Astronomical Society of Coonabarabran

Cycle 24: The second spot group appears!

by Harry Roberts

Sunwatching at present is exciting, as Cycle 23 is still active, yet C24 activity is expected daily. Setting up the 'scope promises the unexpected.

The morning of April 13th (still 12th UT) was such a day; after brief H-alpha observation through passing cloud of some small prominences I switched to white light to search for sunspots, finding none in spite of good seeing and, I thought, a careful search. The phone rang: it was Monty Leventhal to say there was a spot near the NE limb - he had not seen it but emails from US observers reported bright H-alpha plage there and one or two had seen spots at the site. Back to the 'scope: still set up for white light viewing.

Setting the cross-hair eye-piece on the NE quadrant I searched for bright faculae - recalling that an H-alpha patrol image of the 12th had a small bright patch in the NE.

It was hard to find, since the patch had moved away from the limb and the faculae was faint, yet there it was. It comprised a triangle of facular threads that were fairly bright. No spot could be seen at 80X but at 160X I found a single small black spot. Back to 80X and the spot was now easily seen, making transit timing possible.

In H-alpha (again) the site was easily seen, with two bands of bright plage, and a dark spot, that seemed in a slightly different position from the white light spot (?).

"Helio" calculations gave the position as latitude 27º N, longitude 359º. Spots this small are not counted by many sunwatchers, and various groups require a spot to visible for more than 24 hours for it to be counted. I felt that Mt. Wilson would have detected the spot but their daily drawing was not yet available, nor was their digital magnetograph. But a Solar Monitor magnetogram showed the new region had reversed polarity and was most likely a C24 group; the high north latitude confirming this.

It is worth noting that the new cycle has produced only northern hemisphere spots so far, while old cycle (23) activity dominates the southern hemisphere. The first accepted C24 spot was AR981 located at 28ºN, longitude 248º on January 6th. The new group glows brightly on SOHO UV and EUV images. The two sketches record the view in white light and H-alpha, and the position on the sun's disc.

The tiny sunspot group is unspectacular at the time of writing (it might grow more obvious) - but it probably has the distinction of being the second spot group for solar Cycle 24.

c24_spot_2_white_light_jpg