Living within a spiral galaxy gives us the chance to get an up close view of the dust clouds that fill the inter-stellar space in the spiral arms. If it wasn’t for this dust obscuring the starlight from millions of stars then our night sky would look very different.
This image is a wide-field view of the area around Cygnus. Six exposures of 3 minutes each at ISO 800 and f/3.5 with my Sigma 10-20mm zoom.
One of the main attractions of La Palma was it’s views of the Milky Way. It’s southerly latitude opens up views of our galaxy’s centre that just aren’t possible from the UK. This picture is a mosaic of two images taken with the Sigma 10-20mm set at 10mm on my Canon 350D. Each image is a stack of three 3 minute exposures at ISO 800 and f/3.5.
Cygnus and Lyra are at the top of the picture, with Scorpius and Sagittarius at the bottom.
Once I’d got the Astrotrac rather more accurately drift aligned on the final evening, we set about imaging some rather closer views of objects using longer focal lengths. This image of M8 and M20 consists of five 3 minute exposures with a Canon 75-300 zoom lens set at 180mm (f/5) and ISO 400.
Both nebulae are probably part of the same complex, some 5200 light years away and are pictured against the star clouds of Sagittarius towards the Galactic centre.
Well, I needn’t have worried about the clouds. On the West side of the island I had six clear nights out of six (Dan had seven but I was down on the coast that night under the inversion layer!). Six solid nights of getting to bed at 3 & 4 in the morning, getting up at 9 and wandering up volcanoes. At least I got the odd nap during the afternoons.
All of this didn’t leave any time for image processing or blogging so I have a fair backlog to get through. I’ve started with the image I first posted on the Breckland Astro forum. I’ve now removed the colour cast and some of the light pollution gradient although this wasn’t entirely successful.
We took this image on the last evening after the course when I’d finally got the time to drift align the Astrotrac for some exposures using longer focal lengths. However, Dan put his Canon 1000D with 4.5 mm fisheye lens on for this 4 minute shot at f/2.8, ISO 800.
This picture does show some light pollution around the edges but to the naked eye this wasn’t particularly intrusive and the sky was considerably darker than at home. What was definitely missing was aircraft overflights with their navigation lights, they’re banned by the La Palma government for the benefit of the observatories on La Roque de Los Muchachos.
Enroute to La Palma we decided on spending a day in Madrid and totally by chance the hotel was a stones throw away from the Madrid Royal Observatory. What can you do in circumstances like these but organise a tour.
Unfortunately, the tours are conducted in Spanish but the two young ladies who showed us around were very pleasant and would answer questions in English. My thanks to them for making the visit so enjoyable.
The main building was constructed in 1845 although the observatory had been established around 1785 and was home to a Herschel 25ft reflecting telescope of 24″ aperture until it’s destruction by French Napoleonic troops.
The main building has a transit telescope, the slot for which is visible on the right of this picture. Unfortunately, photography wasn’t permitted inside this building but there is a picture in the guidebook. Ask me if you’d like to see it.
Highlight of the visit though was the beautiful reconstruction of the original Herschel telescope, housed in it’s own building.
Tomorrow we meet Dan at the airport for the flight to La Palma. The weather forecast isn’t looking too good so far. Keep your fingers crossed for us.
It’s not everyday that a supernova explodes in a nearby galaxy, especially not as close as M51 (27 million light years). The last one in this particular galaxy was in 2005. Of particular interest this time is that M51 is one of the most imaged objects in the night sky so there’s a lot of possibility for examining it’s evolution before it’s official discovery.
So, here’s Dan & my picture from last night with the supernova marked:
I’ve also put together an AVI with a previous image taken with one of the GRAS scopes which shows the supernova appearance clearly. This file is available here:
With the days getting longer, and the nights corresponding shorter, opportunities for imaging get fewer. Friday night at the observatory looked promising though and once it started to get dark Dan and I had a crack at M57 using his modified Canon 1000D. More on that later. By this time, Cygnus was getting higher in the eastern sky so we moved onto NGC 6888, an emission nebula.
With viable guide stars on top of the nebula, and with it ideally placed for the Alt-Az 20″ (low in the east) we settled on 1 minute exposures at ISO 1600. A few were rejected due to bad tracking but overall the results were very good. The tracking excursions were limited to the Alt axis which we’ve seen before. The usual fix if it’s problematic is to add or remove nose weight but on this occasion it only affected a few frames.
One of the surprising things about the night sky is the number of galaxies out there that can be photographed with a humble 70mm refractor and Canon DSLR camera. With my last few outings concentrating on Ursa Major for this clear night I decided upon the Virgo cluster and the Markarian Chain.
The Virgo galaxy cluster contains upwards of 1200 galaxies and it’s centre is 53 million light years away. Together with the Local Group it forms a small part of the Local or Virgo Supercluster.
The Markarian Chain is named after the astrophysicist who first noticed their common motion in the 1970s.
Imaging these galaxies was surprisingly difficult after the large spirals in Ursa Major. Being further away, they’re smaller and fainter and there’s a lack of bright stars in the near vicinity which makes locating them harder. Fainter means that more exposure is required to bring them up out of the background noise. Being close to the Celestial Equator also means that the polar alignment is rather more critical than I’ve become used to. While I did make a correction to the mount after the first couple of images it still required more refinement.
For these images I put the focal reducing William Optics field flattener on the camera and to compensate for the increased photographic speed of this combination reduced the exposure time to 4 minutes per frame. The focal length is reduced to 336mm. I’m not entirely happy with how this focal reducer works just yet; some more experimentation is required. It may be that it isn’t an ideal combination with this telescope.
I’m not going to even try and label all the galaxies in this image.
Telescope: WO 70mm Zenithstar with FF3
Camera: Canon 350D
Frames: 18x 240 second
After my last picture of M101 I was anxious to see what a little more exposure would do for the image. I got my chance at the beginning of April with a beautiful clear night and exposed 15x 5 minute frames of this area. Leaving the camera on ISO 800 was probably a mistake as it causes the brighter stars to lose colour. In future, I will probably stick to ISO 400 for this length of exposure.
The bright smudge to the right of M101 is NGC 5474, a gravitationally bound near neighbour of M101 and a disrupted dwarf spiral galaxy. The core is offset by it’s interaction with the larger galaxy.
Joan Genebriera of AstroPalma kindly pointed out that there is a large white spot on my last image of Saturn. This is the giant storm that’s been raging since the end of last year so I’m quite pleased to have captured it. There’s a Hubble picture of the storm here: http://planetary.org/image/saturn_JBNY02SQQ_hubble_20110312.png
