad only gives it a mag of 15.5 ?
The revised NGC/IC catalogue doesn't give it a magnitude.
No mention in the original IC of a magnitude.
Cheers:thumbsup:

[glenc]

Can you see m15.5 Ron?

[astroron]

I used Glen to be able to when I first came here
at this dark site.
Not now though as I have a small cataract and
am 79 years old.
Well according to my Supernova searches that is
I have observed a couple of Supernovae at that mag.
not my discovery I might add. ;)
Cheers :thumbsup:

[ngcles]

Hi Glen & All,

A quick fumble through the SIMBAD database on IC 1484 provides a B magnitude of +15.5. The rule of thumb for converting that to an approximate true V magnitude is to add 0.9 magnitudes, so it would seem V mag ~14.6 is about right. Given its diminutive (0.2 x 0.2') size, I'd think a +40cm telescope could see it under a genuine dark sky.

http://simbad.u-strasbg.fr/simbad/sim-id?Ident=IC+1484&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id

It appears to be in a group with NGC 7639 (IC 1485) (+7,951km/s) and NGC 7638 (IC 1483) (+7,990km/s) (so these two are about 360 mly distant) but the recessional velocities indicate IC 1484 (+13,104) is somewhat in the background to the other two (about 600mly distant). There are a few other much fainter galaxies with either KUG or IRAS designations quite nearby and maybe physically associated with the two in the foreground.

Haven't observed any of them myself.

Steve Gottlieb's NGC observing notes contain visual descriptions for the two NGC galaxies and IC 1484 with his 45cm telescope:

NGC 7638 = IC 1483 = MCG +02-59-030 = CGCG 431-046 = PGC 71246

23 22 33.1 +11 19 44

V = 14.4; Size 0.6'x0.5'; Surf Br = 13.1

17.5" (9/7/96): very faint, small, round, 30" diameter, low even surface brightness. Located 8' N of mag 8.3 SAO 108572. A wide pair of mag 11/13 stars is 1.5' S. First in faint group with IC 1484 and IC 1485 = NGC 7639 (uncertain ID). IC 1484 is extremely faint and small, round.


Andrew Ainslie Common discovered NGC 7638, along with NGC 7639 and 7630, on or before 8 Aug 1880 while viewing comet Faye. Common only mentions "there are 2 similar nebulae [to NGC 7630] within 30' sf" but does not provide coordinates for NGC 7638 and 7639. A group of faint galaxies is ~20' ESE of NGC 7630. It's likely that common picked up the two brightest, NGC 7638 = CGCG 431-046 and NGC 7639 = CGCG 431-050.


Stephane Javelle independently discovered these galaxies on 2 Dec 1893 and measured accurate positions. So, NGC 7638 = IC 1483 and NGC 7639 = IC 1485. MCG and CGCG label these galaxies using the IC designation only. See Harold Corwin's NGC/IC notes.

******************************


NGC 7639 = MCG +02-59-032 = CGCG 431-050 = IC 1485 = PGC 71256

23 22 48.2 +11 22 22

V = 14.6; Size 0.6'x0.5'; PA = 123d

17.5" (9/7/96): very faint, small, round, 30" diameter. Similar size as IC 1483 = NGC 7638 but contains a very small brighter core that makes it a little easier to view. Just preceding a small triangle of mag 12-14.5 stars. Also collinear with a wide pair 5' SW near IC 1483. Brightest in a trio with IC 1484 2.1' WNW and IC 1483 4.5' SW.

The identification of IC 1483 is certain but NGC 7639 is uncertain.

Andrew Ainslie Common discovered NGC 7639, along with NGC 7638, on 8 Aug 1880 while viewing comet Faye. This is the last entry in his discovery list. See notes for NGC 7630 and 7638.

*********************************** ***********

and IC 1484:

IC 1484 = LEDA 1392792

23 22 39.9 +11 23 04; Peg

V = 15.1; Size 0.6'x0.3'; PA = 49°


17.5" (9/7/96): extremely faint and small, round. Faintest in trio with IC 1483 and IC 1485 and requires averted vision and GSC finder chart to glimpse occasionally. Located 2.1' WNW of brighter IC 1485.


Stephane Javelle discovered IC 1484 = J. 1-799, along with IC 1483 and 1485, on 2 Dec 1893. The latter two galaxies are probably identical to Andrew Ainslie Common's NGC 7638 and NGC 7639, discovered earlier in 1880. Common mentions two galaxies within 30' SE of NGC 7630 (#32 on his list). MCG incorrectly identifies MCG +02-59-032 as IC 1484, although MCG +02-59-032 = IC 1485.

*********************************** ************

As you can see Steve Gottlieb provides a V mag of 15.1 for IC 1484, I'm not sure where that info is from.


Looking at the SDSS image (and the DSS) of NGC 7638 (IC 1483) shows it to be a somewhat disrupted rather asymmetric barred spiral galaxy. There is another small galaxy (KUG 2320+110B) 1.6 arcmins N that also looks a bit odd (coma-shaped), so these two might be an interacting pair.

https://www.wikidata.org/wiki/Q1168444#/media/File:NGC7638_-_SDSS_DR14.jpg


Best,

L.

[JA]

Thx for sharing that Glen. Out of interest I searched for further information on the refractor: Diameter of 30.3 inches / 77cm with apparently a 17.9m focal length making it around f/23 (You've got to love mixed Imperial and SI).

Videos ....
https://www.youtube.com/watch?v=erWnSAqzgEU

https://www.youtube.com/watch?v=z-EfSzvwBOw

Best
JA

[glenc]

Thanks Les, lots of detail there.
And thanks JA for the telescope info.