Observation of Hickson groups (1,4,6,8,9,11,15)

Observation of Hickson groups (1,4,6,8,9,11,15)
By Steve Gottlieb

The following observations of Hickson Groups were made on November 1 with a 17.5" dob from a dark Sierra Nevada foothill site (limiting mag 6.5) at 220x and 280x. These were generally not easy objects with this aperture so I used Guide Star Catalogue finder charts, Digitized Sky Survey images and Hickson's Atlas of Compact Groups of Galaxies to track them down. I've been working my way through the 100 groups in the catalogue along with Ray Cash with the same aperture scope - definitely a challenging observing project!

Hickson Group Observations
Name RA Dec Description
Hickson 1 00 26.1 +25 44 At 220x Hickson 1 appears as a faint, fairly small glow, ~40"x20" (probably the interacting "A" and "B" component are merged). At 280x, the cores of "A" and "B" were possibly resolved at moments. A distinctive asterism of four stars is superimposed on the group. The "C" component was barely visible 2.8' due W and was just glimpsed several times as a virtually stellar 16th magnitude object collinear with mag 12 stars 1.0' NE and 2.5' NE .
Hickson 4 00 34.2 -21 26 Hickson 4A appears faint, fairly small, round, 35" diameter. Increases to a small, bright core and stellar nucleus with direct vision. On a couple of moments an extremely faint spot (Hickson 4c) was suspected 1.3' NNE. This sighting was verified at 280x, although still required averted vision to glimpse as a 16th magnitude 10" knot.
Hickson 6 00 39.2 -08 24 Only the "A" component was viewed and appeared very faint, small, elongated 3:2 NW-SE, 30"x20", low even surface brightness. Viewed at 220x and 280x (the "b" and "c" components are within 1' preceding). Located 37' N of NGC 191.
Hickson 8 00 49.6 +23 35 The brightest member of Hickson 8 was picked up at 220x 2.1' NW of a mag 13.5 star. Appears very faint, fairly small, irregular, ~0.8' in diameter. There is a "clumpiness" to the image, which gives impression that one or more faint nearby companions may be just below visibility. At 280x, slightly elongated, low even surface brightness. At moments, one or two extremely faint companions (b or c) were highly suspected off the N side.
Hickson 9 00 54.3 -23 33 The "A" component of Hickson 9 was viewed at 220x and appeared very faint, very small, round, 20"-25" diameter, no concentration. A mag 14.5 star is close preceding [30" from center]. There are four mag 10-11 stars in the field including a mag 11 star 1.4' SW. No other members seen.
Hickson 11 01 26.6 -23 14 The brightest member of Hickson 11 was easily picked up at 220x. Appeared faint, moderately large, elongated 4:3 ~N-S, 1.2'x0.9', broad concentration with no well-defined core. Located at the midpoint of a mag 12.5 star 1.4' N and mag 13.5 star 1.3' S. No other members of Hickson 11 were seen.
Hickson 15 02 07.4 +02 07 Five of the six members of Hickson 15 were visible at 280x. The "A" component was faint, elongated 3:2 NW-SE, 35"x25", weak concentration. Forms the N vertex of a triangle with two mag 13 stars 1.2' S and 1.8' SSW. Hickson 15B lies 5.7' SW and appeared faint, round, 30" diameter, weak even concentration to a faint, nearly stellar nucleus. Interestingly, the "C" component was probably the brightest of five viewed although this object was still a faint, small spot of 40" diameter. Hickson 15D was a difficult object appearing extremely faint, round, 20" diameter and situated 25" SE of a mag 14.5-15 star. This was the faintest of five viewed and it lies 1.9' NNW of Hickson 15c (brightest component?). The final member, 15E, was very faint, round, 20" diameter and the second faintest in the quintet. Located 1.0' NE of a mag 13.5 star.

Name	RA	Dec	Description
Hickson 1	00 26.1	+25 44	At 220x Hickson 1 appears as a faint, fairly small glow, ~40"x20" (probably the interacting "A" and "B" component are merged). At 280x, the cores of "A" and "B" were possibly resolved at moments. A distinctive asterism of four stars is superimposed on the group. The "C" component was barely visible 2.8' due W and was just glimpsed several times as a virtually stellar 16th magnitude object collinear with mag 12 stars 1.0' NE and 2.5' NE .
Hickson 4	00 34.2	-21 26	Hickson 4A appears faint, fairly small, round, 35" diameter. Increases to a small, bright core and stellar nucleus with direct vision. On a couple of moments an extremely faint spot (Hickson 4c) was suspected 1.3' NNE. This sighting was verified at 280x, although still required averted vision to glimpse as a 16th magnitude 10" knot.
Hickson 6	00 39.2	-08 24	Only the "A" component was viewed and appeared very faint, small, elongated 3:2 NW-SE, 30"x20", low even surface brightness. Viewed at 220x and 280x (the "b" and "c" components are within 1' preceding). Located 37' N of NGC 191.
Hickson 8	00 49.6	+23 35	The brightest member of Hickson 8 was picked up at 220x 2.1' NW of a mag 13.5 star. Appears very faint, fairly small, irregular, ~0.8' in diameter. There is a "clumpiness" to the image, which gives impression that one or more faint nearby companions may be just below visibility. At 280x, slightly elongated, low even surface brightness. At moments, one or two extremely faint companions (b or c) were highly suspected off the N side.
Hickson 9	00 54.3	-23 33	The "A" component of Hickson 9 was viewed at 220x and appeared very faint, very small, round, 20"-25" diameter, no concentration. A mag 14.5 star is close preceding [30" from center]. There are four mag 10-11 stars in the field including a mag 11 star 1.4' SW. No other members seen.
Hickson 11	01 26.6	-23 14	The brightest member of Hickson 11 was easily picked up at 220x. Appeared faint, moderately large, elongated 4:3 ~N-S, 1.2'x0.9', broad concentration with no well-defined core. Located at the midpoint of a mag 12.5 star 1.4' N and mag 13.5 star 1.3' S. No other members of Hickson 11 were seen.
Hickson 15	02 07.4	+02 07	Five of the six members of Hickson 15 were visible at 280x. The "A" component was faint, elongated 3:2 NW-SE, 35"x25", weak concentration. Forms the N vertex of a triangle with two mag 13 stars 1.2' S and 1.8' SSW. Hickson 15B lies 5.7' SW and appeared faint, round, 30" diameter, weak even concentration to a faint, nearly stellar nucleus. Interestingly, the "C" component was probably the brightest of five viewed although this object was still a faint, small spot of 40" diameter. Hickson 15D was a difficult object appearing extremely faint, round, 20" diameter and situated 25" SE of a mag 14.5-15 star. This was the faintest of five viewed and it lies 1.9' NNW of Hickson 15c (brightest component?). The final member, 15E, was very faint, round, 20" diameter and the second faintest in the quintet. Located 1.0' NE of a mag 13.5 star.