Observing in Tähtikallio Observatory 15./16.9.2012

Date: 15./16.9.2012
Time: 22:00-03:30
Observing site: Tähtikallio observatory, Finland
Instrument: C406/4064mm (16” Catadioptric)

NELM: 6,6
SQM: 21,28
Darkness of the background sky: 2
Seeing: 2
Transparency: 1
Weather: Clear sky, calm, no Moon, +10 °C

Objects observed: Caldwell 30 (NGC 7331) (visual, sketching), Hickson 92 (visual, sketching), Hickson 94 (visual, sketching)

In this session I was able to make some observation and sketching with the 16” Catadioptric telescope of Tähtikallio Observatory in Artjärvi, Finland. This observing session happened during the annual meeting of Finnish deep sky observers.

During this session I observed Caldwell 30 (NGC 7331), which is a nearly edge-on spiral galaxy in Pegasus. Besides this, I observed Hickson 92 and 94, which are faint and challenging groups of galaxies from the Hickson catalogue of compact galaxy groups. Observing conditions were good during the whole session.

Caldwel 30 (NGC 7331): @200x, large and bright, almost edge -on galaxy. The galaxy is very elongated in shape, and it’s length axis is oriented in N-S -direction. The galaxy has an almost stellar core with relatively bright halo that is surrounding it. The brightness of the galaxy decreases rapidly outwards from the core of the galaxy. With instrument like this and this magnification, the galaxy extends almost from the edge of the field to another. It is possible to see hints of EDL west from the core of the galaxy when gazing with averted vision. Of the satellite galaxies of NGC 7331, I was able to see at least NGC 7335. It is visible as a small, fuzzy spot about 3′ to NE from the core of NGC 7331.

Caldwell 30 (NGC 7331) observed with 40'' Catadioptric
Caldwell 30 (NGC 7331) observed with 16” Catadioptric

Hickson 92: @200x, I was able to see four galaxies of this group: NGC 7320 (13,2 mag), NGC 7317 (14,6 mag), NGC 7318B (14,0 mag) and NGC 7318A (14,4 mag). For some reason, I apparently missed NGC 7319 (14,1 mag), which I think, should have been visible with this instrument. All these galaxies were visible as faint, fuzzy nebulas, best visible with averted vision.

Reasons, why I didn’t spot NGC 7319 might be caused by following factors:

-When I was doing this observation, I didn’t have any detailed map of this object. Neither did I have any clear mental map or image of this object in my mind (which on the other hand, is just a good thing).
-I wasn’t alone all the time, and I wasn’t able to focus on the observing as much as I had wanted to
-I hadn’t been obsering with this instrument much before this session
-There might have been some dew on the oculars, and the optical surfaces could have been a little bit dirty

Hickson 92 observed with 40''' Catadioptric
Hickson 92 observed with 16”’ Catadioptric

Hickson 94: @200x, only two galaxies, NGC 7578A (14,9 mag) and 7678B (14,9 mag) of this cluster were clearly visible. Both galaxies appeared as a small, faint, fuzzy nebulas, that were only barely visible with direct gaze, but became better visible with averted vision. Also when comparing my sketch with the SIMBAD photo, it seems that the star-like cores of HCG 94C (16,3 B mag) and D (16,2 B mag) were also visible.

A galaxy cluster Hickson 94 observed and sketched with the 16'' Meade of Tähtikallio in 15./16.9.2012. Only two galaxies (NGC 7578-1, NGC 7578-2) of the cluster were visible.
Hickson 94 observed with 16” Catadioptric

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