Astronomy Education Items
by John Percy
Astronomy educators in the Greater Toronto Area
re-established their "network" and carried out two notable projects
this spring: a teachers' workshop on International Astronomy Day
(hosted by U. of T. in partnership with the Science Teachers
Association of Ontario), and a series of star parties across the GTA,
including at the campus observatory, and at University of Toronto at
Mississauga (aka Erindale Campus) where 500 visitors attended over two
evenings. Members of the RASC Toronto Centre provided telescopes and
volunteer help.
The Science Education Program at the University of Toronto at
Mississauga, coordinated by John Percy, had another successful
year. We added a 4th year project course, which two students took.
One student Yasmine Aslam, working with John Percy, organized a Girl
Guide Science Day at Erindale; over 130 girls took part in a variety
of science-related activities, and received their Scientist Badge.
For the first time, a student in our AST425H project course
completed a project in astronomy education research. Sarah Torrie
developed a manual for astronomy outreach, with an assessment tool
which graduate students and RASC members used to provide feedback and
advice, which was incorporated into a final version. Sarah is a
student in the Early Teacher Project at Scarborough, co-ordinated by
Charles Dyer.
Two students participated in the Research Opportunities
Program (AST299Y) this year: Gurtina Besla and Emily Redelmeier,
both working with John Percy on pulsating red giants. Gurtina used
Fourier analysis to identify the first three examples of
small-amplitude red giants pulsating in multiple periods; these are
consistent with low-order radial modes. Emily used wavelet analysis
as an alternate way of looking for multiple periods in these stars.
The University of Toronto Mentorship Program held its annual
Reception and Poster Session on 23 May. This program enables
outstanding senior high school students to work on research projects
with faculty members. Two students worked with John Percy, Matthew
Coulter and Rebecca Dehmassi. Matthew used a form of autocorrelation
analysis to search for new Beta Cephei stars in binary systems, using
Hipparcos photometry. Rebecca tested the use of Hipparcos photometry
for monitoring the period changes in known Beta Cephei stars. Lucy
Zhang worked with Ue-Li Pen (CITA) on a project on gravitational
lensing.
Michael Allen and Ernie Seaquist, with summer student JoAnne
Hosick, are in the process of installing the Small Radio
Telescope on the roof of the McLennan Labs, for use with AST325H
and other courses. This project was supported by a grant from the
Faculty's Instructional Initiatives Program, with matching funds from
the DAA.
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The DDO AGN Monitoring Program
M. Blake
David Dunlap Observatory,
Richmond Hill, Ontario
M. De Robertis, M. Argote, R. L. Fingerhut, H. K. Song, O. Vaduvescu
Dept. Physics and Astronomy,
York University,
Toronto, Ontario
History of the Project
The AGN monitoring program at DDO was conceived at a meeting in the
fall of 2000 called by Slavek Rucinski regarding possible projects for
DDO. At that meeting it was proposed that a number of circumpolar
AGNs be monitored using the 1.9 m telescope, taking advantage of the
principle competitive advantage of DDO over larger facilities, namely
the ability to obtain observing time over months or years to study a
single object. The 1.9 m telescope is ideal for long-term monitoring
of astrophysical objects because projects requiring modest apertures
but many nights to reap maximum scientific returns are difficult to
perform at larger facilities. There were no expressions of interest
in the project among the attendees at the initial meeting, and the
project was temporarily shelved.
In the spring of 2001, collaborators were once again sought and an
AGN monitoring group was formed. After discussions concerning the
scientific objectives, an appropriate list of objects and instrumental
setup were selected. The first dataset was obtained in September 2001.
These data were essentially proof-of-concept observations intended to
determine whether AGNs and QSOs could routinely be observed given the
light-polluted skies of Richmond Hill. The initial observations
indicated that the QSOs would be difficult to observe, but many bright
AGNs (Seyfert galaxies) were easy targets. Since September 2001,
regular monthly monitoring, weather permitting, has been performed on
a subset of AGNs.
Scientific Goals
AGNs are a hot topic of current extragalactic research. Recent
results suggest that the mass of a supermassive black hole at the
center of a large galaxy scales with the mass of the parent galaxy.
This likely indicates an intimate connection between the two.
Understanding the physics of AGNs--how activity is initiated and
maintained-- should help us understand the processes that lead to
galaxy and structure formation.
In the 1990s, the International AGN Watch concentrated on
monitoring a few objects, particularly NGC 5548, as intensively as
possible over a wide wavelength range. It studied objects with IUE,
HST, x-ray satellites, as well as dozens of ground-based optical
telescopes. Some excellent work on "reverberation mapping" -- mapping
the reaction of the emission-line regions/profiles to continuum
variability -- emerged as a consequence of this campaign.
There are still many uncertainties related to AGNs. There are
basically two types of line profiles in these objects; broad lines
with velocity widths of 5-30,000 km/s, and narrow lines with widths of
<2,000 km/s. It is believed that most objects' broad-line profiles
are fairly stable over year time-scales, but this hasn't been verified
conclusively and there are some objects whose broad-line profiles vary
over several months and longer time-scales. Much can be learned by
monitoring the profiles of a few well-chosen broad-line objects to
search for variations on week-to-month-to-year time-scales. Based
upon the importance and unresolved issues related to AGNs we decided
to initiate a monthly, long-term (2-yr+) optical (spectroscopic)
monitoring campaign of some AGNs in order to search for line-profile
variability.
High-quality monitoring of this sample will provide a database that
will be fairly unique. It is nearly impossible to get data sampled
monthly over few-year time-scales for AGNs. We hope that by studying
how the line profiles vary with time we will better understand the
structure of the broad-line region, the nature of the emission-line
clouds, and the fueling process in general.
Object Selection
Our object selection is limited primarily by the sensitivity of the
guide camera, but there are still many interesting objects within the
capabilities of the DDO 1.9 m telescope. The International AGN Watch
group covered a number of galaxies, but they are currently only
concentrating on NGC 5548 and 3C 390.3. They indicated that our
contribution of spectra taken at regular intervals would be valuable.
Table 1 lists the objects in our program. Column 1 gives the name of
the object, Column 2 gives the redshift and Column 3 gives its
apparent brightness.
Table 1. Program Objects of DDO AGN Monitoring Project
Object Name | z | Apparent Magnitude |
NGC 7469 | 0.016 | 13.0 |
Mrk 335 | 0.025 | 13.85 |
NGC 1275 | 0.017 | 12.45 |
Mrk 3 | 0.014 | 13.34 |
Mrk 6 | 0.019 | 14.19 |
NGC 3227 | 0.003 | 11.79 |
NGC 3516 | 0.009 | 12.40 |
Mrk 421 | 0.031 | 12.90 |
NGC 4051 | 0.002 | 12.92 |
NGC 4151 | 0.003 | 11.85 |
NGC 5548 | 0.017 | 13.73 |
NGC 5929 | 0.008 | 14.00 |
Observational and Data Reduction Procedures
Our observational procedure consists of using the 100 line/mm
grating on the Cassegrain spectrograph, centered at 5700 Angstroms.
This setup gives a dispersion of 3.6 Angstroms/pixel or a resolution
of about 9-10 Angstroms, corresponding to about 450-500 km/s.
Observations consist of taking two - three 20 minute exposures of each
galaxy, with about 5 - 10 objects observed on each night depending
upon the time of year and the weather conditions. The aim is to
obtain observations of each galaxy a minimum of once per month. For
this reason, we typically are awarded 4 nights per month at DDO. Some
targets are observed seasonally, while several objects are circumpolar
and will be observed throughout the year.
The data reductions are complicated by the fact that the CCD being
used has poor sensitivity in the blue region of the spectra. The QE
of this chip is >30% only between 5400-7500 Angstroms. As a result we
are forced to take many flat-field images to reduce the noise in the
blue region. In addition, we must take a short and long Fe-Ar
spectrum for wavelength calibration. The long comparison exposures
are used to obtain positions of the faint blue lines in the comparison
lamp.
Results
We have now become familiar with the observational procedures,
which have evolved somewhat as we gained experience. By June 20, 2002
we have obtained about 70 spectra of 10 AGNs. Figures 1 - 4 show
spectra of Mrk 3, NGC 3227, NGC 4051 and NGC 4151. These are among
the brightest objects in our study. The spectra were obtained on May
26/27, 2002, and are the sum of 2 exposures totalling 20 - 30 minutes
of integration time and cover the wavelength region from 4500 to 7500
Angstroms. The wavelength scale is the observed wavelength scale and
the spectra have not been de-redshifted. The important emission lines
have been identified in each spectrum. The longest baseline we have
covered is that for NGC 7469, for which we have a baseline from
September 2001 to May 2002.
Figure 1. Spectrum of Mrk 3, May 23rd, 2002
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Figure 2. Spectrum of NGC 3227, May 23rd, 2002
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Figure 3. Spectrum of NGC 4051, May 23rd, 2002
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Figure 4. Spectrum of NGC 4051, May 23rd, 2002
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Future Work
We plan to carry out the current program for at least another two
years, assuming the availability of observing time and manpower. We
are just now getting to the point where the scientific returns are
becoming apparent, and the next few months should prove exciting. Our
techniques should continue to evolve as we gain experience and new
science goals may be identified.
The DDO has obtained a new CCD camera which should greatly improve
our ability to obtain higher signal-to-noise ratio data in the blue
region of the spectra and should also be able to observe fainter AGNs
than is currently possible. We are currently improving our data
reduction techniques and ultimately we would like to perform the
reductions in near real-time (within a day after the observing
session) so that we can be aware of any major changes so as to alert
other groups. We have learned a lot in the first 8 months of this
project!
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General Interest
A Personal View of Combating Light Pollution
(Ed. - this article is taken from the text of a message sent by
Tom Bolton, requested by the International Dark Sky Association, in
preparation for awarding to Tom the 2002 Executive Director's
Award.)
I believe I was the first person in Canada to undertake a serious
fight against light pollution. My work has been primarily with
respect to the Town of Richmond Hill, Ontario, which surrounds the
David Dunlap Observatory. I started fighting the growth of lighting
in the Town on a development by development basis in 1972. By 1978, I
had obtained the agreement of the Town and the Region of York to stop
using metal halide and mercury vapour lamps. They also agreed to
shield all new luminaires and gradually replace older luminaires with
shielded ones.
The development-by-development fight continued until late 1986.
However, this effort was proving to be very time consuming for myself,
Town staff and Councillors, and the developers. Moreover, this latter
group was getting tired of all of the bad publicity that I was able to
generate in the local, Toronto, and national media. As a result, the
Town agreed to pass a light pollution control by-law, and the
University of Toronto agreed to pay for the cost of obtaining the
required authorizing legislation from the Ontario Provincial
Parliament. In the meantime, the Town agreed that I would be
authorized to review and approve the lighting plans for all new
developments until the by-law was in effect. I began this work in
late 1986, and it continued until Spring, 1995.
I provided all of the technical input and participated in the
writing of the Provincial authorizing legislation and the by-law. The
former was passed in 1993, and the latter was passed and went into
effect in 1995. Since then, I've provided occasional technical advice
to Town staff who are responsible for enforcing the by-law.
Since 1972, I've taken advantage of every opportunity that was
available to talk to the media about light pollution. I've appeared
numerous times on local television, the national networks, CTV and
CBC, and on CBC International. Numerous articles based on interviews
with me have appeared in all of the major Toronto papers, some of
which have national circulation, as well as the local paper, the
Richmond Hill Liberal. This publicity has inspired the group that
worked to create the Torrance Barrens Dark Sky Reserve in the Muskoka
region of Ontario, and numerous other efforts by amateur astronomers
to control light pollution in their communities in Ontario. I've
served on the Light Pollution, Radio Interference, and Space Debris
Committee of the Canadian Astronomical Society and the Light Pollution
Committee of the Royal Astronomical Society of Canada. I've provided
advice on developing light pollution control by-laws to the Dominion
Astrophysical Observatory, the Observatoire de Mont Megantic, and
faculty at York University in Toronto.
My accomplishments in Richmond Hill would not have been possible
without the occasional assistance of Prof. Stefan Mochnacki, the
support of the Observatory Directors, Professors Don MacRae, Don
Fernie, and Ernie Seaquist, and eventually the support of University
President, Prof. George Connell, who is an enthusiastic amateur
astronomer.
Click here for the
web site of the International Dark Sky Association.
New rose bushes at DDO
I am pleased to inform you that Tom Karmo planted 8 rose bushes in
the area of the dome and the DDO admin building. This is a very
generous donation of his Mother, but Tom himself donated several hours
of his work to professionally plant the bushes. Yakov helped Tom last
evening (i.e., June 10, -ed.) to finish the planting.
This is not the first time that Tom has contributed to improving
the general outlook of the DDO. I am aware of his generous donations
in the last three years in planting flowers around the admin
building. Some of them miraculously survived the onslaught of the
local animals and our contracted (yet unprofessional) gardeners.
I would like to express my most sincere thanks to Tom, his Mother
for their generosity and Yakov for his help.
(signed) Slavek
(Editor's note - we all thank Toomas for brightening up the
grounds of the DDO. All travellers to DDO should take a moment to
stop and smell the roses.)
Kevin Blagrave travels to NASA/Ames Research Center
This past April, I spent three weeks working with Bob Rubin at the
Space Science Division of NASA/Ames familiarizing myself with HST STIS
data of the Orion nebula. These STIS data allow us to look at
spectral changes across the plane of the sky giving us insight into
variations of such parameters as density, temperature, extinction and
ultimately abundances. These data are an integral component of my
thesis research. While in California, I also had the opportunity to
attend a Center for Star Formation Meeting and was introduced to the
extremely important field of laboratory astrophysics at the NASA
Laboratory Astrophysics Workshop.
Marlene Cummins is appointed to an IAU working group
As a result of some activism regarding the new electronic-only
format of the Publications of the Astronomical Society of Australia,
Marlene Cummins struck up a friendly communication with the editor of
that serial, Michelle Storey. Turns out Ms. Storey is also Chair of
the IAU Working Group on Publishing and Marlene was subsequently
appointed to that group as Library Consultant (non IAU members are not
allowed to be members of IAU committees). The WG is, as one member
put it, "an active group with an attitude". Marlene provided input
into the most recent discussion of the committee and was warmly
welcomed by several members.
Rob Reid travels to Haystack
On April 12 I gave a talk on my PhD topic, Smear Fitting, at
Haystack Observatory (operated by M.I.T. and various other
universities, see image below). Despite having read several of the
eminent travel writer H.P. Lovecraft's reports on the area, I managed
to take the not-quite-correct highway and was a few minutes late.
Fortunately the audience was still receptive and it was quite
stimulating to talk about Smear Fitting with a roomful of radio
astronomers. Afterwards I had a quick tour of the facility, and got
to see the famous radome from the inside. It's much bigger (37m, as
opposed to the 25m outdoor dishes of the VLA) than it looks from its
pictures, and the antenna almost fills the dome. Interestingly, the
dome is not in a regular Buckminster Fuller arragement, but
uses fivefold symmetry to avoid contaminating the polarized signal.
Major initiatives at the observatory now are LOFAR, a 327 MHz array
for detecting primoridial deuterium, and new recorders for VLBI.
John Percy's travels
John Percy addressed the Senior Alumni on 2 April, on the topic of
"Frontiers of Astronomy", and gave a similar presentation to the
University Arts Women's Club on 18 April.
John Percy visited North Bay on 15-16 April as the first
CASCA-Westar Visiting Lecturer. This new program, patterned after the
AAS' Harlow Shapley Visiting Lectureship, brings astronomy to centres
in Canada without professional astronomy facilities. He gave two
lectures to grade nine students totalling 700 -- most of the grade
nine students in the North Bay area. The topic was "Planets Around
Other Stars"; it began with the bright solar system planets which were
then visible in the evening sky; then moved on to exoplanets,
highlighting Canadians' contributions to this field. He also gave a
public lecture on the same topic, to over 100 people. He met with
about 30 teachers, leaving behind resources to support the teaching of
the new astronomy units in the school curriculum.
John Percy attended the CASCA 2002 meeting in Penticton, where he
presented a report on the Canadian astronomy education and public
outreach program, and also gave a paper with Gurtina Besla on her
AST299Y project on multiple periods in pulsating red giants. A
highlight of this meeting was a one-day workshop for 60 graduate
students, on education and outreach. This workshop was organized by
the CASCA Graduate Student Committee.
John Percy also attended the RASC General Assembly in Montreal,
18-19 May, in part to promote the national education and outreach
program, in which the RASC is a partner. At that meeting, Bob
Garrison completed his two-year term as RASC National President.
On Radial Velocities Measured with the DDO 1.88 m Telescope
Cassegrain Spectrograph
Submitted by Tom Bolton
From time-to-time I get requests for archival radial velocity
measures from Roger Griffin. I recently provided him with some data
for two stars. One of the stars had a mean velocity published by R.
K. Young based on four prism spectrograms, and I found an additional
nine measures done from 8 A/mm spectrograms using the PDS
microdensitometer. Following are Griffin's comments on these data,
which I think are very flattering to DDO.
The DDO data are very helpful for HD 39743 (HR 2054), and I am
particularly grateful to you for volunteering all those additional
velocities of whose existence I was of course unaware. They fit my
orbit very well, and reduce the standard deviation of the period by a
factor of three, as well as making modest improvements in the other
elements. I found that both your own nine measures, and also (rather
to my surprise) Young's four, seemed to show a standard error that is
only twice what I get from my new(ish) radial-velocity instrument
here, so I weighted them 1/4; many 'old' observations need a far
smaller weighting than that. In assessing their uncertainties, I
allowed myself to reject one of your nine observations, which had a
residual quite out of keeping with the others. I added 0.8 km/s to
Young's observations, which is the value that I take to represent what
- though I never call it so in print! - is probably the error of my
own zero-point. To yours I added 1.8, which could be viewed as
meaning that, as you supplied them, they were probably about 1.0 km/s
below the IAU zero-point, which is only 1 standard deviation away from
the number you gave, so I feel that that is all right.
Best wishes, Roger
Easter and Passover
by Michael Allen
In the previous issue of the Doings (Feb 02), I wrote about some of
the questions received through the info@astro mail alias, one of which
concerned which years the date of Passover falls on the Thursday
before Easter Sunday, thereby repeating what is fabled to have
happened. Easter calculators available on the web (through the USNO,
for example) report the date of the first full day of Passover.
However, Jewish tradition has it that the day begins at sundown.
Therefore, to properly make the calculation, one must use Passover
calculators to find when the first full day of Passover is the
Friday before Easter Sunday (and therefore, the Passover meal
occurs Thursday night; recall that the Last Supper was a Passover
meal).
The calculation was performed again, correctly, to discover that
this Friday-Sunday sequence occurs only twice, in the years 1633 and
1785. I allowed the calculation to test the next five thousand years,
after which I became bored when there were no positive results.
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Library Annual Report (Highlights)
By Marlene Cummins
The Library spent $35,359, slightly over budget ($35k). Last year
the library spent only $22k, which was unusually low. Most of the
increase over last year was in a higher average price per book
purchased (now $117).
We catalogued 212 new books, 10 new serials, and 73 new slides (3
sets), among other things. As before, most of these new books must be
piled on the floor - we've run out of space.
Progress continues in the project to improve the web catalog
database (there are many duplicate, incorrect and missing records in
the web version).
About 190 department theses were added to the catalog database (in
the library and on the web) and on the Library's thesis website
listing- this section is now complete and correct. Our earliest thesis
is dated 1932.
A new library webpage 'Electronic Books at UofT' was created.
Nine books were purchased for DDO this year. The librarian went to
DDO about once a month.
Harvard has a large grant to digitize many serials, including
observatory publications; we loaned several missing issues to that
project.
We have downloaded and printed an occasional book before, but this
year we obtained most of a series of NGST books in that way.
Some web items were catalogued and integrated into the catalog (for
the first time since the first years of the web, when websites were
collected and mounted- but using a separate database). A collection
policy was formulated for this activity. This policy is available on
the web:
http://www.astro.utoronto.ca/internal/web_collection_policy.html.
A new header was designed for the department website
A report on changes in library environment and services was
prepared for the Chair: Future of the Astronomy and Astrophysics
Department Library
Photocopies of conference proceedings tables of contents and
updates to the Astronomy Book and Software Reviews were sent to ADS
for inclusion in their database.
Details of these items and much additional information can be found
in the complete annual report, available in the Library.
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