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Old 23-01-2012, 08:57 PM
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Paddy (Patrick)
Canis Minor

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Join Date: Jun 2007
Location: Strangways, Vic
Posts: 2,214
Open clusters in Canis Major and Puppis + sketch (Thor's Helmet)

Last night was the best transparency around here for quite a long time. Not nearly as good as its best and far from adequate for galaxies, but there are a lot of nice clusters up there. And NGC 2359 (Thor's Helmet) was looking pretty good.

Here are the notes and a sketch using the Mellish technique.

Telescope 400mm f4.9 tri-dob reflector
Eyepieces 28mm UWAN, 17,13,9 mm Naglers, Paracorr
Navigation: Uranometria, Night Sky Observer’s Guide

2300

Seeing good, transparency fair

NGC 2360 OC in Canis Major

135x Intricate cluster of about 100 stars, mostly faint with numerous star poor lanes and many delicate asterisms. A thick and curved V-shaped void points to the E with a bright star near its tip. Another thick E-W dark lane has a delicate line of 6 faint stars in a slight curve as its S edge. NW of centre is a clover-shaped arrangement of dark lanes.

NGC 2359/Gum 4/ Thor’s Helmet Emission nebula in Canis Major

175x 14’x7’ soft glow, a 5’ dome with indistinct base to the east is the centrepiece, with a line of 4 stars on the N edge and a few scattered in the middle. A thick 5’ long westerly projection comes from the S tip of the dome, a longer and fainter one from the NW star in the line at the N edge. Several dark patches can be seen in the dome itself. The whole thing brightens with OIII filter and the size of both horns increases significantly, the N one looking up to 14’ long. The curve of the dome brightens but especially on the northern edge. (see sketch)

NGC 2374 OC in Canis Major

132x 20’x10’ loose cluster of about 40 stars, fainter ones in the western part of the cluster making a distinct W shape. The stars are looser at the eastern end and there is a circle of bright stars to the south.

NGC 2401 Open Cluster in Puppis

175X A faint 2’ round glow with soft edges. With averted vision quite a few faint stars are resolved.

NGC 2396 OC in Puppis

135x 10’ loose cluster of 30-40 stars with one bright yellow star on the western edge. A thin southerly pointing V-shaped asterism is in the western part of the cluster. Less “organised” in the eastern part.

NGC 2423 OC in Puppis

135x Large 19’ cluster of many stars against a busy field. Stands out more as a distinct cluster in the finderscope than in the eyepiece as the field is so full of stars. Several wide dark lanes cut through the cluster creating complex shapes throughout.

Melotte 71 OC in Puppis

175X 10’ dia roughly round cluster of many faint stars, mostly of similar magnitude but there are 3 bright ones close together on the W edge. Several thick dark voids course through the OC

Melotte 72 OC in Puppis

175x An intriguing cluster of haze and stars forming an E-W 5’x3’ trapezoid with a long thin projection to the W. About 50 stars of similar magnitude.
Attached Thumbnails
Click for full-size image (NGC 2359 Thor's Helmetsmall.JPG)
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