Super Wolf Blood Moon – Or, a Luna eclipse.

Partial Luna eclipses (where the moon slides through Earth’s shadow, but a bit remains uncovered) are not particularly rare, there are at least two per year. Full Luna eclipses (where the moon is entirely covered by the Earth’s shadow) are a tad rarer, but not overly.

This isn’t good enough in these social media times, so the boring old Luna eclipse has to become a Super Wolf Blood Moon or some old bollocks.

Anyway, all that could be seen from my window this morning was this.

Neptune attempt 2

Back in January last year I managed to get a photograph of Neptune, a planet I’ve long harboured a soft spot for. This month, Neptune has been nicely placed close to Mars in the south after dark. Having a new telescope I’d planed to get a better image, and perhaps work on imaging all the planets in reverse order.

Several nights ago, the sky was perfectly clear, so I started setting up the telescope. Almost immediately, the clouds started rolling in. Giving up on the telescope idea, I reached for the camera and tripod and just snapped a few frames at 300 mm focal length.

It’s not the most stunning photo of a planet you’ll ever see, but I think it’s a bit more convincing than my previous attempt. You can almost see some blue-green colour to the tiny dot in the image.

Uranus is inconveniently placed close to the waxing moon for the next week or so, meaning it’ll be a while yet until I get the next planet in my solar system family portrait.

Astrophotography – M31 – Andromeda

I’m getting back into astronomy after a very long hiatus. I really want to do some astrophotography, something I didn’t really achieve before.

My previous attempts at imaging the sky though a telescope were with a self-guided Az-El mount crap-scope and a self-made 110 film camera. The results were underwhelming to say the least.

I’ve now got a much nicer telescope – a Skywatcher 102 mm Acromat Refractor on a decent guiding mount – an EQ5 Pro. For a camera I’m using either a Nikon D50 with the IR and Beyer filters removed, or a Nikon D7000 unmodified.

I took a couple of evenings to familiarize myself with the telescope and mount and to get a feel for the night sky again. This Friday was a good clear night, so I thought I’d attach a camera, point the scope at Andromeda and see what happened.

I aimed to collect 150 x 30 sec exposures at ISO 1600. I was relying on the built-in intervalometer in the camera to control the capture, this was my first mistake. I’d not used this feature of the camera before, and I managed to set it up incorrectly. I only managed to collect half the number of images I thought. I also forgot to set the ISO correctly.

I’m also pretty sure the focus wasn’t spot on. It’s hard to see the camera live view when it’s upside down.

Andromeda M31 A pretty poor photo, but my first attempt
Andromeda M31
A pretty poor photo, but my first attempt

The resulting image isn’t great, but it does hint at there being some structure in the fuzzy glow. Ok, some of that is probably JPEG artifacts in the version I’ve embedded here, there’s probably also some banding from the processing.

Things to do for next time:

  • Check the camera settings
  • Check the camera settings
  • Learn to use the intervalometer
  • Focus the scope on a object I can see in the live view more easily.
  • (probably) Use a computer to control the camera so I can sit in the warm with a cup of Tea.

Neptune

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
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.

A starfield - neptune is here somewhere
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.

neptuneoverlay
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.

neptune
Success!
Neptune has been imaged

Success!

Some technical details:

  • Camera:  Nikon D7000
  • Lens: AFS Nikkor 55-300 at 200mm
  • Exposure: 5 seconds
  • 20 exposures stacked with ImageJ

Angular resolution of the dome of Planetarium of Majorca from Palma

WOW – what a clickbait title that is…

Back from having spent a few days between Christmas and New Year in Palma, Majorca. On the last day there I noticed I could just see the dome of the Planetarium of Majorca (or the telescope dome, I’m not sure which) from the hotel terrace. Seeing conditions were not great, but the small white point on the mountain top was clearly visible by reflected sunlight. It did look to be just on the edge of visibility, so now I’m back I wondered just how close to being invisible it really was.

Some Data:

  • Telescope dome position : 39.642528°N 2.950516°E (from wikipedia)
  • My viewing position : 39.555666°N 2.623219°E (from photographic GPS and google maps)
map
Positions of the dome and my viewing point

Some derived data:

  • Dome diameter : 15m (measured off google earth)
  • Distance between these points : 29.668km

Angular size :

equation

  • 5.056×10^-4 radians
  • 0.02897 degrees
  • 1′ 44.3″ arc seconds

This seems pretty small, how’s it compare to things we’d usually see?

  • Sun diameter : 31’30″Full Moon diameter : 29’20”
  • Planet Venus at closest  : 1’00”
  • Brightest star in the sky – Sirius : 0.005936″

(All values from wikipedia)

The dome appears larger than the brightest star in the sky and roughly the same size the planet Venus does. These are both perfectly visible, so why did the dome appear just visible to me? I’m guessing it’s because the dome was only reflecting a small amount of light, and I was viewing it against quite a bright background (blue sky) too. Atmospheric haze and thermal twinkles probably didn’t help.

So although I should have been able to see it pretty clearly (if it had been emitting it’s own light, against a dark background) , I was probably pretty lucky to have seen it at all given the atmospheric conditions.

Happy new year!