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RolandosCY
October 16th, 2016, 11:45 AM
Object of the Week, 16 October 2016: NGC 1023 (Arp 135), a hidden gem in Perseus!

NGC 1023 = Arp 135 = UGC 2154 = CGCG 523-83 = MCG +06-06-073 = PGC 10123
RA: 02h 40' 24"
DEC: +39° 03' 46"
Type: SB(rs)0-
Size: 8.7' x 3.5'
P.A.: 87°
Mag: V = 9.4, B = 10.4


On glorious fall evenings, the jewel-like stars of the constellation Perseus, the Hero, dominate the sky. All skywatchers turn their scopes and cameras to the glorious Double Cluster, the Demon Star Algol, to the superb Little Dumbell Planetary (M76), or the beautiful open cluster M34. Even the faint and challenging California Nebula gets a fair share of attention. Yet, hidden amongst the Hero’s bright stars and popular deep sky objects, is a real gem of a galaxy, that few people are aware of: NGC 1023, also known as Arp 135.

I personally “discovered” this galaxy last August, during my ongoing attempt to survey as many as possible from the galaxies in Halton Arp’s famous catalog. Actually, I should say, I “re-discovered” it, for I had read about this galaxy years ago in Steven ‘O’Meara’s “Hidden Treasures” book, but somehow I managed not to observe this superb “hidden treasure” until now. This galaxy is indeed not well known. A search in the internet reveals rather few amateur photos of it, and even fewer observations. I asked several local friends if they have ever observed it, and none was aware of it, yet some of them knew very well NGC 1275, a much more difficult galaxy in Perseus!

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A DSS image of NGC 1023 and 1023A

So, what do we know about this “unknown” galaxy? NGC 1023 is a barred lenticular galaxy, approximately 34 million light years away, and belongs to the NGC 891 group of galaxies. It has a visual magnitude of 9.4, with a very bright core surrounded by a rather faint halo, giving it overall dimensions of 7.5x3 arc minutes. Astrophysically, it has a very rapidly rotating nuclear region, suggesting the presence of a massive black hole. Also, a large population of globular clusters has been detected, including some very large ones which appear to be similar to the globulars of M31. Halton Arp included NGC1023 as the 135th entry in his “Catalog of Peculiar Galaxies” as “an elliptical galaxy with nearby fragments”. The only nearby fragment appears to be NGC 1023A, a very faint diffuse irregular system located on the southeast edge of NGC 1023. Arp suggests that PGC 10169, a bit further to the east, may be another fragment. Although both of these galaxies are very near NGC 1023, the appearance of the main galaxy does not show the typical effects of tidal interactions, which are almost certain to have occurred.

Well, enough astrophysics. What can be seen visually? Using my 18”, my first impression on seeing NGC 1023 was that under medium powers it appeared quite similar to how M31 appears at low power in a 4-inch refractor, except that the core of NGC 1023 appeared much brighter. Using a much higher power of 297x, NGC 1023 was an amazing and totally unexpected sight. The galaxy is located in a very beautiful star field of 8th to 12th (and fainter) field stars. It has a very bright almost stellar nucleus, surrounded by a very bright, rhombus shaped core. This in turn is surrounded by an elliptical bright region. It is very rare to see a galaxy showing so much detail in its core area. On close scrutiny, there seems to be a dark area between the rhomboid core and the bright outer region, but I suspect that it might be only a contrast effect, for even in an HST photo such a feature is not evident.

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Wide-Field Hubble Observation, NGC 1023

What’s more, there are quite long extensions of light on both the east and west sides of the central area. These extensions of light are quite long and wide, and seem to faint into the background sky without the more typical pointed edges. Although these extensions are quite faint and, unlike the central region, of low surface brightness, they are quite easy to detect and trace. On the southeast edge of the eastern extension, the galaxy NGC 1029A is readily detected as a very faint, roundish patch of light. On both extensions some15th to 16th magnitude stars can be detected. I did not see PGC 10169, but I have to admit that at the time of the observations I was not aware of its presence. At magnitude 17.5 it might be detectable in large scopes under very dark skies.

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Observations of NGC1023 with 18" dob

NGC 1023 is one of the best galaxies to study in small-sized scopes. The central area of the galaxy is readily visible in low powers in both my 5 and 6 inch refractors, and shows the distinct brightness variations, albeit with lower contrast. Although I did not get a chance to try it, I am certain that the galaxy will be readily visible in the popular 80 to 100mm refractors. Using powers of around 100X in both the 5 and 6 inch refractors I could readily detect the faint galaxy extensions, but I could not detect NGC 1023A.

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Observations of NGC1023 using a 6" refractor

As I mentioned above, I could find only a few observations of NGC1023, and most of them agree with what I observed myself. David Tosteson has also observed the “mini M31” appearance and mentions a N-S dark lane, possibly part of the dark area I detected in the central area. Both Tosteson and B. Wilson detected NGC 1023, as did Alvin Huey using his 22”. Neither of these observers mentions PGC 10169.Steve Gottlieb’s observations using 17.5 and 18” scopes are also similar, except that he does not mention NGC 1023A. O’Meara’s observations using his 4” refractor are pretty similar to my observations using five and six inch refractors, but he also mentions that NGC 1023Awas detected in an 11-inch dob by J. Dillon.

For me it is still quite amazing that such a bright and detailed galaxy, in such a popular area of the sky, is not so well known amongst visual observers. I am pretty sure that it might be detectable even in large binoculars, provided the observer can separate the galaxy’s central area from the nearby stars.

So, during the next new moon period, turn your scope to Perseus, zoom in on NGC 1023, and enjoy one of the most beautiful galaxies of the northern sky! And as always,

GIVE IT A GO AND LET US KNOW!

Vic
October 16th, 2016, 12:40 PM
I can confirm that NGC 1023 is a nice binoculars target. I have had 20 observation so far in my logbook and many of them are using my 48×125 binos.
Of course you can see more in bigger aperture. That's why it's also a favourite target for my 16" dobsonian.
Vic

Howard B
October 23rd, 2016, 06:35 AM
I have an observation from 2009:

"I'm sure I've observed 1023 before but not as an Arp galaxy. I could detect the 2nd galaxy cocked at an angle off one end, which is what makes this an Arp. 253x, 21.73 SQM."

2310 2311

Not my best sketch ever, nor my most descriptive notes!

wvreeven
October 23rd, 2016, 07:03 AM
My notes from September 2015 using my 20" under SQM 21.0 skies read:

At 320x I see a large oval patch of light with a non-stellar bright compact nucleus surrounded by a slightly fainter oval region surrounded by faint outer regions. On oe side I see a line of three bright stars. At the end of the line closest to the galaxy I see another faint star. Between that star and the edge of the galaxy I see a faint smudge. That is NGC 1023A.

Uwe Glahn
October 23rd, 2016, 09:19 AM
With my 16" I had difficulties with detecting the fainter companion. My quick and dirty notes:
16", 225x, NELM 6m5+ (good transparency)
bright galaxy; 1:3-1:4 E-W elongated; bright core; 3 stars within the galaxy; with averted vision a very faint hump sits S under the E end of the halo of NGC 1023; difficult to see

Yesterday I gave it another try with my 27" under soso transparency (wet).
27", 172x, 293x, NELM 6m5+
with 4mm EP the bright elongated halo instantly shows a deformity to the S at the E end which is connected with the halo; with 293x the deformity forms an own object, slightly elongated NE-SW, connected with the halo only with averted vision, directly NW of a fainter 14mag star; easy to see

mdstuart
October 23rd, 2016, 09:48 PM
NGC 1023 is a lovely galaxy. I have seen it with direct vision in my 100mm binoculars. I sometimes start a session by looking at this galaxy as my eyes adjust..

Its in the same group of galaxies as that edge on ngc 891 I believe.

Mark

Steve Gottlieb
October 24th, 2016, 05:02 PM
Here's a list of the brighter galaxies in the NGC 1023 group from a 2009 paper by Tully and Trentham, "Dwarf galaxies in the NGC 1023 Group (https://arxiv.org/pdf/0906.2540v1.pdf)". Although NGC 891 is nearly as luminous, it's not surrounded by a large retinue of dwarf companions like NGC 1023.

NGC 1023 S0 02 40 24.0 +39 03 48
NGC 891 Sb 02 22 33.4 +42 20 57
NGC 925 Sd 02 27 16.9 +33 34 45
NGC 1003 Sd 02 39 16.9 +40 52 20
NGC 1058 Sc 02 43 30.0 +37 20 29
NGC 949 Sb 02 30 47.6 +37 08 38
NGC 959 Sdm 02 32 24.0 +35 29 44
IC 239 Scd 02 36 27.9 +38 58 12
UGC 2034 Im 02 33 42.9 +40 31 41
UGC 2023 Sc 02 33 18.2 +33 29 28
UGC 2165 dE 02 41 15.5 +38 44 36
UGC 2126 Sc 02 38 47.1 +40 41 55
UGC 2157 Sdm 02 40 25.1 +38 33 48
UGC 1807 Im 02 21 13.4 +42 45 46
NGC 1023A dI 02 40 37.7 +39 03 27

Jimi Lowrey
October 25th, 2016, 01:37 AM
Steve that looks like a nice mini observing project.

Marko
November 19th, 2016, 09:35 AM
Fun Related Factoids:
- The J. Dillon Jimi mentions has used ngc1023 in his preferred astro email address for at least a decade.
- J. Dillon is a very active member of the loose-knit bay area California group called 'TAC' or The Astronomy Connection.
- J. Dillon is a really great guy
- His 11" dob caries the name he gave it of 'Felix'

Nuff Said (this too is a common J. Dillon phrase)

Marko