The Great Comet of 2020 That Never Was

Back in March, the astronomy crowd was buzzing about a possible”naked-eye” comet expected in late May 2020.  Comet C/2019 Y4 (ATLAS) was first detected at the tail end of December as a very dim magnitude 19.6 object and by mid-March it had brighten to an easy telescope target magnitude of 8. Those not familiar with the magnitude scale, going from 19.6 to 8 is not a doubling in brightness, but around a 4000 times increase!

That dramatic increase in brightness help fuel the hype for the Great Comet of 2020, and there were two other factors that got people excited:

  1. It would be visible at dusk from the Norther Hemisphere, hence within easy viewing to much of the world population.
  2. It was following a similar orbital path as the “Great Comet of 1843“, suggesting that it was from the same original body and could potentially provide the same viewing spectacle. That 1843 comet was visible in daytime!

Well all that went south when the comet’s breakup was observed in late March after peaking momentarily at magnitude 7. It began to dim, along with any hopes of a Great Comet repeat. Below is a graph showing the the original (grey line) and revised (red) comet brightness forecast (dots being observed measurements) on this chart created by Seiichi Yoshida (

Comet C/2019 Y4 (ATLAS) Brightness - Copyright(C) Seiichi Yoshida

Comet C/2019 Y4 (ATLAS) Brightness – Copyright(C) Seiichi Yoshida

Comet C/2019 Y4 is expected to make its closest approach to the sun on May 31st, however most experts believe it will disappear (disintegrate) before that date.  Seeing that I had a small window of opportunity to capture the comet I decided to try my luck last Saturday evening.

Below is an extremely processed (and ugly) image that I got by combining 25 photos (15 seconds each at ISO 3200) using my Skywatcher 80ED scope. The photo just about makes out the distinctive blue-green hue and elongated shape of a comet. It is around magnitude 10, very diffuse and about 147 million km away from us the day this photo was taken.

Comet C/2019 Y4 (ATLAS) on April 18, 2020 - Very faint at about magnitude 10. Imaged with 80ED telescope 25 x 15sec

Comet C/2019 Y4 (ATLAS) on April 18, 2020 – Very faint at about magnitude 10. Imaged with 80ED telescope 25 x 15sec

I pushed the image processing so hard that I was able to pick up faint magnitude 13 galaxies!

On to the next comet!

Telescope: Skywatcher 80ED
Camera: Canon 80D
Image: 25 x 15sec at ISO3200 (6 minutes)

A Crater Named Tycho

10 Days old Moon (April 04, 2020) - Benoit Guertin

10 Days old Moon (April 04, 2020) – Benoit Guertin

The photo above is of a 10-day old Moon taken a few days ago. After the darker “seas” of old lava flow, one particularly bright crater in the southern hemisphere stands out, especially with the rays that appear to emanate from it. That is Tycho, a 85km wide and 5km deep crater and one of the more “recent” ones if you consider 109 million years the not-to-distant past. The Moon is 4.5 billion years old after all… having formed just 60 million years after the solar system. On the Moon, “fresh” material have a higher albedo and hence appear brighter, whiter.

The bright rays surrounding Tycho are made of material ejected (up to 1500km away) from the impact of a 8-10km wide body. In time these rays will disappear as the Moon continues to be bombarded by micro meteorites, which stirs the material on the surface. The rays are more present on the eastern side, as would be expected from a oblique impact.

Tycho is names after the Danish astronomer Tycho Brahe.

The Surveyor 7 space craft landed about 25km north of the crater on January 10, 1968.

Ever wondered how mosaic space photos were done before the invention of powerful software algorithm to stitch them together?  Take a look at the series of Surveyor 7 mosaic photos.  Someone had to painfully print each photo and lay them on a grid in a specific pattern matching optical field and geometry.

Ending the Year with Betelgeuse

A few days prior to the holiday break there was news of Betelgeuse dimming to an all-time low, potentially signaling the start of the process that will transform this star into a Supernova. What? Wait a minute… A star in our own galaxy exploding? But that hasn’t been observed since 1604!

Remnant of SN1604 (NASA)

Remnant of SN1604 – last galactic nova (NASA)

There are plenty of novas at any point in time, they just happen to be in galaxies far away (cue Star Wars intro). During those few days or weeks of otherworldly explosions these stars become the brightest object in their host galaxies.

SN2018ivc in galaxy NGC 1068 (Credit: Bostroem et al., 2019.)

SN2018ivc in galaxy NGC 1068 (Credit: Bostroem et al., 2019.)

So if we can see them when they are millions of light years away, what would an exploding star just 700 light years away, like Betelgeuse, look like?

Well if we base ourselves on SN1604 it will be visible to the naked in eye for three weeks, including during daytime. SN1604 was 20,000 light years away, while Betelgeuse is at a fraction of that, so most experts anticipates that it would be as bright as a full Moon.

Now before we go crazy anticipating when Betelgeuse, a red super-giant, will explode, let me present some information to put everything in perspective.

Betelgeuse is a red super-giant of class M1-2 in the constellation Orion, 2nd in brightness just after Rigel. Betelgeuse is one of the largest start we can see when glancing up at the night sky. If Betelgeuse was our Sun, it would engulfed all planets up to Jupiter. Stars of that size aren’t like the nice Smith Ball of fire we imagine our Sun to be. They are more like a loose ball of foam, constantly bubbling and bloating from the incredible heat created in the inner core. If you are starting to think unstable, you are partly right.

Betelgeuse is also a well documented variable star, meaning it periodically varies in brightness.

Recorded Brightness of Betelgeuse Over the Years (credit: AAVSO)

Recorded Brightness of Betelgeuse Over the Years (credit: AAVSO)

So while it is at an all-time low compared to its known ~425 day cycle, it also has a ~5.9 year cycle, and this episode just happens to be a combination of both lows. So no need to panic… for now.

Betelgeuse will one day end as a type II supernovae, probably not for another 100,000 years. Until then we can all glance up during these cold winter nights at how easily the Orion constellation can be spotted and enjoyed. The three bright stars marking the belt and the hour-glass figure is easy to find. Take a few moments to look at Betelgeuse as on a galactic scale it will be gone tomorrow.

Betelgeuse Red Super Giant in Orion (Benoit Guertin)

Betelgeuse Red Super Giant in Orion (Benoit Guertin)

For the Moon, leave the tripod behind

Most people don’t plan to take photos of the Moon, they just happen. You are outside doing something else and then you spot it over the horizon or high in the sky: “Hey that’s a pretty Moon tonight Maybe I should take a photo!”

I find that normal camera lens, even telephoto don’t do it justice. The setting and focus can be very tricky. The multi-lens setup of telephoto can also cause internal reflections or chromatic aberrations making the resulting photo less appealing.

So just grab the telescope tube and leave the tripod behind.  If you have a small APO refractor you can simply hold the tube, but for anything heavier you’ll need to prop yourself up on something like a railing or a car roof.

The photo below is a single shot at 1/250sec and ISO400 with Canon 80D and William Optics Gran Turismo 71 held on the end of my arms.


80% Illuminated Moon on August 31, 2018 [Benoit Guertin]

The setup takes only a few minutes and the results are always worth it.

Leaving the city lights behind

Nothing like leaving the city lights behind and heading to a rural camp ground to check up on our galaxy.

Every summer the galaxy presents itself across the sky in the norther hemisphere, an ideal time to enjoy the view and spot a few open cluster along the way.


Canon 80D 17mm F/4 ISO6400
Stack of 10 x 10 seconds
No tracking

Messier 3 and a Fast Moving Star

A few weeks ago after taking some photos of Jupiter, I changed my setup to do some long exposures on an easy target: a globular cluster. Unfortunately I forgot to note down the name of what I had photographed!  So a few weeks later when I found the time to process the images I was at a loss to identify what Messier object it was. However, after an evening of matching up stars surrounding the cluster and I was able to correctly identify it as Messier 3.

Globular Cluster - Messier 3 (Benoit Guertin)

Globular Cluster – Messier 3 (Benoit Guertin)

The above was taken with my Skywatcher 80ED and Canon 80D. It is a stack of 27 x 10sec exposures at ISO3200 on an unguided and roughly aligned mount.

Looking at my archives I found that I had imaged M3 about 10 years ago with the same telescope, so I decided to align both old and new image and see if anything would stand out. And to my surprise, spotted one star that appeared to have shifted. To help identify the star I colorized one of the photos and subtracted from the other (done in GIMP).  All the stars within the field of view lined up except this one; the two colored spots are not aligned!

High PM Star BD+29 34256

High PM Star BD+29 34256

To be sure this wasn’t on an error on my part I did a bit of research and found it to be a know high proper-motion star BD+29 34256.

It’s not everyday someone with amateur backyard astronomy gear can show how a star has moved in 10 years.

It’s a good time for Jupiter

The last time Jupiter was in a favorable position for good photos was 2010, so while I have photographed the planet a few times since, the results weren’t really satisfactory.  So on July 7th, finally took the equipment out and set my mind to image some planets (Venus was also in a good position).

As luck would have it, the Great Red Spot was pointing our way, and landed my best shot of it yet. We may be past the May 2018 sweet spot for opposition, but that doesn’t mean you should not attempt to observer or photograph the Jupiter. Still plenty of good days ahead.

Jupiter with moons Europa (left) and Io (right)

Jupiter with moons Europa (left) and Io (right)

I took about 11 video sequences of the planet, and sure enough the last one yielded the best result. I guess as the evening progressed, the air cooled and provided for better viewing.

Skywatcher 80ED
Televue 3X barlow
Vesta Webcam with IR/UV filter
Processing with Registax and GIMP.

In case you missed the Venus-Moon close encounter

Last Saturday evening, if you happened to look outside and had a clear view there is no way you could miss the Venus-Moon close encounter in the dark blue sky. But just in case it was cloudy, or you weren’t paying attention here it is.

Moon and Venus within 8 degrees on June 16, 2018

Moon and Venus within 8 degrees on June 16, 2018

For those curious on the camera setting, the above is cropped from a single frame at 33mm f/4.5 1/30sec and ISO800 with Canon 80D.

Moving up to 85mm gives you the image below, also at 1/30sec and ISO800.  Both images were hand-held from a bedroom window. Could a tripod have helped? Sure, but I figured I could do just fine , especially with image stabilization enabled on the lens.

Moon and Venus within 8 degrees on June 16, 2018

Moon and Venus within 8 degrees on June 16, 2018

To put a bit of perspective on the distance of these two heavenly bodies and their apparent size in the sky I’ve added a bit of information on the above image. While Venus may be nearly 4 times larger in diameter, it looks quite small next to the Moon in the sky.

Constellations at the Zenith

We don’t often look “straight up”. Unless you are laying down, it’s not a comfortable viewing position. However there is lots to see and the Big Dipper (Ursa Major) is right overhead this time of year.

Setting up a camera with a 10 second exposure can capture quite a good deal of the sky, and you don’t have to worry too much about star trails. What stands out is the large variations in the colors of stars, from cooler deep reds, to hot bright blues.

Constellation Near Zenith 08May2018

Constellations right above in the May evening.

17mm f/4
Canon 80D (ISO 3200)
12 x 10sec (2 minutes)

M44 Beehive Cluster


In one of my previous post I mentioned how Messier 44, the Beehive Cluster, would be an easy find the evening of April 22-23, so even if I took this photo on the 21st, the same evening that I took a photo of the Moon, all I needed was to moved a few degrees north after observing the Mooon to image this large open cluster.

Messier 44 - Beehive Cluster. Benoit Guertin - with Skywatcher 80ED and Canon 80D

Messier 44 – Beehive Cluster. Benoit Guertin – taken with Skywatcher 80ED and Canon 80D

Photos of open clusters with small refractors always lack the diffraction spikes that really make the stars stand out.  So a little photo editing did the trick to spice up the image.

Skywatcher 80ED
Canon 80D ISO 3200
Stacked 22 x 10sec