Animation – Movement of Comet 41P

The word “planet” comes from the Greek work “planan” which means to wander. Early star gazers noticed that some bright stars moved with respect to other fixed stars.  Those bright stars are our closest planets: Mercury, Venus, Mars, Jupiter and Saturn. Comets also move a fair bit across the sky, but the origin of the word has more to do about stars “with long hair” than it’s traveling behavior.

Last weekend I managed to photograph comet 41P//Tuttle–Giacobini–Kresák, and I identified in my blog that it’s movement was visible frame to frame. Well I’ve finally gotten around to create a small animation of that movement. For those wondering what’s the comet’s velocity, it’s currently travelling at 37.4 km/s.

Animation of comet 41P/Tuttle–Giacobini–Kresák (45 minutes)

Animation of comet 41P/Tuttle–Giacobini–Kresák (41 minutes)

The above is composed of 32 frames, each a 1 minute exposure spanning a time of 41 minutes. You are probably thinking “it should be 32 minutes, not 41!”. That is because I have a delay between each frame to allow the camera to send the photo to the computer. Hence between the first and last frame, 41 minutes have elapsed.

Large Asteroid to Pass Near Earth

On April 19th a considerable sized asteroid will pass about 4.6 lunar distances (1.8 million km) from Earth.  While there is no chance of it impacting our planet, this 650m asteroid was only discovered three years ago, and it will be the closest encounter of a large asteroid since asteroid Toutatis in September 2004. The next predicted fly-by of a large asteroid is 2027 with 800m wide 1990 AN10.

The expected magnitude could reach up to 11 during the close approach, hence a decent sized scope will be required, and due to the rapid movement may be hard to locate and track.

Sky chart for asteroid 2014 JO25 covering April 18th to 20th 2017

And as a bonus, comet PanSTARRS (C/2015 ER61) will also make its closest approach to Earth on the 19th, but 10 times farther away as the asteroid.  I should be visible with small telescopes or binoculars in the constellation Aquarius in the dawn sky.

Source: NASA/JPL

Comet 41P/Tuttle-Giacobini-Kresak

Periodic comet 41P/Tuttle-Giacobini-Kresak is currently a magnitude 8 object for telescopes and unlike many other current bright comets like C/2015 ER61 (PANSTARRS) and C/2017 E4 (Lovejoy) it is visible for a good portion of the night while the other two are only visible in the morning twilight for those like me in the northern hemisphere.

On April 13th comet 41P was in the constellation Drago, which is where I managed to photograph it.

Comet 41P/Tuttle-Giacobini-Kresak (13-Apr-2017) - Benoit Guertin

Comet 41P/Tuttle-Giacobini-Kresak (13-Apr-2017) – Benoit Guertin

Not much of a tail on this comet, and I’ve checked other photos taken with larger scopes and the result is also just a coma around the nucleus.

Because it is passing near Earth, its movement in the sky is quite noticeable frame-to-frame in the captured images. For the registration and stacking with comets, this is done by alignment on the comet and not the stars, hence the star trails in the above image. I performed another stacking, this time using the stars to align, and the comet’s movement becomes obvious. The displacement measures 2.6 arc-minutes in the 41 minutes that elapsed between first to last exposure.

UPDATE: Created a short video showing the comet’s movement

Distance traveled by the comet in 41 minutes

Distance traveled by the comet in 41 minutes

My setup was less than ideal, as the constellation was only visible from the front of my house.  Yes that is a lovely street-light shining right across the street.  Luckily the telescope was pointing a little to the right, and a rolled piece of cardboard help act as an dew-shield extension to block the glare.  But on the good side I had a nice solid concrete surface and got a very good polar alignment with 1 minutes exposures giving me nice round stars.  Hmmm, might explore this setup a little more often…

Setup in the garage to image comet in constellation Drago

Setup in the garage to image comet in constellation Drago

Telescope: SW80ED
Camera: Canon XTi (450D)
Exposure: 32 x 60sec ISO 800
DeepSkyStacker, IRIS, GIMP

Other comets of interest for 2017


On Wednesday NASA made headlines by announcing that researchers had detected seven exoplanets orbiting a dim dwarf star.  These exoplanets are determined, based on measurements, to be approximately Earth-sized solid planets and three happen to fall in the “Goldilocks Zone” where water could exist in liquid form; not too hot, not too cold.  Lots of people started speculating that in a few years we’ll find out if one of those planets harbors life.  However that is just plain crazy-talk.  The importance of this discover is that complex exoplanet systems do exist; the Solar System is not an exception, and that life is also not an exception.

The TRAPPIST-1 system

The TRAPPIST-1 system contains a total of seven planets, all around the size of Earth. Three of them — TRAPPIST-1e, f and g — dwell in their star’s so-called “habitable zone.” [NASA/JPL]

0.60m Ritchey-Chrétien Reflector [TRAnsiting Planets and PlanetesImals Small Telescope–South / ESO]

0.60m Ritchey-Chrétien Reflector [TRAnsiting Planets and PlanetesImals Small Telescope–South / ESO]

The TRAnsiting Planets and PlanetesImals Small Telescope–South made the discovery back in May 2016 of three exoplanets around the small star.  But it was with the help of larger telescopes and the space-based Spitzer telescope that the count increased to seven and their orbits could be confirmed.  What I find interesting is the initial discover was done by a relatively “small” 0.60m telescope.  OK not your typical backyard astronomy gear, but scale that down by 1/3 and you have equivalent optics for about $3000.  Add a mount and CCD and for $10,000 you could probably have your very own exoplanet hunter!

Back to the crazy-talk of finding life in this exoplanet system… Anyone who has studied the history and formation of the Solar System knows that there have been a series of unlikely events that have led to where we are today.  Starting with the Sun, probably a 3rd generation star, where heavy elements like Calcium and Iron necessary for life as we know it were produced by previous stars and supernovas that used to exist in this spot of the galaxy we now occupy.  All elements beyond Hydrogen are produced by stars, either through fusion or when they dramatically explode as supernovas.  The atoms making up the air, the trees, the oceans, ourselves were not created in our Solar System during its formation.  The Sun is currently only generating Helium and Lithium out of Hydrogen through the wonders of fusion.  All the heavier atoms within us were created by previous stars that no longer exist.  Hence for solid Earth-like exoplanets to exists there needs to have been one to two previous generation of stars in the region.

An alien race observing our Solar System would surely first spot Jupiter.  One could almost say that it characterizes our home in this part of the galaxy.  With its strong gravity this gas giant plays the vital role of neighborhood vacuum cleaner.  It is either mopping up or launching away asteroids and comets that would otherwise impact Earth, bringing relative calm to the inner Solar System.  If Earth was constantly bombarded by solar objects, there is no way that life could suitably evolve from slimy unicellular organisms.  It took 3 billion years for multi-cellular organisms to show up once life appeared on Earth.  If cataclysmic comet and asteroid impacts are a frequent occurrences, then there is little chance that complex organisms would come to be.

Looking at another element, TRAPPIST-1 is described as an ultra-cool dwarf star just shy of 40 light years from Earth in the constellation Aquarius.  If we forget that it’s a fraction of our Sun’s size and brightness (hence heat generation), it is relatively young at 1 billion years old.  So while there may be three planets that could be habitable, life may not have even begun yet.  Our own Sun is 4.3 billion years old, and the animals we see around us have only been around for the last 14-16 million years.  So what could be in a 1 billion year old planetary system? Assuming all the ingredients are there for life to exist, you probably only have bacterial soup.

Now, my article was getting long, and I wanted to cover many more subjects, too many for a single article.  Hence I’ve decided to break them out into the EXOPLANET SERIES and will publish them over time.


Fast Moving Comet Before Sunrise

If you are able to get out of bed early and the sky is clear, equipped with binoculars you should be able to catch a fast-moving comet as it swings by Earth at about 32 lunar distances over the next few days.  The best time is just prior to sunrise as the comet will be higher in the sky in the East.  Use Jupiter as well as bright stars Vega and Arcturus to get your bearings.  With each day the comet will rise earlier and will appear higher in the sky as the chart below shows; comet position at 5am for the next week.  However it will diminish in brightness as it moves away from Earth on after February 11th.

Comet 45P over the next few days starting Feb 10th.

Comet 45P over the next few days starting Feb 10th.

This isn’t the closest a recording of a comet passing near Earth, but it does make it to the 8th spot since modern observation and have been keeping track of near Earth objects (1950).  Back in August 15 2011, it happen to pass even closer, only 23 lunar distances, making it also the 5th closest comet approach.

With a storm system moving up the eastern edge US and Canada, my chances of getting any clear morning sky is pretty slim…

Downloadable PDF Sky Chart: 45p_feb2017_chart

2017 Product – Meade EclipseView

With the total solar eclipse scheduled for August 21st, expect to see new lines of products catering to the novice observer wanting to get up close with the event.  Meade has recently announced the EclipseView product line for April 2017 which includes a binocular, a small refractor and three small reflector telescopes specifically for those wanting to experience the eclipse but with a limited budget and beginner experience.

Meade EclipseView [Meade]

Meade EclipseView [Meade]

The product line offers the following models, all equipped with removable white-light solar filter required to view the sun at all times.

  • 10×50 Binoculars
  • 60mm f/13.3 Refractor (includes 12.5 and 4mm eyepieces and 2x barlow) with an AZ mount
  • 76mm f/9 Reflector  (includes 26 and 6.3mm eyepieces and 2x barlow) with an AZ mount.
  • 82mm f/3.7 Reflector (includes 26 and 9mm eyepieces and 2x barlow) in a compact table-top mount
  • 114mm f3.95 Reflector  (includes 26 and 9mm eyepieces and 2x barlow) in a compact table-top mount

Of the bunch, only the 114mm has the better parabolic mirror, the others opting instead for the simpler spherical mirror.  Therefore the 114mm will provide a sharper view edge to edge, especially a high magnification.

These aren’t new telescopes from Meade, but existing models from their Infinity, Polaris and LightBridge Mini Series kitted for solar observation.  While Meade advertises that these telescopes can also be used at night to view the Moon, planets and the stars, you’ll want to get a red-dot view finder to replace the existing solar pin-hole finder.

Of course you can also add the appropriate solar filter to any telescope, no need to limit yourself to the above gear.



Processing RAW Cassini Spacecraft Images

Did you know that you can get access to the latest RAW images from the Cassini spacecraft directly from the NASA and JPL website?  Not only will you have first look at some stunning images of Saturn, the rings and the Moons like this one below from January 16th.  Click the image below for more information from NASA/JPL on that specific photo.

Daphnis making waves - Cassini spacecraft Jan. 16, 2017 - JPL/NASA

Daphnis making waves – Cassini spacecraft Jan. 16, 2017 – JPL/NASA

But you can also download raw images to try your luck at processing.  For this exercise I selected these series of pictures of the strangely perfect hexagonal-shaped storm on Saturn’s north pole.

Downloaded raw image set

Downloaded raw image set

These are images taken with different filters by the wide field camera, and I noted in an Excel file some information on each image, most importantly which filter was used.  Both the narrow and wide CCD on Cassini operate with two filter wheels, hence each image will always list two filters.  For those surprised at the rather “small” 1 mega-pixel camera, keep in mind the spacecraft was launched nearly 20 years ago, and development started in the 1980s.

There is a very detailed document on how to use, calibrate and process the images found at the following link.  But for what I wanted (quick processing) I only needed to find out which filters were the closest to an RGB setup.

Cassini ISS Broadband Filters

Cassini ISS Broadband Filters

Luckily this is well documented, and found them with the BL1, RED and GRN filters.

The image below is a quick addition of those 3 respective images assigned to red, green and blue channels.  The resulting image would be somewhat near the real colours, but I did not take any time to calibrate, hence they are probably a little off…

Saturn with normal RGB assignment (close to real colours)
Saturn with normal RGB assignment (close to real colours)

I also decided to try something that would provide a little more contrast and dive a little into the atmosphere and went with a IR-Red-Blue for RGB assignment by using a one of the narrow-band filters.

Cassini ISS Narrow Band Filters

Cassini ISS Narrow Band Filters

Saturn with IR, Red and Blue for RGB assignment

Saturn with IR, Red and Blue for RGB assignment

Both images above have not be calibrated, stretch or adjusted other than combine the raw images from Cassini.

The NASA/JPL site even has a section for amateurs to submit their photos and host a gallery to see what others have done.

Cassini NASA/JPL site
Cassini Imaging Science Subsystem (ISS) Data User Guide