AAVSO CONFERENCE, OCTOBER 2005 - PART 4/4
---------------------------------------
John Pazmino
NYSkies Astronomy Inc
nyskies@nyskies.org
www.nyskies.org
2005 November 27
Introduction
----------
The American Association of Variable Star Observers held its fall
convention in Newton, Massachusetts, on 13-15 October 2005. The
meeting was far too complex and lengthy to summarize in a single
article. I'm issuing a series of four articles to adequately treat the
material generated by the meeting. This is the fourth and last in the
series, covering talks and discussions about observatories and other
astronomy centers.
I later inserted in the section about my talk the abstract for it
from the AAVSO jaournal.
ISS-AT - Barry Beaman
-------------------
The International Space Station - Amateur Telescope is an idea for
a small remote access telescope mounted outside of the ISS. It would
be like other remote access ground scope but it will prove to NASA
that home astronomers should be more openly allowed to avail of outer
space facilities.
Drawings portray the scope as innocently riding along with ISS
with no intervention from the onboard crew. It was not explained how
utilities are connected from ISS to the scope, like electric, comms,
or data lines. It wasn't clear how the images are transmitted to
Earth, since the drawings showed no obvious radio antenna.
Nothing is under construction now, altho the scheme began in 2000.
One remote access telescope is installed in Arizona and controlled
from Dyer Observatory in Tennessee but the simulation of space
operations is quite imperfect.
The hope is that the instrument will be fielded by a Shuttle
flight and then repaired and serviced by later Shuttle crews, similar
to Hubble Space Telescope. The time on the scope will be allotted to
anyone on the ground, including AAVSO.
At present the scope is for basic imaging by CCDgraph, so it could
perhaps work for variable star photometry. Images would be beamed back
to a central base, like Dyer Observatory, then relayed to the observer
by email.
As dreamy as this sounds, I found the scheme to be in full
disregard of the recent developments with the Shuttle and ISS.
Preparing a Shuttle crew to deploy and set up this instrument, a95cm
f25 Schmidt Cassegrain on German equatorial mount[!], is simply
crazy. It is all the more daft to consider a repair mission a-la
Hubble, which itself is in danger of being passed over for such a
Shuttle flight!
This is on top of the very stringent schedule for the remaining
Shuttle flights before their termination in 2010. Nothing was noted
about using a Russian Soyuz or Progress craft, or the proposed NASA
Crew Exploration Vehicle, to field and run the scope.
There was no recognition to NASA's ongoing scaling back of science
use, such as there is any to start with, on ISS. This includes
dropping a couple major cottage-size modules and keeping the crew
capacity to just three.
There was no firm launch goal, only a vague one of several years
from now. Several years from now bumps against 2010, when the Shuttle
sails into history and perhaps only shortly before ISS itself follows
Shuttle in its footsteps.
There was no compelling reason to undertake this project in
ernest, with real construction and expense, when a home astronomer is
quite happy to operate remotely the many ground-based scopes. There
was an other presentation at this AAVSO meeting about a remote access
scope that is in operation and works: the SLOOH project. It, as shown,
is far more mature and practical than the ISS-AT.
Grand Central Terminal - John Pazmino
-----------------------------------
[The abstract here for my talk, from the AAVSO Journal, is also in
the NYSkies web as 'gct-univ.htm]
= = = = =
Grand Central Terminal in New York City is acclaimed by
astronomers for its fabled "Sky Ceiling", the largest star map in
human history. However, there are over a dozen astronomy features of
this rail hub dating from its opening in 1913 through its newest
section in the 1990s. These were demonstrated for the first time by
NYSkies at the 2003 Earth Day show in the terminal. NYSkies had about
the most humble of booths but the very grandest of all exhibits!
Slides and handouts highlight the astronomy of Grand Central Station,
station at the center of the universe.
= = = = =
My own presentation, as part of my ongoing promotion of New York
City astronomy, was the astronomy points of interest in Grand Central
Terminal. I gave this talk a second time to the NYSkies Astronomy
Seminar after I returned to the City. I don't give a full account
again here.
The Terminal has in it many features which allude to or directly
exhibit astronomy themes. Of course, there's the Sky Ceiling, with its
reversed stars, but there are over a dozen others. I highlighted
several of them in my digital slideshow and handed out a map with all
of them marked.
This talk was inspired by NYSkies participation in Earth Day of
2003, which was convened in the Terminal. At that time NYSkies was
just a Yahoogroup forum with nothing to exhibit. In planning the booth
at Earth Day it turns out that while NYSkies will have just about the
most modest table, it actually has the far and away grandest of
exhibits!
A careful inspection of the depot, both on my own, with
suggestions from colleagues, and assistance from Metro North,
uncovered over a dozen genuine astronomy points of interest. Metro
North is the railroad who owns and runs Grand Central Terminal. These
I plotted on a floor plan of the Terminal, along with a labeled
photograph of the Sky Ceiling. This was the distributed map and also
my hometown poster on my hotel door.
Some features date from the opening of the depot in 1913. Others
are new from the renovations of the 1990s. All are in the public areas
accessible when ever the Terminal is open.
SLOOH Project - Matt BenDaniel
----------------------------
SLOOH, said 'SLOO' like to slew a gun to aim it, is a pair of
Celestron C-14 scopes fitted with Santa Barbara CCDgraphs and filters,
placed in the Canary Islands. They are near the major observatories on
la Palma, to enjoy the same clean dry air with them. About 70% of the
nights are clear and seeing is generally near 1/2 arcsecond
resolution.
The instruments are visited every so often by a local crew to fix
and adjust the equipment. Otherwise the entire operations are remotely
governed from the base in England. All facility functions are
controlled with interlocking to prevent conflicting operations. A
small weather station advises of clouds, excess wind, precipitation
and then puts the observatory in shutdown state.
By subscribing you can either join an existing observing run or
construct your own. In the latter case you, thru the website
www.slooh.org, give the date and hour in UT, and the object. The
latter may be stated in several ways such as proper name, catalog
designation, coordinates. The central base does a sanity check for
latitude, altitude, proximity to Sun and ground obstructions on the
mountain.
Assuming good sky, the one or the other identical instrument
images the target and beams the file to the central computer at the
base. From there it is posted on the website for you to retrieve. The
file is in FITS format of several megabytes.
One major advantage for American subscribers is the timezone
shift. The Canary Islands are four hours ahead of Eastern time, so
while it is still late afternoon in New York, it is nightfall over
there. This allows capturing images to prepare for work later that
same night.
Subscriptions are $50/year for institutions, like schools and
clubs. There are about 6,000 subscribers, including individuals, but
most of them are schools in England. There is little timezone shift
for them, but the observatory is far south of England, giving a
latitude advantage for southern targets.
Stamford Observatory - Charles Scovil
-----------------------------------
This was not a formal presentation but the banter Scovil and I
shared on the way home from AAVSO. He offered to drive me to the
Stamford station of Metro North, near his home. He related many
interesting tales of the Observatory.
The Observatory is part of the Stamford Nature Center in
Connecticut, opened in the mid 1960s. It has a Maksutov telescope on
fork mount, the largest in th western hemisphere at 55cm aperture. It
was built and donated by Perkin-Elmer, then a major optical company in
Connecticut.
The corrector plate was cast by a contractor of Perkin-Elmer, who
fused three chunks of glass into one. Altho the finished blank looked
solid, it had three cells of optical density at the three sites of the
chunks. The melt was not thoroly homogenized! P-E applied the optical
surface according to the design optical density of a uniform melt.
The figure did not confirm to any of the three cells. This showed
up in careful inspection of the images, as if they were formed by
three distinct lenses.
In 1971 P-E took back the optical tube to fit a new, properly
annealed, corrector. In the meanwhile, the Observatory attached a
knock-around 15cm Newton scope on the fork mount. The thing was
comical, this small home-size instrument, a better one for the 1970s,
on this super massive mount. In time the Maksutov came back and has
performed perfectly ever since.
By the 1990s photographic plates were no longer available; their
manufacturers discontinued them. The scope was fitted with a CCDgraph,
which is the only imaging method used there today.
The Observatory is used principally for making AAVSO charts for
newly enrolled variables or for revisions of older ones. Scovil worked
closely with Clinton Ford, who lived nearby, to make the master
tracings of the photographic plates for blueprints. The tracing was
then lettered and lined by hand in draftsman style. The nitidity of
charts varied widely with the tracer.
Since the founding of AAVSO, thru the late 1960s, AAVSO charts
were blueprints, this duplication method being the only readily
available one in the days before photo-offset and xerography.
Ford stocked the charts at his own house for distribution to AAVSO
observers as they requested them. There was a small charge of about 15
cents per chart. By the mid 1960s xerography was cheap enough and
available at printing shops to be a reasonable alternative to
blueprints. Blueprinting itself was on the decline for public use,
becoming more confined to traditional engineering and construction
customers.
Among the first xerographic, which in that time really meant that
employed in Xerox's own machines, charts was for nova Delphini in
1967. Part of the honor came from the need to get out a chart quickly
to start observing the star while it was still bright. The Xerox
machine at local printing shops turned out dozens of copies in a few
minutes.
By the 1970s, most AAVSO charts were issued as xerograms, or more
generally as photocopies. The master sheet was still a tracing from
photographs with hand lettering and lining.
After Ford passed away about 1980, Scovil and his staff at
Stamford Observatory took over the entire chart production and
distribution service.
When the chemocamera was set aside as obsolete and replaced with a
CCDgraph, the master sheet was a digital print of the image. This was
cleaned up with a image processor. Much of the lettering and lining
could be stored in a template, into which the star image was digitally
inserted.
When the AAVSO website got under way, the charts were placed in a
files directory for direct downloading with no fee. For convenience
the images were stored in GIF and PS form to accommodate just about
all computers among the observers.
The Observatory today is considering two new projects. One is a
new planetarium. The nature center has a small ancient Spitz
projector, wholly out of date for today's astronomy education, in a
separate hall on the campus. The new facility may be a wing attached
to the Observatory structure. This will allow passing visitors between
the scope and planetarium indoors.
I hazarded that now would be the time to consider a Zeiss
projector. Scovil blanched, thinking I meant the classical big monster
like in the Hayden Planetarium or Boston Museum of Science. I noted
that since the fall of the Berlin Wall, the east and west Zeiss
companies reunited and offer small models. During the Cold War, only
the east company made the both large and small models and they were
essentially not allowed in the United States. The west company made
only the fullsize or mid size (still huge) models.
I explained that several facilities in the City region have these
already and Charles should inspect one of them. When I got back home I
sent Charles some litterature about Zeiss's line of small projectors.
I found there were more installations around new York than I knew!
The Observatory wants to build a planet walk similar to the one in
Ithaca, New York, where Clinton Ford grew up. It's a series of tablets
or stelae set apart in proportion to the planet distances from the
Sun. Each tablet has a picture and chitchat about the planet. In
Ithaca these are deployed along a downtown street more or less
linearly. It is a memorial to Carl Sagan, of nearby Cornell
University. The Stamford campus is laid out in random paths with
gardens and ponds; there is no straight line for the stelae. Scovil
plotted on a grounds map the planet orbits and thinks of placing
stelae at each place an orbit crosses a path. This would allow
visitors to find each in turn without making the grand tour of the
entire campus along the winding paths.
An other problem is that the campus has tall bushes and trees that
block the sightline to adjacent tablets. Scovil is trying to devise a
way to inform a visitor standing at one tablet how to get to the next
one or return to the Sun at the Observatory front door.
Stamford had its fun with the 2003 Mars opposition with the
heaviest crowds piling into the Observatory right on the proximity
day. Visitors thinned out rapidly in the days after proximity.
For the 2005 opposition there was the nonsense of the mistaken
news of an other proximity like in 2003! What happened all over the
world was that some news media simply reprinted articles from 2003 on
the belief that 2005's opposition was a repeat show! They even left
the wording the same, leaving out the actual year or day or the week!!
Cincinnati Observatory - Gerald Dyck
----------------------------------
This was the most bizarre talk of the convention! Dyck gave an
illustrated history of the Cincinnati Observatory, the first public
observatory in the United States. It opened in 1848 under its first
director Ormsby Mitchel. Mitchel, to raise money traveled around the
country giving lectures on astronomy and selling subscriptions,
shares, for the project. The main telescope was a Merz refractor from
Germany of something over 11 inch aperture (about 28cm).
The Observatory was originally sited on Mount Adams, after James
Adams the US president. After a few years it had to be moved out of
the town to Lookout Hill to escape from industrial air pollution. Many
light pollution fans believe that before widespread use of electric
illuminations, the skies over towns were completely clear and dark.
Dark they were, but not clear. Smoke, soot, fumes filled the air over
industrial towns of the 19th century before air pollution was a social
issue.
A second house was opened for a Clark refractor of 8 inch (about
20cm) aperture. The two instruments worked side by side continuously
for over a century. A third hut for a transit telescope was never
occupied but is used for general rooms.
Mitchel himself became a Civil War general on the Union side. He
took part in the Great Locomotive Chase near Chattanooga, Tennessee,
and was stationed in the marshes and swamps of Virginia. There in 1864
he died of yellow fever.
Today the Observatory is under renovation in the motif of the mid
19th century with new exhibits about it and Mitchel. The grounds will
period landscaping. The old site at Mount Adams is oblitterated under
a housing estate.
The talk was quite well organized, illustrated, presented. Dyck
answered questions. I asked about the lens theft of a few years ago.
He didn't know about it!
I gave a knockoff account and asked for details.
He said he visited the Observatory (many pictures in the talk were
his from the visit) and read many of the papers and books about it. He
never heard of any theft of a telescope lens.
I withdrawed the question, on the chance that I misremembered the
incident from an other facility. He finished up with other questions.
At the next break several delegates herded me into a corner. They
confirmed my question. There WAS a major episode at the Observatory.
The objective lens of the Clark refractor was stolen and later
recovered. They were shocked that Dyck didn't hear about it while
compiling the lecture.
When I got home I looked up in PazMiniBits and, yep, I covered the
story in 1999 and 2000! In summary, in September or October 1981 the
Cincinnati Astronomical Society, who now runs the Observatory, found
that the objective of its Clark telescope was missing! After looking
and inquiring they gave it up for lost and bought a replacement clark
lens from England.
The original, missing, lens was 8-1/4 inch aperture; the new was 8
inch. The Observatory functioned well with the 8 inch lens but never
forgot about the theft of the 8-1/4 inch lens (about 21 and 20 cm).
In December 1998 word came that Roane State Community College, Oak
Ridge, Tennessee, was building a new observatory and was donated a
Clark lens for the main refractor.
clark lenses are thoroly documented and cataloged and tracked by
many astronomy historians. So it was a mystery what lens this could
be. A Robert Thomas said he bought the lens from an observatory that
burned down and now donated it, an 8 inch glass, to the college.
The Cincinnati club began an investigation. Eventually it turned
out that Thomas had the actual lens stolen from Cincinnati in 1981. He
apparently hid it in his house for SEVENTEEN YEARS!
In August 1999 Thomas was arrested for assorted federal crimes.
The lens was returned to Cincinnati in April 2000 and at a televised
ceremony it was fitted back on the refractor. It seated perfectly and
matched up with all of its accessories.
A detailed account was published in the May 2000 Sidereal
Messenger, newsletter of the club, posted on the club's website!
How could Dyck miss this incredible story?!?!
The delegates noted that in the talk Dyck consistently said the
Clark lens was 8 inch, NOT 8-1/4, diameter. This was the size of the
replacement, but the original was by now in use for over five years!
He also consistently said the Merz lens was a little over 11 inch, to
the extent of correcting a question about the Merz '11 inch' lens.
How could Dyck be careful about the fractional inch of the Merz
lens and ignore the fractional inch of the Clark lens?
Maria Mitchell Observatory - Paul Valleli
---------------------------------------
Maria Mitchell, which is said 'ma-RIGH-ya' and not 'ma-REE-ya',
Observatory built up a collection of survey plates that is routinely
mined for variable star studies. They were taken with a Cook 7.5 inch
(about 18cm)h, f4.5, astrograph installed in 1913 with a triplet
objective lens. The scope was decommissioned in 1995 when the
astrographic-grade plates were discontinued by Kodak.
The lens from the start never performed well at all. There was
strong astigmatism and coma off axis. The lens design was a marvel at
the time for covering a 15-degree field on the plate, but by any
modern standards the images are tough to interpret properly.
The main use was photometry, which requires symmetrical images to
define the center of illumination. SOme astrometry was done but this,
too, requires round images.
The Observatory on and off since installation tried to remedy the
defective images by fiddling with the central, flint, element of the
lens. The front and rear lenses were left alone. No matter how this
element was faced, rotated, shifted axially, the images remained of
degraded quality. The extent of the aberrations did alter but not to
overall improve the images.
In 1941 J W Fecker company put the lenses in a new cell, with some
shifting of the center one. This still did not fix up the situation.
Altho the scope is now fitted with a CCDgraph, it is out of service
pending some final resolution of the aberration problem.
James Baker, of the Baker-Nunn camera fame, took a butchers at the
problem and started some computer simulations. He died earlier in 2005
leaving the unfinished, but very informative, workpapers to the
Observatory.
He used the plates themselfs to examine the aberrations for each
modification of the triplet lens. Because the plates and the changes
to the lens were carefully recorded, it was a simple chore to
associate the proper images with each lens alteration.
The Observatory will consider a trade of the entire instrument for
a 50-60 cm reflector with computer controls. The Cook scope comes with
a 12.5cm guide scope, electric clockdrive, original weight clockdrive,
accessories, Alvan Clark mount, and pier.
AAVSO database validation - Kerriann Malatesta &a
-----------------------------------------------
NASA in 2002 awarded AAVSO a grant to error-check its database of
variable star observations. The project ended in 2004 for all records
from 1911 thru 2001, about 9.5 million datapoints.
The database prior to the project had about 6% erroneous points;
this was reduced to about 4-1/2%.
The errors were overwhelmingly transcribing, copying, conversion
in the original reports from the observers. AAVSO keeps the original
reports for the indefinite past. Some example errors are noted here.
Wrong star. The observer listed the wrong name of the star, so the
data were posted against it and not the correct one. Writing 'del Cep'
in the stead of 'mu cep' will cause the lightcurve of del Cep to show
excess scatter.
The designation is wrong. This is commonly the plus or minus
declination field. In the older handwritten or typed forms, a negative
declination is underlined. This loses the data because surely there is
no star symmetrical to the correct one in the opposite hemisphere.
Julian day conversion can be tricky because it is based on
Universal Time, not the local zone time. Mistakes up to the tens place
can be caught by a datapoint displaced horizontally on the lightcurve
(Julian Day is the horizontal axis).
Transposed digits are harder to catch,except in egregious cases.
Putting '8.7' for an estimated magnitude in the stead of '7.8' will be
suspect by the vertical displacement of the datapoint on the
lightcurve. '
The residual 4-1/2% error may be irreducible because there was not
enough circumstantial evidence in the report form to offer a suggested
correction. Some of this residuum may come from real erratic behavior
of the star. In a few cases these could be trapped by comparing
reports from the same observer on other well-behaved stars.
Since 2001 the incoming data are sanity checked by error-checking
computer programs. By now virtually all reports come to AAVSO in
digital form in a layout ready to enter the program.
Harvard plate digitization - Howard Los
-------------------------------------
harvard College Observatory is about to start a massive project to
digitize all of its 600,000 survey plates. These are now housed in the
cellar of Philips Hall,built for this purpose in the 1930s, on the
Harvard University campus. The hall has an auditorium on the first
floor, often used for AAVSO conventions, and general offices on the
second floor. The roof has the Palmer dome for millimeter radio
mapping of the Milky Way; this was moved to here from Columbia
University in the 1980s.
A
t the fall 2002 AAVSO meeting, we toured the plate rooms to
inspect the hundreds of file cabinets, worktables, historical
instruments -- including Leavitt's plate microscope for discovering
the period-luminosity curve for delta Cephei stars -- and sample
historical plates, like the discovery plate for one of Saturn's
fainter moons.
At that time there was a crude scanning project underway with
commercial high-resolution scanners from Umax. The work was just
starting, with too little experience to asses its continuation. As it
turned out in the next two years, the results were mostly useless.
The Umax rig took ten minutes to scan each plate, which then had
to be manually inspected for overall quality. There were frequent do-
overs. On top of all that, the resolution, while excellent for
stringent graphic arts, was lousy for the plates.
The Observatory is building a custom scanning engine from scratch.
Enough is constructed to do mechanical testing, shown by videos. The
base is a block of granite a meter cube, placed on the foundation
plate of the building. The hall is on solid earth fill, away from
street vibrations. To further stop vibration, the scanner itself is
lifted above the granite block on air suspension.
The scan head has a 4K x 4K pixel CCD chip on a 45 x 45mm
aperture. Resolution on the scale of the plate is about 150 lines/mm,
better than that of the original photographic emulsions. The
individual emulsion grains are well imaged!
The plate is held in a crawling holder driven by a linear stepping
motor. This indexes the plate under the scan head while the head
slews crosswise. The apertures are tiled digitally to knit the entire
plate into one computer file.
The plates will be loaded into the holder by hand in strict number
order, as noted on the plate's protective envelope. A 25 x 25 cm plate
can be completely scanned and saved in 30 seconds! Each plate
transforms to a FITS file of 916Mb size!
Eventually every Harvard plate will be online thru a website for
anyone to download directly. Each plate will also have indexing
information for searching and navigating the plate collection.
CCD survey of open clusters - Jeff Wilkerson &a
---------------------------------------------
Wilkerson and his team started out hunting for Kuiper objects by
seeing occultations of stars in open clusters. Open clusters provide a
dense star field for the Kuiper object to cross and be tracked. They
found nothing resembling Kuiper objecs but did find hundreds of new
variable stars. They shifted gears to variable star hunting and
recording.
They use the observatory of a local college, with modest but
suitable equipment, about what an advanced home observatory would
have. They take thousands of brief exposures of each field on every
possible night for a whole semester. Each exposure is only a ew
seconds.
The shots are unfiltered for simplicity. The original scheme was
to capture successive coverings of the cluster stars as the Kuiper
object traversed the field. The three main fields are M23, M67, and
NGC129.
These images allowed discovery of short-period stars and compiling
of tight lightcurves. Because the images are unfiltered and undergo
minimal calibration, the photometry is so far only a relative one. Yet
the results are extremely valuable. Types of variable so far found
include delta Cephei, W Ursae Majoris, eclipsing binaries, and
assorted catalclysmic stars.
With data taken for several months in the semester, they expect to
uncover numerous longer period stars but they hadn't gotten around to
that yet. The team hopes to extract some parameters for the delta
Cephei and eclipsing binary stars to help better fix the distance to
the clusters.
Conclusion
--------
This is thefourth and final of four articles about the AAVSO 2005
October convention. The articles are named 'aavso05a.htm', '...b.htm',
'...c.htm', '...d.htm'.