Solar Highlights for March 18

Solar Rotation Nos: 2201 to 2202

Very low levels of sunspot activity (almost zero) throughout March 2018. Plenty of spotless days and short-lived tiny sunspots.

Here is a summary together with a selection of images made by our observers.


AR2700 was a small Axx type sunspot that appeared near the western limb on the last few days of February. It was seen at latitude +7° until March 3rd.

The Sun was spotless from the 4th until the 15th.

AR2701 suddenly popped-up near the centre of the solar disc on the 16th at -12°. It was a type Axx but had gone by the 17th.

A spotless Sun was seen on the 17th.

AR2702 was a type Bxo sunspot at +21° but near the western solar limb. This sunspot lasted a single day (18th) but had gone the following day.

The Sun was spotless from the 19th to the 30th.

2018 March 25 @1423UT white light whole disc. Image taken by Cliff Meredith

AR2703 was another southern hemisphere sunspot at latitude -08°. It was type Axx and came over the eastern limb on the 31st. It was hard to see.

SPA Sunspot Mean Daily Frequency (MDF): 0.02 (was 0.59).
SPA Relative Sunspot Number: 00.21 (was 10.30).

Solar Prominences, Plage, Filaments and Flares

There was little in the way of disc features in hydrogen-alpha throughout March. The exception was a grouping of filaments seen near the eastern limb on the 5th and near the NW limb on the 17th.

There were some prominences throughout the month, along the solar limb, but they were mostly all small. Three small proms were seen on the SW and S limb on the 7th.

2018 March 17 @1545UT Ha whole disc drawing made by Ian Lee

The 19th saw three bright proms along the SW limb, one of these was a broken arch type.

Mark Beveridge captured this image of the Sun in calcium light on the 24th. It shows a remarkably uniform pattern across the solar disc.

2018 March 24 @1310UT CaK whole disc. Image taken by Mark Beveridge

The 23rd saw five small proms and the 24th a ‘smoke-stack’ type prom on the NW limb. An increase in the number of small proms was apparent on the 29th.

2018 March 25 @0913UT Ha prominences. Image taken by Carl Bowron
2018 March 30 @0920UT Ha whole disc drawing made by Ian Lee

It was not until the 31st that activity picked-up with a beautiful high arch type prom on the western limb plus AR2703 just over the eastern limb with a bright area of plage surrounding it.

There were no solar flares reported.

SPA Prominence Mean Daily Frequency (MDF): 1.11 (was 1.92).

In March, Brian Gordon-States observed 24 days in total. Alan Heath and Jonathan Shanklin both observed 21 days each with Bob Steele reaching 16 days.

Detailed count records of Active Regions and Relative Sunspot Numbers came from: Michael Fullerton, Brian Gordon-States, Alan Heath, Mick Jenkins, Ian Lee, and Jonathan Shanklin.

Images and drawings were supplied by: Mark Beveridge, Carl Bowron, Mick Jenkins, Ian Lee and Cliff Meredith.

Geoff Elston