Category Archives: Astronomy

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Abell 1656 – Coma Cluster – 2015-05-18

Coma Cluster (Abell 1656)
Imaged 2015-05-18

The Coma Cluster is a large cluster of galaxies that contains over 1,000 identified galaxies. Th image below shows a just a few hundred. The magnitudes of the ten brightest galaxies are between 12–14. The two largest galaxies at the centre are supergiant elliptical galaxies: NGC 4874 and NGC 4889. The Coma Cluster is part of the Coma Supercluster.

Abell 1656 - Coma Cluster - crop - 2015-05-18

Abell 1656 – Coma Cluster – crop – 2015-05-18

As its name implies, the cluster is located in the direction of the constellation Coma Berenices. While the three bright stars in the constellation are between 28 Mly and 167 Mly from us, the Coma Cluster of Galaxies is 321 Million lights years away.

The North Galactic Pole is located in Coma Berenices. So looking towards Coma Berenices is then looking up from the galactic plane and therefore there are fewer stars than when looking through the plane.

The Coma Cluster is one of the first places where dark matter began to be suspected. In 1933 Fritz Zwicky showed that the galaxies of the Coma Cluster were moving too fast for the cluster to be bound together by the visible matter of its galaxies. It is now thought that about 90% of the mass of the Coma cluster is dark matter.

Image details:
AT106 with AT2FF
Canon T2i (Astronomy UV/IR filter mods)
– 17 x 600sec frames at ISO1600 (total integration time 2hr 50m
CGE Pro
Guided with Shorttube 80 and Chameleon
Metaguide with FlexRX
Image capture with Backyard EOS
Calibrated, stacked and processed with PixInsight
Cropped, original pixel scale

M96 Group in Leo – 2015-04-14

M96 Group in Leo (the Leo I Group)
acquired 2015-04-14

The image below shows 5 of the 8 brightest galaxies in the M96 group. There are estimated to be as many as 24 galaxies in the group, all of which are in the same general vicinity and gravitationally bound to each other.

M96 Group - 2015-04-17

M96 Group – 2015-04-17

From left to right:

NGC 3384
– Mag 10.9
– Size 5.5′ x 2.5′
– Distance     35.1 Mly
M105 (NGC 3379)
– Mag: 10.2
– Size: 5.4′ x 4.8′
– Distance: 32 Mly
NGC 3389/3373 (Below NGC 3384)
– Mag: 11.2
– Size: 2.7′ x 1.2′
– Distance: ?
M96 (NGC 3368)
– Mag : 10.1
– Size: 7.6′ x 5.2′
– Distance: 31 Mly
M95 (NGC 3351)
– Mag: 11.4
– Size: 3.1″ x 2.9′
– Distance: 32.6 Mly

There are few other faint fuzzies that may not be part of the group. While visually in the field of view, they are either closer or further away from the M96 cluster of galaxies.

Taken 2015-04-18
AT106 with A2FF
Canon T2i (astrodon UV/IR inside)
14 x 360s @ISO1600 (another 28 subs had lost the guiding)
– total integration 1hr, 24min
CGE Pro guided with Shorttube80 and Chameleon
– Metaguide with FlexRX
Captyured with Backyard EOS
Calibrated, Stacked and Processed with PixInsight
Full Frame, original pixel size.

Eskimo Nebula – 2015-03-23

Eskimo (Clown) Nebula (NGC 2392, Caldwell 39)
Taken 2015-03-23, 21:00 to 23:30edt

Eskimo Nebula - Full Frame - 2015-03-23

Eskimo Nebula – Full Frame – 2015-03-23

This is a planetary nebula called the Eskimo Nebula or sometimes Clown Face Nebula. Planetary nebulas get their name because they appeared to early telescope observers like giant planets. They are actually an expanding shell of ionized gas ejected from a catastrophic event in the late stages of medium to small star’s life. (Contrast this to supernova for giant stars.) The Eskimo nebula actually has two shells of expanding gas which gives it an unusual appearance.

Distance 3000 light years
Apparent mag 9.1
Central star mag 10.5
Visual Size 48 x 48 arc-sec

A closer crop and up-sampled 2x is easier to look at, but does not show any more detail:

Eskimo Nebula - - Crop - 2015-03-23

Eskimo Nebula – – Crop – 2015-03-23

Celestron HD11
Canon T2i with Astrondon uv/ir filter inside
Guided with Celstron OAG, Chameleon and Metaguide

HDR at ISO1600
– – 15 x 120s
– – 7 x 180s
– – 18 x 240s
– total integration 2hrs

Venus and Mercury – 2015-05-06

Mercury

Mercury was at its greatest elongation for 2015 om May 6th at 21deg, so i decided to try to capture an image of it. Being low in the sky it’s hard to get a clear view through the murky unstable surface air. So i decided to capture the image just after sunset at 20:19edt when it was still relatively high. Mercury was not yet visible unaided, but it showed up well in the telescope. The sun had just set at 20:16 when i captured the image, so it was only 0.5deg below the horizon. Nautical dusk wasn’t until 21:31. The down side was the bright evening sky reduced contrast. Given it’s very difficult or unusual to resolve any surface details of Mercury in a backyard telescope, the lack of contrast wasn’t going to matter.

Mercury 2015-05-06, 20-19edt

Mercury 2015-05-06, 20-19edt, Monochrome

Being only 7.9″ in angular size, it is very difficult to resolve any surface details at the best of times. And being so low in the sky and taken only minutes after sunset, the unstable surface air and low contrast obscured what details might be obtainable. The only interesting feature then is the phase. Mercury is also grey, like the moon, so a colour image wouldn’t actually have any colour.

I used the Celestron HD11 with a 5x Powermate. The effective focal length is therefore 14,000mm at effectively f/50. I capture a 60sec AVI (movie) at a resolution of 640×480 at 30fps with a monochrome Point Grey Chameleon (no filters). That works out to 1792 frames. Using Autostakkert2, i selected the best 10% of the frames and stacked them into a single image. Further processing with PixInsight (wavelets and curves) sharpened up the edges to reveal a nice waxing crescent – but no surface detail.

The specs for Mercury that evening were:

  • Mag: +0.4
  • Size: 7.9 arcsec
  • Illumination: 38%
  • Azimuth: 286deg
  • Altitude: 18deg
  • Elongation from Sun: 21deg (at maximum)

I tried using a 35nm IR pass filter with the above setup, but at f/50, there wasn’t enough light. The advantage of using IR is it less affected by the turbulent air and the narrow bandwidth improves focus. A future project is to try the IR filter with the HD11 at prime focal length or with a 2x powermate.

Venus

Venus was at a greater elongation [from the sun] so i waited until 21:04edt to capture that image. The sun was now 7.5deg below the horizon and closer to nautical dusk (21:31).

Using the same technique above, i captured two 60sec AVIs and processed them with the same method. Then i combined the two resulting images which reduced some blotches.

Venus 2015-05-06, 21:04edt

Venus 2015-05-06, 21:04edt, Monochome

Venus is blanketed by a thick white cloud, but unlike Jupiter and Saturn, there is no colour or banding visible in white light. (I have seen some images in UV that do show some some cloud details.) So even though Venus is a reasonable 18arcsec in angular size, the only interesting feature is the phase.

The specs for Venus that evening were:

  • Mag: -4.14
  • Size: 18 arcsec
  • Illumination: 64%
  • Azimuth: 280deg
  • Altitude: 28deg
  • Elongation from Sun: 43deg (maximum is 45deg)

Venus and Mercury Comparison

Since i had the two images created with the same gear, i decided to display them side by side to show the relative angular sizes:

Venus and Mercury 2015-05-06

Venus and Mercury 2015-05-06

 

Examples of What Other People Can Do

While it’s difficult to get images that show any detail on either Mercury or Venus, it is possible to capture images using relatively modest ground based equipment (not billion dollar mountain top scope). The links below to Daniele Gasparri’s web site [external link] show some impressive images that have been acquired using a C14 combined with various filters.


Mercury by Daniele Gasparri [External Link}


Venus by Daniele Gasparri [External Link}

Super Moon versus Micro Moon – 2015-03-05

The term “Super Moon” appears in the popular press to describe the full moon when it appears the largest. This occurs when the moon is at its closest to the earth (Perigee). The term gives the impression this is an extraordinary or even catastrophic event. Exaggerated media reports often predict flooding, earth quakes and even volcanic eruptions. Most of which of course are false. It is true that that when the moon is at its closest to the earth the tides can be somewhat higher and an alignment of the sun, earth and moon does have a measurable affect – just not extreme. And if this occurs in the spring, during a spring tide (not the same thing), then the tides can actually be a concern.

The opposite of the “Super Moon” is the “Micro Moon” which describes the smallest full moon. This occurs when the moon is at its furthest from the earth (Apogee).

The difference between the super moon and micro moon is not likely to be noticeable when viewing the moon in the evening sky. But the side by side comparison below of the super moon taken 2014-09-08 and the micro moon taken on 2015-03-05 shows just how different they are!

Super Moon - Micro Moon Comparison

Super Moon – Micro Moon Comparison

The Perigee Full Moon can appear as large as 34.1 arc-minutes (apparent angular size). While the Apogee Full Moon can appear as small as 29.3 arc-minutes (Wikipedia). That’s about a 15% difference. The difference in apparent size is a result of the moon being different distances from the earth.

The moon orbits the earth in an elliptical path (an oval) at an average distance of 385,000km. At its closed point – perigee – the moon is 362,600km from the earth. At its furthest point – apogee – the moon is 405,400 km away from the earth. That’s an 11% difference! The shape of the orbit is constant, so once a lunar sidereal month (360° rotation) of approximately 27.3days, the moon is at its closest to the earth, and about 2 weeks later, it is at its furthest. (It takes 29.5 days for the moon to complete a synodic orbit which returns the moon to the same orientation relative to the sun and earth – e.g. new moon or full moon.)

Moon Elliptical Orbit

Moon Elliptical Orbit

The phase of the moon – the part we see illuminated – depends on the alignment of the sun, earth and moon. As the moon orbits the earth, we see a different portion of the sunlight part and the part in shadow (although we always see the same side of the moon). For example, when we see the waxing crescent moon, the moon is between us and the sun and a little to the left of the sun from the perspective of earth’s northern hemisphere. So the part in sunlight is facing mostly away from us and we see only a small sliver of that. The rest of the moon’s face we see is mostly in shadow.

Waxing Crescent Moon

Waxing Crescent Moon

As the moon orbits the earth, we see a portion of the sunlit part from a different angle. So we see different phases at different points in the lunar orbit.

Phases of the Moon

Phases of the Moon

A full moon occurs when the sun, earth and moon are aligned (in that order) – referred to as “opposition”. A new moon on the other hand occurs when the moon is between the sun and the earth – referred to as “conjunction”. Although aligned when viewed from above, when viewed from the side, the full moon or new moon is usually above or below the earth-sun plane (the ecliptic). This is because the moon’s orbit is tilted compared to the earth-sun orbit by about 5.1°. When the side view also lines up, we get a solar or lunar eclipse.

An “ordinary” full moon can happen at any point around the moon’s elliptical orbit, so the earth-moon distance can be anything between the closest and furthest distance. In the diagram above, the full moon is a little past perigee and so not at its closest. Occasionally the full moon occurs when the moon is at perigee (closest). Because it’s at its closest, it appears larger than other full moons that occur at other points in the lunar orbit. This is what’s called the “Super Moon”!

Perigee Full Moon Alignment

Perigee Full Moon Alignment

But the moon is going to be at perigee at some point in every lunar month. For example, from the “Lunar Phases” diagram above we see the waxing gibbous moon is at perigee and therefore would appear larger than other gibbous moon views. What makes the Perigee Full Moon a “Super Moon” is that the sun-earth and moon are aligned so the combined effect of their gravity is also at a maximum. The affect is measurable and at some times of the year can result in significant, but still modest increase in tides. Hence the term “Super Moon” which is chosen to evoke a sense of awe and unfortunately panic.

The compliment to a Perigee Full Moon is the Perigee New Moon. Like the full moon, occasionally the new moon occurs when the moon is at perigee (closest).

Perigiee New Moon Alignment

Perigiee New Moon Alignment

Also like the Perigee Full Moon,  the sun-earth and moon are aligned for a Perigee New Moon, so the combined effects of their gravity is also at a maximum. Since the moon and sun are on the same side during a new moon, their gravitational affects on the earth add together. I would expect any noticeable affects to be larger than the equivalent Perigee Full Moon. The term “Super Moon” then also applies to the Perigee New Moon, but because the new moon is directly in line with the sun, we can’t see it, and hence goes unnoticed and generally unreported.

The alignment of a full moon at perigee occurs about every 14 full moons. Relaxing the definition of “Super Moon” a little to occurring close to perigee, we can get a perigee new moon before and after a perigee full moon. (Or conversely a perigee full moon before and after a perigee new moon.) This means it’s possible to get 3 “Super Moons” in a calendar year; most times 2 (a full moon and a new moon) and rarely no “Super Moon” in a calendar year. (There are 12 and sometimes 13 full moons in a calendar year. )

On the other end of the scale, the new moon and full moon can occur when the moon is at apogee – furthest away. When this happens the moon will appear its smallest and the combined gravitational affects of the moon and sun will be at a minimum when compared to other new and full moon events. The complimentary term is sometimes “Micro Moon”.

When the new moon occurs at apogee, nothing really happens and since we can’t see it in the glare of the sun, it’s pretty much a non-event.

Apogee New Moon Alignment

Apogee New Moon Alignment

When the full moon occurs at apogee, again nothing happens, but we do get to see it. While it is 15% smaller than the perigee full moon, it’s not something that anyone would notice.

Apogee Full Moon Alignment

Apogee Full Moon Alignment

Our perception of the size of the full moon is influenced to a much greater extent by the foreground. For instance, people generally report that the full moon on the horizon is significantly larger than the same moon high overhead. Although in reality, they are the same angular size. There is no mysterious atmospheric affect at play, only our own perceptions.

The precise prediction of when a perigee or apogee moon will occur is a little complicated.

  • it takes the moon about 27.3days to make a 360° trip around the earth
  • but the earth has moved around the sun in that time so it takes about 29.5 days between full moons (or new moons)
  • the earth takes 365-1/4 days to move around the sun changing the earth-sun alignment with the major axis of the moons elliptical orbit as it goes
  • the lunar orbit precesses (the axis of the orbit rotates) once every 3232.6 days or about 8.85 Earth years which also changes the earth-sun alignment with the major axis of moons elliptical orbit
  • so working out all these moving parts to find an alignment is complicated
  • then there is the affects of the other planets on the orbits (perturbations) and tides which changes the shape of all the orbits and speed of rotation

Micro Moon – 2015-03-05

To complement the “Super” moon of September 9th, 2014, the moon was at it smallest for 2015 on March 5th. The conditions were almost just as good as in September 2014, so i managed to capture a view of the apogee full moon (furthest away) that was almost indistinguishable from the Super moon expect that it was 10% smaller.

Micro Moon - 15.14days - 2015-03-05

Micro Moon – 15.14days – 2015-03-05

The Pelican in the Nebula – 2015-01-12

I always struggle to get my imagination to see where an astronomical object gets its name. My recent image of the Pelican Nebula (IC 5070) was no exception. I could not find a drawing that showed the pelican and there are only limited and conflicting descriptions of where the pelican is. So i decided to make my own sketch.

IC5070 - Pelican Nebulae - 2014-10-24 - 2views

IC5070 – Pelican Nebulae – 2014-10-24 – 2views

Images of Comet c/2104 Q2 (Lovejoy) – 2015-01-19

Using a Stellavue 80mm APO (with 0.8x reducer) and a Canon T2i, i took some images of comet Lovejoy. The main imaging run was 30 x 2 min exposures at ISO1600. The comet is bright enough that the core is blown at this exposure. So i also took a series of shorter exposure sets at 60s, 30s and 15s. Unfortunately, i could not create a high dynamic range image (HDR) with the short exposures – either automatically with the tools i have nor manually.

I was guiding on a star and not accounting for the relative motion of the comet. At 2 min expsoures, it’s manageable as the comet is not moving so fast that it would show any noticeable signs of being stretched in each frame. However, after an hour it had moved considerably in the FoV, so each frame had to be realigned to the comet’s new location. The 30 aligned frames were then stacked with a rejection filter. This provided the best image of the comet at the expense of dimming the background stars. (A simple averaging would keep each star and the result would be a line of stars giving the impression the comet was racing past them – which it is.)

Comet c2104 Q2 Lovejoy 2015-01-19 comet aligned

Comet c2104 Q2 Lovejoy 2015-01-19 comet aligned

The part of the tail visible in the image above is 2.2deg wide. This works out to 3.3Mkm in actual length and that’s not all the tail. The distance from earth to the comet was about 85 Mkm when the image was taken.

To get an image with the background stars, i reprocessed just 5 of the images and aligned on the stars. Even with a 10min lapsed time, the comet is still not stretched too much in the final image.

Comet c2104 Q2 Lovejoy 2015-01-19 star aligned

Comet c2104 Q2 Lovejoy 2015-01-19 star aligned

Comet c/2104 Q2 (Lovejoy) – 2015-01-15

A bright comet is moving through the solar system and in January is just getting bright enough to be visible unaided.

I managed to see Lovejoy unaided from my location just south of Carp at 10pm on January 15th. The light pollution map shows my location as orange, but it’s probably a little better than that looking south west where the comet was.

The comet was just visible with averted vision and occasionally while looking directly at it. With binoculars it was of course obvious, but no tail was detectable. With my 173mm, f/5.7 Dob, the core was very distinct within the larger halo. Still no tail.

For brightness comparison, Botein, Epsilon and Zeta Aries were also just visible – mag 4.34, 4.69 and 4.84. However 63 and 47 Aries – mag 5.09 and 5.78 – were not.

North America and Pelican Nebula – 2014-10-24

The region around the brightest star Deneb in the constellation Cygnus is occupied by a giant cloud of ionized molecular hydrogen (H II or H2) which is categorized as an “emission nebula”. Three degrees towards the north are two nebula named the “North America Nebula” (NGC 7000) and the “Pelican Nebula” (IC 5070).

NGC7000-IC5070 - North America and Pelican Nebulae - 2014-10-24 v1

NGC7000-IC5070 – North America and Pelican Nebulae – 2014-10-24 v1


The image spans 3.2 x 3.0 degrees which translates to an object size of 96 x 89 ly

The interesting  “North America” shape is caused by interstellar dust blocking some of the light from the nebula. Therefore the stars in the “”Gulf of Mexico” are in front of the dust and closer to us than the actual nebula. The peninsula is referred to as the “Cygnus Wall” and the bright filaments along the wall are regions of intense active star formation.

IC5070 - Pelican Nebula 2014-10-24 v3 high contrast

IC5070 – Pelican Nebula 2014-10-24 v3 high contrast


The Pelican nebula is supposed to look like a pelican taking flight. With the low contrast in my image it’s hard to make out. The pelican is facing towards us and to the left. The top of it’s head is the peak above the bright filament in the upper centre and it’s full beak is pointing down to the left and formed by the cloud along the upper left edge of the nebula. The vertical filament itself outlines the back of the pelican’s neck. The right part of the nebula is then the bird’s right wing on the downward part of a stroke. The left wing would be behind the pelican’s beak.

The pelican shows up better in the high contrast version of just IC 5070 (reprocessed from the same image above).

Generally emission nebula are difficult to see. Although quite large and bright in H-alpha, it is not possible to see this object unaided. The ionized hydrogen glows strongly deep red from the primary Blamer series Hα (hydrogen alpha) at 656nm. Unfortunately our night time vision (scotopic vision) tops out at 620nm, so we cannot see the Hα faint red glow. (Our day time vision – photopic vision – can see deep reds up to about 750nm when they are bright daylight intensities.) But the nebula also glows in other wavelengths so it is possible to see it.

There are some reports that the formation can be seen with binoculars or a small telescope using a UHC filter. I suspect this has to be done under dark skies and ideal conditions. I have never been able to make it out from my semi-rural location.

North America Nebula
– Magnitude: 4.0
– Angular Size: 120 x 100 arc-min
– Distance: 1,600 ly

Pelican Nebula
– Magnitude: 8.0
– Angular Size: 60 x 50 arm-min
– Distance: 1,800 ly

This is a two pane mosaic. The left part of the NA Nebula is from a data set acquired 2010-10-09 using a TV Pronto and Canon XS. The right side of the image, including a good portion of the NA nebula and all of the Pelican Nebula was acquired 2014-10-24 with a Stellarvue 80mm APO and a Canon T2i. The Pronto and SV80 have the same FL of 380mm, but the cameras are different so the image scales of the two sub-frames are different. The Pronto image was up-scaled to match the image scale of the Canon T2i and then aligned and merged to form the composite image.