AAQ Visual Observing Section
Selected Deep Sky Objects In Triangulum AustraleNow that the winter months are almost upon us, I thought we could spend some time in this interesting part of the sky. With the full splendor of the Milky Way around Scorpius and Sagittarius still to reveal itself, the south east night sky is a fine supporting act at this time of year. You will find Tim Napier-Munn’s comments on viewing these objects with his 14’ SCT in different text. WDS I 332 (RA. 15 21.2 Dec.-67 30) mags. 6.4 & 8.2, sep.1.1”, pa. 107˚ (1991) At first glance I thought this was a very easy pair with 40x, showing a nice off white primary and contrasting secondary. Two widely-separated stars with a colour contrast: pale yellow and dull azure blue. In fact the brighter one is actually the close double I 332. May have had glimpses at 861x but not clear. I332 is Hartung 688. RMK 20 (RA. 15 48.4 Dec.-65 27) mags.6.2 & 6.4, sep. 1.8”, pa. 146˚ (1986) I could just glimpse these with 120x, but 160x is needed for clear separation of the two similar magnitude components. Close double. Just visible at 237x, easier at 556x. RMK20 is Hartung 708. Epsilon TrA / Dunlop 188 (RA. 15 37.3 Dec. -66 20) mags. 4.2 & 9.4, sep. 82.1”, pa. 220˚. What a beautiful wide pair with 40x! Look also for the beautiful crimson star set in the same fine star field. Nice wide double with great colour contrast – a bright orange primary and blue secondary. NGC 6025 (RA. 16 03.7 Dec. -60 30) Set in an attractive star field this fine open cluster only needs 40x to see the loops and chains of bright stars that intersect through the middle. Dunlop 194 (RA. 15 55.3 Dec. -60 45) This consists of three, maybe 4 components that make up a pretty group with the bright primary in the centre. With 320x I thought I may have had a hint of separation of SLR11, but it was very difficult and not certain. HJ 4813 (RA. 15 56.1 Dec. -60 10) mags. 5.9 & 8.4, sep. 4.6” pa.100˚ (1991). Look for the strong orange primary giving a good colour contrast with the fainter secondary. I needed 120x to separate them, with the split barely visible with 80x. Split at 111x. Easier at higher mags. NGC 5979 (RA. 15 47.7 Dec. -61 13) With a magnitude of 11.5 I did not expect to find this planetary nebula. At 80x it clearly appeared using averted vision as a very small grey coloured out of focus star. Dunlop 203 (RA. 16 33.4 Dec. -60 55) mags. 7.9 & 8.2, sep. 22.4”, pa. 275˚ (1992). Another easy pair of similar magnitude stars at 40x. Nice easy pretty wide double. WDS I 336 (RA. 16 32.3 Dec. -62 18) mags. 7.8 & 8.1, sep. 1.1”, pa. 198˚ (1991). What I originally thought was WDS I 336 turns out to be this really attractive pair that are clear with 40x, but I needed 80x for a good view of the much fainter secondary. It forms a triangular grouping of stars with I 336 at its apex. However my charts show no double at this position, (RA. 16 34.2, Dec. -62 08) so it must be a chance alignment. I think I did finally glimpse I 336 with great difficulty with 320x. Interestingly there was another fainter wider pair in the same 320x FOV. Split OK at 556x in poor seeing. A bit easier at 861x. Iota TrA./ Dunlop 201 (RA. 16 28.4 Dec. -64 04) A truly stunning pair that with 80x appear set in a beautiful star field – look for the yellow primary and much fainter blue secondary. (Hartung 741) Its an optical double (not a binary) so its interesting. Split at 142x. Supposed to be 5.3, 9.4, 13”, 12˚, (1961) but I found a 1975 measure at 17.1” and 0˚. I did a quick check with the Micro Guide and I make it 13.6”, 2˚, so I think it’s moving quite fast or someone’s got it wrong. What does it look like to you? Colour pale yellow and blue with a strong magnitude contrast. WDS I 15 (RA. 16 20.4 Dec. -64 40) mags. 7.8 & 8.1, sep. 1.1”, pa. 198˚ (1991). Yet another case where first observation showed what appeared to be a really interesting contrast of a very wide easy pair at 40x, but in fact I could not see the true secondary with 320x. Very close by in the same field of view is a fainter much closer pair that needed 80x to be just resolvable. Look for the cross shape formed by these two pairs along with two other bright stars nearby. Split with 556x in poor seeing. A bit better at 861x. HDS 2347 (RA. 16 37.2 Dec. -67 01) mags. 7.1 & 9.7, sep. 0.2”, pa. 233˚ (1991). This was not at all difficult, and was easily seen even with the finderscope. What was interesting was the colour variations between the four components that form a trapezium shape. An asterism of four widely separated stars in the shape of a broad arrowhead, three of similar brightness (7.1, 7.1, 7.4) and a fourth dimmer star (9.0). The middle bright star is double HDS 2347, but is too close to split. As far as I could judge the bright stars are not in exactly the positions which Cartes du Ciel says they should be. HDS 2404 (RA. 17 00.2 Dec. -69.16) mags. 5.9 & 8.2, sep. 1.0”, pa.188˚ (1991). Could not split with 320x. Couldn’t split at 556x in lousy seeing. E-69-14 The magnitude 12.4 galaxy close to Alpha was not seen.
LUNAR OCCULTATIONSHere are a few interesting occultations for our SE Qld members to view, these ones are disappearances of brighter stars behind the dark lunar limb. I find the multiple star occultations very interesting events to watch. Times are approximate. It’s a good idea to check for these at least 15 minutes prior, as the exact time will vary depending on your location. 28/05/07 6.15 pm 7.6 mag 1943 - double star OTHER INTERESTING HAPPENINGSThe minor planet Vesta reaches opposition on the 30th May, when it will be located in Ophiuchus. At magnitude 5.4 it should approach naked eye visibility. For more information check your copy of “Astronomy 2007”. Jupiter reaches opposition on the 6th June and will therefore be at it’s most favorable for this year. Now is the best time to watch the movement of the four Galilean moons. Listed here are just some of the shadow transits across Jupiter’s disc – you can find more details regarding the times of these and others in “Astronomy 2007”. Don’t forget the 9th June – between the hours of 7.17 pm and 8.03 pm there will be simultaneous shadow transits of two moons – Io and Ganymede. 30/4/07 2.20 am shadow transit start – Io References:Sky Atlas 2000.0 Tirion & Sinnott Back To Deep Sky Observing Articles Back To Visual Observing Section Main Page
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