Picture of the Month for 2015

• December 2015 - Picture of the Month

  NGC 1555 (Hind's Variable Nebula) in the Constellation of Taurus

  I’m a fan of variable stars and I don’t get the chance to put an image of one on the website often. I'd have to admit that might be because they’re… not particularly spectacular normally.

  

  I think that T Tauri in the image above is an exception being associated with an interesting class of objects: the nebula surrounding the young star that also varies in brightness.

  This beautiful image was provided by Bill Snyder, who acquired and preprocessed the data that was subsequently postprocessed by Warren Keller.

  For a more detailed version please visit Warren's website: Billions and Billions.com.

  James Whinfrey - Website Administrator.

• November 2015 - Picture of the Month

  This month I've gone for some objects that I'm unlikely to see through a telescope. It's time to visit the southern skies again with both colour and narrowband images of a star cluster and its nebula.

  The Tarantula Nebula in Dorado

  

  I'm a bit of a sucker for hydrogen alpha and the detail it seems to draw out of certain nebulous regions. This image by Steve Crouch from Australia brings out the extent of this gas cloud beautifully.

  On the other hand full RGB colour can be impressive too. Which do you prefer?

  

  Clicking on either image will open a new window with a larger version from Steve's site.

  Steve's Description

  This huge emission nebula complex in the Large Magellanic Cloud would more than cover the whole constellation of Orion if placed at the position of the Orion Nebula. It is visible with the naked eye as a hazy spot.

  Camera and Telescope

  STXL6303 and 36.8 cm Ritchey Chretien

  Exposure Details

  Ha=195m, OIII=210m, SII=225m, R=G=B=30m all unbinned. Ha, OIII and SII combined as luminance over RGB layer.

  For more images from Steve please visit his CCD Astronomical Images from Canberra website.

• October 2015 - Picture of the Month

  NGC 80 and Arp 65 in the Constellation of Andromeda

  

  Image was provided courtesy of Makis Palaiologou, Stefan Binnewies, Josef Pöpsel: www.capella-observatory.com.

  Interestingly, Owen's covered this group in a previous Galaxy of the Month (November 2012). He used an image from the Digitized Sky Survey, but I think that this one is much better. Worth a read though.

  Capella Observatory provide a version of this image in which the galaxies are tagged with their names.

  That, and Owen's piece, should make it easier for those thinking of having a go at this one. Good luck.

  James Whinfrey - Website Administrator.

• September 2015 - Picture of the Month

  M27 - The Dumbbell Nebula

  I took my first images of M27, the Dumbbell Nebula in Vulpecula three years ago with a DSLR camera and this year thought to return to it to see what my QSI camera would reveal. I have read that in 1991, it was discovered that there exists a very faint outer halo around the main nebula that extends out to at least twice the 8 x 6 arc minute extent of the 'normal' nebula but is around 1000 times fainter. I wondered, therefore, if I had any chance of revealing this outer halo.

  I gathered nine hours of H-alpha, Oxygen III and Sulphur II narrow band data and 3.5 hours of LRGB data during the three weeks 22 July to 10 August and have generated the two attached images.

  

  The first image is a narrow band HST palette rendering with an LRGB image of the stars blended with it. In this image S II data are assigned to red, H-alpha to green and O III to blue.

  

  The second image is also narrow band but with with H-alpha and S II data are added together and assigned to red (their normal colour), O III is assigned to blue and a synthetic green has been generated as a combination of O III (80%) and H-alpha (20%). This image has also been blended with the LRGB image and has the more normal looking colours.

  I have read that the outer halo is cooler than the hotter central nebula and we can see the chaotic boundary between the two as the hotter core pushes outwards. We can see the cool outer halo of gas from the original supergiant star penetrated by columns of glowing hydrogen-alpha originating from the central star in the regions from the top to the left side: 1 o' clock round to 9 o'clock.I'm wondering if what we are seeing is evidence of the central star precessing and periodically having outbursts of radiation. At the 4 o'clock location there is a powerful jet which seems to extend as an extremely faint extension beyond the outer halo itself.

  Image details

  23' 35" X 16' 51" at 0.97 arc sec / pixel Exposure times: three hours, each of narrow band data in 20 minute frames; two hours of luminance and 30 minutes each of RGB in five minute frames

  Equipment

  254 mm Newtonian at F/4 plus TV Paracorr giving F/4.5 QSI 583 plus Astrodon LRGB and 3 nm narrow band filters

  David Davies (21 August 2015).

  All images are courtesy of David Davies, Cambridge, UK. Please click on the images for the high resolution versions. For more images from David please visit his Flickr Photostream.

• August 2015 - Picture of the Month

  M92 revisited with some galactic extras

  

  Images Courtesy of David Davies, Cambridge, UK. Please click on the images for the high resolution versions. For more images from David please visit his Flickr Photostream.

  I first observed M92 visually several years ago and was struck by the beauty of this globular cluster that is often spoken of as the poor relation of the Great Cluster, M13 in Hercules. I understand that M92 is believed to contain stars that are nearly as old as the universe itself, since these stars contain just 0.5% of the metal elements that our sun contains. It is an intriguing object.

  Therefore M92 has always been my list for imaging. Two years ago I succeeded in capturing a relatively low resolution image in black white with my ED80; clouds prevented capturing any colour data.

  Friday 17 July produced a rare clear night with stable seeing and reasonable transparency. In planning the image capture I could see that there are many galaxies in the background of this area of sky and so offset the field of view of the image to also capture what I could of the background galaxies.

  I elected to use my Equinox F/7.5 ED120 refractor rather than my faster Newtonian to get a wider field of view and as clean an image possible, without diffraction spikes. A test exposure time of five minutes showed that I would get sufficient signal but not saturate the brighter stars. To reduce the risk of not having a complete set of colour data, I captured a set of RGB images first and then captured the luminance data I could before the onset of dawn stopped work. Data capture started around midnight and I had to stop at 02:20 as the sky was brightening. I managed to capture two and half hours of data.

  I've attached two images. The first is the complete LRGB image. The second image (NGC 6332) is a crop from the lower right part of the frame. This has been enlarged by a factor of two and is shown as a negative image. I have annotated it with the names of some of the galaxies that I've been able to identify from the NGC and LEDA catalogues.

  

  The brightest galaxies are magnitude 13 to 14; the smaller galaxies still showing a distinct shape are around magnitude 16 to 17 and the faint, tiny smudges are around magnitude 18 to 19.

  The faintest galaxy I've been able to identify is magnitude 19.2. I've also identified the double star HIP 84333 but my studies show that the apparent double visible in the image is an optical double; the true binary is only 0.4" from the primary and was discovered by the Hipparcos satellite.

  The image scale of the galaxies image is 0.62 arc sec/pixel - half that of the main image image scale 1.24 arc sec per pixel.

  The Equipment

  • Telescope: Skywatcher Equinox ED120.
  • Mount: Skywatcher EQ6.
  • Camera: QSI 583 with SX Lodestar as off-axis guider Automatic focussing with Scopefocus.

  Image Processing notes

  The colour subs were plagued by satellite trails so I used median stacking in Deep Sky Stacker to eliminate them (mostly). Pixinsight w used to align, calibrate and integrate the colour frames. Photoshop was used to assemble and finish the LRGB image with a little saturation boost applied to the stars and a little high pass sharpening applied to the galaxies.

  David Davies (21 July 2015).

  So there are some challenges to those with large telescopes and other imagers. Can you provide us with some observations of these objects?

  I realise that Hercules is slipping to the West, but the nights are getting darker... and there's are always your archives to scour.

  Update

  And someone has taken a look! Dale Holt has pointed his 20 inch telescope and Watec 120N+ deep sky video camera in the direction of M92. Visit his blog to find out more and see his sketches.

  James Whinfrey - Website Administrator

• July 2015 - Picture of the Month

  NGC 6744 in Pavo

  Something from the southern skies this month with data collected by The Star Shadows Remote Observatory (SSRO) at PROMPT2 - CTIO near La Serena in Chile.

  This image is provided with the kind permission of Warren A. Keller. The images were acquired by SSRO: Warren Keller, Steve Mazlin, Steve Menaker, Jack Harvey.

  Please click on the image to be taken to Warren's website for a higher resolution version.

  

  In Warren's words

  NGC 6744 in Pavo likely resembles our Milky Way, and is one of its largest and closest neighbors. At 30,000,000 light years distance, it is approximately twice the diameter of our own galaxy. Its flocculent (fluffy) arms are rife with pink, HII star forming knots.

  This data set from 2014, is the second I have processed from the SSRO archive. I dedicate this work to the late Tammy Plotner, who passed away at much too young an age. She was a great friend to astronomy, and a supporter of mine. May you go among the imperishable stars!

• June 2015 - Picture of the Month

  Three Galaxies in the Constellation of Coma Berenices

  

  Image Courtesy of David Davies, Cambridge, UK. Please click on the image for the high resolution version.

  For more images from David please visit his Flickr Photostream.

  Here is a target from Ruben Kier's book The 100 Best Astrophotography Targets.

  This is NGC 4725, AKA "The Ringed Galaxy" or "The One-armed Spiral Galaxy" in Coma Berenices. Also in this image is NGC 4747 (top left) which is interacting with NGC 4725. To the right we can see magnitude 13.5 NGC 4712. NGC 4725 is about the same size as the Milky Way and about 41 million light years distant.

  One of my aims in imaging this galaxy was to capture the faint outer halo of NGC 4725 and also to see if I could image any of the disrupted tails from NGC 4747. Scanning this image reveals many small faint galaxies.

  This image comprises 12 x 10 minutes of luminance, binned 1 x 1 and 5 x 5 minutes each of RGB binned 2 x 2 captured with a F/4 Newtonian and QSI 583 camera with a Lodestar as off-axis guide camera.

  Image capture was with Nebulosity V4; calibration and stacking with Deep Sky Stacker and processing with Pixinsight and Photoshop. This is a crop of the original image.

  David Davies (22 May 2015).

• May 2015 - Picture of the Month

  Hickson 44 in the Constellation of Leo

  

  Image Courtesy of David Davies, Cambridge, UK. Please click on the image for the high resolution version.

  For more images from David please visit his Flickr Photostream.

  This is my first observation of the Hickson 44 group of interacting galaxies in Leo some 80 million light years away.

  The group comprises NGC3190 (incorporating NGC 3189) in the centre; NGC 3187, a heavily distorted galaxy to the right; NGC 3185, a barred spiral galaxy to the bottom and the big elliptical galaxy NGC 3193 to the upper left. Many other fainter galaxies are visible in this image.

  I captured the data for this image on the nights of 10th and 14th April 2015. The exposures were restricted to 5 minutes each to prevent the brightest stars (magnitude 7.6) saturating. The image comprises 28 luminance subs to try and capture these faint structures plus nine each of RGB exposures for colour.

  The telescope is a 10-inch F/4 Newtonian with a QSI 583 camera with Lodestar providing off-axis guiding mounted on an EQ6 mount.Image processing was with Deep Sky Stacker, Pixinsight and Photoshop. 

  David Davies (20 April 2015).

• April 2015 - Picture of the Month

  NGC 2736 (the Pencil Nebula) in Vela

  

  Image Courtesy of Steve Crouch, Canberra, Australia. Please click on the image for the high resolution version.

  Steve's Description

  NGC 2736 is known as the pencil nebula and is an outlying filament of the Vela supernova remnant the centre of which being some 4 degrees to the west. It was discovered by John Herschel in 1834 and is sometimes called Herschel's ray.

  Camera and Telescope

  STXL6303 and 36.8 cm Ritchey Chretien

  Exposure Details

  Ha:OIII:OIII with LRGB data. About 31 hours total imaging time.

  For more images from Steve please visit his CCD Astronomical Images from Canberra website.

• January 2015 - Picture of the Month

  Sh2-155 The Cave Nebula in Cepheus

  Our images this month are courtesy of David Davies from Cambridge in the UK. They provide an interesting comparison of the difference aperture can make when imaging nebulae. Please click on either image for the high resolution version. For more images from David please visit his Flickr Photostream.

  I've been collecting data for an image of the Cave Nebula over four nights during December (5, 7, 13 15) and it has been a chapter of carelessness and frustration. I ended up binning hours of data after discovering it was slightly out of focus or was captured with the wrong filters. In the end I did some work on what I could rescue and the attached image is the result.

  I set off trying to image the Cave in narrow-band but soon discovered that although the main cup-shaped nebula is rated as reasonably bright (integrated magnitude 7) it covers around 15 arc minutes of sky and is quite faint. The surrounding nebulosity comprising emission, reflection and dark nebulae is much fainter. Hydrogen-alpha emission can be acquired fairly readily but oxygen III and sulphur II emissions are very faint indeed. I decided to cut my losses and abandoned my acquisition of oxygen and sulphur, changed the filter wheel to RGB and acquired around an hour of each.

  I was interested to see the Cave in its context and chose to image it with my ED120 refractor plus a reducer/flattener to give a field of view of 81 x 61 arc minutes. The attached image is a crop to approximately 60 x 60 arc minutes.

  

  The image is Hydrogen-alpha, RGB; four hours of hydrogen-alpha in 20 minute subs; 132 minutes of RGB in 8-minute subs; all binned 1 x 1. Processing was in Pixinsight with a final touch-up in Photoshop.

  • Telescope is Skywatcher Equinox ED120 with a Skywatcher X0.85 reducer/flattener.
  • Camera is a QSI 583 wsg with Astrodon LRGB and 3 nm narrow band filters and Lodestar guide camera.
  • Mount is a Skywatcher NEQ6 controlled via EQMOD.
  • Image capture was with Nebulosity and Scopefocus for automatic focusing.

  I was curious to see what my 10-inch Newtonian would make of it so here is the Cave again but this time captured with a 10-inch Newtonian. The faster optics and longer exposures have yielded a deeper image.

  

  A hydrogen-alpha RGB image captured on the nights of 19 and 24 December 2014 from Cambridge, UK. Two hours each of RGB in 10-minute subs plus one hour of hydrogen-alpha in 20-minute subs.

  • Telescope is a 10-inch Newtonian plus Televue Paracorr at F/4.5.
  • Camera is a QSI 583 wsg with a Lodestar camera as off-axis guider.
  • Mount is a Skywatcher NEQ6.
  • Image processing with PixInsight and Photoshop.