AEA Astronomy Club
Newsletter July
2017
Contents
AEA Astronomy Club News & Calendar p.1
Video(s) & Picture(s) of the Month p. 2
Astronomy News p. 7
General Calendar p. 12
AEA Astronomy Club News & Calendar p.1
Video(s) & Picture(s) of the Month p. 2
Astronomy News p. 7
General Calendar p. 12
Colloquia, lectures, mtgs. p. 12
Observing p. 14
Observing p. 14
Useful
Links p. 16
About the Club p. 17
Club News & Calendar.
Club Calendar
About the Club p. 17
Club News & Calendar.
Club Calendar
Club Meeting Schedule:
6 July
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AEA Astronomy Club Meeting
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Pizza Party &
Video Presentation
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(A1/1735)
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AEA
Astronomy Club meetings are now on 1st Thursdays at 11:45 am. For all of 2017, the meeting room is A1/1735.
Club
News:
Eclipse News. There will be a meeting for the Aug. 21
eclipse on July 26 at 11:30am in A1/4626 (the executive board room). Mainly for those going with the group to
Rexburg Idaho, but also of some interest to anyone planning to see the total or
even partial eclipse (70% from L.A.).
We have 100 eclipse glasses
for the group going to centerline, and have ordered 100 more to accommodate
requests for other friends and family.
We should have extras for club members who are not going to centerline, but
will see the partial elsewhere. We also
have a large sheet of solar filter film from Baader Planetarium to be cut up
for people wanting to make custom filters for binoculars, cameras and
telescopes. Send Mark Clayson a request
for glasses or film (specify size, number).
And if interested in one of our custom eclipse T-shirts ($13), let
Marilee Wheaton know the number and size(s).
Mt. Wilson. Another group of 18 are anxiously looking
forward to our night on the Mt. Wilson 100-inch telescope Sept. 23.
An
interesting compact telephoto for cell phones:
Astronomy Video(s)
& Picture(s) of the Month
(from Astronomy
Picture of the Day, APOD: http://apod.nasa.gov/apod/archivepix.html Juno Flyby Video
Here’s an animation created of images from the most recent Juno flyby of Jupiter. The music is from 2001: A Space Odyssey. You should watch this video in full screen mode - click on the square box in the lower right corner.
VIDEO: Eclipse Across America: Path Prediction Video https://apod.nasa.gov/apod/ap170619.html
Video Credit: NASA GSFC's Scientific Visualization Studio; Blue Marble data courtesy Reto Stöckli (NASA/GSFC)
Explanation: Where will
you be during the Eclipse across America? On August 21, the shadow of the Moon will cross the continental USA for the first
time since 1979. The
predicted path -- a certainty given modern astronomical knowledge -- is shown in the featured NASA video. Most people in the USA will be
within a day's drive to the path of the total solar eclipse, while
the rest of North America will see a partial solar eclipse. In the path
of totality, given
clear-enough skies, the Moon will block out the Sun making it eerily dark for
as long as 2 minutes and 40 seconds. If interested in attending an eclipse party, please
contact your local amateur astronomical society, science center, park, or
university to see if one is already being planning. Some eclipse chasers have traveled to the end of the world to see a total eclipse of the Sun, and along
the way have recorded many entertaining adventure stories.Video Credit: NASA GSFC's Scientific Visualization Studio; Blue Marble data courtesy Reto Stöckli (NASA/GSFC)
VIDEO: Views from Cassini at Saturn https://apod.nasa.gov/apod/ap170618.html
Credit: Images: Cassini Imaging Team, ISS, JPL, ESA, NASA; Video Compilation: Chris Abbas;
Music Credit & License: Ghosts I-IV (Nine Inch Nails)
Explanation: What has
the Cassini orbiter seen at Saturn? The featured music video shows some of the early highlights. In the
first time-lapse sequence (00:07), a vertical line appears that is really
Saturn's thin rings seen nearly edge-on. Soon some of Saturn's moon
shoot past. The next sequence (00:11) features Saturn's unusually wavy F-ring that is constrained by the two shepherd moons that are also continually perturbing it. Soon
much of Saturn's extensive ring system flashes by, sometimes juxtaposed to the
grandeur of the immense planet itself. Cloud patterns on Titan (00:39) and Saturn (00:41) are highlighted. Clips from flybys of
several of Saturn's moon are then shown, including Phoebe, Mimas, Epimetheus, and Iapetus. In other sequences, moons
of Saturn appear to pass each other as they orbit Saturn. Background
star fields seen by Cassini are sometimes intruded upon by bright passing
moons. The robotic Cassini spacecraft has been revolutionizing humanity's knowledge
of Saturn and its moons since 2004. In September, Cassini's mission will be brought to a dramatic conclusion as the
spacecraft will be directed to dive into ringed giant.Credit: Images: Cassini Imaging Team, ISS, JPL, ESA, NASA; Video Compilation: Chris Abbas;
Music Credit & License: Ghosts I-IV (Nine Inch Nails)
Highlights
of the Summer Sky
Illustration Credit & Copyright: Universe2go.com
Explanation: What's up in
the sky this summer? The featured graphic gives a few highlights for Earth's
northern hemisphere. Viewed as a clock face centered at the bottom, early
summer sky events fan out toward the left, while late summer events are
projected toward the right. Objects relatively close to Earth are illustrated, in
general, as nearer to the cartoon figure with the telescope at the bottom
center -- although almost everything pictured can be seen without a telescope.
Highlights of this summer's sky include that Jupiter will be visible after
sunset during June, whileSaturn will be visible after
sunset during August. A close grouping of the Moon, Venus and
the bright star Aldebaran will
occur during mid-July. In early August, the Perseids meteor shower peaks.
Surely the most famous pending
astronomical event occurring this summer, though, will be atotal eclipse of the Sun visible over a thin cloud-free swath
across the USA on 21 August.Illustration Credit & Copyright: Universe2go.com
Image Credit: X-ray - NASA,CXC,SAO, R. Montez et al.; Optical - Adam Block, Mt. Lemmon SkyCenter, U. Arizona
Illustration Credit: NASA, JPL-Caltech, Spitzer Team, T. Pyle (IPAC)
Black Holes
of Known Mass
Illustration Credit: LIGO, NSF, Aurore Simonnet (Sonoma State U.)
Explanation: Add GW170104 to
the chart of black holes with known mass. The extremely energetic merger of two
smaller black holes corresponds to the Laser Interferometer Gravitational-wave
Observatory's (LIGO) third detection
of gravitational waves. The newfound black hole has a mass about 49 times that
of the Sun, filling a gap between the masses of the two merged black holes
detected previously by LIGO, with solar masses of 62 (GW150914) and 21 (GW151226). In all
three cases, the signal in each of the twin LIGO detectors was unambiguously
identified as coming from black hole mergers while a fourth case (LVT151012)
resulted in a lower confidence detection. GW170104 is estimated to be some 3
billion light-years away, more distant than present estimates for GW150914 and
GW151226. The ripples in spacetime were
discovered during LIGO's current observing run, which began November 30, 2016
and will continue through the summer.Illustration Credit: LIGO, NSF, Aurore Simonnet (Sonoma State U.)
Shadowrise
and Sunset
Image Credit & Copyright: Göran Strand
Explanation: The road
tracking through this stunning 360 degree view crosses a remote mountain area
of Jämtland, Sweden, planet Earth. A 3x8
mosaic of still images, the panorama was taken on May 3rd from a small drone
200 meters above the ground. The scene records the warm light of the Sun
setting in the northwest and the planet's dark shadow rising in the southeast.
A small sun pillar gives
away the Sun's position just below the horizon while the pinkish anti-twilight arch or belt of Venus outlines
Earth's shadow. In the middle of the remarkably clear sky, the First Quarter
Moon is visible above the mountains, its half illuminated disk separating
shadowrise and sunset. A range of exposures was used to cover the large
difference in sky brightness. The tallest peak left of the sunset is Storsnasen, some 1400 meters above sea level.Image Credit & Copyright: Göran Strand
Astronomy
News:
Astronomers detect orbital motion in pair of supermassive black holes
VLBA reveals first-ever black-hole 'visual binary'
Artist's conception of the pair of supermassive black
holes at the center of the galaxy 0402+379, 750 million light-years from Earth.
Credit: Josh Valenzuela/University of New
Mexico
Using the supersharp radio
"vision" of the National Science Foundation's Very Long Baseline
Array (VLBA), astronomers have made the first detection of orbital motion in a
pair of supermassive black holes in a galaxy some 750 million light-years from
Earth.
"This is the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole 'visual binary,'" said Greg Taylor, of the University of New Mexico (UNM).
Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another some time in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.
"We believe that the two supermassive black holes in this galaxy will merge," said Karishma Bansal, a graduate student at UNM, adding that the merger will come at least millions of years in the future.
The galaxy, an elliptical galaxy called 0402+379, after its location in the sky, was first observed in 1995. It was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the galaxy, instead of one, Taylor and his collaborators concluded in 2006 that it contained a pair of supermassive black holes.
The latest research, which Taylor and his colleagues are reporting in the Astrophysical Journal, incorporates new VLBA observations from 2009 and 2015, along with re-analysis of the earlier VLBA data. This work revealed motion of the two cores, confirming that the two black holes are orbiting each other. The scientists' initial calculations indicate that they complete a single orbit in about 30,000 years.
"We need to continue observing this galaxy to improve our understanding of the orbit, and of the masses of the black holes," Taylor said. "This pair of black holes offers us our first chance to study how such systems interact," he added.
The astronomers also hope to discover other such systems. The galaxy mergers that bring two supermassive black holes close together are considered to be a common process in the universe, so astronomers expect that such binary pairs should be common.
"Now that we've been able to measure orbital motion in one such pair, we're encouraged to seek other, similar pairs. We may find others that are easier to study," Bansal said.
The VLBA, part of the Long Baseline Observatory, is a continent-wide radio telescope system using ten, 240-ton dish antennas distributed from Hawaii to St. Croix in the Caribbean. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. That extraordinary resolving power allows scientists to make extremely fine measurements of objects and motions in the sky, such as those done for the research on 0402+379.
The Long Baseline Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
Materials provided by National Radio Astronomy Observatory.
FULL STORY
Low-mass stars always born with a sibling: Many, like our
sun, split up
This is a radio image of a very young
binary star system, less than about 1 million years old, that formed within a
dense core (oval outline) in the Perseus molecular cloud. All stars likely form
as binaries within dense cores.
Credit: SCUBA-2 survey image by Sarah
Sadavoy, CfA
Did our sun have a twin when it was
born 4.5 billion years ago?
Many stars have companions, including our nearest neighbor, Alpha Centauri, a triplet system. Astronomers have long sought an explanation. Are binary and triplet star systems born that way? Did one star capture another? Do binary stars sometimes split up and become single stars?
Astronomers have even searched for a companion to our sun, a star dubbed Nemesis because it was supposed to have kicked an asteroid into Earth's orbit that collided with our planet and exterminated the dinosaurs. It has never been found.
The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion.
"We are saying, yes, there probably was a Nemesis, a long time ago," said co-author Steven Stahler, a UC Berkeley research astronomer.
"We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years."
In this study, "wide" means that the two stars are separated by more than 500 astronomical units, or AU, where one astronomical unit is the average distance between the sun and Earth. A wide binary companion to our sun would have been 17 times farther from the sun than its most distant planet today, Neptune.
Based on this model, the sun's sibling most likely escaped and mixed with all the other stars in our region of the Milky Way galaxy, never to be seen again.
"The idea that many stars form with a companion has been suggested before, but the question is: how many?" said first author Sarah Sadavoy, a NASA Hubble fellow at the Smithsonian Astrophysical Observatory. "Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds."
The idea that all stars are born in a litter has implications beyond star formation, including the very origins of galaxies, Stahler said.
Stahler and Sadavoy posted their findings in April on the arXiv server. Their paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.
Stars birthed in 'dense cores'
Astronomers have speculated about the origins of binary and multiple star systems for hundreds of years, and in recent years have created computer simulations of collapsing masses of gas to understand how they condense under gravity into stars. They have also simulated the interaction of many young stars recently freed from their gas clouds. Several years ago, one such computer simulation by Pavel Kroupa of the University of Bonn led him to conclude that all stars are born as binaries.
Yet direct evidence from observations has been scarce. As astronomers look at younger and younger stars, they find a greater proportion of binaries, but why is still a mystery.
"The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them," Stahler said. "Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution. We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion."
According to Stahler, astronomers have known for several decades that stars are born inside egg-shaped cocoons called dense cores, which are sprinkled throughout immense clouds of cold, molecular hydrogen that are the nurseries for young stars. Through an optical telescope, these clouds look like holes in the starry sky, because the dust accompanying the gas blocks light from both the stars forming inside and the stars behind. The clouds can, however, be probed by radio telescopes, since the cold dust grains in them emit at these radio wavelengths, and radio waves are not blocked by the dust.
The Perseus molecular cloud is one such stellar nursery, about 600 light-years from Earth and about 50 light-years long. Last year, a team of astronomers completed a survey that used the Very Large Array, a collection of radio dishes in New Mexico, to look at star formation inside the cloud. Called VANDAM, it was the first complete survey of all young stars in a molecular cloud, that is, stars less than about 4 million years old, including both single and multiple stars down to separations of about 15 astronomical units. This captured all multiple stars with a separation of more than about the radius of Uranus' orbit -- 19 AU -- in our solar system.
Stahler heard about the survey after approaching Sadavoy, a member of the VANDAM team, and asking for her help in observing young stars inside dense cores. The VANDAM survey produced a census of all Class 0 stars -- those less than about 500,000 years old -- and Class I stars -- those between about 500,000 and 1 million years old. Both types of stars are so young that they are not yet burning hydrogen to produce energy.
Sadavoy took the results from VANDAM and combined them with additional observations that reveal the egg-shaped cocoons around the young stars. These additional observations come from the Gould Belt Survey with SCUBA-2 on the James Clerk Maxwell Telescope in Hawaii. By combining these two data sets, Sadavoy was able to produce a robust census of the binary and single-star populations in Perseus, turning up 55 young stars in 24 multiple-star systems, all but five of them binary, and 45 single-star systems.
Using these data, Sadavoy and Stahler discovered that all of the widely separated binary systems -- those with stars separated by more than 500 AU -- were very young systems, containing two Class 0 stars. These systems also tended to be aligned with the long axis of the egg-shaped dense core. The slightly older Class I binary stars were closer together, many separated by about 200 AU, and showed no tendency to align along the egg's axis.
"This has not been seen before or tested, and is super interesting," Sadavoy said. "We don't yet know quite what it means, but it isn't random and must say something about the way wide binaries form."
Egg-shaped cores collapse into two centers
Stahler and Sadavoy mathematically modeled various scenarios to explain this distribution of stars, assuming typical formation, breakup and orbital shrinking times. They concluded that the only way to explain the observations is to assume that all stars of masses around that of the sun start off as wide Class 0 binaries in egg-shaped dense cores, after which some 60 percent split up over time. The rest shrink to form tight binaries.
"As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis," he said. "These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars."
"Within our picture, single low-mass, sunlike stars are not primordial," Stahler added. "They are the result of the breakup of binaries. "
Their theory implies that each dense core, which typically comprises a few solar masses, converts twice as much material into stars as was previously thought.
Stahler said that he has been asking radio astronomers to compare dense cores with their embedded young stars for more than 20 years, in order to test theories of binary star formation. The new data and model are a start, he says, but more work needs to be done to understand the physics behind the rule.
Such studies may come along soon, because the capabilities of a now-upgraded VLA and the ALMA telescope in Chile, plus the SCUBA-2 survey in Hawaii, "are finally giving us the data and statistics we need. This is going to change our understanding of dense cores and the embedded stars within them," Sadavoy said.
Materials provided by University of California - Berkeley. Original written by Robert Sanders. Note: Content may be edited for style and length.
General Calendar:
Colloquia, Lectures, Seminars, Meetings, Open Houses & Tours:
Colloquia, Lectures, Seminars, Meetings, Open Houses & Tours:
Colloquia: Carnegie (Tues.
4pm), UCLA, Caltech (Wed. 4pm), IPAC (Wed. 12:15pm) & other Pasadena (daily
12-4pm): http://obs.carnegiescience.edu/seminars/
Carnegie
astronomy lectures
– only 4 per year in the Spring www.obs.carnegiescience.edu. Visit www.huntington.org for directions. For more
information about the Carnegie Observatories or this lecture series, please
contact Reed Haynie. . Click here for more information.
6 July
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AEA Astronomy Club Meeting
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Pizza Party & Video Presentation
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(A1/1735)
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7
July
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Friday Night 7:30PM SBAS Monthly General Meeting
in the Planetarium at El Camino College (16007 Crenshaw
Bl. In Torrance)
Topic: “Planetary
Defense from Asteroids and Comets”
Nahum Melamed, the Aerospace Corporation
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10 July
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LAAS General Mtg. 7:30pm Griffith Observatory
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July 13 & 14 The von Kármán Lecture Series: 2017
Five
Years of Exploring Gale Crater with the Curiosity Mars Rover
Nearly five years after
its celebrated arrival at Mars, the Curiosity rover continues to reveal Mars as
a once-habitable planet. Early in the planet’s history, generations of streams
and lakes created the landforms that Curiosity explores today. The rover currently
is climbing through the foothills of Mount Sharp, a 3-miile-high mountain
formed from sediment brought in by water and wind. This talk will cover the
latest findings from the mission, the challenges of exploration with an aging
robot, and what lies ahead.
Speaker:
James K. Erickson, Mars Science Laboratory Project Manager, JPL
Dr. Ashwin R. Vasavada, Mars Science Laboratory Project Scientist, JPL
James K. Erickson, Mars Science Laboratory Project Manager, JPL
Dr. Ashwin R. Vasavada, Mars Science Laboratory Project Scientist, JPL
Location:
Thursday, July 13, 2017, 7pm
Click here to add the date to your online calendar
The von Kármán Auditorium at JPL
4800 Oak Grove Drive
Pasadena, CA
› Directions
Friday, July 14, 2017, 7pm
Click here to add the date to your online calendar
The Vosloh Forum at Pasadena City College
1570 East Colorado Blvd.
Pasadena, CA
› Directions
Thursday, July 13, 2017, 7pm
The von Kármán Auditorium at JPL
4800 Oak Grove Drive
Pasadena, CA
› Directions
Friday, July 14, 2017, 7pm
The Vosloh Forum at Pasadena City College
1570 East Colorado Blvd.
Pasadena, CA
› Directions
Observing:
The
following data are from the 2017 Observer’s Handbook, and Sky & Telescope’s
2017 Skygazer’s Almanac & monthly Sky at a Glance.
Current
sun & moon rise/set/phase data for L.A.:
http://www.timeanddate.com/astronomy/usa/los-angeles
Sun,
Moon & Planets for July:
Moon: July 1 1st
quarter, July 9 full, July 16 last quarter, July 23 new, July 30 1st
quarter
Planets:
Venus
visible before & during dawn all July in ENE. Mars
out of sight all July. Mercury
visible all July low in evening twilight. Saturn
visible all month evening &
late night south to SW. Jupiter all July
evening WSW.
Other
Events:
5,12,19,26 July
|
LAAS
The Garvey Ranch Observatory is open to the public every
Wednesday evening from 7:30 PM to 10 PM. Go into the dome to use the 8 Inch
Refractor or observe through one of our telescopes on the lawn. Visit our
workshop to learn how you can build your own telescope, grind your own
mirror, or sign up for our free seasonal astronomy classes.
Call 213-673-7355 for further information.
Time: 7:30
PM - 10:00 PM
Location: Garvey
Ranch Obs. , 781 Orange Ave., Monterey Park, CA 91755
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13 July Neptune 0.9deg
N of Moon, occultation
15 July
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SBAS
Saturday Night In Town Dark Sky Observing Session at Ridgecrest Middle School– 28915 North Bay Rd. RPV, Weather
Permitting: Please contact Greg Benecke to confirm that the gate will be
opened! http://www.sbastro.net/
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20 July Venus 3deg
north of Moon
22 July
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LAAS Private dark sky Star Party
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22 July
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SBAS
out-of-town Dark Sky observing – contact Greg Benecke to coordinate a
location. http://www.sbastro.net/.
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29
July South Delta-Aquarids Meteor Shower Peak
There
are two branches of the Delta Aquariid meteor shower, Southern and Northern.
The Southern
Delta
Aquariids are considered a strong shower, with an average meteor observation
rate of 15–20
per
hour, and a peak zenith hourly rate of 18.
29 July
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LAAS
Public Star Party: Griffith Observatory Grounds 2-10pm
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30
July Mercury at Greatest Western Elongation
Internet
Links:
Telescope, Binocular & Accessory Buying
Guides
General
About the
Club
Club Websites: Internal (Aerospace): https://aeropedia.aero.org/aeropedia/index.php/Astronomy_Club It is updated to reflect this newsletter, in addition to a listing of past club mtg. presentations, astronomy news, photos & events from prior newsletters, club equipment, membership & constitution. We have linked some presentation materials from past mtgs. Our club newsletters are also being posted to an external blog, “An Astronomical View” http://astronomicalview.blogspot.com/.
Club Websites: Internal (Aerospace): https://aeropedia.aero.org/aeropedia/index.php/Astronomy_Club It is updated to reflect this newsletter, in addition to a listing of past club mtg. presentations, astronomy news, photos & events from prior newsletters, club equipment, membership & constitution. We have linked some presentation materials from past mtgs. Our club newsletters are also being posted to an external blog, “An Astronomical View” http://astronomicalview.blogspot.com/.
Membership. For information, current dues & application, contact Alan Olson, or see the club website (or Aerolink folder) where a form is also available (go to the membership link/folder & look at the bottom). Benefits will include use of club telescope(s) & library/software, membership in The Astronomical League, discounts on Sky & Telescope magazine and Observer’s Handbook, field trips, great programs, having a say in club activities, acquisitions & elections, etc.
Committee Suggestions & Volunteers. Feel free to contact: Mark Clayson, President & Program Committee Chairman (& acting club VP), TBD Activities Committee Chairman (& club Secretary), or Alan Olson, Resource Committee Chairman (over equipment & library, and club Treasurer).
Mark Clayson,
AEA Astronomy Club President
