Here's the home of 2021's 'Image of the Month' pictures. Enjoy!
2021 : 2020 : 2019 : 2018 : 2017 : 2016 : 2015
Image of the Month for September 2021: Saturn and its four largest moons.
This image from the 28 August 2021 is a composite of two different exposure lengths. The background image with the moons is a stack of about 100 exposures several seconds long.This had to be sharpened a lot as seeing blurred the moons into 'soft' patches at this magnification. On this image there were also some 'hot pixels' stacked as patches of tiny bright dots and, of course, Saturn itself was greatly over-exposed, see below. On the other hand, 'lucky imaging' of Saturn using the 5% best of 4Gb of 16-bit video was sufficient to get much better detail and good colour. The final step was positioning the 'good' Saturn centrally over the over-exposed version and matching the brightness of the two image's backgrounds.
Image of the Month for August 2021: Eagle Nebula, M16 with the Pillars of Creation
The centre of this image of the Eagle Nebula, Messier 16
, shows the famous'Pillars of Creation' imaged by the Hubble Space Telescope.
Image of the Month for July 2021: The Sadr Region Nebula
I have finally managed to find an affordable adaptor to go between old M42 lenses and my ZWO electronic filter wheel. This has opened the magical door to wide-field narrowband imaging. This was my first attempt, using a 3D printed holder to mount my ASI 1600MM-PRO mono camera on my HEQ5, via my side-by side adaptor to also carry a guidescope. The constellation of Cygnus veritable boils with nebulosity, and the region surrounding its central star, Sadr, is particularly complex. Over most of this image the background is fairly bright, being a region of the Milky Way which is dense with stars, and decorated with wisps of Hydrogen nebulosity. At the centre the nebulosity is denser with additional sulphur in the brightest patches (yellow) and areas of ionised oxygen (blue). The supernova remnant, the Crescent nebula stands out at bottom right. What appear to be dark gaps in the nebulosity are actually foreground clouds of dark, cold material blocking our view of the nebulosity and the Milky Way, with just the relatively few stars that are closer still being visible in these areas. The lens used was a Zeiss Sonnar 135 f/3.5 that I bought second hand in the early 80s. Hoarding is fine when you hoard useful things!
Image of the Month for June 2021: The Hercules Galaxy Cluster
May 2021 was a really wet, cloudy month. I had equipment problems around a few clear nights around the new moon at the start of the month, and it wasn't clear again until after the next full moon, too late in the year for 'astro dark'. Less well known than the Great Cluster in Hercules, M13
, this concentration of galaxies looks completely different. It should be better known, as with between 200 and 300 galaxies in a compact area this is the densest concentration in northern skies apart from the Coma Cluster. Around half of the galaxies are spiral galaxies, a high proportion, and there are several pairs of interacting galaxies. This image is cropped to the densest part of the cluster, at least 80-100 galaxies are visible in the uncropped image. The cluster is part of the local group of galaxies. This LRGB image was taken using a mono camera with over an hour of luminance data and more than half an hour on each of Red, Green and Blue. Baader L filter and ZWO RGB filters and an ASI1600MM-Pro camera. Telescope was a Skywatcher 150PL on an HEQ5-pro mount.
Image of the Month for May 2021: The Tadpoles Nebula
The Tadpoles Nebula, IC410 is a hydrogen-rich nebula in the constellation of Auriga. Bright stars in the cluster at its heart, NGC1893, are responsible for blasting the spiralling trails of gas from the spherical object at top left, giving the nebula its popular name. This image used the so-called Hubble Palette mapping Sulphur to red, Hydrogen to Yellow and Oxygen to blue.
Image of the Month for April 2021: The Cosmic Jellyfish, IC433
The Jellyfish Nebula, IC433 is a supernova remnant in the constellation of
Scientists think that the star which created the nebula is a rapidly spinning neutron star or pulsar numbered CXOU J061705.3+222127, or J0617 for short, which is a powerful x-ray source.
I stacked the image with Deep Sky Stacker then assigned the Sii,Ha,Oiii data (from ionised sulphur, hydrogen and oxygen)to RGB in that order, which gives the 'Hubble palette'. I used Photoshop CS2 to stretch details and adjust the colour palette (this is usually done so that the strong Ha signal appears yellow, rather than bright green).and then used Astra Image for fine-tuning and some gentle contrast enhancement.The oxygen rich areas are visible as a slight violet halo around the outer parts of the nebula.
Image of the Month for March 2021: Monkey Business
The Monkey Head Nebula, NGC2174 is a beautiful target with lots of fine details, especially around the edges.
The image was rotated and cropped to create a composition with some space for the 'monkey' to gaze into, perhaps remembering Ham the chimpanzee and the other primates that paved the way for humans into space.
I stacked the image with Deep Sky Stacker then assigned the HaSiiOiii data to RGB in that order, which gives more attractive colours and more natural stars than the 'Hubble palette'. I used Photoshop CS2 to stretch details and adjust the colour palette and then used Astra Image for fine-tuning and some gentle contrast enhancement.
Image of the Month for February 2021: The Flaming Star Nebula
The Flaming Star nebula, also known as IC 405 surrounds the star AE Aurigae. Most of its colour comes from emission of Hydrogen and Sulphur light, highlighted in this narrowband image. The image has been updated to include the blue reflection component imaged in broadband blue light.
Image of the Month for January 2021: The Horsehead and Flame Nebulas
The Horsehead Nebula or Barnard 33 is a small dark nebula, whose fame arises from two things - fortuitously lying in front of a 'curtain' of ionised hydrogen gas and a remarkable resemblance to a horse's head. This image also shows the bright double star Alnitak (note the smaller companion star just left of the main star), and the bright Flame nebula (NGC 2024 or Sh2-277). Again the Flame nebula is the result of bright hydrogen behind a dark dust cloud. Smaller areas of blue reflection nebula where the dusty nebulas scatter starlight are also visible in the image. This image is a composite of three monochrome images filtered for the light of hydrogen alpha, sulphur ii and oxygen iii mapped in that order as red, green blue and then colour balanced.
Compare this image to the images for the month for December 2019, taken using a tri-band filter and colour camera or that for January 2016, taken with a colour camera and no filter.