2014 October 3

Storms on Uranus and Saturn imaged by amateur astronomers in Australia

David Arditti

As we reported in August, a number of storms bright in infrared light are currently occurring in the atmosphere of Uranus. They were discovered with the 10 metre Keck telescope in Hawaii using adaptive optics and a 1600nm filter.

On October 2 well-known Australian planetary observer Anthony Wesley became probably the first amateur to succeed in imaging one of these features. He used a 16-inch (41cm) f/4 Newtonian telescope with an experimental combination of a TeleVue 2.5x Powermate and eyepiece projection using a high quality 18mm Orthoscopic eyepiece. The filter was infrared 650–850nm and the camera was a PointGrey Grasshopper 3 with a Sony IMX174 sensor.

Wesley has also produced an animation of images taken at 15-minute intervals which shows beyond doubt that this feature is real and rotating with the planet.

Other observers are encouraged to try to detect the storm both by visual observation and imaging, though a large telescope (by amateur standards) will almost certainly be required. Here is a list of predicted transit times (in UT) and longitudes for the storm for the rest of October. These are based on an estimated drift rate for the storm of -17.2 degrees per day, a figure that may get refined with further observation. Opposition of Uranus is October 7.

2014 Oct 04   00:36 ( 214°)   17:15 ( 202°)
2014 Oct 05   09:53 ( 189°)
2014 Oct 06   02:32 ( 177°)   19:11 ( 165°)
2014 Oct 07   11:50 ( 152°)
2014 Oct 08   04:28 ( 140°)   21:07 ( 127°)
2014 Oct 09   13:46 ( 115°)
2014 Oct 10   06:25 ( 103°)   23:03 (  90°)
2014 Oct 11   15:42 (  78°)
2014 Oct 12   08:21 (  65°)
2014 Oct 13   01:00 (  53°)   17:38 (  40°)
2014 Oct 14   10:17 (  28°)
2014 Oct 15   02:56 (  16°)   19:35 (   3°)
2014 Oct 16   12:13 ( 351°)
2014 Oct 17   04:52 ( 338°)   21:31 ( 326°)
2014 Oct 18   14:10 ( 314°)
2014 Oct 19   06:48 ( 301°)   23:27 ( 289°)
2014 Oct 20   16:06 ( 276°)
2014 Oct 21   08:45 ( 264°)
2014 Oct 22   01:23 ( 251°)   18:02 ( 239°)
2014 Oct 23   10:41 ( 227°)
2014 Oct 24   03:20 ( 214°)   19:58 ( 202°)
2014 Oct 25   12:37 ( 189°)
2014 Oct 26   05:16 ( 177°)   21:55 ( 165°)
2014 Oct 27   14:34 ( 152°)
2014 Oct 28   07:12 ( 140°)   23:51 ( 127°)
2014 Oct 29   16:30 ( 115°)
2014 Oct 30   09:09 ( 103°)

Another Australian amateur imager, Trevor Barry, has meanwhile been continuing to observe Saturn, depite that planet’s closeness to the Sun in the sky now, and remarkably resolved the anticyclonic fossil remnant of the Great Storm of 2011 on 2014 October 1. He measured its position to be (System 3) longitude 178°, latitude +42.7°. This may be the last observation of this apparition, but it has enabled Trevor to add a further point to the drift chart for this spot, compiled from data from the Cassini probe and from amateur imagers Barry, Wesley, Phil Miles and Damian Peach.