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Gary last won the day on September 27

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  1. Ah, yes, another one of those ‘named’ nebulae. Although a singular honour, I do wonder, occasionally, if the person has ever looked into the eyepiece and thought “Really? I look like that?” IC 2599 is also known as the Gabriela Mistral Nebula, in honour of one of Chile’s most famous poets and Nobel Prize recipients. It’s good to see some southern hemisphere folks getting some celestial recognition. The nebula is in the Carina constellation, approximately 7500 ly from us and spans about 40 ly across. IC 2599 is associated with the open cluster NGC 3324 – a very luminous group of hot, young stars – that provides the radiative energy heating and sculpting the nebula. Because IC 2599 is a strong HII region, and because the only clear nights I had to capture the data were lit by the moon, I decided to image in H-alpha light. This is what gives it its vivid, monochromatic red hue.
  2. Gary

    Messier 17

    When one has been struggling with cursed objects (DSOs that, despite repeated best efforts, never seem to yield decent data), I have found that it is a good idea to go back to something reasonably basic but still interesting. Messier 17 is just such an object: big, bright, easily identified, and colourful. M 17 goes by several names. The one I grew up with was the Swan Nebula, but it is also known as the Omega Nebula, the Checkmark Nebula, and the Horseshoe Nebula. Most of these names are based on the lighter central region that is seen through most telescopes. If you squint, you can imagine a pale swan gliding leftwards through the middle of the nebula. The distinctive, dark shape that helps form the ‘neck’ of the swan is the result of large clouds of dust blocking the light from emission nebula behind it. M 17 is an HII region in Sagittarius, and resides about 5500 light years from us. Its center is illuminated by one of the youngest cluster of stars; just a million years old. Date: 13 July 2020 Constellation: Sagittarius R.A.: 18h 20m 57s Dec.: -16° 10' 40" Photo stuff: 18 subs@300s ea.; ISO 800; Canon 60Da on Meade RCX400 16” f/8 with a .7 focal reducer
  3. This is a wide field image of the Large Magellanic Cloud. NGC 2070 (The Tarantula Nebula) is clearly visible at centre right, an N11 (The Bean Nebula) is in the lower left corner. In fact, the LMC is chocka with what astronomers refer to as DSOs, or deep space objects. Almost any condensed knot of light has a designation in one or more astronomical catalogues. The central bar of the dwarf galaxy is clearly visible in this image. It is thought that some of the LMC's spiral arms were ripped off in tidal interactions with the Small Magellanic Cloud and our own, much larger, Milky Way galaxy, which just goes to show that it's a galaxy-eat-galaxy universe out there. The LMC can be seen straddling the border of the Mensa and Dorado constellations, and is approximately 163 kly away. Date: 21 October 2016 Constellation: Dorado/Mensa R.A.: 05h 23m 35s Dec.: -69° 45' 22" Photo stuff: 50 subs@120s ea.; ISO 800; Canon 60Da with Canon 28-135mm; f/5.6
  4. The "Cat's Paw" Nebula can be found in Scorpius. NGC 6334 is relatively nearby, astronomically speaking - about 5.5 kly away from us - and, at 50 ly across, it is intrinsically large. Visually, it is covers a section of the sky that is approximately 40' x 23', which is slightly larger than the full moon. It is another of those popular objects for astrophotographers, and for good reasons; it's big, bright, and has an interesting shape. In a wider view of the object, there is no mistaking why it was given its name. With this image, however, I chose a much closer framing of the object to show the stunning amount of nebulosity and activity taking place inside it. This is an incredibly productive stellar nursery; many of its stars are only a few million years old - mere babies! These hot new stars help provide the radiation that makes this emission nebula glow so brightly. At the other end of the stellar life cycle, information given out by the ESO suggests that the burst 'bubble' in the top of the image may be due to a star that is either at the end of its allotted time or has already exploded. The Paw is reddish when photographed without a filter, but the deep red hue of this image is due primarily to the addition of H-alpha light to the mix. As I have mentioned elsewhere in this blog, H-alpha light is perceived by human beings as a very deep red (656.28 nm) part of the visible spectrum. When added to a 'normal' light image, it not only provides artistic interest, but, also, information about the amount and structure of ionised hydrogen gas in a region. Photo stuff:Date: 06 August 2019R.A.: 17h 20m 14sDec. -36° 02' 39"Canon 60Da on Meade RCX400 f/8 16" with 0.70 focal reducer22 subs @ 300s ea., normal light; 23 subs @ 300s ea., Ha light; ISO 1600, all subs
  5. Gary

    IC 4603

    This is not the prettiest of astronomical objects, but I like it for the sheer amount of action that it implies - interstellar dust and hydrogen gas are blowing every which way, and star formation is occurring at quite a clip due to an ancient supernova having taken place nearby. IC 4603 - the central nebulosity in this image - can be found near Antares, but just inside the borders of the constellation Ophiuchus. The dust is illuminated by the light of SAO 184376, a bright (Mag. 7.6), pre-main sequence, B-type star, which gives us that distinctive blue of a reflection nebula. Photo stuff:Date: 06 & 07 July 2019R.A.: 16h 25m 22sDec. -24° 18' 41"Canon 60Da on Meade RCX400 f/8 16" with 0.70 focal reducer55 subs @ 300s ea.; ISO 1600
  6. I published a wide-field photo of Messier 20 (about 4.1 kly, in Sagittarius) back in June, which prompted me to go after a proper 'head and shoulders' shot - with a twist, as this time I combined luminance and narrowband light. "Narrowband" is a term used by astrophotographers to denote the use of one or more filters to gather image data from very narrow slices of the spectrum. In this image, those filters were hydrogen-alpha (looking through it, an intense red), hydrogen-beta (dark blue), and oxygen-III (cyan/green-ish), bolstered by the luminance data. Besides making for some very striking photos, narrowband filters can give a better sense of the structure and composition of a nebula. Be warned, though: data acquisition to get a fair image can be a lengthy and challenging task, and, despite the technical aspects, the final post-processing is very much more an art than a science. Photo stuff:Date: 07 and 12 July, 2019R.A.: 18h 10m 04.0sDec. -21° 48' 21.1"Canon 60Da on Meade RCX400 f/8 16"; Astronomic .7 focal reducerLuminance: 17 subs @ 300s ea.; ISO 1600 Narrowband: 12 subs @ 300s ea. filter; ISO 1600
  7. Gary

    NGC 5367 and CG12

    This is a rather complex pair of objects in the constellation Centaurus. The blue reflection nebula is NGC 5367. While the nebula is quite pretty, the more interesting object, for me and for the professional astronomy community, is the brownish cloud that envelopes and slightly obscures NGC 5367. This is the cometary globule CG12, which extends somewhat further off the left side of this image. Cometary globules get their name from their appearance, which vaguely resembles a rather poorly formed comet. Most of these types of globules hang about near the galactic plane but CG12 is a bit unusual in this respect. Gopinathan et al. (2004) have suggested that it sits about 200 pc (~650 light years) above the plane at a distance of 550 pc (~1800 light years) from us. Photo stuff:Date: 28 June 2019; 03 July 2019R.A.: 13h 58m 00.5sDec. -40° 03' 07.2"Canon 60Da on Meade RCX400 f/8 16" with 0.70 focal reducer36 subs @ 300s ea.; ISO 1600
  8. Gary

    IC 4605

    A welcome run of clear nights recently allowed me to lose yet more sleep and get some imaging done. This is the result of one of those runs. IC 4605 is a beautiful reflection nebula that is lit up by the bright (magnitude 4.8) blue, main sequence star, 22 Scorpii, which lies about 413 light years away from us. Although the star is visible from a reasonably dark sky site, long exposures with a camera are needed before the tenuous dust clouds that envelope it can be seen. This nebula is part of the much larger and very colourful Rho Ophiuchi Nebula complex. I have an image of that somewhere that I'll try to dig out and post here when I get a chance. Photo stuff:Date: 28 June 2019R.A.: 16h 30m 14.4sDec. -25° 07' 08.0"Canon 60Da on Meade RCX400 f/8 16" with 0.70 focal reducer24 subs @ 300s ea.; ISO 1600
  9. As I was making my way through my past images, I came across one from 2017 that - rather oddly - I had not yet fully processed. This is a wide field photo of the Trifid Nebula (Messier 20). It is a perennial favourite of astrophotographers, and a relatively easy target for beginners to learn data gathering and post-processing. M20 is a stellar nursery located about five degrees west from Lambda Sagittarii and two degrees northwest of Messier 8 (Lagoon Nebula). It has the unusual characteristic of having several distinct components: reflection (blue), emission (pink), and dark (the 'lanes') nebulae, along with a prominent star cluster (NGC 6514). Photo stuff: Date: 02 May 2017 R.A.: 18h 00m 19.1s Dec. -22° 48' 20.5" Tamron 500mm f/8 catadioptric lens mounted on Canon 6D 22 subs @ 120s ea.; ISO 800
  10. This one was unplanned. The sky cleared, I stepped out into the backyard, and there was Jupiter about 3 degrees from a just-past-full moon. I grabbed a few shots and created this composite. The composite was necessary to show all the objects, of course, because exposing for the moon completely dims Jupiter and loses its Galilean moons, while exposing for Jupiter makes the moon look like the lens is staring at the sun. In the end, I processed three separate frames (Moon, Jupiter, and the Galilean moons) as they appeared through the viewfinder. Date: May 21, 2019 (about 01:00) R.A. (approx.): 17h 22m 10s Dec. (approx.): -21° 07' 50" Photo stuff: Exposure times: Moon = 1/640s and Jupiter = 1/4s; ISO 400; Canon 6D; Tamron 500mm f/8 catadioptric lens
  11. Gary

    NGC 2736

    This is another of those "challenging" objects I unwisely decide to tackle occasionally. This one is worth it, though, I think. Herschel's Ray, also known as the Pencil Nebula, is a beautiful swipe of blue and pink shock waves in the constellation Vela. At 3/4 of a light year in size, it is a reasonably sized object in its own right. However, it is just a tiny portion of the truly gigantic Vela Supernova. That "remnant" is what was left after a very large star cataclysmically exploded as a Type II supernova about 11,000 years ago. The force of this destruction, in turn, created a swath of delicate nebulae across at least 8 degrees (ye gods!) of the southern sky. At its distance (815 ly), this equates to an object about 100 ly across. The hues in NGC 2736 are due to two different types of nebulae: pink indicates an emission nebula, while blue is the light scattered off a reflection nebula. When we view this object, we are actually looking at the ripples of a sheet of gas almost edge-on. Dates: 04 February, 2019R.A.: 09h 03m 23.9sDec.: -45° 30' 56.9"Photo stuff: (subs) 131 frames @ 180s ea.; ISO 800; Canon 60Da on the Meade RCX400 16" f/8; Astronomics 0.7 focal reducer
  12. I know, I know - not the prettiest name for a such an interesting galaxy, but I didn't come up with it. NGC 2442 is an example of a peculiar, barred spiral galaxy. In this case, its peculiarity is most likely due to gravitational tides when it interacted with another galaxy at some point in its history; possibly the smaller one (PGC 21456) visible to its right. Besides leaving it with an odd shape, the interaction would have started a burst of star formation evident in its arms. The Meathook, which is approximately 56 Mly away, can be found in the constellation Volans. Although not the brightest of galaxies (sorry, Meathook), it can be seen in relatively small telescopes if you are a practiced observer and under good, dark skies. Dates: 01 March, 2019; 05 March, 2019R.A.: 06h 37m 08.9sDec.: -69° 34" 16.2"Photo stuff: (subs) 37 frames @ 180s + 34 frames @ 300s ea.; ISO 800; Canon 60Da on the Meade RCX400 16" f/8; Astronomics 0.7 focal reducer
  13. A while back, I had picked up a "new" (to me) Tamron 24 mm lens. I decided to do some wide-field, night-sky photography to try it out and, eventually, came up with this image. The Moa (in NZ) or the Emu (in Australia), seen in profile, is a series of visually connected dark regions in this portion of the Milky Way. Look for the two bright stars in the middle of the image. These mark the neck and shoulder. Just above and to the right is the head and beak, which, to astronomers, goes by the unlovely name of Caldwell 99 ("The Coal Sack Nebula"). Just above that is the Southern Cross. Moving down and to the left from the two pointer stars, we see the body of the bird; further down are its feet. The dark areas are not empty regions. Rather, most are dust lanes and dark nebulae that block the light from the background stars. This dust is extremely fine - generally smaller than smoke particles - so it takes large amounts of it to screen out starlight. Astronomers can use specialised telescopes and sensors to peer through this dust to find what it is hiding. The Moa is easily visible in Canterbury most of the year from a good dark site on a clear night. Note, though, being the clever bird it is, it seems to be doing a head stand around 22:00 during the mid- to late winter evenings. As of the date of this post (05/09/2018), it appears to be just completing a back flip in the southwest. Look for it to right itself in the southeast by the beginning of April, around the same time in the evening. Date: June 19, 2017 Image centre (HD 131376): R.A.: 14h 55m 58s Dec: -60° 54' 21.3" Photo stuff: Canon 6D with Tamron 24mm at f/8; 11 frames at 120s ea.
  14. NGC 346, which resides in the Small Magellanic Cloud (SMC), is an open star cluster with surrounding nebulosity. At magnitude 10.3 and having a smallish size (~14 x 11 arcseconds), it is relatively easy to spot with a small telescope. This photograph was taken through H-alpha, H-beta, and OIII narrowband filters, which reveal the different densities of ionised hydrogen and oxygen gases in NGC 346 and the surrounding N66 gaseous region. My guess is that the apparent structural elements of the nebula in this image are likely the result of high-velocity stellar winds causing interstellar gas to pile up but I can't seem to find a good reference for this. Although the SMC is a typical dwarf galaxy (that is to say, old and not creating many new stars), the NGC 346 & N66 region is a stellar nursery, shining with the light of many young, bright O-type stars. Nota et al. (2006) suggest that some are as young as 3 to 5 million years old (practically a baby, by stellar standards). The nebula also contains one of the brightest stars in the SMC - the very hot Wolf-Rayet star, HD 5980 - and the supernova remnant SNR0057-7226. It is clear from this image that I'm still very much at the beginner's stage of narrowband imaging, although I'm encouraged by the fact that this time last year I had just started to consider using this sort of filtration. Actually, I'm still genuinely surprised when I can get any sort of an image with a procedure that is this complex. It is very rewarding, though, so I'll just strap on the mental crampons and continue to scale this learning curve. Dates: 18 August, 2018; 25 August, 2018R.A.: 00h 58m 51sDec.: -72° 11' 09" Photo stuff: all filters 20x180s + 6x600s ea.; ISO 800 for the 180s subs; ISO 1600 for the 600s subs; Canon 60Da on the Meade RCX400 16" f/8 Post-processing notes: Narrowband composite created with MaxIm DL6; H-alpha(656.28 nm); OIII (486.00 nm); H-beta (500.70 nm); all 100%
  15. Gary

    Quarter Moon

    Among astrophotographers, I suspect that our moon is a seen as a bit too common to spend much time on. After all, we can observe it with the naked eye - why waste precious minutes on it when we can be chasing down some truly weird objects out there in the universe? And yet, I find that I come back to it quite often, either for a photograph or, more often, just to consider it's many features through a decent telescope or set of binoculars. There is still something beguiling about getting up close and personal with all those craters. There are quite a few interesting features visible in this image. Three of my favourite craters - yep, I'm a guy who has "favourite craters" - are right in the middle of this image of the moon. Ptolemaeus (the larger one), Alphonsus (middle), and Arzachel (top, smallest) form a slightly curved line running along the day/night terminator. You can see a clearly defined central peak in the middle of Arzachel, and another that is a bit harder to make out in the middle of Alphonsus. These peaks are reasonably common amongst lunar craters between 15 km and ~120 km in diameter. Arzachel and Alphonsus are at the top end of this range, at 96 km and 119 km diameter, respectively (Ptolemaeus is 153 km wide, so no peak). These pointy mountains are created in the initial impact, which has such force that the central rock rebounds upwards much like the water does when a pebble is dropped into it. In the bottom left quadrant, we see some larger and smoother expanses. These are "seas" or mares, so-called because pre-telescope civilizations believed them to be large bodies of water. The larger, middle one, which has a more blue-gray appearance, is Mare Tranquillitatis (Sea of Tranquillity); the site of the first lunar landing.
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