Monthly Archives: May 2015

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}