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The Newsletter of the Ottawa Centre, RASC
Volume 57 – No. 8 (or 9 or 10?) – December 2018
Annually, about the end of November, we have our Annual Dinner Meeting. This
year’s event was especially well attended with almost 100 people enjoying the
magnificent dinner. Our guest speaker, Dr. Jan Cami was very entertaining with his
fascinating talk Are We Alone? The Search for Life in the Universe. Also at the dinner
we honour those who have distinguished themselves as observers or in their
contributions to our monthly meetings or this publication. This year there were two
new awards: the Rolf Meier’s Planetary Observer of the Year Award; and the first
ever President’s Award.
As well as the usual features, this month we have our out-going President Tim Cole’s
annual report. Additionally, we have an interesting proposal on Radio Astronomy by
Marcus Leech who gave a presentation on this topic a few months ago.
The December meeting was our AGM and we have a few new members of Council,
including a new President, Mike Moghadam and a new Vice-President Stephen
Nourse. Mike (just call him Mr. President) has been very active, and visibly,
involved in the club for years and really needs no introduction. Stephen has been less
visible but still actively involved as a Councilor until a couple of years ago. Many
who have been members for a while will know him and recognize how lucky we are to have him back
As the year draws to an end, I would like to take this opportunity to thank all those who have
contributed to Astronotes, both voluntarily and otherwise. Without you this job would be very difficult;
with you it has been a pleasure. I also need to thank all my proof readers, especially my Assistant
Editor, Doug Fleming, who save me from embarrassing myself more than usual. To the entire Council
and Membership of the Ottawa Centre, all the best of the season and a happy, prosperous, clear skied
It's been a productive year for the Ottawa Centre. Our outreach efforts are the most visible things we do, and our public star parties at Carp continue to be very popular. Members-only star parties at the Fred Lossing Observatory are also well-attended.
We've made quite a few improvements to the Fred Lossing Observatory. In addition to the 18-inch Starmaster, we will soon have a 14-inch SCT in a separate dome. This will be available to FLO key-holders, and we'll be working out details presently. There's a larger mound for setting up your own telescopes, available to all Ottawa Centre members, and a larger parking area. Our window the south has been widened with the removal of many of the trees that were blocking our view. We're looking into more improvements, based on usage and suggestions. Our relationship with the Mississippi Valley Conservation Authority continues to be cordial and mutually beneficial, and we have good reason to expect this to continue.
For those of you who recall the older 16-inch telescope with fondness, we're happy to report that it will also have a new home and continue to be preserved for years to come.
The Ottawa Centre continues to have an excellent relationship with the Canada Aviation and Space Museum. One major advantage of our status as a Museum affiliate is that we have this meeting venue in exchange for supporting the Museum's astronomy-related outreach activities. It's another mutually beneficial partnership that provides considerable value to the Ottawa Centre.
Sadly, we can never avoid mortality. We learned of the demise of Arthur Griffin in September 2017 only after last year's General Meeting, and in 2018, the Ottawa Centre lost Paul Comision, William Dey, and Ian Halliday. I trust you'll join me in saluting their lives and accomplishments, and in honoring their memories.
Ours is an active and energetic club, and as always, we want to acknowledge members who've made outstanding contributions. Making an outstanding contribution in the Ottawa Centre takes effort – we have no shortage of highly capable members.
Paul Sadler, our seemingly tireless star party organizer, has introduced some much-needed innovations. In addition to proper surveys of what members want from star parties, Paul prepared an extensive analysis of this year's star parties and has more clearly defined the tasks needed to make star parties work. This will help us spread the effort out and make it easier for people to pitch in without taking on too much of a burden.
You've probably noticed that our Centre website is more stable, attractive, and useful than ever. That's due to our webmaster Mick Wilson, who has somehow managed to tame (or at least control) the Web Gremlins.
Danel Polyakov brings talents beyond his years to the challenging task of handling outreach activities. He's made it possible for Ottawa Centre volunteers to share our mutual love of astronomy with groups throughout Ottawa and the surrounding areas. Those dedicated and passionate volunteers include Dave Chisholm, Gerry Shewan, Attilla Danko, Ingrid de Buda, Kelly Jordan, and many others.
As part of our outreach activities, Ingrid de Buda and Attilla Danko have continued to organize and lead our popular Telescope Clinics and the cadre of volunteer telescope whisperers.
Gordon Webster has managed to keep our AstroNotes newsletter interesting and relevant. I suspect it's as much due to his ability to encourage and cajole contributors as his editorial skills. In addition to that, Gordon has been very active with members' star parties at FLO, and with the ongoing work in upgrading FLO.
Our FLO co-directors, Dave Lauzon and Rick Scholes have been instrumental in making the Fred Lossing Observatory a facility we can take pride in. Andrew Brown has also used his considerable abilities to make our second observatory building a reality.
Our monthly meetings are popular and well-attended. A great deal of their success rests on the Meeting Chair's shoulders. Oscar Echeverri, in addition to his role as the Ottawa Centre Treasurer, has done a masterful job, bringing in some top-notch speakers and re-establishing the popular Observing Challenges.
There are other aspects to monthly meetings that make them special. It's when you get a chance to see our librarian Estelle Rother and find a gem in our Centre library. Outside, Art and Anne Fraser have coffee and cookies ready for our re-caffeination and replenishment.
Some of you have made use of our telescope library. Darren Weatherall continues to keep telescopes and related gear in good working order.
Chris Teron received our first Ottawa Centre President's Award. You know him for his ongoing efforts to keep the monthly meetings running smoothly, but he also does a lot of things that most people don't know about. On the org chart, he's the Ottawa Centre Secretary, but he's also our liaison with CASM, the Centre's de facto historian and lore master, and the default host of our Council Meetings. In addition to that, he's got a long history of acting as the Ottawa Centre's resident architect and builder. Over the last two years Chris has put a lot of work into the planning and organization behind the FLO upgrades, and has also done some of the literal heavy lifting out there. Louisa, Chris's wife, deserves a lot of the credit for all that, too.
The President's Award was created as something to have available in our back pocket, something to honor someone who's run out of awards to get. I guess it shouldn't have surprised me that Chris would be first one to earn it.
While we're mentioning awards, Mike Moghadam received the 2018 Qilak Award. For those of you who aren't familiar with it, that's the RASC National award for Outreach and Communication.
These aren't the only people who generously donate enormous time and skills to the Ottawa Centre. All of you who volunteer your services merit our gratitude, and we can't continue to function without you.
It's been an honor to have served as president of the Ottawa Centre, and to be associated with you all. The Ottawa Centre is in good hands with our new Council, and I look forward to our club continuing to be a valuable part of our lives for years to come.
Clear skies, and all the best for the coming year.
By Dave Chisholm
Full Moon December 22nd
On Dec. 12, the comet will be at its closest to the sun; on Dec. 16, it will be closest to Earth at a distance of 11.5 million kilometres. Astronomers are anticipating that by then — as it will only have been a few days after its closest approach to the sun — 46P/Wirtanen will brighten to naked-eye visibility.
The Geminids is the king of the meteor showers. It is considered by many to be the best shower in the heavens, producing up to 120 multicolored meteors per hour at its peak. It is produced by debris left behind by an asteroid known as 3200 Phaethon, which was discovered in 1982. The shower runs annually from December 7-17. It peaks this year on the night of the 13th and morning of the 14th. The first quarter moon will set shortly after midnight leaving dark skies for what should be an excellent early morning show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Gemini, but can appear anywhere in the sky.
The Ursids is a minor meteor shower producing about 5-10 meteors per hour. It is produced by dust grains left behind by comet Tuttle, which was first discovered in 1790. The shower runs annually from December 17-25. It peaks this year on the night of the 21st and morning of the 22nd. This year the glare from the full moon will hide all but the brightest meteors. If you are extremely patient, you might still be able to catch a few good ones. Best viewing will be just after midnight from a dark location far away from city lights. Meteors will radiate from the constellation Ursa Minor but can appear anywhere in the sky.
The Quadrantids is an above average shower, with up to 40 meteors per hour at its peak. It is thought to be produced by dust grains left behind by an extinct comet known as 2003 EH1, which was discovered in 2003. The shower runs annually from January 1-5. It peaks this year on the night of the 3rd and morning of the 4th. The moon will be a thin crescent and should not interfere with what could be a good show this year. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Bootes but can appear anywhere in the sky.
Rise/Set 06:31/15:34 -> 06:35/15:10
Greatest Western Elongation, December 15th
Look for it just before sunrise in the eastern sky.
Visible in the early morning.
Rise/Set 03:53/14:31 -> 03:52/13:44
Visible first part of evening.
Rise/Set 12:44/23:30-> 11:23/23:19
Rise/Set 07:03/16:04 -> 05:38/14:28
Visible first part of the evening first half of month
Rise/Set 09:35/18:13 -> 07:51/16:31
Visible all night.
Rise/Set 14:25/03:54 -> 12:26/01:53
Visible all evening.
Rise/Set 12:51/23:49 -> 10:54/21:53
FLO Update – Watch this space!
Preparing the site.
On November 30th Chris Teron, Andrew Brown, Oscar Echeverri, Gordon Webster and Andrew Webster showed up at the FLO to begin construction of the deck that will house the dome for the SCT 14” that will be installed there in the next few weeks.
Bolting things together.
The framing was inspected and approved later that week and the decking will be installed December 21st assuming the weather cooperates. If time permits, the observatory pod will be installed at the same time. Weather permitting the telescope will be installed before the end of the year!
AND THE WINNERS ARE…
The Annual Dinner Meeting is where we honour those members who have distinguished themselves over the past year. Every year we award an outstanding observer, an outstanding presentation and an outstanding AstroNotes article. This year we had two new awards, the Rolf Meier Planetary Observer award and the first President’s Award.
This year’s winners are:
Paul Comision Observer of the Year - Paul Klauninger Rolf Meier Award for Planetary Observing - Taras Rabarskyi Best Presentation of the Year - Doug Luoma, “Solartown” Eclipse 2017 Best AstroNotes Article of the Year - Stuart Glen, “The Hug” President’s Award - Chris Teron
Canadian Centre for Experimental Radio Astronomy
Memo: 9 The IDEA experiment: Amateurs looking for D1
To: Interested parties
Cc: Open Source Radio Telescopes
From: Marcus Leech, firstname.lastname@example.org
Subject: Amateur attempts to observe the Deuterium line
This memorandum describes a distributed experimental approach for a group of amateur observers to loosely collaborate to observe the Deuterium line, at 327.384352 MHz
Deuterium, the isotope of Hydrogen, is estimated by Big-Bang cosmology to have a residual density with respect to plain Hydrogen of roughly 1.0e-5. That is, roughly 1 in 1.0e5 neutral hydrogen atoms in the ISM are likely to be Deuterium. We refer to this as D1, like the neutral ISM hydrogen atom is referred to as H1.
It is the case that in many parts of the sky, H1 can be detected with quite-modest equipment with impressive fidelity. For example, on a 1.2m dish antenna, with a not-horrible LNA and SDR based spectrometer, H1 will show up in the spectra after only a few 10s of seconds of integration time.
It makes sense, then, that under similar observing conditions (equivalent effective antenna area, amplifier noise temperature and RFI conditions), that an attempt to detect D1 should “merely” require an integration time that is 1.0e5 times longer.
This translates into an integration time of approximately two years, compared to a putative 30 seconds or so required for a good H1 signal.
Past experiments by Rogers, et al,1 near the MIT Haystack Observatory, were successful in observing D1 near the galactic anti-center.
The approach used was conceptually quite simple. A number (24) of 5x5 dipole-array “modules” acted as independent spectrometers, with digital beam-steering to track the target sky region. The modules were NOT mutually coherent, but simply improved sensitivity by sqrt(N), N being 24 in the case of the Haystack experiment.
1 See: https://www.haystack.mit.edu/ast/arrays/deut/deut_memos/memoindex.html
A proposed amateur-scale attempt
We propose a conceptually-similar attempt, based on loosely-coordinated, independent, inexpensive spectrometer stations, using the North Celestial Pole as a target region.
The NCP is not known for having a large abundance of H1, but it does have enough that detection of it with modest instruments is quite easy and routine.
The NCP itself, when in the center of a telescope FOV appears to be stationary, which makes long term observing of the region a simple process, not requiring active tracking.
An instrument with a somewhat “sloppy” Field of View (FOV) is easy to construct, and when pointed at the NCP region, will have a significant area with the field, including areas with nontrivial amounts of H1. We estimate that an antenna with a 10-20° field would be ideal. This is not much larger than the single-module FOV used by the Haystack instrument.
The proposal, then, would be for a number of distributed stations to establish antennae of suitable parameters pointed at the NCP, and attach these antennae to a suitable spectrometer system and gather spectral data over an extended time period, largely uninterrupted.
We have elected to call this distributed experiment IDEA. The International Deuterium Experiment for Amateurs.
According to an interesting treatise on antenna theory2 the maximum gain of ANY antenna that can fit inside a given sphere describing its maximum dimension is strictly limited.
This means that one can analyze possible designs in terms of the “largest tolerable sphere size”.
It is tempting to consider “the usual suspects” for antennae, including Yagi-Uda antennae and parabolic dish antennae, as well as large broad-side arrays.
In the end, the individual experimenter will have to make up their mind for themselves, but the requirement is for roughly 15-18dBi gain, giving a suitable field-of-view size for the antenna.
One of the surprises in this search is the 3d-corner reflector antenna. Normally considered for microwave work, but also entirely practical for low-UHF experiments like the one at hand. The advantage of a 3d corner reflector design is that it is very easy to build and get working. A disadvantage is that the gain increases non-linearly towards a limit proportional to lambda. It turns out that a 3d corner reflector that is 2.8 lambda is nearly indistinguishable from one that is 3.2 lambda or 4.2 lambda, etc. The “sweet spot” for construction at our design frequency (92cm), is approximately 2 lambda, or 1.8m, or 6ft. Construction of side and bottom panels from lumber and chicken-wire would be straightforward and inexpensive. The launch angle of such an antenna is at 45 degrees from each surface. This, purely coincidentally, would mean that such an antenna placed pointing northwards, with the base flat on the ground, would naturally point at the NCP, due to the happenstance of our local latitude (44.9° north).
2 L. J. Chu. Physical limitations of omni-directional antennas. Journal of Applied Physics, vol. 19, December 1948. Pages 1163-1175.
The illuminating monopole for such an antenna is placed roughly 0.6 lambda from the vertex of the side panels, attached to the bottom panel, with the monopole being approximately 0.75 lambda long.
More design information on the so-called truncated form of this antenna can be seen in an article published in QSL magazine, by Dragoslav Dobričić, YU1AW3A rough sketch is shown below.
Other antennae with roughly-similar gain properties will, of course, work admirably. Anyone with a 3m-12m dish that is otherwise-idle could press that dish into service readily, using perhaps a loop feed or even a simple dipole with a backing ground plane.
Low Noise Amplifiers
The primary concern with the required low-noise amplifier is dynamic range, since the low-end of UHF even in “quiet” locations can still be pretty “full”.
Fortunately, the commercial world has the same problems with linearity, and modern, inexpensive, MMIC amplifiers, such as the SPF-5189Z are readily available. Pre-packaged units with connectors on a PCB are readily available from eBay and Amazon.
A two-stage approach, with a filter in between the two stages should be more than adequate to drive fairly-long coaxial cables at this frequency.
Filters for this frequency are somewhat rare, but not entirely non-existent. There have in the past been radio-based systems that use 327.5MHz and 327.8MHz, so there are SAW filters whose bandwidth covers the desired frequency range “around”.
The SAW filters in this case would be used between LNA stages to try to eliminate any tendency for the ultimate back-end receiver system to produce intermodulation products.
It is also quite likely that some type of low-loss, but broader-band, filter will be required between the antenna and LNA in many locations. Good-quality cavity filters with custom tunings are available from various Chinese suppliers (through Alibaba) for roughly US$60.00 each.
Another approach is to use a series of quarter-wave stubs in front of the LNA. Perhaps one stub providing a bandpass at the notional Fc, and a pair of other stubs providing notch responses either side. Such filter architectures aren't difficult to produce and are low-loss. But the work on something like that may exceed the cost of simply having a few cavity filters made in China.
This author has previously used the Made-in-China approach for 611MHz filters used in front of our LNAs in the CCERA 611MHz interferometer with excellent results.
The required bandwidth for a receiving system for the D1 line is quite modest. For galactic hydrogen a total Doppler frequency range of roughly 2MHz is usually assumed, and for D1, that range would be roughly 4.3 times smaller, or 460kHz. We know, however, that the range of Doppler velocities in the NCP area are modest—on the order of 5 to 10km/sec. This means that the Doppler shift of the “line” would be on the order of 10kHz.
We propose that the ultimate FFT bandwidth would be about 10 times this, or 100kHz.
Existing cheap, SDR-based, receivers can easily meet these requirements. In particular the RTLSDR type devices are ubiquitous, cheap, and easy to interface to software systems like Gnu Radio4.
The RTL-SDR type devices have relatively-poor oscillator precision, at approximately 100ppm. This precision (and related stability) is entirely adequate for this type of rough qualitative observation, but the keen can easily modify the devices to use a shared 28.8MHz reference clock of substantially-higher quality. Such oscillators are routinely available on eBay for roughly $10.00 each, and one can connect a number of RTL-SDR devices to a single clock.
4 See: http://www.gnuradio.org
The computational requirements for computing spectra over a bandwidth of 100kHz are very modest indeed.
We created a simple proof of concept signal flow in Gnu Radio which brings signals in from 3 RTL-SDR radios at 1Msps each. It then shifts the signal slightly away from the inevitable DC offset artifact, and filters-and-decimates down to 100ksps. It then computes the 2048-bin FFTs at “real-time” rates and dumps the data into a NULL SINK for test purposes. The result consumed roughly 30% of the available CPU on an Odroid C1 single-board computer, along with consuming perhaps 15% of the available memory. This means that a keen observer could use this configuration to process spectra from three, or perhaps four antennae simultaneously, with a computer that costs US$49.95 in single-unit quantities, with receivers that are available on outlets like eBay for U$10.00 each.
The data requirements are quite modest. Since the integration times are very long, each instrument need only provide an integrated spectrum every few minutes at the very most.
Each spectral “record” if rendered into a text-based format like .csv would be approximately 2030k bytes, depending on numerical formats, etc.
If we assume one of these records every 5 minutes, that's 8Mbyte/day/station, or 3.2Gbyte/year/station.
A station with multiple antennae may choose to average their antennae data together prior to logging.
If we assume a participation level of 100 stations, that is only 320Gbyte/year for the entire “system”.
It may be the case that some type of “cloud” storage solution would be ideal for coordinating data storage, and if so, it would still be fairly cheap (perhaps $10.00/month for storage of data across the entire system).
At some point in time, a grand coordination of data sets will be required, and that will require developing algorithms for RFI excision, baseline subtraction, etc.
But that event would occur at the earliest perhaps a year after the start of the project. Specific strategies can be developed as data arrives from stations, to identify non-ideal data and excise it and process it appropriately. But the main thing, up front, is to acquire the data with as much quality as can be achieved with a project that is:
• Low budget
• Highly distributed
• Uncertain outcome
Ideal station characteristics
An ideal station is situated in an area of lower population, far away from large urban centers and sources of RFI. Such a station would need access to the Internet, but not at blindingly high speeds. Indeed, one could imagine a “remote” station where data are accumulated for weeks at a time, with manual shuffles of physical media and a data upload performed close to “civilization”.
Stations will require adequate time-keeping, but not at scales one would have to consider for VLBI. Records would be tagged with LMST so that they can be coordinated post facto. If the station is able to maintain time to within a few seconds of UTC, that should be adequate. If a station has a reliable internet connection, then the use of NTP would be strongly encouraged.
Access to the NCP becomes more awkward as one moves further south in latitude. Any station in the band from 20N to perhaps 60N latitude would be a good candidate.
We propose a large-scale, low-budget, loosely-collaborative project to detect the D1 line in the region of the North Celestial Pole.
Rough analysis suggests that the project has a modest probability of success, with individual investments being quite low.
Comments and suggestions are enthusiastically encouraged.
MMIC amplifiers - Monolithic Microwave Integrated Circuit amplifiers
PCB – printed circuit board
SAW filters – A radio frequency filter based on Surface Acoustic Wave technology
LNA – A Low Noise Amplifier typically used in radio astronomy and satellite communications
SDR – Software Defined Radio
RTLSDR – Inexpensive SDR radios based on the RTL2832U DVB-T chip
VLBI – Very Long Baseline Interferometry
LMST – Local Mean Sidereal Time
NTP – Network Time Protocol
Monthly Challenge Objects
The weather for the past few weeks has not been very cooperative so there are no new challenges this month since there have been so few opportunities to hunt for these objects. Remember to share your observations with the rest of us at the next meeting and also here in AstroNotes.
Estelle’s Pick of the Month
If you were at the December meeting you saw Brian McCullough’s presentation on his 50-year journey to the Moon and the surprise he found when he got there. Who’s that with the red nose?
FLO Star Party Dates for 2018/2019
We will be continuing the Ottawa Centre’s Members Star Parties at the FLO through the winter this year. If you haven’t attended before, be sure to mark at least one of these dates on your calendar. You are welcome to bring family members or a guest.
November 10 – waxing crescent Moon – sets 7:03 PM NO GO
December 8 – waxing crescent Moon – 1.8% sets at 5:42 PM – can you spot it? NO GO
January 5, 2019 – New Moon & Partial Solar eclipse
February 9 – Waxing crescent – 19.5% sets at 10:09
March 9 – Waxing Crescent – 8.4% sets at 9:05
April 6 – One Day Moon 1.7% sets 9:02 PM
7:30 PM Friday January 4, 2019 at the Canada Aviation and Space Museum (directions). Note there is a $4.00 parking fee for museum parking. The meeting runs until 9:30 pm
PLUS: all our regular meeting features: Ottawa Skies, 10-minute Astronomy, Observer Reports, and of course, the beloved Door Prize!
All RASC monthly meetings are free and open to members and non-members alike. Refreshments will be available and this will be a wonderful opportunity to meet new friends who share a common interest and chat in a relaxed, stimulating and fun environment. Please join us!
The Ottawa Centre 2018 Council
President: Mike Moghadam (email@example.com)
Vice President: Stephen Nourse
Secretary: Chris Teron (firstname.lastname@example.org)
Treasurer: Oscar Echeverri (email@example.com)
Centre Meeting Chair: Oscar Echeverri (firstname.lastname@example.org)
Councilors: Carmen Rush, Gerry Shewan, Jim Sofia
National Council Representatives: Karen Finstad
Past President: Tim Cole
2018 Appointed Positions
Membership: Art Fraser
Star Parties: Paul Sadler
Fred Lossing Observatory: David Lauzon & Rick Scholes (email@example.com)
Light Pollution Abatement: OPEN
Public Outreach Coordinator: Danel Polyakov
Hospitality: Art & Anne Fraser
Stan Mott Astronomy
Library: Estelle Rother
Ted Bean Telescope Library: Darren Weatherall
Webmaster: Mick Wilson (firstname.lastname@example.org)
AstroNotes Editors: Gordon Webster & Douglas Fleming (email@example.com)