December 2014 - Picture of the Month
NGC 1566 ("Spanish Dancer" galaxy) in Dorado
Image Courtesy of Steve Crouch, Canberra, Australia.
Please click on the image for the high resolution version.
Steve's Observation Notes:
This magnitude 9.4 Seyfert galaxy is roughly 8.3' x 6.6' in size. It is the second brightest Seyfert galaxy after NGC 1068 (M77) and the brightest member of the Dorado galaxy group. The distance is not very accurately known and given as 38.4 million light years with an error of 18.6 million light years.
This image shows a supernova (discovered in September 2014) just to the right of the central nucleus. The luminance data (with the supernova) was taken on 12 November 2014 when it had started to fade. The discovery visual magnitude was given as 14.6.
- Camera and Telescope
- STL6303, STXL6303, 31.75cm and 36.8cm Ritchey Chretiens Focal Ratio F9
- Exposure Details
- RGB 100:100:100 all 1x1 with Astrodon filters using 31.75cm
RC. Luminance 150 minutes with 36.8cm RC.
For more images from Steve please visit his
CCD Astronomical Images from Canberra
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