An Observation of the LGG 117 Group in Taurus
I'm delighted to be posting some sketches and observation notes from Andrew Robertson in Norfolk for our December Galaxy of the Month. It'd be great to see more of your observations, especially for our featured objects. I hope Andrew's contribution will help inspire our members (and non-members too).
Please click on the image of his observing record for a larger version that may be easier to read.
Andrew's Observation Notes
South Norfolk, 12” D-K Tak Mewlon 300, diagonal used so laterally inverted, 27mm Panoptic used to give FOV of ½ deg and x135, 18mm Tak LE x200 used to give detail (what detail there was!).
Only an hours clear window centred on the observation with clagg or thin cloud around so poor transparency (approx. NELM 5) and poor seeing.
NGC 1587/8 were easily split and readily seen as two separate GX’s but I was struggling to see any detail. 1587 clearly had a brighter core and a small outer halo which didn’t appear uniformly round but I was struggling to pinpoint it’s exact shape. The halo didn’t quite extend to 1588 so there was a definite gap. 1588 was just a faint roundish fuzz which was bigger than a star. NGC 1589 was clearly extended, edge-on with an elongated core.
Andrew Robertson - 15 December 2014
December 2014 - Double Star of the Month
The double stars being featured this month require apertures around the 30-cm mark. Both are close binaries with periods in excess of 200 years and both are slowly widening, but at the time of writing each pair is at or below 0".5 separation.
52 Arietis (03 05 26.69 +25 15 18.7) is also known as STF 346. At discovery this was an 0".7 pair and motion during the remainder of the century was slow but by the early 1930's the pair was out of reach of all telescopes and circling around each other at the rate of 1 degree per week.
Since then the companion has been heading out towards the discovery position but even now it is still a difficult pair. The ephemeris for 2014.6 gives 258 degs and 0".49, and the stars are almost equally bright, both being around 6.2 visual. The writer was just able to measure it for the first time last autumn with a 20-cm Cooke refractor and will attempt to get some confirming measures later this year.
The two stars are accompanied by a 10.8 at 5" distance which is physically attached to the system. Another star of mag 13.2 at 105" appears to have been found by Smyth in 1835 and is mentioned in the Cycle of Celestial Objects. Smyth gave the magnitudes of C and D as 15 and 13, no doubt reflecting the difficulty of seeing C rather close to the bright binary components.
At the turn of the nineteenth century, Walter F. Gale was an active amateur astronomer living in Paddington, New South Wales and found a few double stars with an 8.5-inch reflecting telecope made by George With. He published a short list of discoveries in Astronomische Nachrichten in 1896, consisting of 5 double stars and a ring planetary nebula (IC 5148 - the Spare Tyre Nebula). Two of the pairs turned to be already known so the WDS now contains but three of his double stars.
The second object on the list was a close pair in Reticulum now called GLE 1 (04 16 20.92 -60 56 54.8). The stars, whose visual magnitudes are 6.8 and 7.5, passed through periastron in 2002 and are now slowly widening again although the current separation (0".35 at 218 degs) does require at least 30-cm and a good night. This system also contains the star TT Ret which is an alpha CVn variable with small amplitude and period of 2.8 days.
Bob Argyle - Double Star Section Director
Object of the Season (Winter 2014/15)
NGC 4449 in Canes Venatici
Irregular galaxy NGC 4449 in Canes Venatici will be announced in DSO 166, and the results will be published in DSO 168.
Please click on the image for a high resolution version taken by the Hubble Space Telescope (HST).
- Position (2000)
- 12 28 11.0 +44 05 33 (CVn)
- Visual magnitude
- 9.4 mag
- 5.5' x 3.6'
- 12.5 Mio. ly
- Other Designations
- I 213, h 1281, GC 3002, UGC 7592, CGCG 216-5, MCG 7-26-9, PGC 40973
Wolfgang Steinicke - Nebulae and Clusters Section Director