Abolished in 1859, Oak Apple Day was established in 1660 by a parliamentary act declaring
[29 May ] to be for ever kept as a day of thanksgiving for our redemption from tyranny and the King’s return to his Government, he entering London that day.
It’s now the day where I usually post this video of a CT scan of an Oak Apple complete with a few developing wasps.
My interest in Oak Apples is less to do with the restoration of the monarchy, and more to do with the use of them in the production of iron gall Ink, which was commonly used as a writing ink from around the 5th century until the invention of more modern inks in the 1900s
In the video we can see the bodies of several developing gall wasps. The Oak Apple was taken from a batch bought for making ink, so the wasps were long since dead.
I’ve always had an interest in astronomy and have dabbled in astrophotography since I got my first digital camera back in the late 1990s. Over the years I’ve got images of all the planets except Neptune and Pluto. The latter of these is never going to be an easy target for the lazy amateur (me), but maybe, just maybe Neptune is possible.
I’ve had a soft spot for Neptune since the Voyager 2 flyby in 1989 – I’ve still got the article I tore out from a newspaper at the time.
Newspaper article on the Voyager 2 flyby of Neptune in 1989
As it happens, Neptune is nicely placed in the sky right now – just between Venus and Mars and close to a couple of guide stars.
Braving the frost, I took the camera out to the garden, mounted it on a slightly wobbly tripod and took some images of the general area of sky I knew Neptune was lurking. Some processing and stacking with ImageJ and I had a star-field that might contain my target.
Mars, Neptune and some stars though the trees
It’s easier to see the faint points of light of the guide stars and Neptune if you invert the colours, so you’re seeing black points on a white / grey background.
I used Stellarium to predict the current positions of Mars, Neptune and the guide stars and overlaid that on top of my image stack. This lined up reasonably well, there are some angular offset and slight scale differences between the two images, but it’s close enough for guidance.
A prediction from Stellarium overlaid on top of my stacked images
With the assurance that I had Neptune in my images I was able to definitely pick it out from the stellar background.
Sometimes when you’re looking around for something to scan in your new-ish CT scanner the answer just lands in your lap.
I’ve been doing #xraymyadvent again this year, but thought I’d test out the new scanner with an item more in keeping with the scanner’s intended use. Searching around the lab I found no obvious items. Until I looked down at the floor, this is what I found.
A poor dead mouse.
This is just 60 projections from the full CT scan – it looks like the scanner worked well.