Deep Sky Ranch 10/25/08

Steve Gottlieb

My usual observing haunt at this time of year is Lake Sonoma, set in the beautiful vineyards to the northwest of Healdsburg. But Lake Sonoma's poorest viewing area is to the south-southwest, where the light dome from Santa Rosa makes viewing far southern targets difficult. But looking due south of Kevin's Deep Sky Ranch, the sky is perfectly dark to the horizon (or at least the low ridge to the south), so I decided to spend much of the evening with my 18" Starmaster scraping the horizon in Grus, Pisces Austrinus and Sculptor. If you're not familiar with Grus, just head south of the lonely southern beacon, Fomalhaut. With a good southern horizon, mag 1.7 Alpha Grucis (AlNair) at -47 degrees dec shouldn't be difficult to spot in fall evenings. When I dipped my scope down to -40 degrees dec, I was surprised how steady the stars appeared with a dark and contrasty background sky at 280x -- great conditions for hunting faint galaxies. It turned out, conditions were excellent all night with fairly warm temps, no moisture or wind, and with pretty steady and dark skies we all stayed pinned at the eyepiece for nearly 8 hours of observing.

NGC 7201 Group – This small group in Pisces Australis is located 1.3 degrees NE of the NGC 7173 group (AKA HCG 90) and contains 3 NGC galaxies, with one an interacting double.

NGC 7201 22 06 31.9 -31 15 47
V = 12.8; Size 1.6'x0.5'; Surf Br = 12.4; PA = 128d
Fairly faint, fairly small, very elongated 3:1 NW-SE, 0.6'x0.2', small bright core. First and furthest south in a linear trio with N7203 6.6' NNE and N7204 13.5' NNE. This galaxy has a higher surface brightness than N7203. The group is located ~1.3 degrees NE of the N7173 group (HCG 90).

NGC 7203 22 06 43.9 -31 09 45
V = 12.6; Size 1.6'x0.9'; Surf Br = 12.8; PA = 72d
Fairly faint, fairly small, elongated 5:3 WSW-ENE, 0.65'x0.4', gradually brightens to a large, brighter core. Middle of linear trio of elongated galaxies with N7201 to the SSE and N7204 to the NNE. A mag 11 star lies 2.9' ENE.

NGC 7204 22 06 54.0 -31 02 59
V = 13.5; Size 1.2'x0.5'; Surf Br = 12.7
This interacting double system is the furthest NNE is an equally spaced trio with N7203 6.9' SSW and N7201 13.5' SSW. At 174x it appeared faint, fairly small, elongated 2:1 E-W, fairly low surface brightness with no concentration. At 283x, it appeared brighter on the western side (due to the small companion galaxy just off the NW end), but the duo was not cleanly resolved.

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The "Grus Chain" -- this is North-South string of 8 or 9 galaxies spread out over 1.5 degrees. The northern end (IC 5269 and IC 5270) is in Pisces Austrinus but the other members lie in Grus.

IC 5269B 22 56 36.7 -36 14 59
V = 12.4; Size 4.1x0.8; Surf Br = 13.6; PA = 96d
Extremely faint, fairly small (only core region observed), 0.8'x0.4', elongated 2:1 E-W, low even surface brightness, requires averted vision. Located 14.5' NW of IC 1459 in the Grus Chain

NGC 7418 22 56 36.2 -37 01 48
V = 10.9; Size 3.5x2.6; Surf Br = 13.2; PA = 139d
Fairly bright, very large, elongated 3:2 NW-SE, 2.5'x1.8', broad weak concentration. The halo fades into the background without a well- defined edge. This is the largest galaxy visually in the Grus Chain (brightest member IC 1459).

NGC 7418A 22 56 41.1 -36 46 21
V = 13.2; Size 3.7x1.8; Surf Br = 15.1; PA = 83d
Extremely faint, small, round (only viewed the core), 20" diameter, requires averted vision to glimpse. Located between IC 1459 and N7418 in the Grus Chain (15.5' N of N7418). A mag 11 star lies 2.5' NE.

IC 5264 22 56 53.0 -36 33 15
V = 12.6; Size 2.5x0.5; Surf Br = 12.7; PA = 82d
Fairly faint, moderately large, edge-on 5:1 WSW-ENE, ~1.5'x0.3'. Located 6.5' SW of IC 1459 in the Grus Chain.

NGC 7421 22 56 54.3 -37 20 50
V = 11.9; Size 2.0x1.8; Surf Br = 13.2
Fairly faint, moderately large, ~1.5' diameter, diffuse with only a very weak concentration. At moments I had the impression of an elongated brightening or bar in the central region. Located near the southern end of the Grus Chain of 9 galaxies with N7418 20' NNW and IC 1459 53' N.

IC 1459 22 57 10.5 -36 27 45
V = 10.0; Size 5.2x3.8; Surf Br = 13.2; PA = 40d
Very bright, fairly large, elongated 4:3 SW-NE, sharply concentrated with a very bright core. The brightest portion of the halo extends 1.5'x1.1' and this is surrounded by much dimmer outer envelope. Bracketed by by a mag 11 star 3' WNW of center and a mag 12 star 2.7' E. This member of the Grus Chain of 9 galaxies is possibly the brightest southern galaxy missed by John Herschel.

IC 5269 22 57 43.6 -36 01 34
V = 12.2; Size 1.8x0.8; Surf Br = 12.5; PA = 51d
Fairly faint, small, elongated 2:1 SW-NE, 40"x20", weak concentration. Near the north end of the Grus Chain with IC 5270 10.5' NNE at the end.

IC 5270 22 57 54.9 -35 51 29
V = 12.3; Size 3.2x0.6; Surf Br = 12.9; PA = 103d
Fairly faint, moderately large, elongated 3:1~ E-W, 1.2'x0.4'. This galaxy sits at the north end of the Grus Chain that extends to N7421 ~1.5 degrees south.

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More Grus galaxies

NGC 7404 22 54 19.0 -39 18 50
V = 12.8; Size 1.5x0.9; Surf Br = 12.9; PA = 2d
Faint, fairly small, elongated 5:3 N-S, 0.4'x0.25', very small brighter core. Located 22' NNW of the bright edge-on N7410 and 11' NE of mag 7.3 HD 216443.

NGC 7410 22 55 00.7 -39 39 42
V = 10.3; Size 5.2x1.6; Surf Br = 12.5; PA = 45d
Bright, large, very elongated 7:2 SW-NE, ~3.0'x0.9'. Contains a bright, round core ~25" diameter which gradually increases to a very bright nucleus. At moments a stellar nucleus was visible that appeared offset to the SW of center. The surface appears irregular or mottled. NGC 7404 lies 23' NNW.

NGC 7658A 23 26 24.8 -39 12 58
V = 14.2; Size 0.6x0.2; Surf Br = 11.7; PA = 137d
Difficult observation due to low altitude and faintness of this double system. This is the northern "knot" of two extremely faint glows (separation 40") that were occasionally visible. Too faint for any details.

NGC 7658B 23 26 25.0 -39 13 38
V = 13.9; Size 0.9x0.3; Surf Br = 12.3; PA = 128d
This is the southern "knot" of two extremely faint glows (separation 40").

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The NGC 630 field -- NGC 630 straddles the Sculptor and Phoenix border. In fact, NGC 630 has a close companion, less than 2' SW and the two galaxies are different constellations!

NGC 626 01 35 12.0 -39 08 48
V = 12.7; Size 1.9x1.9; Surf Br = 13.9; PA = 43d
Fairly faint, fairly small, round, 0.8' diameter, small bright core, very faint halo. NGC 630/ESO 297-008 lies 13.5' SSE.

NGC 630 01 35 36.5 -39 21 29
V = 12.5; Size 1.6x1.4; Surf Br = 13.3; PA = 60d
Moderately bright, fairly small, slightly elongated, 0.6'x0.45, small bright core increases to the center, fairly high surface brightness. Forms a close pair with slightly fainter ESO 297-008 1.8' SW. N626 lies 13.5' NNW.

ESO 297-008 01 35 30.7 -39 23 01
V = 12.9; Size 1.4'x1.1'; Surf Br = 13.2; PA = 64d
Fainter member of a close pair with N630 1.8' NE. Appeared faint or fairly faint, fairly small, elongated 4:3 SW-NE, 0.8'x0.6', low even surface brightness. This galaxy is only ~0.5 mag fainter than N630, so it's surprising that John Herschel missed it when he discovered N630 from the Cape of Good Hope.

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A few other highlights --

MR 2251-178 22 54 05.8 -17 34 55
Size 0.2'x0.15'
This relatively close quasar was easily picked up as a mag 14.5-15 star. At moments, though, it appeared to be quasi-stellar with a very small 3"-4" fuzzy halo. MR 2251-178 was the first quasar that was initially discovered in X-rays, and the first one found to host a warm absorber. This is an unusual quasar with a high ratio of X-ray/ optical luminosity and is surrounded by the largest known quasar emission-line nebula.

II Zw 96 = "Baby Boom Galaxy " 20 57 23.9 +17 07 39
Size 0.6'x0.3'
Faint, very small elongated glow oriented NW-SE, ~20"x10" with a faint but distinct stellar nucleus offset to the south side. Located 5.6' NE of mag 7 HD 199480 and 10.5' WNW of mag 7.6 HD 199647. This is an interacting merging galaxy with super-starburst regions and was imaged by HST as part of a collection of 59 merging galaxies. See http://www.spacetelescope.org/images/html/heic0810bk.html

WLM System 00 01 56.9 -15 27 01
V = 10.6; Size 11.5'x4.0'; Surf Br = 14.6; PA = 4d
This local group dwarf irregular was visible at 115x as a large, faint, elongated glow, ~10'x5', oriented N-S, with a very low surface brightness. A couple of very faint stars are superimposed and a mag 14.6 star is off the west side near the middle. I looked for the mag 16.1 globular cluster that is close south of this star, but it was only suspected a couple of times and could not be confirmed (see below). In Kevin Ritschel's 33", the globular was still quite faint, but visible as a very dim "star" 38" south of the brighter field star.

WLM Globular Cluster #1 00 01 49.5 -15 27 31
V = 16.1
In Kevin's 33", the 16th magnitude globular in the WLM Dwarf Irregular was faint, but visible as a very dim "star" 38" south of a much brighter mag 14.5 field star. The globular seemed close to 2 magnitudes fainter than the nearby star. In any case, the observation was confirmed and the position verified on a photo with respect to nearby stars. This globular is the only one known in the WLM system (rare in dwarf galaxies) but is similar to the halo globulars in our own galaxy in terms of mass and age.

--Steve