Tag Archives: DSO

Durham Region Light Pollution and where to find a Dark Sky Site

Light pollution map of Durham Region.

When I first started observing with my telescopes, I had an idea what light pollution meant, but did not realize its impact on visual observation especially on Deep Sky Objects (DSO’s). I thought I could observe anywhere I wanted  as long as it was a cloudless sky. I live in the Durham Region after all. Not so fast.

I spent an entire week hunting for the M13 and the Andromeda Galaxy to no avail. Why? Because my sky was brighter than these faint objects. I eliminated most of the local light pollution from my backyard by turning my kitchen lights off, my cell phone, light shields for my telescopes, and used a blanket over my head to block out my neighbour’s lights. After 15 mins of dark adaptation, I still see nothing of these objects.

It turns out that there is a ‘light dome’ high above my sky. The light pollution map above represents the intensity of this light dome super imposed over a map of Durham Region and eastern Greater Toronto Area (GTA). In the order of brightness level:

  • White – Entire sky is grayish or brighter.
  • Red – Milkyway at best very faint at zenith.
  • Orange – Milkyway washed out at zenith and invisible at horizon.
  • Green – Some dark lanes in milkyway but no bulge into Ophiuchus.
  • Yellow – Zodiacal light seen on best nights.
  • Blue – Low light domes on horizon.
  • Grey – Faint shadows cast by milkyway visible on white objects.
  • Black – Gegenschein visible. Zodiacal light annoyingly bright.

I live a suburb of Oshawa in a red zone and within a few minutes of a white zone in the core of the city. By driving to an orange zone 20 minutes away, I was able to see some of the Milky Way’s ‘spilled milk’ look across the sky whereas it was not at all visible from my backyard. I finally found M13 and it didn’t take long for it to ‘pop’ out of my eyepiece. If you want to know the light pollution map in your area, check out Dark Sky Finder by Jonathan Tomshine: http://www.jshine.net/astronomy/dark_sky/ and you will find some dark sky sites around the GTA area within an hour’s drive.

In the Durham Region, I do most of my DSO observations from Long Sault Conservation Area which is just outside the grasp of the red zone. Sometimes I use my local club’s DRAACO observatory which is well within the orange zone. It is well worth the drive for a great night of visual observation and sketching.

I Bagged My First DSO with a Pair of Binoculars

My Nikon 8×40 Action VII

Last night, I setup my Newt to look for M13, the Hercules globular cluster. My 4th attempt.

Earlier in the day, I had been in contact with another astronomer an hour away to the north. At night fall, he texted me and told me that he’s got M13 in his CPC 800 through 18mm and it was brilliant taking up a third of the frame. That prompted me to quickly setup my gear in the yard: collimated scope, eyepieces, Stellarium, eye patch, towel & coffee… check! Darkness was good (before the moon rose anyway), excellent transparency, good seeing, no wind, normal humidity, and mild temperatures.

After an hour, I still could not find M13. I know where it should be and what it looks like. I tried it with my binoculars and I still can’t find it. I brought out my 90mm refractor and I still cannot find it. I has been 2 hours and the moonlight has started to make the sky glow. So I packed up.

The last thing I brought back inside were my binoculars (Nikon 8×40 Action VII). But before I walked in, I thought of checking out Andromeda with my binos. I slewed towards Cassiopaea then scanned downwards diagonally to where it points. Then, there it was. I noticed a blurry dark grey patch at the corner of my eye. I slewed towards it, past it, back and forth. It was undeniable: that was the Andromeda Galaxy. My first DSO. The feeling was a mix of excitement and awkward fear. Excited because I finally bagged my first DSO ever. Awkward fear was because it was like unveiling a ghost that had been staring at me since birth and all I saw was a tiny portion of it.

My bino’s beat out my telescopes even on a sky with moonlight. I suspect the problem is with my eyepieces. Today, I will be receiving my first real eyepieces (Celestron X-Cel LX). The forecast tonight looks good and will give it another go at M13.