Copernicus

The bad weather has continued for the last few weeks but I've managed to grab a couple of breaks in the cloud. This included using my Revelation 20x100 binoculars on the Orion Nebula - the nebula filters really brought out the detail even under suburban skies. The Pleiades also looks much better through the wider field of view of the binoculars than through the telescope. I've also managed to set-up a few times just to have thick cloud appear within minutes. Such is the British weather. Looking at my observing logs, my 2 decent sessions from the last 2 months compares with the 19 I racked up in the same period last year.

Anyway, I ventured out with the laptop and webcam last night to what looked like promising skies. The weather forecast predicted clear skies until beyond midnight but I thought it best to crack on with taking videos. I chose the Moon ahead of targetting Orion with the diffraction grating, while hoping that I'll get another chance to have a crack at Orion before the spring.

Since this was almost exactly 2 months since my last lunar observation I was presented with the same collection of prime targets as my previous set of posts. With a thin veil of cloud drawing in I decided to play it safe and target Copernicus with a 2x Barlow. Considering the haze when I finished recording I am quite pleased with the result:


The hazy cloud has washed it out and made it a bit blurry but I feel like I'm getting better at recording with the 2x Barlow. How long it will take me to get to grips with the 5x Barlow is another matter.

Clavius

My last stop was much further south at the huge crater Clavius just below Tycho. At 225km diameter Clavius is one of the largest impact craters on the Moon.


Clavius is a relatively old crater having been formed around 4 billion years ago. Despite its age Clavius is well preserved but has numerous other impact craters on the crater floor. Starting from Rutherford on the southern rim, Clavius D, C, N, J and JA form an anti-clockwise arc across the crater floor. The decreasing size of these craters means they are often used to test the resolution of amateur telescopes. Clavius JA doesn't show up well in this photo but is usually quite clear if I use a Barlow lense. The other craters on the rim are Porter (north-east), Clavius L (west) and Clavius K (south-west).

In contrast Tycho, visible in shadow to the north-west of Clavius, is a very young crater around 100 million years old. There is speculation that Tycho was formed by an impactor from the same family of asteroids that produced the impactor that caused the extinction of the dinosaurs on Earth.

For completeness the crater on the terminator south-west of Clavius is Blancanus; the large crater to the north-east is Maginus; and the crater in the south-east with the prominent central peak is Moretus.

Copernicus

It's a short hop from Eratosthenes to Copernicus and this gave me a chance to get a contrasting picture to the full-moon shot I took a few months ago.

Here are the pictures side by side:




As I mentioned in my July post, the bottom picture is misaligned - the crater in the bottom right is the one at the top edge of the other picture. Eratosthenes just drops off the bottom of the full-moon shot.

The misalignment doesn't matter much since the object of interest is Copernicus itself. The shadows really show up the 1km depth of the crater. Actually I think a little less shadow would have given a better result as more of the crater floor would have been visible. Copernicus is a young crater and has lots of features on the crater floor that would have shown up nicely.

Eratosthenes

My next stop along the half-moon terminator was Eratosthenes. Named after the father of geography, inventor of the system of latitude and longitude, and all round Greek genius, Eratosthenes is located on the south edge of Mare Imbrium at the western end of the Montes Appenninus. It's a relatively deep crater that catches the eye due to it's prominent location and proximity to the crater Copernicus.

Similarly to my observations of Plato described in my previous post, I was dodging light cloud for much of the session. Here's the best shot:


Eratosthenes is the crater towards the bottom-left. The depth of the crater and terraced inner rim are clearly seen. There are also multiple central peaks visible and little evidence of lava flooding which suggests the crater may be younger than flooded craters such as Plato. In fact Eratosthenes is believed to be around 3.2 billion years old and its formation marks the start of the Eratosthenian Period which is partly characterised by reduced volcanic activity.

Looking closely at the bottom-left quarter of the picture it is possible to see the ejecta from the neighbouring crater Copernicus, which show up as lines of lighter coloured material. The three craters at the top of the picture, moving left to right, are Timocharis, Archimedes and Autolycus.

Plato

After much too long a break I've finally managed to get some new Moon pictures. Despite some intermittent wispy cloud and a sudden onset of fog I got a fairly good run at a near half moon.

Starting from the north, this post concerns Plato (the favourite crater of Space-1999 fans). As suggested by having a famous name, Plato is one of the most distinctive lunar craters. Those with good eyesight can spot it with the naked eye as a dark patch near to centre-top of the lunar disk. Plato is about 100km in diameter and has a dark, lava filled floor. It is located at the western end of the mountain range Montes Alpes and between Mare Imbrium (the Sea of Showers) and Mare Frigoris (the Sea of Cold). Plato is nearly 3.8 billion years old and slightly younger than Mare Imbrium to the south.

Here's the best picture of the bunch (which isn't bad considering there was never more than a couple of minutes between clouds):


The angle of the sunlight shows the irregular rim and jagged peaks casting shadows across the crater floor.

For completeness, the crater on the terminator towards the top of the picture is Fontenelle. The four craters forming an arc in the top-right are Anaxagorus, Epigenes, Timaeus, Archytas and the large, flatter crater in the top-right corner is Goldschmidt. The mountain to the south of Plato is the 2.4km high Mons Pico.

Sunspots

There's still not much action on the sunspot front but at least there is usually something to look at pretty much every day. A couple of weeks ago I pulled the camera out again for a few snaps.


I thought I'd also have a go at zooming in on one of the sunspots using the webcam (in this case the one towards the bottom of the disk in the image above). I had the usual problem of achieving focus throughout the video capture but some detail shows up.

Altair

Last month I tried a few different ideas with my Star Analyser diffraction grating. One of the bigger successes was taking some black and white images as well as the usual colour shots. Since it's usually best to experiment on something that's easy to find and that this was still summertime, I settled on Altair.

Altair is one of our near neighbours, about twice the mass of the Sun and ten times as luminous. Similarly to the other two points of the summer triangle, Altair is of spectral class A so has some fairly strong Balmer lines that should show up nicely using the Star Analyser. Here's what I ended up with:


Both sets of spectra have their merits but the black and white trio show much more detail. The colour pictures show a clear H-Beta absorption line (in the light blue) but the H-Alpha and H-Gamma lines (in red and blue, respectively) have to be searched for. The black and white shots not only clearly show these three absorption lines, but also show the H-Delta line.

It is also much easier to locate the peak luminosity when looking at the black and white images. Looking at the colour images the peak luminosity could lie anywhere in the light blue, green or yellow. The black and white images quite clearly show luminosity peaking in yellow.