Backyard Astronomers Capture Impact on Jupiter

Video

With Earth having passed between Jupiter and the Sun on March 8th, we have some of the finest observations of the Jovian planet. It’s only normal to have a few backyard astronomers setting their sights on the largest planet (myself included, still got unprocessed videos from March 27th). However Gerrit Kernbauer was lucky enough to record an unusual event: something slammed into Jupiter!

Phil Plait of Bad Astronomy reported that Gerrit Kernbauer with his 20cm telescope in Austria, captured on March 17th what appeared to be an impact of sort.

The issue was to confirm that it was an actual impact, and not some other natural effect or electronic noise in his setup. What better than to have a second independent observation, and that came from John McKeon with a 28cm telescope in Ireland.

Maybe I should go take a look at my videos on Jupiter from March 27th just in case… Actually with my 80mm telescope, I don’t think it would have picked up such an impact.

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Messier 38 and NGC1907 – Open Clusters in Auriga

Image

Following my previous post on Messier 36, a simple 2 degree slew of the telescope and I was centered on Messier 38 (NGC1912). This open cluster measures 21 light years across ( 21′ apparent) or twice the size of M36. It is also much older than M36 which is why you’ll find less hot blue stars within the group if you compare with M36.

Just half a degree below is an older and smaller open cluster NGC1907. While some have speculated that they are locked together (a binary cluster?) this cluster is 500 million years old, almost twice the age of M38, hence were formed at different periods and most likely from different molecular gas. This is just a chanced fly-by with no interactions.

Open Clusters Messier 38 and NGC1907

Skywatcher 80ED
Canon Digital Rebel XTi (400D)
30 x 30sec (ISO 800)
Registration with IRIS
Post-Processing with GIMP

Messier 36 – Open Cluster in Auriga

Image

Open Cluster Messier 36 (NGC 1960) is located in the Auriga constellation. Located about 4,100 light years from Earth, and 14 light years across, it has at least 60 members. It is very similar to the Pleiades (M45) and if M36 was at the same distance (M45 is 10 times closer) it would be of similar magnitude. Two other open clusters from Messier’s catalog are located nearby: M37 and M38. The stars in the cluster are of spectral type B2, and fairly young: 25 million years.

Open Cluster Messier 36. Skywatcher 80ED, Canon 400D 18x30sec

The blue-ish stars contrast with the older yellow and orange stars in the background. This can be further enhanced by using the SBLUR function in IRIS to selectively blur and enhance the colors of bright stars. While the colors are exaggerated in the image below, it is nevertheless interesting to see the vast diversity of stars and their color.

Open Cluster Messier 36. Skywatcher 80ED, Canon 400D 18x30sec (SBLUR for colour)

Telescope: Skywatcher 80ED
Camera: Canon Digital Rebel XTi (400D)
Exposure: 18 x 30sec (ISO 800)
Date: 18Mar2016

Composition with Landscape

Posted on March 21, 2016 by Benoit Guertin

I’ve mentioned it before that you don’t need a fancy telescope and tracking equatorial mount to get into astrophotography. Simply a camera on a tripod with a short focal lens can do wonders, especially with the high ISO settings in new cameras. A single 10 seconds exposition can reveal lots of stars, however to capture more photons a longer exposure is not better as the stars will become streaks. But one can easily improve the image and get better signal/noise ratio by stacking multiple images.

However, there is one drawback to stacking multiple exposures if you decide to also capture the landscape: Earth rotates, therefore the sky moves while the landscape stays still. If you align the images using the stars, then the landscape becomes a blur. Not the end result that we want. Luckily a quick composition with two layers and a mask solves everything.

Below is a single 10 seconds exposure at ISO 800 with a 17mm F4 lens; you have the landscape with city lights and the stars above. Yes that is Orion…

Single 10sec exposure (ISO 800)

In order to improve my signal, I worked with IRIS to align and stack 5 frames, this reveals many more stars, but also amplified the light pollution.

Aligning and stacking 5 images. More stars appear.

Luckily within IRIS there is a function to remove sky gradient. The algorithm takes a series of sample points and attempts to make the sky uniform. Not bad, the images are not a hopeless case.

Removing the sky gradient with IRIS

As mentioned above, the alignment was performed with the stars, hence the background is now blurring. Below is a close-up.

But when aligning on stars, the landscape blurs.

That is just 5 images, stack a much larger quantity or with more time between frames and it will only get worse. It becomes pointless to shoot with the landscape if the end result is blurry. Luckily working with layers in a photo editor can easily solve the issue. We want to keep the stars from the stacked image, but the landscape from a single frame. Follow these easy steps:

Load into your base layer one of you single frames. This is what will be used for the landscape.
Load into a new layer your stacked image. As your stacked image contains more and brighter stars select to Lighten Only instead of normally adding both layers. You can play with the brightness of the stacked layer, and/or darken the base layer to get the desired blending.
Create a mask to the stacked layer such that the blurred landscape is not permitted to show through. See image below, I simply grabbed the airbrush and blackened the landscape area in the mask such that it will not show through the layer. Note that the I only edited the mask, not the image itself.

Creating a mask for my layer: white is transparent, black will block

The end result, is improved image of the sky, and a landscape that is still sharp.

Both layers added with the mask

Below is a comparison the composition with stack and layer (left) and a single shot (right). We are able to achieve both of our goals of getting more stars (more signal) while keeping the landscape from becoming a blur.

Comparing the composition with layers (left) and single shot (right)

And why not take some time to identify some key features in the image.

Constellations Orion and Taurus above the landscape. (Click to open)

Changes in Lunar Size

Image

While doing some organization in my astrophotos I came across a picture composition that I created back in September 2015 following the Super Moon Lunar Eclipse, but which I never posted.

I had selected two Lunar Eclipse photos that I had taken with the exact same equipment, but on different year and wanted to see the difference in size with this “Super Moon”. Was it really that much bigger…

Lunar Size Comparison Between February 2008 and September 2015 Lunar Eclipse
– Benoit Guertin

The Moon’s orbit is elliptical and eccentric which causes the Moon’s distance to vary by 50,200km from perigee (closest) to apogee (furthest). The end result is a 12% change in apparent diameter as viewed from Earth. The above image only shows a 7% difference as while the background Moon was taken at perigee (famed Super Moon) the foreground was an arbitrary reference of the February 2008 lunar eclipse.

Telescope: Skywatcher 80ED (600mm)

Closest Comet in 246 Years

Status

There’s a good article in Sky & Telescope on comets 252P/LINEAR and the smaller fragment P/2016 BA14, explaining observation opportunities. A comet hasn’t passed this close to Earth in 246 years. And as it does the wonderful green halo around 252P/LINEAR is sure to grow but will probably remain around magnitude 6.

As the comet flies by Earth it will sweep through the constellations quickly and then fade back to below magnitude 12 in short order. Therefore try not to miss it.

Comets to Pass Near Earth

Status

Two comets will pass near Earth between March 21st and 23rd. Comets 252P/LINEAR and P/2016 BA14 will pass between 14 and 9 lunar orbits with the Earth. As both comets have similar orbits they most likely broke in two following a close encounter with a planet’s gravity.

252P/LINEAR has surprised everyone by brightening to magnitude 6 as it was predicted to remain in the 12-14 range. Presently accessible to folks in the southern hemisphere it will be visible to northern observers after the Earth fly-by.

ExoMars March 14th Lift Off, The Sign of a Earth-Mars Close Approach?

Posted on March 14, 2016 by Benoit Guertin

In the early in the morning of March 14th, 2016, a joint EASA-Roscosmos mission blasted off from Kazakhstan on top of a Proton launch vehicle. The space vehicle will take 7 months traveling through space before arriving to Mars around October 19th. The mission is actually composed of two vehicles, which will separate 3 days prior to the Mars arrival: Trace Gas Orbiter (TGO) and Schiaparelli, the later entering the martian atmosphere and landing on the surface.

ESA–Stephane Corvaja, 2016

I wondered if the launch signaled an upcoming Earth-Mars close approach. A space program wanting to reach Mars on a budget would select a launch date at a time when both planets are at their closest to reduce the fuel required, and time spent traveling through space. Sure enough, the next Earth-Mars close approach is May 30, 2016, a few days after opposition of May 22nd. An upcoming great opportunity to turn the telescope to Mars and hopefully capture some of the planet’s features. Mars’ angular size varies from as little as 3.5″ to an easy observing 25.1″ which is quite dramatic.

Earth-Mars close approach happen roughly every 26 months, and often coincide to Mars missions launches. The following list from NASA of recent Mars mission launches show a lovely two year interval.

2001:      Mars Odyssey
2003:      Mars Exploration Rovers
2005:      Mars Reconnaissance Orbiter
2007:      Mars Phoenix Lander
2009:      (skipped opportunity)
2011:      Mars Science Laboratory/Curiosity Rover
2013:      MAVEN

The last one in 2013 was in November, hence a Mars 2016, 28 months later falls within that window of opportunity. The ExoMars program actually has two space vehicles. The next one is planned for… you guessed it 26 months later: May 2018 launch.

Sources:
[EASA] [NASA]

Tripod and a Camera? Make a TimeLapse

Video

You don’t need a telescope to enjoy astro-photography. All it takes is a camera, a tripod and a timer remote controller to take interval images without you having to be there. I know that most of the image taking is done with the camera connected to a computer. But this remote controller allows for control of the shutter in the BULB setting without a laptop. See it as a “grab-n-go”, travel-light type of accessory to the camera.

Set it up to take a large sequence of shots and you got the makings of a timelapse video. Because there is no tracking with the tripod, keep the exposures under 10 seconds. Then use video editing software like Microsoft Movie Maker to covert all those images into a video (see my article here).