Jan 15

THE OBSERVER
OF THE TWIN CITY AMATEUR ASTRONOMERS
Volume 40, Number 1
January 2015
INSIDE THIS ISSUE:
Editor’s Choice: Image of the Month……..……………….1
A Note from President Weiland..…………………..……….2
2015 Annual Meeting and Banquet……….…..…….…...2
Calendar of Celestial Events – January 2015..……......3
New & Renewing Members/Dues Blues…………..…….3
Subscribing to Our E-Mail Lists………………………….……3
This Month’s Phases of the Moon……..……………...…..4
Celestial Calendar of Events (continued)………………..4
Board of Directors: Why Not You?……………….…….….4
Call for Club Award Nominations………………………….4
Astrobits…………………………………………………………………5
Sky Interpretation (Part 3)……………………………………..7
Education/Public Outreach for December 2014…..11
Astrophotography on the Cheap (Part 1)………………12
Building a Dobsonian Telescope…………………………..17
Last Minute Images………………………………………………18
How Time Flies…….……….…….........................….…....18
TCAA Treasurer’s Reports: December 2014………....19
EDITOR’S CHOICE: IMAGE OF THE MONTH
~ commentary by Craig Prost ~
The TCAA is an affiliate of the Astronomical League.
For more information about the TCAA, be certain to
visit our club website.
Messier 45 – The Pleiades cluster is an open cluster of young, hot stars
about 440 light years from Earth. This star cluster was one of the first to be
written about in Chinese culture around 2400 BC and was even mentioned a
few times in the Bible. The Greeks incorporated this cluster into their
mythology as the seven daughters of Atlas being chased by Orion. Zeus felt
bad for the girls and transformed them into doves that flew to the heavens.
This cluster is a reflection nebula. The blue hue is from the reflection of
light from hot blue stars off the galactic dust the stars are passing through.
The cluster is only about 100 million years old and within the next 300
million years will no longer appear like it does because gravitational forces
from the galaxy will pull the roughly 1000 stars of the cluster apart.
I captured the data over two years, 10 total hours of exposure, and
three different telescopes and cameras.
Vol. 40, No. 1
The OBSERVER
The OBSERVER is the monthly
electronic publication of the Twin
City Amateur Astronomers, Inc., a
registered 501(c)(3) not-for-profit
educational organization of amateur
astronomers interested in studying
astronomy and sharing their hobby
with the public.
TCAA OFFICERS
President
Tom Weiland
309-830-0167
[email protected]
Vice-President
Dave Osenga
309-287-0789
[email protected]
Secretary/Webmaster
Lee Green
309-454-7349
[email protected]
Treasurer/ALCor/Registered Agent
Duane Yockey
[email protected]
309-452-3936
3rd Director/Property Manager
Tim Stone 309-531-2401
[email protected]
4th Director/Historian/Editor
Carl Wenning
309-830-4085
[email protected]
January 2015
A NOTE FROM PRESIDENT WEILAND
I trust this finds you all recovered from the hectic month of December. I certainly
hope that you had an opportunity to enjoy time with family and friends however you
chose to celebrate the holiday season.
January always brings with it a chance to look back at the past year and forward to
the next year. TCAA had an exciting year with the continuing improvements to our
newest observatory, the Prairie Sky Observatory. With the addition of two piers (a total
now of four) and an upgraded telescope configuration we continue to increase our
capacity for both photographic and visual astronomy as well as providing another
venue for our Public Observation Sessions (POS). I hope all TCAA members will join in as
we prepare for another exciting year of activities that will allow us to share our “hobby”
with others.
A great opportunity to become more active as a member is available next month at
the TCAA annual meeting on Saturday, February 7, 2015. More information is included
in this issue of The OBSERVER, but I want to again remind you of this date so that you
can make sure it is on your calendar. This is our annual business meeting with dinner
and an invited guest speaker. This year’s featured speaker is Bill Kemp, a regular
contributor to The Pantagraph. Please put this date on your calendar. All TCAA
members are encouraged to attend.
Finally, I want to thank every member who helped to make 2014 such a memorable
year for Twin City Amateur Astronomers. Thanks to all those who participated in our
POS and many other outreach activities. Thanks to The OBSERVER editor and
contributors. Thanks to our donors! Thanks to our officers, minor officers, and directors
for maintaining our equipment and facilities and helping to steer TCAA through 2014.
And thanks to ALL our members for their support through membership in TCAA.
Clear Skies,
President Tom Weiland
2015 ANNUAL MEETING & BANQUET
5th Director
Robert Finnigan
309-846-9533
[email protected]
This year’s Annual Meeting and Banquet will take place on Saturday, February 7, at
6 p.m. We will meet at the Normal Township Hall, 304 E. Mulberry Street in Normal
(just northeast of Ace Hardware). We begin gathering at 6:00 p.m. with the banquet
beginning at 6:15 p.m.
The OBSERVER
The banquet this year will feature Keller’s Catering, and will be available for a fee
Carl J. Wenning, Editor
of
$20
per adult and half that for children ages 12 and under. Our banquet will consist
21 Grandview Drive
of a selection of three entrees (roast beef, ham, and chicken breast), au gratin potatoes,
Normal, IL 61761-4071
green beans, 7-layer salad, rolls, and cake. Drinks will consist of coffee, tea, and water.
Submission deadline is one day Table service will be provided.
before the end of each month.
Our business meeting will consist of reports, award presentations, and election of
the 2015-16 Board of Directors. Nominations for board members and club awards are
MEMBERSHIP DUES
still being accepted so, if interested, please consider nominating yourself.
Mr. Bill Kemp will be honoring us with his presence as keynote speaker. Bill has
Individual Adult/Family $40
served
as librarian for the not-for-profit McLean County Museum of History for elevenFull-time Student/Senior $25
plus years. You might be familiar with him as he writes the weekly McLean County
(senior status equals ages 60+)
History column in the Sunday Pantagraph. His talk is titled The Night the Stars Fell and
To join, send your name, contact
is about the greatest meteor shower in U.S. history – with a McLean County twist. You’ll
info and dues payment to Duane
not want to miss it!
Yockey, TCAA Treasurer, 508 Normal
TCAAers must make banquet reservations by January 30th (no reservations are
Avenue, Normal, IL 61761.
required for the business meeting) by visiting: http://tcaa.us/AnnualMeeting2015.aspx.
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The OBSERVER
CALENDAR OF CELESTIAL EVENTS – JANUARY 2015
MORNING STARS (1/15): Jupiter & Saturn
EVENING STARS (1/15): Mercury, Venus, Mars, Uranus, & Neptune
3/4 Quadrantids Meteor Shower. The Quadrantids is an above
average shower, with up to 40 meteors per hour at its peak
emanating from Bootes. It is thought to be produced by dust
grains left behind by an extinct comet known as 2003 EH1,
which was discovered in 2003. The shower runs annually from
January 1-5. It peaks this year on the night of the 3rd and
morning of the 4th. Unfortunately the nearly full moon will
block out all but the brightest meteors this year.
4 Earth at Perihelion – Earth makes its closest approach to
the sun for the year at a distance of 0.98328 AU.
4 Full Moon. The Moon will be roughly opposite the Sun and
will be fully illuminated as seen from Earth. This phase occurs at
04:53 UTC. Early Native American tribes knew this full moon as
the Full Wolf Moon because this was the time of year when
hungry wolf packs howled outside their camps. This moon has
also been known as the Old Moon and the Moon After Yule.
8
Conjunction – Jupiter is located 5.1°north of the Moon.
10 Conjunction – Mercury is located 0.6° to the lower right of
Venus; if you have not seen Mercury before, this is the time.
13 Third Quarter Moon – Moon rises at midnight; sets at
midday.
January 2015
NEW & RENEWING MEMBERS
The following individuals have paid dues for new
or renewed memberships as of December 31st, 2014.
(Others who paid after that date will appear in the
February 2015 issue of The OBSERVER.)
Allan Saaf
Duane Yockey
Orlyn Edge
Larry Leetzow
Michael Wanless
DUES BLUES
If you have received a “your dues are due”
statement along with the email that brought you this
issue of The OBSERVER, please remit your dues to Mr.
Duane Yockey, TCAA Treasurer, 508 Normal Avenue,
Normal, IL 61761. Current dues are $25 for senior (60
years of age and over) and $40 regular.
SUBSCRIBING TO OUR E-MAIL LISTS
By subscribing to a group’s mailing list you will
receive email messages from the group so you won’t
have access to the group’s web features (like photos,
files, links, polls, calendar, etc.) unless members
activate it later. The club now has two email listservs.
The main email listserv is known as the TCAA listserv.
It will be used to share announcements and reminders
about astronomical and club events. To join this main
listserv you must do the following:
1. Subscribe: Send a blank email to [email protected] Note: You’ll be sent a
confirmation email from the group. Reply to the
confirmation email to activate your subscription.
16 Conjunction – Saturn is 1.9° to the lower right of the 2. Unsubscribe: [email protected]
Moon.
3. To post a message: [email protected]
14 Mercury GEE – Mercury is at greatest elongation 18.9°east
of the sun. Now is a good time to look for Mercury after sunset.
20 New Moon. The Moon will be roughly between the Earth and
the Sun and will not be visible from Earth. This phase occurs at
13:14 UTC. This is the best time of the month to observe faint
objects such as galaxies and star clusters because there is no
moonlight to interfere.
A second listserv – TCAA–imaging – is for club
astronomical photographers as well as those who
want to view their images and follow their discussions.
It is an easy way to keep up with all the stuff we’re
doing at the observatories.
21 Conjunction – Mercury is located 3.0° below the Moon and 1. Subscribe: [email protected]
2. Unsubscribe: [email protected]
Venus is located 5.6° to the left of the Moon.
3. To post a message: [email protected]
22 Conjunction – Mars is located 3.9° to the left of the Moon;
Neptune is about 3.5° to the lower left of the Moon.
26 First Quarter Moon – Moon sets at midnight; rises at midday.
3
Once members join a Yahoo! group, they can manage
group and subscription settings whenever it is desired
to customize the group experience.
Vol. 40, No. 1
The OBSERVER
January 2015
THIS MONTH’S PHASES OF THE MOON
Full Moon
January 4
Third Quarter
January 13
New Moon
January 20
First Quarter
January 26
All moon phase dates are given for Central Standard Time. Additional moon phases can be found for the 2015 calendar
year by clicking here. These four images were provided by J.K. Howell of the Champaign-Urbana Astronomical Society and are
used with permission.
CALENDAR OF CELESTIAL EVENTS (CONTINUED)
Question: The December solstice occurred on the 21st, yet the earliest sunset and latest sunrise did not occur on that date for
the northern hemisphere. What gives?
Answer: While it is a commonly believed that the latest sunrise and earliest sunset occurs on the date of the December
solstice, this just is not so. While the shortest period of daylight does occur on the solstice, is because of the differences
between the times of sunrise and sunset, and not the actual times of sunrise and sunset. It so turns out that the date of last
earliest sunrise was December 7, 2014 and the next latest sunrise will be January 5, 2015. This situation results from the fact
that Earth's orbit around the Sun is elliptical, and also due to the fact that Earth’s rotation axis is inclined about 23.44 degrees
to its orbital axis. The tilt of Earth’s axis causes a changing daily path across the sky for the sun giving us changing lengths of
days over the course of a year. But, due to its elliptical orbit, Earth moves fastest when it is closest to the Sun in early January,
and slowest when it is farthest from the sun in early July. In early January, Earth traveling more rapidly than average around
the sun, it continues to spin on its axis at the same rate no matter where it is in its orbit. As a result, the sun moves more
rapidly toward the east along the ecliptic requiring more than 24 hours to bring it to the same point in the sky. This strange
and complex confluence of events causes the latest sunrise and earliest sunset to be offset from the date of the solstice by
about two weeks.
BOARD OF DIRECTORS: WHY NOT YOU?
Nominations are now being sought for the 2015-2016 Board of Directors. A new Board will be elected at the club’s
Annual Meeting on February 7th. In accordance with the club’s Bylaws, the president and vice president are determined by
the Board members at their first meeting and are selected from among the Board members. Other officers and positions –
secretary, treasurer, historian, newsletter editor, ALCor, and property manager – are appointed from the membership. If you
are interested in running for the Board of Directors or accepting an appointed position, please contact TCAA President Tom
Weiland at [email protected]. Nominations will be accepted up to the time of the elections at the Annual Meeting.
CALL FOR CLUB AWARD NOMINATIONS
Each year at the club’s Annual Meeting and Banquet, Board members are elected, bylaws amendments voted upon,
annual reports are given, and members are recognized for their service to the club and field of amateur astronomy. 2015 will
be no different. The Board of Directors is now calling for award nominations in three categories.
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Nominations are now being accepted for the John and Bertha Kieviet Founders Award. This award is conferred upon a
TCAA member to recognize demonstrated leadership to the club. Those so recognized need not have been a president of the
club. If leadership is interpreted in terms of service to the membership, this is as close as the TCAA comes to having a
distinguished service citation.
Nominations are now being accepted for the Eugene and Donna Miller Family Award. This award acknowledges the
strong efforts by a family to participate in the club as a unit. One or more parents are recognized for their efforts to instill
within their children interest in and dedication to amateur astronomy.
Nominations are now being accepted for Lifelong Honorary Membership. This designation is reserved for those TCAA
members show have provided exceptional meritorious services to the club in terms of contributions of time and resources.
This signal honor has been conferred only five times in the 55-year history of the TCAA.
During the past 5 years, the following individuals have been recognized:
Award
Kieviet Founders
Miller Family
Lifelong Honorary
2010
Not awarded
Paul Pouliot
Not awarded
2011
William Carney
Not awarded
Robert Finnigan
2012
Lee Green
Not awarded
Not awarded
2013
Not awarded
Not awarded
Not awarded
2014
Not awarded
Not awarded
Not awarded
Please e-mail your nomination(s) to President Tom Weiland at [email protected] or Secretary Lee Green at
[email protected]. When recommending candidates a short description explaining why you feel the nominee(s)
deserve(s) the award(s) is required. The current Board of Directors and appointed officers will make decisions about the
awards during the January 6th Board meeting, so be certain to get your nominations in at least a day before.
ASTROBITS
 While in Florida on December 5th, member Dave Peters reported on the launch of spacecraft Orion. (See his image to the
right.) According to Dave, “It was cloudy but I saw the flame for about 20 seconds before it disappeared into the clouds.
Then a loud rumble occurred for about a minute. It was enjoyable. Yesterday
they canceled. First the weather delayed them, then they found a valve
problem. I'm glad they got it fixed and successfully launched today.” What an
auspicious time and place to be!
 The club leadership is looking into two maintenance problems at the Sugar
Grove Nature Center observatories. As noted in the minutes of the November
Board of Directors meeting, Prairie Sky Observatory needs some sort of track
treatment to reduce rusting, and Sugar Grove Observatory needs to have its
cooling fan either lubricated or replaced. See the images below.
 December 2014 has been a “record breaking” month according to the National
Weather Service – record breaking to the extent that it has proven to be the
cloudiest December since record keeping began.
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 Carl Wenning had a busy but
enjoyable day on Monday,
December 8th. He hand
lunch with Doug Lehr,
former nature interpreter at
Moraine View State Park
from 1999-2000. Doug, as a
very few of the readers will
recall, worked with the
TCAA to hold public talks
and viewing sessions during those summers. He also started a small nature center that was abandoned following his
departure. Also, Carl met with five members of the CUAS over dinner at the Farmer City Family Restaurant to talk about
our experiences with building public observatories. They were most interested in hearing about our vision statements,
our motivation, our relationships with other entities, and financial support for the efforts. Carl encouraged the group to
build a substantial observatory with the expectation that someday, somehow, someone would step forward with the
donation necessary to install one or more major telescopes. In the mean time, the facility would be an excellent location
to house and use some of the members’ larger instruments.
 On December 9th, Carl W. met once again with Dr. Patrick McGuire from Berlin Free University who happened to visiting
town. You might recall that Patrick is from Bloomington, and works on the mapping of Mars for the European Space
Agency. He shared with Carl his work which is an extremely high-resolution surface map that is freely available online at
http://maps.planet.fu-berlin.de/. Check out the detail by clicking on that web page’s long vertical boxes; they will take
you to thumbnail images of maximum resolution images all over the surface of Mars.
Index map to the surface of Mars created in part by Patrick McGuire working with ESA On the actual web page, click on
any of the boxes to gain access to high-resolution orbiter images. Before downloading massive image files, click on the
“preview” button to see what you will get before downloading.
 Tim Stone and Bob Finnigan were able to install the two Aspen cameras – one new and one repaired – on the 20” and 10”
telescopes respectively. The work was done on the evening of December 11 th. They were also able to install the off-axis
guider assembly (MOAG) and SBIG tracking camera. They then took a ten-minute image of M1, the Crab Nebula in Taurus,
with the 20” that appeared “very good” according to Bob. Tim subsequently noted, “I have not yet finished the checkout,
but so far it's looking like the problems with the cameras have been resolved.”
 We have finally heard back from the Secretary of MSRAL, the group that we thought was going to join NCRAL for the
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2016 NCRAL convention. Despite earlier indications from the NCRAL leadership that MSRAL might be willing to join us,
that won’t be the case. According to MSRAL Secretary-Treasurer Jackie Beucher, “This was discussed at our meeting last
summer, and I think the answer was ‘no’. We wanted to keep our MSRAL meeting separate. Some years it is tough, when
no club volunteers, but we don’t have that issue right now. Sorry I am so late in letting you know.”
SKY INTERPRETATION: PART III
~ by Carl Wenning ~
Editor’s note: The following article is a snippet from my chapter “Sky Interpretation” that I wrote for the Master
Naturalist program’s guidebook – hopefully to be published by the University of Illinois’ Cooperative Extension Service before
long. Over the coming months (when it’s getting too cold for many of us to observe and we become temporary armchair
amateur astronomers) I’ll be highlighting sections of the chapter for our readers. We continue now with the second part
following the introduction that was published in November’s issue of The OBSERVER.
The Moon’s Motions and Phases
The moon’s motion is a bit more complicated than that of the sun, or so it seems. The moon moves from east to west
across the sky daily due to Earth’s rotation. At the same time, the moon moves from west to east among the background of
stars – just like the sun – but this time due to the moon’s monthly revolution about Earth. As a result of these combined
motions, the moon moves across the sky going from east to west on a daily basis, but does not move as quickly as the
background stars. Those move from east to west at a rate of about 15° per hour (360°/24 hours). The moon drifts eastward
among the background of stars at a rate of just over 13° per day. As a result, each evening the moon starts its westward trek
across the sky some 13° farther to the east among the stars. This causes a day-to-day delay in the moon’s rising (and setting)
that averages about 50 minutes over the course of a year.
During the moon’s westward motion across the sky and eastward motion among the stars, the moon continually shifts its
position in the sky with respect the sun. Once every 29½ days, the moon passes the sun as seen from Earth and this results in
new moon phase. About 7⅓ days later, the moon reaches first-quarter phase. In another 7⅓ days, the moon reaches full
phase, then similarly third-quarter phase, and finally new phase once again.
As the moon orbits Earth (see Figure 2), we see more and then less of its sunlit surface. When the moon is located
roughly in the same direction of the sun, the moon’s night side faces us and we “see” a new moon phase. About a week later,
the moon is now one-quarter of its way around Earth in its orbit and we see the side facing the sun being brightly lit and the
side opposite the sun in darkness. About a week later still, and we see the moon roughly opposite the sun in the sky. It now
appears fully illuminated and the side opposite Earth is in darkness. A week further along and the moon it is three quarters of
the way around Earth in its orbit and we see it lit half way once again. So, the phases of the moon are caused when observer
sometimes see more and sometimes less of the moon’s day and night sides; lunar phases have nothing whatsoever to do
with the shadow of Earth.
Figure 2. Explaining the Phases of the Moon.
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The moon’s phases are variously described, but the best terms to use include waxing, waning, crescent, and gibbous.
When the side facing us becomes increasingly lighted (moving from new to first quarter to full), the phase is said to be
waxing; when the moon becomes increasingly darkened (moving from full to third quarter to new), the phase is said to be
waning. The phases either side of new are known as crescent when the moon is less than half full; the phases either side of
full are known as gibbous when the moon more than half full. The monthly cycle of the moon’s phases go as follows: new,
waxing crescent, first quarter (sometimes called evening half moon), waxing gibbous, full, waning gibbous, third quarter
(sometimes called the morning half moon), waning crescent, and new. The cycle then repeats.
Eclipses
Moon phases have absolutely nothing to do with Earth’s shadow falling on the moon. The only time this occurs is during
a lunar eclipse (from the Greek word ékleipsis meaning “abandonment”) when the moon fades from the sky as it passes
through Earth’s dark shadow. This occurs only at full moon phase.
At the time of new moon, the moon usually passes above or below the sun in the sky as seen from Earth. A similar
situation occurs at the time of full moon when the moon passes above or below Earth’s shadow. The moon’s orbital plane is
inclined just over 5° to the ecliptic. As a result, of this misalignment, eclipses of the sun and moon do not occur during most
new and full moon phases. Solar eclipses (or abandonments) occur only at new moon phase when the moon crosses over the
face of the sun as seen by earthlings. Lunar eclipses occur only at full moon phase when the moon passes through Earth’s
shadow. (See Figure 3.)
Figure 3. The shadows of Earth and Moon; images not to scale.
There will be from 4 to 7 eclipses visible from Earth each year. There are between two and five solar eclipses each year,
with between zero and two of them being total eclipses. There are between zero to three lunar eclipses per year where the
Moon passes through at least a portion of the Earth's dark central or umbral shadow (where the sun cannot be seen from the
perspective of the moon thereby producing a partial to total umbral eclipse. Earth’s penumbral shadow surrounds the umbral
shadow. Within the penumbra Earth blocks only part of the sun from the perspective of the moon.
Though lunar eclipses are less common than solar eclipses, people more commonly observe lunar eclipses. This is
because lunar eclipses are much more widely visible from Earth (more than half the planet at a time over the course of the
hours-long event) when compared to solar eclipses that are visible only from restricted regions of Earth’s surface at any one
time.
Solar eclipses come in three types – partial, total, and annular. The latter occurs where the sun appears as a ring of light
in the sky because the moon is located too far from the Earth to totally block the sun from view. (Total solar eclipses occur
only when the moon is near Earth; annual solar eclipses occur only when the moon is far from Earth. These variations show
that the moon follow an elliptical orbit around Earth.) The dark umbral eclipses of the moon come in two types, partial and
total. (Penumbral eclipses are barely noticeable to the casual observer.)
During a lunar eclipse, the moon will take on an array of colors appearing anywhere from a dull white, to orange, to red,
to brown. These colors originate in Earth’s atmosphere as light passing through the atmosphere at the day-night boundary
loses primarily blue light by filtering allowing primarily red light to be refracted into the dark umbral shadow behind Earth.
This is the same phenomenon that causes red sunrises and sunsets on Earth. During a lunar eclipse, the moon is viewed with
the light of a sunrises and sunsets all around the world. Table 1 is a listing of all lunar eclipses visible from Illinois through
2025.
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Date of Eclipse
Type of Eclipse
April 4, 2015
Total
September 27, 2015
Total
January 20, 2019
Total
November 19, 2021
Partial
November 8, 2022
Total
September 18, 2024
Partial
Table 1. Lunar eclipses by type visible from Illinois through 2025.
The conditions of solar eclipses will vary dramatically during a single eclipse due to the location of the observer and the
Earth-Moon distance. Total eclipses of the sun can be seen as such along a long, narrow ground track only about 300 miles or
less wide. Either side of that ground track, observers will see a partial eclipse. Under certain circumstances, the moon will be
located too far from Earth during a solar eclipse to entirely cover the sun. This leaves a ring of light in the sky in what is
known as an annular (from Latin for “ring”) eclipse. The last such event to occur in Illinois was May 10, 1994. Table 2 is a
listing of all solar eclipses visible from Illinois through 2025. Southern Illinois will experience two total solar eclipses during
this time interval. Most locations on Earth experience this rare dual event approximately once every 300 years.
Date of Eclipse
Type of Eclipse
August 21, 2017
Total/Partial
June 10, 2021
Partial
April 8, 2024
Total/Partial
Table 2. Solar eclipses by type visible from Illinois through 2025.
Earthshine
When the moon is close to the sun in the sky (during waxing and waning crescent phases) the moon’s dark night side can
been faintly illuminated. This illumination comes from Earth. Light reflects from Earth to the moon and back again. This faint
illumination is known as Earthshine – not moonshine – for a very obvious reason!
Lunar Topography
The presence of dark basaltic lavas filling numerous craters on the moon’s near side – as opposed to the basalt free lunar
mountains that are made up mostly of a lighter anorthosite – gives the moon a unique topology – patterns of light and dark.
The dark regions tend to be round and smooth – so smooth in fact that early astronomers observing through rather poor
quality telescopes called these areas walled seas or “maria”. The light regions tend to be rugged and are today referred to as
highlands. The mixture of darker maria and lighter highlands gives rise to several images when the imagination is put to use.
(See Figure 4.) Some see a man in the moon, others a matronly woman’s face looking upward to the left, others still a woman
reading a book. The Swedes always claimed that Jack and Jill went “up the hill” to fetch a pail of water. The hill actually turns
out to be the moon. Anyone who looks carefully at the time of full moon can see the two standing side by side on the surface
of the moon with the pail between them and there, on the ground between them, a splash of water.
Figure 4. Images visible on the moon to those with an active imagination.
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Tidal Locking
Observant moon watchers will note that the moon always keeps the same side facing Earth. This is due to tidal locking
that keeps the moon’s rotation pretty much in lockstep with its revolution. As a result of tidal locking, the moon rotates once
on its axis for each time it revolves around Earth – one rotation per revolution. Tidal locking results from Earth’s gravity
“holding on to” dense mass concentrations (dark basaltic lavas) that appear on the near side of the moon as “seas” (and not
much at all on the far side). This coupling is not entirely synchronous and – in combination with the moon’s inclined and
ellipsoidal orbit as well as the changing position of the observer – results in libration. As a result of the combination of these
effects the moon liberates or wobbles back and forth and tip up and down over the course of a month. This allows humans to
see some 59% of the moon’s surface over time.
The Moon Illusion
The full moon upon rising and setting appears much larger than when viewed higher up in the sky. The fact of the matter
is the moon is actually larger when higher in the sky because the distance between the observer and the moon is smaller – if
only by a tiny amount. This large apparent difference in size is known as the moon illusion. This illusion is also seen as the sun
and star patterns such as Orion or the Summer Triangle when near the horizon. When measured with scientific instruments,
the difference is actual angular size is almost imperceptible. What causes this illusory change in size?
The simplest explanation is that we are viewing the railroad track (or Ponzo) illusion inverted. (See Figure 5.) We
probably all have seen two blocks of identical size resting as it were on parallel railroad tracks that converge in the distance.
One block looks nearer and the other block looks farther. The more distant block appears larger than the nearer block despite
the fact they are of identical size. The background in some way influences the apparent sizes of the blocks.
Figure 5. The Ponzo Illusion
The sky overhead by day seems much closer than the sky near the horizon as shown in Figure 6. Clouds overhead might
be two or three miles up whereas the same cloud near the horizon will be many more miles distant. This gives the impression
the higher means nearer and lower means farther. This impression is somehow carried over into the night sky. When viewing
the actual moon at different elevations above the horizon, the same moon appears larger when viewed against the distant
horizon and smaller when viewed higher up in the sky. It is as if the railroad track illusion has been turned upside down. The
lower block now appears larger than then higher block. So it is with the moon illusion. What you see is not real. That’s why
it’s known as an illusion.
Figure 6. The hemispherical appearing sky causes the moon illusion.
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Calendar Keeping
The motions of both sun and moon are used for the keeping of calendars – civil and religious. For instance, the year is
roughly equal to the period of time required for Earth to orbit the sun once. (Technically, this is known as a sidereal year –
the time required to move precisely 360° around the sun measured with respect to the stars. It has a length of 365.256363
days. The year of 365.242199 days and upon which the civil calendar is based is known as the tropical year. The two differ in
length by only 20.4 minutes. The difference is due to Earth’s precession or wobbling on its axis.)
The period of the month is based upon the moon’s synodic period, 29.5 days, which is the period from full to full or new
to new phase. It is also the period of time it takes the moon to go through a complete orbital motion with respect to the sun
that – like the moon – is moving eastward along the ecliptic. The time required for the moon to orbit 360° with respect to the
stars is known as the sidereal month. It consists of some 27.3 days.
It is interesting to note that the names of weekdays are based on the sky as well. Such can be seen in the worlds
“Saturday” (Saturn day), “Sunday” (sun day), and “Monday” (moon day). In Nordic the names of the planetary gods also can
be found: Tiu’s day (Tuesday), Woden’s day (Wednesday), Thor’s day (Thursday), and Freya’s Day (Friday). And in Spanish we
have lunes (Moon’s day or Monday), martes (Mars’ day or Tuesday), miércules (Mercury’s day or Wednesday), jueves
(Jupiter’s day or Thursday), and viernes (Venus’ day or Friday).
Today’s civil calendar is based primarily upon the motion of the sun. Religious calendars historically have been based on
the motions of the moon. In Christianity, Judaism, and Islam, events such as Easter, Passover, and Ramadan are based on the
phases of the moon. For instance, Easter falls on the first Sunday after the first full moon of spring. A similar rule applies to
Passover. The Jews add an “intercalary” month about every three years to bring the civil and lunar calendars back into
alignment so that Passover remains a spring event. Moslems do not introduce this extra month into their lunar calendar and,
as a result, the month of Ramadan – which lists one synodic month – can start during any season of the year. During 2014
Ramadan began on June 28th and ended on July 28th. During 2015 Ramadan begins on June 18th and ends on July 17th – 11
days earlier. This earlier start each year is due to the difference between 12 lunar months (354.37 days) and the length of the
civil year of 365.25 years. This amounts to approximately 11 days (365.25 days – 354.37 days = 10.88 days).
EDUCATION AND PUBLIC OUTREACH FOR DECEMBER 2014
Carl Wenning gave a telescope talk and
demonstration to a group of 5-6 Boy Scouts
at the Challenger Learning Center on
Saturday, December 6th. The group, working
on the Astronomy merit badge, was
assembled from different troops. Among the
Scouts was our own Bryce Heiniger. Carl
enlisted Bryce’s aid in describing how
reflecting telescopes work because he has
become a capable observer making good
progress on his AL Messier observing
program. At the completion of this activity,
Carl (a registered Astronomy merit badge
counselor) recommended to program
director Stacey Shrewsbury that Bryce be awarded his merit badge as he clearly has demonstrated all the skills expected.
Congratulations, Bryce, on earning this merit badge – one of the more difficult among those currently available. Also in
attendance at this session was Bryce’s dad Mark.
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January 2015
ASTROPHOTOGRAPHY ON THE CHEAP (PART 1)
~ by Tim Stone ~
Astrophotography can be an expensive hobby. Along with the obvious expense of an observatory equipped for
astronomical imaging, there are other expenses that present a barrier to entry. One of the primary hidden costs is the
software needed to process images. Sophisticated image processing systems like Photoshop and PixInsight cost hundreds of
dollars, and there seems to be no end of niche software to accomplish particular effects. Being somewhat of a frugal person,
before I bought Photoshop I thought I'd try using freely available software to process the astronomical image data I could get
from sources like the Hubble Legacy Archive. After a while I concluded that it was not feasible, shelled out the money for
Photoshop, and went on from there. It turns out, though, that some good processing can in fact be done with no-cost
software. I just didn't know what I was doing back then!
This is the first of a series of articles in which I will demonstrate a process to create good astronomical images using only
free software. You will learn how to acquire image data from the Hubble Legacy Archive, convert the image data into
processable TIFF data, and apply some basic processing to enhance the image and save it as a JPG file. Then, building on
those tools and techniques, you will learn how to create full color images. Finally, you will learn to further enhance the basic
color image. With these procedures you can create beautiful astrophotos without dropping a cent. If the bug bites, you can
then consider whether or not you want to invest in paid software to advance your skills and capabilities.
We will work with data from the Hubble Space Telescope of NGC 4038/4039, a beautiful interacting pair of galaxies that
fits nicely in the Advanced Camera for Surveys field of view. Below is my version of this image, created using only the
software described in these articles. If the thought of creating this image by yourself excites you, then read on!
Acquiring data from the HLA
Every single image the Hubble Space Telescope has ever taken is publicly available on the Hubble Legacy Archive,
provided it has cleared the scientific embargo period. A sophisticated search engine makes locating image data for particular
objects or coordinates a snap. The first order of business is to bring up the HLA search page in your browser. If the simple
search screen (the default) is shown, then click on the “advanced search” link next to the Search and Reset buttons. This will
show the Advanced Search page. It has the selection criteria at the top, and a tabbed section at the bottom, in which the
search results will be shown. The “Inventory” tab will show a table of search results; “Images” will show a thumbnail view of
the results; “Footprints” will show the field with all individual results annotated; “Cart” will show all the files you have
ordered.
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Type “NGC 4038” in the text field at the top of the form, and then deselect all the instruments except “ACS” in the
“Selection:” section. Click the “Search” button, and the HLA will return all the HST images ever taken with the ACS instrument
that include NGC 4038. The resulting page should look like this:
You can click on the “Images” tab to see thumbnails for each of the results, or you can scroll down the “Inventory” list
and click on the “Display” link for any results that look interesting. For this exercise, we are interested in the ACS/WFC image
made using the F550M filter (green) with the WFCENTER aperture. This beautiful image is actually a stack of six individual
frames, combined in such a way as to eliminate the ugly inter-CCD seam running through the middle of raw ACS images.
When you’ve found this image on the Images tab, click on the “FITS-Science” link. This puts the image in your shopping cart.
Now click on the “Cart” tab. You’ll see the file you ordered in the cart contents list. At this point, if you’d like, you can go
find more data you’d like to order. Bear in mind, though, that these files are not small. The one we’ve selected is 135mb! For
our purposes right now, you can go ahead and click the “Fetch HLA Data” button, and let the download begin.
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Once the download is complete, you should see a file in your download directory (or wherever you store downloads)
with a name starting with “HLADATA.” The remainder of the name is unique and not predictable. You may use Windows, or a
free utility such as 7-Zip to open this file. The zip file contains one subdirectory, which contains a file named
“HST_10188_10_ACS_WFC_F550M_sci.fits” Copy that file to a working directory. That’s all it takes to get data from the
incredible treasure-trove of the Hubble Legacy Archive. Now you’re ready to start processing the data!
Conversion to TIFF
The next step in creating an astrophoto you can show the world involves converting the image embedded in the FITS file
you just downloaded into a format that can be displayed on a web page, sent via email, or printed. In addition to format
conversion, the image in the FITS file isn’t particularly bright. It will need to be “stretched” in order to have an image you can
proudly display.
In astronomical imaging, virtually all image data are contained in files formatted as FITS - Flexible Image Transport
System. This universally recognized file format ensures that both image data and information about that data are inseparably
linked, including information about the imager, imaging system, object being imaged, exposure times, temperatures,
technical factors, and such. Unfortunately, most commonly used image viewing software does not recognize this format.
Even Photoshop requires a plugin to process FITS files. However, since NASA was the creator of this format, it gave the world
a program to read them, enable some rudimentary processing, and create TIFF files from them, which are usable by virtually
all image viewers and processors, both free and paid software. This program is called FITS Liberator, and is freely available
from NASA on SpaceTelescope.org. You should download and install this tool now so you can follow the next step of this
tutorial.
Once you’ve installed FITS Liberator, double-click on its icon to start it. It will show a file selection window, and you
should navigate to the working directory where you copied the FITS file, select it, and hit OK. You should now see the FITS
Liberator processing window.
The window includes a zoomable viewer, a histogram, a section for processing parameters, and on the far right the
buttons for loading and saving files. As you can see, the raw data are rather low contrast, not at all what is needed for a
pleasing image. This is because astronomical objects are quite dim, and even long exposures can sometimes yield only a few
hundred or a few thousand photon counts. This is evident by the histogram's shape, with the majority of the pixels at the far
left, the dark end of the histogram.
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An image’s histogram is very important. This graph shows the distribution of pixels of different brightness, generally
proceeding from the darkest at the left to the brightest at the right. Again, we can see from this histogram that the image
data are very strongly concentrated to the left, the dark end of the histogram. The viewer seems to show the image, but this
is because the viewer is applying its own stretch so you can see what’s there.
Before stretching, make sure the checkboxes on the right side of the window for “Preview,” “White clipping,” and “Black
clipping” are checked. There are many stretching schemes in FITS Liberator. The one most often used for amateur
astrophotography is "Log(x)." Select the Log(x) stretch function on the dropdown just to the right of the bottom edge of the
image viewer. This will stretch the image, and you'll see that the histogram shape has significantly changed. The sharp
concentration at the dark edge has disappeared, with a much more gradual slope downward to the right. You can also see
the galaxies better now.
We still have a ways to go, though. We can see by the blue and green places in the viewer that the image is both black
and white clipped. This is not good, so we will make a set of adjustments to set appropriate black and white points. These are
the points in the histogram below which any data will be interpreted as black, and above which any data will be interpreted
as white. First, we adjust the black point, by moving the black slider underneath the histogram. Move it to where it just
touches the left side of histogram. If you move it farther to the right, you'll notice portions of the image turning blue. FITS
Liberator is showing areas of the image that are being "clipped," where there are data that are not black but is being turned
black because of the black point you've selected. If you move it farther to the left, you’ll notice the background brightening,
lowering the overall contrast of the image. Select a black point that doesn’t clip, but still maintains a nice dark background.
Once we've selected our black point, we'll do the same with our white point. The default position for the white point has a
considerable amount of the histogram to its right. The bright pixels are also clipping, and FITS Liberator shows that by turning
clipped pixels green. You'll see that many of the stars are clipped. There are approaches and techniques for avoiding star
clipping, but for this exercise (this is free software, after all) we'll have to accept that stars will be clipped. Even with clipped
stars, the galaxy is still too dim, so we will have to move the white point to the left to brighten it. Be careful not to move it so
far that bright areas of the galaxies are clipped. Only move it to the point where the galaxy shines clearly in the viewer.
For this activity, it may be helpful to use the zoom feature of the viewer to look more closely at particular areas of the
image. When zoomed, you can click and drag in the image to see different areas. For my black and white points, I moved my
sliders to where -0.06 showed in the black level indicator below the sliders, and 0.47 showed in the white level. This did leave
a few areas of the galaxy white clipped, but that’s a reasonable compromise. To move the white slider to the point where
nothing is white clipped would result in a rather dark image.
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Now we're ready to save a TIFF of this image. Click the “Save File” button and in the resulting file locator window,
navigate to your working directory, and then click “Save”. Don't change the file name; it's useful to be able to correlate your
TIFF files with your FITS files. And there you have it. You've created a stretched TIFF file from the FITS file for NGC 4038/4039.
Process for a beautiful result
The final step in this exercise is to convert the TIFF file to a JPG file suitable for showing all your Facebook friends. To do
this, you will need photo-editing software. There is plenty of this out there, but the free software we will use is Paint.net. It’s
great for general photo editing, can read the 16 bit TIFF files produced by FITS Liberator, and like all photo software, can store
images as JPG files. Go ahead and download and install this software. If you already use other photo editing software, and it
can read 16 bit TIFF files, then you can probably do the steps below in that program. You’ll have to translate the instructions
from Paint.net to whatever program you’re using.
Once you’ve installed Paint.net, double-click on its icon to start it up. You’re presented with a screen with a few auxiliary
windows showing. There are windows for “Tools,” “History,” “Layers,” and “Colors.” These are useful windows, but if they are
in the way, you can close them. You can always reopen them by clicking on their respective icons in the upper right of the
main window.
Open your TIFF file by clicking on the Open Folder icon in the upper left, or using File->Open in the window’s menu bar.
Navigate to your working folder, select the TIFF file, and click the OK button. Your image now appears in the main editor
window.
Your image at this point is almost 6000x6000 pixels. This is far too large unless you use a website like Astrobin.com that
can manage full resolution images. Email and social media use much smaller versions of images. 800x800 pixels is a good
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starting point. Click “Image->Resize” in the window’s menu bar, type 800 in the image width, and hit OK. This makes the
image a very manageable size. If you find it’s too small, change the size to something larger. Be aware, though, that you will
have to undo the first resize before you resize it again. “Edit->Undo” in the window’s menu bar will do that. Don’t forget!
Now it’s time to save your image as a JPG by clicking File->Save As from the window’s menu bar. Click in the “Save as
type:” list below the file name, and select JPEG. Again, don’t change the name, as it is always useful to correlate various
versions of files. When you click the “Save” button, another dialog will show asking you to select a “Quality.” For most
purposes, 80% is a reasonable setting for this. Slide the Quality slider until 80% shows to the right of it, or simply type 80 into
the field. Click the OK button, and you’re done!
What’s next?
While you’re probably excited to have processed a Hubble Space Telescope image into your very own version, you may
feel this exercise has come up short. You have a black-and-white image that doesn’t really stand out. In the next article, I will
describe how to create full color images and use Paint.net to apply adjustments to them to enhance the image. For now, you
have the tools and a basic workflow to process HST images into usable versions for your own use. Take some time to practice
this workflow, and get to the point where you can follow it pretty much without aid. You will do this a LOT if you decide you
want to take up this beautiful and rewarding aspect of astronomy.
BUILDING A DOBSONIAN TELESCOPE
~ by Scott Woodrum ~
Hello TCAA, My name is Scott Woodrum. I’m a new member of the group and I want to share with you the Dobsonian
telescope I’ve built following the plans posted at http://stellafane.org/tm/dob/index.html. My goal was to build a simple,
portable 6” telescope within a limited budget. I estimate the final cost for the optics and other raw materials to be around
$250.00 and 20-25 hours of time.
The plans and photos on the Stellafane site are for building a 6”,
f/7.5 scope; I went with a 6”, f/8 mirror design. By using the telescope
design software sponsored by Stellafane (http://stellafane.org/tm/newtweb/newt-web.html) I was able to fit everything into a 4’ Sonotube
without cutting.
I deviated from the Stellafane plans in a few areas. For example, I
used ¾” plywood for most of the rocker mount. I went with a cheaper
and readily available textured laminate for the altitude/azimuth bearing
contact materials. The ground board is mounted on lockable caster
wheels rather than the suggested hockey pucks. Other than those few
things, the final product is closely patterned after the one on the web
site.
The telescope saw first light on December 11, 2014 from my
backyard in Normal. I experimented with various eyepieces and was
easily able to resolve Jupiter and its moons. I pointed at a few of the
brightest stars and aligned the finder scope. The azimuth/altitude
bearings were quite smooth and held the telescope in position without
requiring a lot of effort to move.
Overall I’m very happy with the way the telescope turned out. I can’t
wait for warmer weather and darker skies to really get an idea of how it
will perform! The plans from the web were very detailed and complete
and kept the required tools to a minimum. If I had to do anything
differently, I might have purchased a Crayford-type focuser, as the
scratch-built PVC focuser is simple but requires some manual effort to find/maintain focus – but that is only a minor problem.
I would highly recommend following a similar approach to building a first scope for a beginning maker.
If anyone is interested in building a similar scope or has any questions, send me an email at [email protected].
Thanks! Clear Skies!!
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January 2015
LAST MINUTE IMAGES
As this issue of The OBSERVER was about to go to press, Bob Finnigan provided a couple of images showing the
excellence of the new Aspen camera recently obtained and mounted on the 20” PlaneWave telescope of PSO.
Messier 1, the Crab Nebula, taken Thursday, December 18
with the 20” PlaneWave telescope. The image consists of
one 10-minute exposure with the new Aspen camera, Moag,
and SGIB guider. No flats were used in processing this image.
This image of Messier 1 was taken on December 28th, again
using the 20” telescope of Prairie Sky Observatory. This image
is a composite of three 20-minute color pictures (red, green,
and blue) and 3 20-minute images in the light of H-alpha.
HOWTIMEFLIES
TCAA Historian Carl Wenning provides monthly updates about the history of the club going back to intervals of 50, 25,
and 10 years. Details about all mentioned events will be found in either the Twin City Amateur Astronomers: 1960-2010 or in
The OBSERVER archive found on the TCAA website.
50 Years Ago: January 1965 – The club is using IWU’s 6¼-inch refractor at Behr Observatory following twice-monthly club
meetings. The observing membership has just completed a “run” of viewing four different Cepheid variable
stars lasting as many months. Attention is now being turned to Mira long-period variables starting with
Omicron Ceti. David Williams is leading the effort.
25 Years Ago: January 1990 – Because the club’s silver anniversary meeting at Ewing Manor was such a joy, the club held its
30th anniversary meeting there as well. Mr. Fred Fissel Jr., owner of the TCAA observatory site just north of
Normal, passed away on January 12th. Though never a club member, he was a good friend of member Bob
Mayo. Mr. Fissel was also a beekeeper, and that’s where the name “Beehive Observatory” originated.
10 Years Ago: January 2005 – On January 29th, twenty-nine members and friends of the TCAA participated in a mission at the
original Challenger Learning Center at “the formal terminal building of the Central Illinois Regional Airport”.
The membership had a rendezvous with a comet by the name of TCAA1. Participants experienced what it might
be like to work in a space ship and at mission control. Participants were elated with the experience.
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TCAA TREASURER’S REPORT – DECEMBER 2014
OPERATING FUND BALANCE – November 30, 2014 -
$ 2,480.23
Income
Michael Wanless (Dues) Orlyn Edge (Senior Dues) Larry Leetzow (Senior Dues) Allan Saaf (Dues) Duane Yockey (Dues) -
$
$
$
$
$
41.00
26.00
26.00
41.00
40.00
PayPal (Michael Wanless) PayPal (Allan Saaf) PayPal (Orlyn Edge) PayPal (Larry Leetzow) -
$
$
$
$
1.20
1.20
0.87
0.87
Expenses
OPERATING FUND BALANCE – December 31, 2014 -
$ 2,650.09
OBSERVATORY FUND BALANCE – November 30, 2014 -
$ 4,491.65
Income
None -
$
0.00
None -
$
0.00
Expenses
OBSERVATORY FUND BALANCE – December 31, 2014 -
$ 4,491.65
INSURANCE ESCROW BALANCE – November 30, 2014 -
$ 5,274.00
Income
None -
$
0.00
None -
$
0.00
Expenses
INSURANCE ESCROW BALANCE – December 31, 2014 -
$ 5,274.00
TOTAL TCAA FUNDS – December 31, 2014 -
$12,415.74
Respectfully submitted,
L. Duane Yockey, Treasurer
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