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Urban Astronomy2018-09-09T18:38:12+00:00

URBAN ASTRONOMY

The purpose of the page is to bring amateur astronomy back to the cities, back to those areas that are affected by heavy light pollution. Amateur astronomy used to be called “backyard astronomy”. This was in the days when light pollution was not a problem, and you could pursue your hobby from the comfort of your backyard. But as cities like Galway grew, so did light pollution, and the amateur astronomer was forced to drive further and further out into the country to escape that light pollution. It is not uncommon today for a Irish city dweller to drive 40 miles to enjoy his/her hobby. But many people do not have the time or the resources to drive great distances to achieve dark skies. That is the reason for the creation of this page, to allow those who want to enjoy the wonders of the heavens in the comfort of their own neighbourhoods to do so, and to maximize the observing experience despite the presence of heavy light pollution.

Runaway light pollution is robbing us of the night sky. How often have I heard people lament, “I remember when I was a kid I could see the Milky Way crossing the sky. I haven’t seen it in years.” Many young people today don’t even know the simple joy of standing under a truly dark sky. But take heed; all is not lost.
Many amateur astronomers who live in and around major cities enjoy wonderful views through their telescopes any clear evening they wish. They just have to know a few tricks to pull out the best their equipment has to offer.
First, let’s look at the problem of light pollution and define a few terms. Light pollution comes in two varieties: sky glow and local, or line-of-sight, glare. Sky glow refers to the sickish orange glow we see rising above our horizons, the combined effect of hundreds, even thousands of lights on buildings, in car parks and along roadways all casting some of their light skyward. The net result extinguishes faint stars and washes out the sky.
OBSERVING THE BRIGHT STUFF

The Moon, Sun, Planets and bright stars are all easy telescope targets from the city

  

The Moon, the Sun, and three of the five naked-eye planets always put on great shows through telescopes. All are so bright that they punch right through light pollution, haze, and smog as if those problems weren’t even there. That’s why many urban astronomers prefer to stick close to home when stargazing. No matter where you are, the Moon never fails to please. With one glance, you’re instantly transported into lunar orbit. Dark maria, towering mountains, and all those craters appear so close, it almost feels like you can reach out and touch them. Occultation of bright planets by the Moon viewing can be fascinating and useful.

Many amateurs complain about the Moon’s overwhelming glare, especially during the gibbous and full phases. Although it will not damage your eyes, the Moon’s brightness can be diminished by using a neutral-density Moon filter or by placing a stop-down mask in front of your telescope

  • The Moon, as impressive from the City as a dark site and a great interest when Deep Sky is unavailable, even to rural dwellers
  • Seeing can be excellent in cities due to micro-climate
  • Jupiter – Lots of features, belts, spots and ovals and moon events
  • Mars – Polar cap, dark markings and clouds are visible
  • Saturn – Rings and subtle detail on the globe
  • Phases of Venus
  • Comets if bright or with Swan band filter. Good target for CCD photography
  • Artificial satellites and Iridium flares, predictions at heavens-above website

The brightest star in a binary system is designated as the “A” star and is often referred to as the system’s primary. The fainter companion star is dubbed “B.” Usually, the distinction between the two is obvious, but, in some systems with equal-magnitude components, it can be difficult to tell which is which. Adding to the mix, if there are still more stars involved, they will be assigned letters in alphabetical order, such as “C,” “D,” and so on.

  • Variable stars
  • Double stars, Alberio in Cygnus (above) one of my favourite doubles

 

THE URBAN DWELLER

If you live in a high-rise apartment, inquire about using the roof at night. Viewing from a roof gets you above many earthly obstructions, such as trees and possibly other buildings, as well as above many sources of street-level lighting.

There are some disadvantages to keep in mind, however. Roofs absorb a tremendous amount of heat even on the coldest winter day, only to radiate it back out at night. That rising heat can distort the view badly

  • In the City, contrast is key
  • Refractors offer  excellent contrast
  • Reflectors :- go for a long f ratio and quality optics, even at the expense of aperture
  • Low central obstruction is best
  • Try and maximise the Signal/Noise ratio
  • Keep optics clean
  • Go for a well baffled scope or add baffles to your existing scope
  • Consider 7X50 Binoculars for quick looks
  • The best telescope is the one that gets used most
  • Short setup time means the scope gets used more
  • Block out stray light. Use existing structures such as sheds and foliage to block the direct view of Pick the darkest section of your site lights.

During New Moon. The Moon reduces contrast. After 10:00PM. This gives dust and water in the air time to settle. After 11:00PM. Most shops turn off their lights by this time and sky glow is reduced considerably.  After 1:00AM. Less traffic on the streets and light pollution is reduced. Ask your neighbours over for an observing session

If you live in a high-rise apartment, inquire about using the roof at night. Hopefully, there is an easy way to access the roof in the first place, either by elevator or a short flight of stairs. Viewing from a roof gets you above many earthly obstructions, such as trees and possibly other buildings, as well as above many sources of street-level lighting.