Transit of Mercury

Mercury transit
The transit of Mercury 9 May 2016 at 16:24 (13:24 GMT) Click to enlarge, then click again for full resolution.

Several trial runs the last few days indicated that a roll of filter material (black polymer) I have had since the 1999 solar eclipse,  was not suitable for high-resolution solar photography.


The Thousand Oaks Optical Type 2+ filter, on the other hand, is very well suited for high-resolution solar photography. Unfortunately, my filter was only 90 millimetre diameter, made for the Meade ETX-90. I had to reduce the telescope's aperture from 120 mm to 90 mm. Nevertheless, the resolution decrease caused by the full aperture black polymer filter was greater than the resolution decrease caused by aperture reduction with the type 2+ filter.


I cut an annulus of thick plywood and made a cylinder of foam plastic sheeting to adapt the 90 mm type 2+ filter to a Skywatcher ED 120 refractor. Duct tape secured all the parts.



Mercury traverses south of two sunspot groups at 16:24 (14:24 GMT) 9 May 2016.


Filter: Thousand Oaks Optical Type 2+

Optics: Skywatcher Esprit ED 120 mm (stopped down to 90 mm) + TeleVue Powermate 4x

Camera: SkyNyx 2.2

Stacking and processing: AviStack2