Download For Me? You Shouldn`t Have! - Robert Ferguson Observatory

Spring2003
2010
Spring
Volume
XIII
Number 2
2
Volume
VI Number
For Me? You Shouldn’t Have!
By Robert Davis
I had a very good birthday this
year. Friends and family got together
and a good time was had by all and
NASA launched a new solar
observatory in my honor. Maybe they
didn’t really launch in my honor but it
was on my birthday which is pretty cool.
This new solar observatory is called
SDO: Solar Dynamics Observatory and
it was launched on February 11, 2010.
(You might want to make a note of the
date for next year.) According to the
mission’s website, “SDO is designed to
help us understand the Sun’s influence
on Earth and Near-Earth space by
studying the solar atmosphere on small
scales of space and time and in many
wavelengths simultaneously”. I guess
one could say it will shed some light on
sunlight.
SDO will be in an orbit 36,000
km (about 22,400 miles) above the
Earth. The orbit will be an inclined
geosynchronous orbit which will allow
for continuous observations of the Sun.
There are other orbits that would have
achieved the same viewing capabilities
but the other reason for the
geosynchronous orbit is that it allows for
a single dedicated ground station to
receive the tremendous amount of data
that SDO will be transmitting. SDO will
have a continuous science downlink rate
of 130 Megabits per second. It is
going to need that bandwidth to transmit
all the imaging data that it will generate
because SDO will be taking a whole
lot of pictures. How many pictures?
Stay tuned.
Public Viewing at
Robert Ferguson
Observatory
April 24, Saturday
Public Solar Observing
Public Observing Night
noon – 4 pm
9 pm
May 15, Saturday
Public Solar Observing
Public Observing Night
noon – 4 pm
9 pm
June 5, Saturday
Public Solar Observing
Public Observing Night
June 12, Saturday
Public Solar Observing
Public Observing Night
July 10, Saturday
Public Solar Observing
Public Observing Night
solar magnetic field lines
We’ve all heard about solar
wind, solar flares and coronal mass
ejections (CMEs). We’ve heard about
Sun spots and the 11 year Solar Cycle.
All of these phenomena occur because
the Sun is a very active object and
sometimes it is more active than others.
Scientists have some ideas about how
the Sun works and why space weather
happens but they don’t have a very
good handle on how to predict how
the Sun will behave in the future. Being
able to predict solar activity is
important because there are currently
(turn to SDO Page 7)
http://www.rfo.org
noon – 4 pm
9 pm
noon – 4 pm
9 pm
noon – 4 pm
9 pm
Evening public viewing is $3 per adult, 18
years or older, plus $8 per car State Park
fee. Donations accepted. Dress for cold
nights! For current observatory
information call (707) 833-6979.
RFO Classes (see Page 3)
Night Sky Spring/Summer Series
April 6 & 13
June 8, 15 & 22
July 6 & 13
August 10
Observing Labs
Star Formation: June 13
Star Death: September 6
State Park Closure Update
Although Sugarloaf Ridge State Park is
closed three days a week, this closure is not
affecting observatory operations. Dates
that RFO is open are special events; docents
and visitors are able to access the
observatory.
Page 2
Focused
A quarterly newsletter
published by:
The Valley of the Moon
Observatory Association
P.O. Box 898
Glen Ellen, CA 95442
707.833.6979
www.rfo.org
Editor:
Publisher:
Derek Braud
Colleen Ferguson
Contributors:
Robert Davis
Colleen Ferguson
Loren Stokes
Jack Welch
President's Message
Subscriptions
Fill out & mail form on back page or subcribe
online at www.rfo.org (see Join Us!)
Advertising
Contact the editor, Derek Braud:
[email protected]
Submission Guidelines
Unsolicited submissions are welcome and will
be published at the discretion of the editorial
staff. Send submissions to the editor,
Derek Braud: [email protected]
VMOA Mission Statement
The VMOA is a group of volunteer amateur and
professional astronomers organized as a nonprofit association to provide educational
programs about science and astronomy for
students and the public. To that end, the VMOA
operates the Robert Ferguson Observatory in
Sugarloaf Ridge State Park in association with
California State Parks.
VMOA Board of Directors
President:
Vice President:
Treasurer:
Secretary:
Members:
Colleen Ferguson
Larry McCune
Steve Peterson
George Loyer
David Cranford
Rob Davis
Mark Hillestad
Bill Russell
Gordon Spear
Steve Smith
by Colleen Ferguson
After a long, wet winter the skies above
RFO are clear and dazzling for spring.
Sugarloaf Ridge State Park by day is
filled with colorful wildflowers, brilliant
green hills and whitewater streams.
Recent solar viewing shows that our sun
is becoming active again, bouncing up
from the bottom of the 11-year solar
cycle. After many Saturday afternoons
explaining to the public what an amazing
and rare sight they were seeing – a
spotless disk – the solar astronomers
are looking forward to pointing out solar
phenomena again. The increase in solar
activity is turning into a new goal for
RFO: acquiring a Coronado 90 solar
telescope. The Coronado 90 will
provide incredibly sharp, high-contrast
h-Alpha views that can reveal detail and
structure and produce stunning visual
and photographic images. It is used
around the world by serious solar
enthusiasts and professional research
facilities. In a rave review of this
telescope at nightskyobserver.com,
author Kevin Berwick pointed out that
the sun is completely unaffected by light
pollution and that with this scope we
can view prominences every day
without waiting for a total eclipse and
paying the high cost of travel. Here’s
an excerpt from the portion of the
Spring 2010
review titled First Light: “The overall
impression, particularly at low power,
is that the Sun is transformed from a
harmless outdoor light into a seething
‘Death Star’. You really do get an
appreciation of the fact that what you
are witnessing is a contained
thermonuclear explosion.” His only
regret was that he did not buy one
sooner so that he wouldn’t have to wait
so long for the next solar maximum.
We’re starting fund raising now in hopes
that we can raise $10,000 and start
enjoying the sun’s increasing activity with
an awesome new solar scope.
Meanwhile the amazing team of
telescope makers designing and
constructing Project 40 are making
great progress. The large primary
mirror is going through the final stages
of testing and polishing and the
secondary mirror is being ground. Parts
for the drive mechanisms are arriving
and being tested. Minor details are
being added to the design drawings to
make sure everything will work together
as the telescope starts to be assembled.
After so long in the planning stages this
project is really coming together!
Thanks to everyone who is giving their
time, technical talents, and funds to
make this dream a reality.
Please join me in welcoming
two new members to the VMOA
Board. Many Focused readers are
familiar with Rob Davis since he writes
entertaining and informative articles for
most editions. He is also the highlight
of most of our docent meetings at RFO,
sharing “What’s Going On Out There”
with a mix of technical information and
just plain fun. Rob often volunteers for
private and public events at RFO. Steve
Smith was the winner of the first “Docent
of the Year” award, presented in 2009.
Although he flirts with other RFO
telescopes the CCD seems to have
captured his heart. Steve volunteers for
almost every event at RFO and so he
Spring 2010
Page 3
2010 RFO Class Schedule
Night Sky Spring/Summer Series
Each class includes a lecture on the constellations of the season, their history and mythology, and how to find objects within
them. Learn the bright stars, deep-sky objects, and visiting planets of the season’s skies. After each presentation (sky
conditions permitting), you will enjoy a review of the constellations in the actual night sky and learn how to find them for
yourself. The constellations, and the objects within them, will be viewed through binoculars and telescopes, including the
Observatory ’s 24-inch reflecting telescope, until or beyond 10:30 pm (depending upon interest and enthusiasm).
The remaining Spring Series classes will be held on Tuesdays at 7:30 pm on:
April 6 & 13
The opcoming Summer Series classes will be held on Tuesdays at 7:30 pm on:
June 8, 15, & 22, July 6 & 13, and August 10
Fee: $75 for 6-class series or $23 for a single class
E-mail: [email protected] to reserve a space in this popular class
Observing Labs
An intensive telescope observing session after a brief presentation on the night’s theme. Handouts/Observing lists
provided. Attendance limited to 6.
Star Formation: Diffuse Nebulae, Star Formation, and Open Clusters
Sunday, June 13, at 8:30 pm [Raincheck date: none]
Star Death: The End of Stellar Fusion
Monday, September 6, at 7:00 pm [Raincheck date: none]
Fee: $30.
For reservations, email: [email protected]
brings to the board a wealth of
knowledge about current observatory
operations.
Another new happening for
RFO is creation of a ‘facebook’ page.
If you’re an active ‘facebook’ user
check it out! Just search for the group
Robert Ferguson Observatory and
become a fan.
I continue to be very impressed
with the generosity and talent of the
volunteers that make the observatory
the incredible place that it is. Thanks to
all of the docents - those who interact
with the public at our events and those
who work behind the scenes - as we
go into the busy observing season
ahead. You are all awesome!
Please include your mailing
address and phone number. If you have
any questions, please contact June
Have you been wishing that you had a Ferguson at (707) 762-7064 or
garment with the RFO logo? You can [email protected].
have the RFO logo embroidered on
New! Subscribe, Renew and
your own shirt, hat or lightweight jacket.
Donate Online
The garment should have no
seams or pockets to interfere with the VMOA supporters now have the option
embroidery. The embroidery will be of subscribing, renewing their
placed in the upper left side of the subscription or making a tax-deductible
donation online.
garment unless otherwise requested.
Just send your garment
Visit: www.rfo.org
before April 30, 2010 to:
So I walk on uplands unbounded, and
June Ferguson, 809 Gilardi Drive, know that there is hope for that which
Petaluma, CA 94952 and enclose Thou didst mold out of dust to have
$8.18 for the embroidery and sufficient consort with things eternal.
funds for return shipping.
-The Dead Sea Scrolls
RFO Logo Embroidery
Available
Page 4
Spring 2010
Watching the 2010 Spring Sky
by Jack Welch
Saturn begins this spring at opposition in Virgo on 3/
21. The rings are still at a small angle, 3.2°, after Earth crossed
the ring plane last year. The angle will decrease to a minimum
of 1.7° in late May, then begin increasing again. All this spring
will be the best time for observing Saturn in telescopes so it is
clearly the star of the show! Saturn ends retrograde motion
on 5/31.
Mercury provides its best evening appearance of 2010
from about 3/25 to 4/15, though Mercury dims substantially
during the last few days of this period, and the brighter Venus
is nearby throughout Mercury’s brief appearance. Best
viewing is during the first week of April. Start looking for
Mercury in the west around 8:00pm. Mercury will also provide
a poor morning apparition from about 5/22 to 6/13 when it
will be low in the east about 30 minutes before sunrise. Look
for it at about 5:15am. The crescent moon will be above
Mercury on 6/10. And a very thin 1.2% crescent moon will
be north (left) of Mercury on 6/11.
Venus is the “Evening Star” all this spring and
through most of the rest of 2010. It will rise before twilight
by the end of April, becoming more prominent. The crescent
moon joins Venus on 4/15 and 16 (see illustration). While
a challenge, try to spot the now dim Mercury below the
crescent moon on 4/15 using binoculars or a telescope.
Note that on 4/16 the crescent moon will be very near the
Pleiades (M45). Use binoculars to spot the Pleiades stars
in the twilight sky. The crescent moon again joins Venus on
6/14 (see illustration). Note that Mars and Regulus are a
bit higher in the same view and that Venus is nearing M44
in the middle of Cancer. Venus will be very near the
Praesepe (M44) star cluster on the evening of 6/19. Start
looking in late twilight around 10pm and use binoculars.
The pair will drop to less than 6° above the horizon by the
end of twilight at 10:34pm.
Mars is in the western evening sky all spring. It is
now fairly far away and small so no longer a worthwhile
12
telescope target. But it remains a bright and colorful sky
decoration. In mid-April, Mars passes
just north of Praesepe (M44), with the
closest approach between the 14th and
18th. Observe them around 10pm and
use binoculars. On the evening of 6/5
Mars, at magnitude 1.1, will be very
near the bright blue star Regulus in Leo,
at magnitude 1.4. This should be a
lovely colorful pairing in binoculars and
can be appreciated for several days
before and after. Look for them
around 10pm.
Jupiter has emerged into the
morning sky, rising during twilight
during most of April, then before
twilight and climbing higher after April.
At 6:00am on 4/11, Jupiter will be
below the crescent moon, 6° above the
horizon a bit south of east. The next
morning a 4% crescent will be to the
left (north) of Jupiter, both at low
altitude. At 4:30am on 5/9 the crescent
moon will again be above Jupiter, which
will be at 7°. Finally, at around 4am
on 6/6 the moon will again be near
Jupiter.
Spring 2010
Page 5
a while later, though well before the
moon enters the umbra at 3:17am. At
that time the moon will still be quite
high in the southwest. Maximum
eclipse is at 4:38, early in nautical
twilight while the moon will still be 11°
high. The eclipse will still be in
progress when the moon sets around
5:53.
The solar system has a few
other events to watch this spring. On
the evenings of 4/12 and 4/13, we can
try to spot a couple of comets. The
Comet C/2009 O2 (Catalina) will
be very near the star upsilon Tauri
amidst the Hyades open star cluster!
Look for it in the west around 9:30pm
after twilight but before it drops too
low in the west. Later, at about
10:30pm, look for Comet 81P/Wild
in the vicinity of the star iota Virginis.
A finder’s chart will probably help in
this latter case. Both comets should
be somewhere around 9th magnitude,
so a telescope is necessary.
However, binoculars are also worth
Besides the moon pairings already mentioned, the
moon will be near the bright red star Antares in Scorpius at
about 4am on 4/3, 10pm on 5/28 (though it will be easier to
see if you wait later for it to rise higher), and at 2am on 6/
24. At 8:00pm on 4/14 we have a nice chance to see an
ultra-thin 0.6% crescent moon. It will be only 4° above the
horizon 17° north of due west. You will need binoculars to
help pick it out of the twilight glow. It will set quickly, so
timing is important. A thin 1.5% crescent will be 7° high
25° north of west at 8:45pm on 5/14. You will have more
time to catch this very thin crescent, but use binoculars again.
At about 10:50pm on 5/17 the moon will occult the
magnitude 5.9 star 61 Geminorum. It will disappear behind
the dark limb of a 20% crescent 29° from the southern
cusp. The moon will be 13° high in the west-southwest.
Next, there will be a 3.9% crescent moon at 9:30pm on 6/
13.
Finally, the moon saves its most dramatic display
for a few days into the summer. The full moon the morning
of 6/26 will experience a nice partial (about 50%) lunar
eclipse. The moon enters the penumbra at 1:58am. This is
a subtle event and the eclipse won’t become noticeable until
a try.
Finally, two of the brighter asteroids are at opposition
this spring. Pallas is first on 5/4 in Serpens. Look for it at
magnitude 8.7 about 2.5° south of the star Alphekka in
Corona Borealis. Ceres comes next on 6/18. It will be at
magnitude 7.2 in Sagittarius. Consult a finder’s chart.
Spring officially begins at the Vernal Equinox at
10:32am on 3/20 this year, and ends at the Summer Solstice
at 4:28am on 6/21. Try to get your eyes to a telescope or
two during that time to see some of the spring’s lovely objects,
such as the “Black Eye Galaxy” (M64) or the “Sombrero
Galaxy” (M104) or the “Turtle in Space” planetary
nebula (NGC6210) or any of the many gorgeous globular
clusters visible this time of year! All and more are reason
enough to visit RFO. We’ll see you there!
Which city is faster paced: New York or Los
Angeles? If you look at the difference in latitude
between the two, New Yorkers spin around the
Earth at about 775 mph, while Angelinos spin at
about 850 mph. For the ultimate in fast paces
try an equatorial habitat, where one can spin at
the top Earthly rate of 1,038 mph.
Page 6
Spring 2010
Etendue and the LSST
By Loren Stokes
The Large Synoptic Survey Telescope (LSST) is
currently being constructed and should see first light in 2015.
Its primary mission is to detect and determine the orbits of
near-Earth asteroids that could cause regional devastation if
they ever strike Earth. The telescope’s primary mirror is
8.4 meters in diameter, and its huge 3,200 megapixel camera
will see nearly ten square degrees of sky at once. Located
in northern Chile, it will take a 15 second exposure every
20 seconds. It will cover the entire sky every three nights
with a sensitivity of magnitude 24.5. This sensitivity should
allow detection of asteroids as small as 100 meters.
By repeatedly measuring the entire sky every few
nights, asteroids can be discovered by their movement
relative to the fixed background stars. They will be found
automatically by computer. Over long periods of positional
measurement, the orbits of newly discovered asteroids can
be calculated with better and better accuracy.
The Figure of Merit of such sky survey telescopes
is called etendue, which is French for “extent.” It is the light
collecting area of the telescope (in square meters) multiplied
by the area of its camera’s field of view (in square degrees).
This Figure of Merit describes how quickly a telescope can
image the entire sky. A large light collecting mirror means
short exposure times of the digital camera. A large field of
view means fewer exposures are needed to cover the entire
sky.
To appreciate how amazing is the design of the
LSST, we need to look at the etendue of typical telescopes.
Let’s start with the RFO’s 14-inch robotic scope. The
primary mirror has an area of about 0.1 square meters. The
field of view of the digital camera is about 0.2 degrees across
(40% the diameter of the full moon), and the viewing area is
the square of this, 0.04 square degrees. The etendue is
therefore 0.1 square meters times 0.04 square degrees, or
0.004 (in units of square meters square degrees).
Note that simply doubling the telescopes primary
mirror diameter does not change the etendue if the same
focal ratio and same camera are used. Doubling the mirror
diameter increases the light collecting area by four, but
doubling the focal length means the camera sees one half as
much field of view and one fourth as much viewing area. So
the etendue remains unchanged. To increase the etendue
we need a telescope with a lower focal ratio.
Consider a 10-inch f/4 reflector with a camera using
the largest available amateur CCD chip, 36 x 36 mm. The
primary mirror has an area of about 0.05 square meters.
The camera field of view is 2 degrees and has a viewing area
of 4 square degrees. The etendue is therefore 0.2, which is
50 times greater than that of the 14 inch scope. This camera
attached to the RFO’s 24-inch f/4.5 Newtonian telescope
(primary mirror area of 0.29 square meters) would have a
field of view of 0.75 degrees and a viewing area of 0.56
square degrees. The etendue would be 0.16 which is less
than that of the 10-inch f/4 telescope. Etendue decreases as
the square of the focal ratio.
The LSST uses an 8.4 meter diameter primary mirror
with a focal ratio of 1.18. The secondary mirror is f/-1 and
the tertiary mirror (the inner 5 meters of the primary mirror)
has an amazing focal ratio of f/0.83. Three lenses before the
camera correct for off-axis distortion. The camera is a mosaic
of CCD chips measuring 64 cm (25 inches) across and is
bigger than a refrigerator. The field of view is over 3 degrees
and the viewing area is 9.6 square degrees. The light gathering
area of the annular primary mirror is 33 square meters. The
etendue is an astounding 320. This is 1,600 times that of the
10-inch f/4 example above.
Current dedicated sky survey telescopes have
primary mirror diameters of 1 to 4 meters and an etendue
range of 5 to 50. The LSST etendue is nearly ten times
larger.
(Continued on next page)
Spring 2010
(Continued from previous page)
Within eight years of operation, the LSST should
find 90% of near-Earth asteroids larger than 140 meters
and determine their orbits. Other asteroids, comets and icy
objects beyond Neptune should be discovered. As a bonus,
by frequently imaging the entire sky, transient events outside
our solar system and galaxy should be discovered. It is
expected that so many events will be found that amateur
astronomers will have ample opportunity to follow up using
their telescopes and CCD cameras.
Page 7
variability and how the physical processes inside the Sun are
related to surface magnetic fields and activity.
Remember all those pictures we mentioned earlier?
That is where AIA comes into play. AIA will image the solar
atmosphere in multiple wavelengths to link changes in the
surface to changes in the interior. It will be observing in 10
different wavelengths and will snap a picture every 0.1
seconds. Ten images a second – one in each of the ten
wavelengths! So with all of that data to work with it may not
be too long before our favorite weather website will not only
be able to tell us if we should go to the beach on the weekend
but also whether or not we should launch a satellite.
For more information about the LSST visit
http://www.lsst.org/lsst
(SDO: from Page 1)
over 2,000 satellites in orbit around Earth and all but one is
man made. The Sun could wipe out a whole lot of them with
a big enough ‘hiccup’. A large CME aimed directly at Earth
would send a large cloud of charged particles our way and
wreak all sorts of havoc. Power grid failures could occur
and the GPS system could go down leaving untold millions
of people wandering around lost for days. This would just
not be a good thing.
So scientists would really like to gain a better
understanding of what makes the Sun tick. They would like
to understand it so well that they would be able to predict
the Suns’ behavior. One of the ways they hope to gain this
understanding is by observing the Sun in greater detail than
has ever been done before and thus SDO was created. SDO
has three main instruments on board: the Helioseismic and
Magnetic Imager (HMI), the Atmospheric Imaging Assembly
(AIA) and the Extreme Ultraviolet Variability Experiment
(EVE). EVE will be measuring the extreme ultraviolet spectral
irradiance (basically the energy radiated from the Sun in the
ultraviolet wavelengths) to better understand its influence on
Earth’s climate and near-Earth space. HMI is designed to
cover the full disk of Sun but at a resolution 50% greater
than what SOHO is capable of. HMI will be studying the
photosphere and solar oscillations in an effort to better
understand the interior sources and mechanisms of solar
For more information about the SDO visit
http://sdo.gsfc.nasa.gov/
SWEET DONATION FROM DOCE LUNAS
RESTAURANT
In the last issue of ‘Focused’ we announced that the nearby
restaurant Doce Lunas offered to donate $1 to the RFO for
every dessert ordered during the month of December 2009.
Well, it turned out to be a sweet deal for the RFO as $280
was donated. Doce Lunas is just down the hill from the RFO
in the town of Kenwood at 8910 Sonoma Highway.
Incidentally, Doce Lunas can be translated to mean either
‘sweet moons’ or ‘twelve moons’ depending on the language
root you use. How about ‘twelve sweet moons’, full moons,
when the RFO is typically not open; can’t think of a better
reason to get on over to Doce Lunas for something sweet!
Thank you very much Jackie and Alex Purroy for your
gracious, dare I say, sweet donation to the RFO.
http://www.rfo.org
Valley of the Moon Observatory Association
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