Many members of RAG turned up with scopes and filters to watch the planet Mercury transit the sun today.
The Met Office predicted variable weather and there was even an icon on their website showing simultaneous sun, cloud, rain and and rainbow – never seen that before! However, they were absolutely right because at one point we did indeed see all those things in the sky at the same time.
Due to cloud, we missed those few minutes when Mercury crossed onto the sun, but at various points in the afternoon were able to view it on the solar disc together with a solar prominence through gaps in the cloud. The sky improved towards the end of the afternoon but Mercury dropped behind trees at about 15:45 which meant further observations were not possible. Of course, it was followed by a clear night…..why couldn’t that have been 8 hours earlier?
I started off with my ASI120MC, and started packing up after getting plenty of video, but changed my mind after looking at the satellite images of cloud.
It did indeed clear up and I got plenty of DSLR images of the transit after less optimistic souls fled in the face of the rain and cloud! Those who stayed on saw Mercury on the preview screen and we also got stunning views through Andy’s Daystar Quark.
I couldn’t get anything usable out of Registax or Autostakkert so I manually stacked the ten highest scoring images (and added a bit of colour, to make the image easier on the eye):
I’d read a few bits and pieces online about Starnet++ – a software module that uses a neural network to identify and remove stars from astronomical images in order to enhance nebulosity and process it separately to stars.
The software is free and you can find it at the link below. It was originally published as a Pixinsight module, but can now be downloaded and run standalone on Windows: https://sourceforge.net/projects/starnet/
I’ve found it’s pretty good- I’ve been playing with it today on an image of the Western Veil I took a few weeks back. This is my original processing of the image:
To use the technique I started again with the stacked file and used Pixinsight to remove the background light pollution gradients, calibrate the colours and do an initial stretch. I then put the image through the Starnet routine and it returned me the image below:
I then used the Clone Stamp tool to clean it all up (possibly more time needed on this!) and tweaked the curves to give it some contrast and got this:
I really like this, but I felt it would be better with some stars blended back in, so I went back to the image I submitted and processed purely to get the brightest stars at a prominence that I liked. I then blended the two images using Pixelmath (in the way I used it here, it’s identical to blending layers in Photoshop or GIMP with lighten):