Setup for the Geminids

With the Geminids peaking tonight and a clear sky after two nights of snow, I charged the camera battery and got a quick setup going to take some pictures of the sky.  As for any nigh sky photo, both lens stabilizer and auto-focus is set to OFF and focused manually at infinity. Then found a corner of the yard shielded from stray lights and planted the tripod, roughly aiming the camera 70deg up and pointing east (the constellation Gemini was rising at 10pm).

However at -15C outside, the old battery wouldn’t last very long.  I left it running for about 30 minutes, taking 20 seconds exposure at ISO 800 with a 17mm F4 lens.  The camera is now thawing (covered with frost after bringing it indoors) and will wait until tomorrow before checking the pictures out.

Setup for the 2017 Geminids

Setup for the 2017 Geminids

In the brief moments that I was outside I caught a 2-3 meteors and one really bright one (easily visual magnitude -4). So even living in the city, the Geminids are visible and accessible to all.  With my feet deep in snow I wasn’t dressed well enough to hang around in the cold wind to watch the show for long. So I hope the camera managed to capture a few.

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Watching the Geminids

It’s that time of  the year again: the Geminid meteor shower. It is visible almost all the month of December, however the best and peak viewing, with up to 120 meteors an hour, is between December 12 and 15.  It should be a good year because we are heading towards a new Moon on December 18th, so no bright moon to ruin the show.

This meteor shower is called the Geminid because the radiant (apparent direction of travel in the sky) of the meteors is centered on the constellation Gemini.  However the source of the debris is not a comet like most other meteor showers, but an asteroid: 3200 Phaethon. The asteroid and orbit were discovered in 1983 and is too good of a match with the Geminids to be anything other than the source of the debris. However its makeup is closer to asteroid belt material, so it may very well be a 5km chunk from a larger asteroid, with all the associated debris.

To watch the Geminids, the best time is past midnight as the constellation will rise east around 10pm.  The higher it is in the sky the better. The Geminids do regularly create fireballs: bright displays that can exhibit colour and even leave a smokey trail, so observation even in light polluted city sky is possible.

Here are some tips for the observation:

  1. Dress to be warm.  You’ll be sitting still in the cold night. Nothing will get you indoors faster than the shivering knowing that warmth is only a few feet away.
  2. Lay down or recline in a chair.  Standing and looking straight up is very uncomfortable and quite the strain on the neck.
  3. Give yourself a good 15 minutes for your eyes to adjust to the darkness  If you give up after 2-3 minutes, your eyes are still adapting to night vision and will miss the fainter meteors.
  4. Find a spot away from sources of lights.  Of course heading out of the city is best, but if you can’t, just find a spot in your backyard without the glare of street lights and neighbors’ porch lights. That also means no electronic screens to ruin your night vision.

You can also setup a camera on a tripod to see if you capture some of the meteors. Grab a short focal length, remove auto-focus and go for a 10-20 second exposure setting.

Clear skies!

Color of the Moon

The Moon is white right? OK, OK… it only looks white because of the high contrast with the dark sky, it’s more grey.  What? No? You mean it has color?

From samples returned by the Apollo missions we know that two of the main minerals making up the lunar regolith is titanium oxide (TiO2) and iron oxide (FeO) based basalts.  While TiO2 is quite white and used in many household products from white toothpaste to white kitchen tiles, FeO is rust and closer to orange-brown (think Mars). On the Moon the result is a slightly blue-ish color in the areas with high TiO2, and more of a brown-red for the higher FeO and low TiO2 zones.

A normal image of the moon taken with DSRL, the different in hues is subtle as seen below.

Moon Natural Color (November 7, 2017) - Benoit Guertin

Moon Natural Color (November 7, 2017) – Benoit Guertin

But it can be exaggerated by playing with the color saturation, and you get the image below, where various hues of blue-grey, orange and brown become apparent. The sharp boundaries between colors are caused by the different mineral make-up of the lava flows during the early formation of the Moon. Common interpretation of the age of the lunar surface is that the blue-grey areas are “younger” than the orange-brown.

Moon with exaggerated colors

Moon with exaggerated colors

Who says you can’t pull scientific information with simple backyard astronomy gear? The same technique, but with narrow-band filters is used by NASA and other space and research agencies to catalog the make-up of the lunar surface.

So if you are planning lunar prospecting for future mining rights, all you need is a telescope and a DSLR.

Cassiopeia – the W in the sky

Some constellations are easier to spot than others.  Cassiopeia with its distinctive W is visible year round in the northern hemisphere above the 34th parallel. In the image below it easily stands out from the fainter background stars.

Cassiopeia above the three line - Benoit Guertin

Cassiopeia above the three line – Benoit Guertin

The five stars drawing a W in the sky are all naked eye magnitude 3 and brighter stars, and in the image above I used a layering technique to increase the color and brightness of those stars to really make them stand out.

  1. Duplicate your base image, and set this layer to lighten only
  2. Apply a blur to the top layer(about 8-12 pixels)
  3. Increase the color saturation and brightness.  Play with the curves to brighten the bright stars, but not the background sky.
  4. Use a mask as required to filter out the bright foreground elements, such as light reflecting off a building roof-line in my image above.

Canon Rebel XTi
17mm f/4
4 x 20sec ISO800

 

This Weekend: 4 Planets in Plain Sight

If you are able to get out of bed early before sunrise and the sky is clear, you can catch a view of our three closest planets, and if you include Earth that makes 4.  Mercury was at the greatest elongation on September 12th (furthest from the Sun when viewed from Earth) which makes it a good time to spot without the glare of the Sun.  But it happens that Mars and Venus are also on that same side of the Sun, making a chanced planetary alignment.

The sky map below [click for larger] shows the position of Mercury, Mars and Venus for the morning of the 16 to the 19 of September.  Bright star Regulus and our Moon are also there to make this a worth-while event, especially on Monday the 18th.

September_AlignmentMars and Mercury will be closest on the 16th, while the 18th will probably be the most photogenic as the Moon will be a thin crescent in the middle of this alignment.

Solar Eclipse – Post Processing

With the eclipse behind us, and all the gear put away it’s time to transfer and process the images to create something memorable.  I decided to make a mosaic with some of the photos of the eclipse, as well as the visible sun spots. Click on the image below for a high-resolution version.

August 21, 2017 Solar Eclipse

August 21, 2017 Solar Eclipse

The weather cooperated and I had the right gear to get some decent photos. Before the start of the eclipse, the sun presented two observable active sun spot regions: 2671 and 2672. This helped in achieving a proper focus and gave something to observe prior to the start of the eclipse.

Sunspot Region 2671 (right) and 2672 (left)

Sunspot Region 2671 (right) and 2672 (left)

As I had installed and aligned my Vixen equatorial mount the night before, once I had proper focus with the camera, it was child’s play to start an automatic sequence of images every 60 seconds. Hence for the entire solar eclipse, it was hands-off and automated. I could simply glance once in a while at the screen or grab one of the hand-held solar viewers to look up.

58% Cover from the Montreal, Canada Location.

58% Cover from the Montreal, Canada Location.

While the effect was nowhere near that of those in the path of totality, the light level and heat did drop at the peak of the eclipse. The brightness was lower, not like when there are high altitude clouds as the shadows were still sharp and well-defined. And the sun’s rays did feel cooler, a welcomed relief from standing under the sun for the last hour.

In the end, it was a fun experience, especially with the kids. And with over 150 images taken I decided to compile them into two formats. A time-lapse video and a mosaic as seen above.

The video was actually the quickest thing done. With Microsoft Movie Maker, it takes the Canon CR2 RAW files directly and stitches them together into a video. It actually took me longer to find a suitable soundtrack to the clip.

With that experience under my belt, I’m looking forward to April 8th 2024 total solar eclipse that will pass close to home.

Telescope: Skywatcher 80ED with Thousand Oaks R-G solar film
Camera: Canon Rebel XTi (450D)
Setting: 1/1000s at ISO 100

Partial eclipse and sunspots

As the moon moves out of the path of the sun, it exposes the sunspots AR2671 adding some interest to the show as it comes to an end.

With over 150 photos taken during the eclipse, time to create a time lapse video.