This document provides an overview of astronomy night hosted by the Sussex County Amateur Radio Club. It discusses what astronomy is, including the study of celestial objects across optical and non-optical wavelengths. It also describes radio astronomy, which studies celestial objects at radio frequencies. The document outlines different types of telescopes used in optical and radio astronomy and how they are used to observe different astronomical phenomena like stars, galaxies, and nebulae.

1. Astronomy Night at the
Sussex County Amateur Radio Club

2. Welcome!
• This presentation came about due to the
amount of interest in the topic of astronomy
by club members
– After all we congregate and interact using radio
waves
– Astronomers congregate and interact using light
waves a few frequencies above our community’s
wavelengths

3. What is Astronomy?
• Astronomy is a natural science which is the
study of celestial objects
– Sun, Moon, Planets, Planetary moons
– Stars, Nebula, Clusters, Galaxies
• In other words- the known Universe in optical
and non-optical wavelengths
– Ever hear of radio-astronomers?

4. Radio-Astronomers?!?
• Yes! Radio astronomy is a subfield of
astronomy that studies celestial objects at
radio frequencies.

5. Radio - Astronomers
• Our Cousin HAMs ( in a sense) Radio
Astronomers see some pretty neat stuff!
An optical image of the
galaxy M87 (HST), a radio
image of same galaxy
using Interferometry (Very
Large Array-VLA), and an
image of the center
section (VLBA) using a
Very Long Baseline Array
(Global VLBI) consisting of
antennas in the US,
Germany, Italy, Finland,
Sweden and Spain. The jet
of particles is suspected to
be powered by a black
hole in the center of the
galaxy.
This is the primary
difference between
optical astronomy
and radio
astronomy.
We glean different
information from
using different
wavelengths

6. Radio / Optical - Astronomy

7. Radio - Astronomy
• Observations from the Earth's surface are limited to
wavelengths that can pass through the atmosphere. At
low frequencies, or long wavelengths, transmission is
limited by the ionosphere, which reflects waves with
frequencies less than its characteristic plasma
frequency.Water vapor interferes with radio
astronomy at higher frequencies, which has led to
building radio observatories that conduct observations
at millimeter wavelengths at very high and dry sites, in
order to minimize the water vapor content in the line
of sight. Finally, transmitting devices on earth may
cause radio-frequency interference. Because of this,
many radio observatories are built at remote places.

8. Astronomy
• Astronomy is one of the oldest sciences.
• Prehistoric cultures have left astronomical
artifacts such as the Egyptian monuments
and Nubian monuments, and early
civilizations such as the Babylonians,
Greeks, Chinese, Indians, Iranians and
Maya performed methodical observations
of the night sky.
• However, the invention of the telescope
was required before astronomy was able
to develop into a modern science.
• Historically, astronomy has included
disciplines as diverse as astrometry,
celestial navigation, observational
astronomy and the making of calendars,
but professional astronomy is nowadays
often considered to be synonymous with
astrophysics.

9. Star Maps
• Star maps have been around since man started
looking at the night sky
– From culture to culture remarkably similar but each
culture saw something different in the sky dependent on
their “world view”
– For example the Greeks immortalized their heroes and
villains in the night sky
– Orion
– Perseus
– Andromeda
– Hercules
– Cassiopeia
– Cepheus

10. Star Maps – Guideposts to the Stars

11. Star Maps – Guideposts to the Stars
• Sky charts provide “coordinates” that pinpoint
a star’s address in the night sky.
– Stars stay located in the same area of the sky for
most of our lifetimes
– That’s not to say they’ll be in the same location a
million years from now. That happens due to the
fact that everything is moving and expanding in
the universe, so ten generations from now their
positions relative to Earth would have moved.

12. Star Maps – Guideposts to the Stars
• Our night sky is really a clock
– Stars move around on sidereal time.
– Sidereal time is based on one rotation of the Earth
in relation to any star
• Sidereal time is divided into 24 hours but the day itself
is 4 minutes shorter
– How do find sidereal time?
• You can use a chart or a formula

13. Star Maps – Guideposts to the Stars
• So why is it important to know sidereal time?
– Because you can calculate the appearance of a night sky
object.
• You can also figure out trajectories – but not in this presentation!
– Start by figuring out what your local mean time is
• Local Mean time = Greenwich Mean time –
Longitude west (your longitude in hours and minutes
in time)
– For example GMT= 12Hrs 00mins
Long = 5Hrs 26 mins
LMT= 6hr 34 min

14. Star Maps – Guideposts to the Stars
• Next Find your sidereal time
– You’ll need to find a chart that tells you what Greenwich
Sidereal time is at 0hrs.
• Local Sidereal time = Local Mean time + Greenwich
Sidereal time + (LMT /6) a correction factor
LST = LMT + GST+(LMT/6)
Or go to http://www.jgiesen.de/astro/astroJS/siderealClock/
• So why is this important?
– You’ll know when and where an object will come up over
the horizon but more importantly “navigate” your scope
towards it in the night sky

15. Star Maps – Guideposts to the Stars

16. Optical Astronomy
• Optical Astronomy deals with what the human eye can see
and some wavelengths we can’t see.
• Instead of using antennas and radio receivers professional
and amateur astronomers use optical devices called
telescopes to capture light, focus it, and create an image
the human eye can see.
• Telescope – origins of the name
– 1640s, from Italian telescopio (Galileo, 1611), and Modern Latin
telescopium (Kepler, 1613), both from Greek teleskopos "far-seeing,"
from tele- "far" (see tele-) + -skopos "watcher" (see
scope (n.1)).
– Said to have been coined by Prince Cesi, founder and head of
the Roman Academy of the Lincei (Galileo was a member). Used
in English in Latin form from 1619.

17. Telescopes
• Most of us believe Galileo was the first person to create the
telescope, and the invention of the telescope is largely attributed to
him.
– However…. Galileo was the first to use a telescope for the purpose of
astronomy in 1609 (400 years ago in 2009, which was celebrated as
the International Year of Astronomy). Hans Lipperhey, a German
spectacle maker, is generally credited as the inventor of the telescope,
as his patent application is dated the earliest, on the 25th of
September 1608.

18. Telescopes
• So essentially a telescope “receives” light
waves (photons) at various optical frequencies
• Telescopes condition the light by
magnification or wavelength separation
• We think of just amplifying the light by
magnification, but when you look through a
telescope’s lens your eye is receiving all the
optical wavelengths including infrared, and
ultraviolet wavelengths

19. Telescopes
• Types of telescopes
– Refractors , Reflectors, Complex

20. What to Use and How to Use it
• Just like HAMs have base stations, mobiles,
portables, and handhelds….amateur
astronomers have options as well, depending
on what they want to do, and where they
want to observe.

21. What to Use and How to Use it
• Some amateurs are interested only in objects
nearby, and use refractors.
• Refractors will work fine, are relatively easy to set
up, and will magnify sufficiently well to provide
astonishing detail on the moon, or planets.
• The majority of good quality refractors will come
with a “German equatorial mount”
• “Christmas scopes” have lower quality optics, and
cheaper alt azimuth mounts.

22. What to Use and How to Use it
• Some amateurs are interested in “deep sky” and objects nearby.
– All types of telescopes will work fine, however when viewing “deep
sky” objects you’ll need to capture more light, and magnification
isn’t always the best way to observe
• SIZE MATTERS – to an extent, there’s limitations.
• Reflectors using mirrors greater than 6 inches in diameter, generally
work best for weekend amateurs
• Refractors will work as well, but the lenses will need to be higher
quality and made with more precision.
– Apochromatic lenses will provide color correction
• Mounts can be equatorial, or alt azimuth.
– Spending a little more on solid mounts is well worth the effort to
minimize vibration in the system

23. Alt- Azimuth Mounted Telescopes
These are great when you just want to go camping on a weekend, or
step outside in your backyard and do visual observing

24. Equatorial Mounted Telescopes
These are great when you want to spend time outside “tracking” a sky
object , doing imaging, or want the telescope to guide itself. Takes a
little more time to set up, but well worth it!

25. Short Video
http://youtu.be/_TNrPLHB21k

26. The Night Sky
• Telescopes have evolved over the last 400+ years to a
point where amateurs and professional astronomers
have been able to collaborate and share observations
and events.
• Basically for the first 300 years or so manually driven
observation was the way astronomers viewed the night
sky
• To do so they relied heavily on equatorial mounts since
telescopes using those mounts could utilize precision
gears, and weights to move the large telescopes they
carried
– Remember size matters?

27. Aperture Size and Light Gathering
• Objective diameter alone determines the light power of your
telescope
– That’s why size matters but…..
• All stars are “rated” by their star magnitude (relative
brightness)
– The star magnitude scale base is measured upon the un-aided human
eye’s ability to see the faintest star.

28. Aperture Size and Light Gathering
• On a scale of -2 to 24 the human eye can see a star with a
magnitude of ~6.2mag so…
– There’s a brightness difference along the scale
• A magnitude of 1 has a relative brightness of 100 ( 1st magnitude star like
Spica is rated 100)
• A 9th magnitude star is 100 times fainter!
– Telescopes have a limit on what light they can gather
• A 6inch diameter Newtonian has a limit of magnitude 13.5
• A 12 inch 14.5
• The 200 inch Mt Palomar Telescope has a 20.5 magnitude limit.
– http://www.stargazing.net/david/constel/constel/
ursaminor.html

29. Magnitude Needed to see an object of this brightness* Examples
-26 the sun
-13 full moon
-6 crescent moon
-4 naked eye: easy even from large cities planet Venus
-2 naked eye planet Jupiter
-1 naked eye Sirus brightest star,
0 naked eye: difficult if near bright summer evening star
artificial lights but generally Vega; C/1996 B2
visible even from large cities (Hyakutake) at peak
+1 naked eye: brilliant as seen from planet Saturn
dark, rural areas
+2 naked eye: difficult but visible from stars of Big Dipper
3 naked eye: rural, suburban, small city faintest naked-eye
binoculars: bright, urban areas stars visible from
4 naked eye: (outer) suburbs faintest naked-eye
binoculars: cities (stars), suburban stars visible from
areas (diffuse objects such as comets)
5 generally binocular objects from urban moons of Jupiter
and suburban areas; faintest naked-eye
stars visible from "dark" rural areas
located some 40 miles (60 km) from
major cities

30. What’s Up in the Night Sky?
• Planets
– Mercury- hard to see
due to its proximity to
the sun
– Venus – You don’t need
a scope but if you do
you’ll need filters
– Mars – What a gem!
– Jupiter – one of the
neatest sights to see in
the night sky
– Saturn – Spectacular

31. What’s Up in the Night Sky?
• Deep Sky
– Open Clusters
– Nebulas
– Galaxies

32. What’s Up in the Night Sky?
• Today we use software to make multiple
digital exposures to spectacular images of
what we see with our scopes!
Image taken from a 10
inch Newtonian scope
using multiple
exposures

33. Read more: http://www.universetoday.com/41889/who-invented-the-telescope/#
ixzz39ExCEWjO
http://en.wikipedia.org/wiki/Magnitude_%28astronomy%29
http://www.stargazing.net/david/constel/constel/ursaminor.html
https://sites.google.com/site/greekastronomyabc/constellations
http://www.jgiesen.de/astro/astroJS/siderealClock/
http://www.astro.umd.edu/~jph/GST_eqn.pdf