I’ve now added another 20 minutes of luminance frames and 12 minutes each of red, green and blue to this data set and stacked with the original 20 minutes of luminance to create a colour image.
Just to the right of M83, 2 background galaxies are just visible. These are PGC724525 (closest to M83) and PGC48132 and are about magnitude 16.
M101 is another spiral galaxy in Ursa Major but because it is presented face on it is rather faint and difficult to see in binoculars unless you have a very dark sky. Overall, the spiral arms cover an area almost the size of a full moon. However, in small telescopes only the central core will be visible.
27 million light years away, it’s discovery is credited to Pierre Méchain in 1871 and it’s spiral structure was first described by Lord Rosse in the 19th century using his 72″ reflector. It’s diameter of 170,000 light years is about twice the size of our own Milky Way galaxy. An unusual feature of this galaxy is the large number of star forming areas in the spiral arms. Some of these can be seen in this image as small bright regions with the characteristic blue tint of hot young stars.
Ongoing problems with tracking limited the maximum sub-exposure times to 120 seconds and a lot of these still had trailed stars leaving me with a stack of 16. As a result, the final image is rather noisy.
Friday evening was clear with some haze low in the sky, but, with Ursa Major high in the sky, presented an opportunity to try imaging M81 again. The CG-5 mount had some problems with intermittent tracking resulting in a lot of trailed images which had to be discarded and the corrector plate of the Celestron 9.25″ was fogging on the inside due to the high humidity. None of the images obtained were of good quality and I suspect the secondary mirror had fogged as well.
Despite the problems, 19 2 minute images were stacked and processed for this image:
Much more detail is apparent than in my earlier attempt. The Celestron is now drying out in a room with a de-humidifier running so hopefully the fogging problems won’t be repeated next time out.
The first galaxy to be discovered, outside of the local group, M83 was first catalogued as Lac.I.6 by Nicholas Louis de la Caille from his Cape of Good Hope observatory in 1752. It was re-catalogued by Charles Messier in 1781 who, observing from Paris, noted “it appears as a faint & even glow, but it is difficult to see in the telescope, as the least light to illuminate the micrometer wires makes it disappear. One is only able with the greatest concentration to see it at all”.
This monochrome image is a stack of 10 2 minute exposures using GRAS-15 in Australia processed in Maxim DL. Despite the near full moon this image clearly shows the dust lanes that wind their way down the spiral arms to the compact nucleus.
If the previous images of merging galaxies looked rather gentle then this is anything but. Several hundred million years ago, these galaxies were both spirals, rather similar to our own. Now, as the first image shows, they are almost totally disrupted with clumps of new stars ignited by the gravitational interaction.
The second image has been processed to over-expose the galactic cores and show the features that give this pair of galaxies their common name. Two gravity waves have produced long streams of stars, dust and gas stripped from the merging galaxies.
For astonomers wanting to study galactic interaction this pair present an ideal target as they’re are close neighbours at 45 million light years distance.
These images were produced on GRAS-15 and are a combination of 10x 300 second luminance frames binned at 1×1 and 6 each of red, green and blue filtered images binned at 2×2.
Given a very dark clear night, a good pair of binoculars and a set of sharp eyes, it’s possible that you may just be able to see a faint fuzzy blog under the handle of the plough in Canes Venatici. This is ARP 85, the galaxy pairing of Messier 51 & NGC 5195. M51, also known as The Whirlpool, is one of the finest examples of a spiral galaxy, discovered by Lord Rosse in 1845 who first recognised the spiral structure using his 72 inch reflecting telescope at Birr Castle, Ireland.
For many years it was believed that NGC 5195 was merely on the same line of sight as M51 and further away, however, simulations suggest that NGC 5195 first passed through the disk of M51 some 500 – 600 million years ago travelling towards us before another encounter 50 to 100 million years ago took it back through the spiral. The resulting gravity waves have triggered areas of star formation in the spiral arms of M51.
About 23 million light years away, M51 has a diameter of 76,000 light years and a total mass of about 160 billion suns.
Imaged on GRAS-001, this is a stack of eleven two minute exposures, processed in IRIS.
Just over a moons width away from M81 lies the galaxy M82, also in Ursa Major. With a really dark sky both are visible in binoculars as faint smudges. In space, the two are about 150,000 light years apart and are part of a galaxy cluster that is about 12 millions light years distant.
A bright moon and high haze limited imaging to bright objects on Tuesday evening but I did get a picture. I also determined that I had some issues with the imaging process, more on this below.
After the imaging run I noticed that the camera was set to jpeg rather than RAW image quality. After some work I traced this to a ‘fast mode’ setting in the capture software. Now that I’ve isolated this problem, next time out I should get some rather sharper, lower noise images.
After a cloudy start to Tuesday evening the sky cleared so I took some pictures of M81 in Ursa Major. M81 was discovered by Johann Bode in 1774 and is named Bode’s Nebula. At about 12 million light years distance it’s one of the closest galaxies outside the local group.
Telescope was the Celestron 9.25″ with f/6.3 reducer. 13 exposures of 2 minutes each were taken with the Canon 350D plus 5 dark frames.
The slightly mis-shapen star at 2 o’clock from the galaxy is actually a double star, HP38635A & B.
Making the news this week; M31, the Andromeda galaxy is due to collide with our own Milky Way in some 3 billion years. While this isn’t anything to lose sleep over, there are plenty of galaxies out there already experiencing this. Whilst individual stars are unlikely to collide in this process (there’s too much space between them, even in the relatively crowded space of a galaxy), the galaxy structures are massively disrupted due to gravitational forces. In this picture, we can see NGC 3226 (small elliptical) and NGC 3227 (spiral) interacting. Collectively, this pairing has the catalog id ARP 94 and is about 55 million light years away.
This picture is taken with GRAS-005, a Takahashi Epsilon 250 (Hyperbolic Flat-Field Astrograph) with an SBIG-10XME camera, 4x 5 minute exposures.
Boxing day was clear and bright which continued into evening so a visit to the observatory was in order to take some more footage of Venus (pictures to follow, hopefully).
Once Venus had set then I switched to the Canon 350D as the sky was beautifully transparent (a truely rare occurance this year!). I had some problems with the EQ-5 mount as it wouldn’t align, seemingly unable to locate Vega during a single star align. Giving up on this I manually aligned it on Orion for some pictures of the nebula. 15 30-second exposures at ISO 800 are combined for this image.
