THE ONE METRE INITIATIVE UPDATE JUNE 2009

 

Frank P. Roy, Elektra Observatories

frank.roy@elektraobservatories.org, http://elektraobservatories.org

 

Introduction

 

The project is moving forward with the completion of the design, analysis and error budget of the entire optical system as of late March 2009. The OMI will use a ¾ sphere Calotte dome for similar reasons as the TMT. Significant endorsements and support has been garnered from all the nearby counties (4) and many of the municipalities within, in addition local politicians including several Ontario and federal ministers support the idea. We have broad support from the local business community and tourist associations. A large volume of press coverage since October 2008 in the form of newspaper articles, TV, radio interviews and magazine articles has given the OMI much needed exposure. Significant effort has been put into raising the capital to build the Observatory; a 30 page business plan has been prepared and moved to international investors who are seriously considering the proposal. The business case clearly shows the financial viability of the project and that it can be self sustaining from revenues. We have now secured through LOU’s and verbally, 3 partnerships with Canadian Universities. A 0.7m fully corrected Richer-Chrétien telescope has been added to the portfolio to supplement the 1-metre and address outreach and education.  A 100 Mbps wireless link will be used to connect to the outside world thereby permitting near real time data downloads of approximate 1-minute for a raw image (~600 MB). The effects of economic spin-off can be demonstrated to be significant and potentially become an important economic component of the counties and townships through tourism. A ‘Canadian Astronomy Centre’ to exploit the expected tourist influx is also explored.

1       Dome

A ¾ sphere Calotte style dome (as opposed to the slit as indicated in the December 2008 Newsletter) will be used to house the OMI for several important advantages; similar indeed to the advantages outlined by the TMT.

 

a)     A smoother profile flow will improve air flow and thus reduce air turbulence around the dome and especially in the immediate vicinity of the circular opening. This will have a net positive impact on dome and shell seeing (surface of dome).

 

b)     A circular aperture will minimize wind buffeting and stray starlight from outside the field-of-view and closely matches the telescope FOV (circular opening is ~1.3m).

 

c)      The ¾ sphere and a smooth closed opening are more immune to snow accumulation.

 

d)     The Calotte design is mechanically simple and thus more reliable.

 

The dome and building will be constructed of carbon fibre sandwich core (CFSC). This light but extremely stiff nano material absorbs very little heat and has high dimensional stability over temperature which will ensure stable azimuth and aperture movements. The light weight will reduce gravitational loads on the struts and aid in the thermal management of the dome building which in term will improve the seeing by minimizing thermal effects. The dome will be elevated by some 3m from the ground level thus a allowing a smooth free air flow below the telescope and around the entire structure thus minimizing turbulence and cool down time and thus improving the seeing. The outside diameter of the dome is ~6m with 3 struts and 6 leg support. The pier is a 1,219mm diameter tube with a 914mm hollow core to reduce thermal mass.

 

Figure 1 3D rendering of the OMI 3/4 Sphere Calotte dome, top and side (open) view

 

Figure 2 3D rendering of the OMI Calotte dome, side (closed) view

 

2      Optical Design and Analysis

 

A full optical design and analysis including spot diagrams, ghosting/simulation and tolerance with error budgets was completed in March 2009. The optical design chosen is a prime focus with a 4 element field flattener/corrector with a parabolic primary M1. The goal of the optical design was to achieve a cost efficient wide field instrument; a prime focus approach was able to this meet requirement. The update includes the addition of a wideband luminosity filter (420 – 870 nm).

 

2.1                     Spot Diagrams

 

Most of the energy in the g’r’i’ band reside within a single 9um pixel of 0.76 arcsec. The z’ band is slightly worst. The u’ band has the bulk of the energy within 2x2 pixels, and is mostly limited by the glasses available today. In addition to the standard u’g’r’i’z’ set a luminosity (L) 400 – 700 nm and wideband luminosity (wL) 420 – 870 nm filters have been included. The L filter (300 nm) can reach about 0.45 mag deeper and the wL (420 nm) about 0.67 mag deeper has compared to the r’ filter. This is very useful when detection is the overriding concern.

Figure 3 OMI spot diagrams

 

Figure 4 OMI spot curve with 80% encircled energy in arcsec, based on 9um pixel pitch and 0.76”/pixel

 

 

2.2                     Ghosting Analysis

 

The ghosting analysis test the image on the detector from any double bounce reflections between any pair of refractive surfaces. Then according to the geometric image size to estimate the relative intensity. In this analysis, the multi reflections among the refractive surfaces are neglected. Integrated ghost simulation: executed in non-sequential ray tracing, this analysis includes all possible reflections among the surface, unless the minimum relative intensity is less than the threshold. All refractive surfaces are assumed AR coated to 2% reflectivity with the detector modeled with ~10% reflectivity. There are two types of ghosts: image and pupil ghost. The image ghost are from individual beam and the pupil host is imaged on or very close to the detector; It can be very problematic, since every image source will contribute light to the pupil ghost.

 

10-4 relative brightness (ghost to image) setup as criteria of the maximum acceptable integrated brightness. The relative brightness of pupil ghost should be several magnitude lower, if there is an obvious pupil ghost pattern on the detector.

 

Figure 5 OMI ghosting diagram

 

 

Table 1 Relative geometric ghost image intensity for any double bounces between two surfaces.

Every intensity in the table indicate the double bounced ghost image from the surfaces listed by surface number. The most strong image ghost is from surface 10 and 9, which are the surfaces of filter.

 

Figure 6 The worst ghost images comes from the surface filter reflections

 

All reflection and image rays are integrated on detector.

 

Figure 7 On axis integrate ghost images on detector

Figure 8 On axis integrate ghost images cross section

 

 

Figure 9 On axis integrate ghost images cross section

 

Figure 10 Off Axis Integrate Ghost Images On Detector (Test for both image and pupil ghost)

Figure 11 Off Axis Integrate Ghost Images Cross Section

 

Figure 12 Off Axis Integrate Ghost Images Cross Section

 

Conclusions:

  • The worst ghost images come from Filter reflections.  The geometric relative intensity of which is about  8e-9.
  • The worst integrated ghost image intensity will be not more than 1e-6.
  • The off axis integrated image patterns show that there is no serious pupil ghost images there.

 

2.3                     Tolerance and Error Budget

 

For a complete report please contact us.

 

 

Table 2 Optical Parameter Detail

 

3      On-Site Communications

 

Mallory Hill is located in the Township of North Frontenac, 12 km north of Plevna, the nearest village (pop. ~250). Plevna now has 150Mbps of wireless broadband service of which the OMI has agreed in principle to use 100Mbps. A 12km wireless connection to Plevna from Mallory Hill will link us to the outside world. The 100Mbps will give a raw data rate of about 10MB/s which is sufficiently fast to permit near real time data downloads (~1min download for a full raw image).

 

4      Financing

 

Financing will be via a combination of commercial and non-commercial means. Non-commercial can be corporate sponsorship, philanthropic, private donations and government grants at various levels (federal, provincial and regional).

 

Currently we have submitted the total proposal to international investors, who are looking at the first commercial viable major observatory in Canada POSITIVELY. As part of the financing we have prepared a detailed 30 page business plan that outlines in detail how the facility will operate etc.

 

5      University Partnerships

 

University partnerships are key to the initiative and are expected to be the main user of the facility. In addition the universities will play of vital role as science partners. Partners will have guaranteed telescope time via internal peer reviews. Early partners may be asked to join the board of directors.

 

The University of Western of Ontario has agreed to be the key science partner through a Letter of Understanding (LOU). They will play a vital role in developing some of the science programs and will assist in telescope calibration etc, and act as the main repository for data. Paul Wiegert is our principal associate at Western. Western’s main interest is minor planets including NEO’s.

 

Queen’s University in Kingston has also signed on as a partner through an LOU. Stephane Courteau is the lead at Queen’s. Queen’s main interest is to provide telescope time for graduate and undergraduates for a variety of astrophysical research projects. Queen’s is the nearest university to the OMI, within a 2 hours drive from the facility.

 

The University of Montreal has also agreed in principal (verbal) to join us in a partnership. The OMI will complement the MMO and relieve some of the time allocation pressures on the 1.6m. The unique wide-field and high throughput capabilities will benefit Québec researchers (CRAQ). René Doyon is the principal contact at UoM.

 

Our emphasis is to give priority to Canadian universities. As the capabilities of the instrument are clearly demonstrated we are expecting strong international interest. We invite all Canadian Universities who grant astronomy/astrophysics degrees to contact us. Telescope time is on first come first serve model.

 

6       0.7m Telescope Added to Portfolio

 

A 0.7m f/8 fully corrected R-C telescope has been added to the portfolio. The telescope will use all the key technologies of the OMI including extensive use of carbon fibre, low mass open-back cellular mirror, ¾ sphere Calotte dome of Carbon fibre elevated off the ground. The imaging train will be a high end off-the-shelf with back illuminated large format CCD with 14 filter changer, field de-rotator and provision for an f/6 corrected configuration. The mount will be a high performance alt-az with 10º/s slewing.

 

The 0.7m will supplement the 1-metre and act as our main outreach and education instrument. There will be sufficient performance that many fields of research will benefit.

 

Table 3 0.7m telescope brief specifications

Parameter

Specification

Aperture (clear)

0.70 m

Mode

Corrected Richer-Chrétien (corrector/flattener)

f/ratio (M1-system)

2.75-8

Focal Length (effective)

5600 mm

Field Flattener/corrector

75 mm image circle, <8% vignetting

M1-M2 Mirrors

Open Back Cellular

Coatings

Enhanced Aluminum Coatings on M1-M2

M1 perforation

~200 mm

Image Scale (f/8)

36.8”/mm, 0.33”/pixel with 9um pixels

Filters

u’, g’, r’, i’, z’, up to 14 50 mm square filters

Field of View

0.37º X 0.37º with 36 x 36 mm CCD

Useful Spectral Range

400nm – 20um (camera dependant)

OTA Length - Width

1.7 m – 0.86 m

Guider

Off Axis

OTA construction

Carbon Fiber Sandwich Core

Mount Configuration

Altitude-Azimuth Fork with field de-rotator

Slew Rate

10º/s

Pointing Accuracy

15” rms within 65 degrees zenith angle

Tracking

2” rms of 300s

Guiding Resolution

0.1” at 14Hz update

Drive System

Direct Metrology with compensation for refraction, mount geometry and flexure

Dome

¾ Sphere Calotte type 3 m elevated

Dome Diameter

3.75 m OD, carbon Fibre Sandwich Core

 

7      Operations

 

The total annual operational cost of the facility is in the $100K range, with the bulk of that cost salaries. Staff will comprise of an executive director and at least one on-site staff, with potentially more during the tourist season to greet tourist. The cost includes all recurrent charges such as communications, site maintenance, insurance etc.

 

8      Endorsements And Support

 

Much effort over the last eight months has been expended to gather support from the surrounding communities including the 4 nearby counties and many of the townships within. In addition the idea is supported by the local MPP and MP. 5 Ontario ministries have also acknowledged that the OMI will be important to the local economy and help with Canadian universities who offer astronomy programs and be a welcome addition to Canada’s scientific assets. Local businesses, the tourist industry and at least one centre of the RASC all support the idea enthusiastically. The Township of North Frontenac, where the OMI is located, has enthusiastically endorsed the OMI. Indeed they provide a link to our website and information about the OMI in their Township site.

 

Written endorsements:

County of Frontenac

County of Lennox & Addington

County of Hastings

County of Renfrew

Town of Bancroft

Township of North Frontenac

Township of Addington Highlands

Township of Central Frontenac

Ottawa Valley Tourist Association

Frontenac Community Futures Development Corporation

Kingston Centre, Royal Astronomical Society of Canada

Verbal endorsements and or support:

Mayor of Kingston

Randy Hillier, MPP Lanark, Frontenac, Lennox & Addington

Scott Read, MP Lanark, Frontenac, Lennox & Addington

Ontario Ministries who support idea (letters):

Leona Dombrowsky, Minister of Agriculture and Rural Affairs

Aileen Carroll, Minister of Culture

Kathleen Wynne, Minister of Education

Donna Cansfield, Minister of Natural Resources

Fareed Amin, Deputy Minister, Ministry of Economic Development

Monique Smith, Minister of Tourism

Federal Ministries who support the idea (letter):

Steve MacLean, Canadian Space Agency

 

Tourist Associations Support:

Land O’Lakes Tourist Association

 

9      Press Coverage

 

The OMI has had extensive press coverage in terms of newspapers, radio, TV, magazines and reports on many web-sites over the last 8 months. At least 20 newspapers articles have appeared with multiple radio interviews and TV reports. The media is excited about the idea of a major astronomical observatory, especially that the Observatory will be within 3 hours drive of millions of people. They were very impressed by the spectacular night skies of the area. In one radio interview we talked that within 3-5 meters a person simply disappears into the darkness, and that the Milky Way actually cast a shadow.

 

10 Economic Spin-Off

 

Significant economic spin-off through tourism is expected by the presence of a major astronomical observatory in the area. We know from empirical data published by Sépaq (Société des établissements de plain air du Québec) in their August 4, 2008 press release that the Mont Mégantic park generates over $10 million into the local economy. The main attractor here of course is the MMO and the Astrolab who get some 15,000 annual visitors.

 

The OMI with the nearby Bon Echo Provincial Park and access to a larger population base could potentially have a larger economic impact. Bon Echo alone sees almost 200,000 visitors annually.

This fact has been recognized by the Townships and Counties who enthusiastically support the Observatory. To fully benefit by the OMI an astronomy centre (visitor centre) similar to the Astrolab would need to be established. We have looked into this aspect. The astronomy centre could host a planetarium, roof-top telescope (~20”), display areas (including OMI research), boutiques, ski rentals and a restaurant. The astronomy centre could also host a motel to accommodate over-night guest. In addition the exceptionally dark skies of the area would be a perfect setting for telescope rentals, clam-shell domes for amateurs to set-up their own equipment and would be a superb setting for a spectacular astronomy/star festival. The festival would have the darkest night skies in north-east North America where the Milky Way cast a shadow and some 10,000 stars can be seen by the naked eye!

 

The economic spin-off of a major astronomical observatory and the associated astronomy centre would not only benefit the area economically in a significant way but also educate and promote astronomy and science in Ontario.

 

11 Acknowledgement

 

We deeply appreciate a $14,000 grant provided to us by the Frontenac Communities Futures Development Corporation (FCFDC). The grant was used in part to pay for the optical analysis, Error Budget and a draft of the Calotte dome. The FCFDC mandate is to spur economic development in the County of Frontenac. This County is in desperate need of economic development, the presence of a Major Astronomical Observatory would be a much welcome asset. The FCFDC recognized some 5 years ago that the spectacular night skies are a high value natural asset to the county. Indeed the FCFDC approached us for the grant.

 

12 Conclusion

 

Enthusiasm and support for the OMI is overwhelming and extremely encouraging and shows the very strong support we have from the local communities, (counties, townships, local businesses, tourist associations etc). The biggest stumbling block for realizing the OMI is securing the funding. This is being addressed aggressively and many approaches are being investigated, most being out of the realm of the academic world (i.e. non standard forms of funding). If Canadian astronomers have any use for the OMI, support and or endorsements from that community would be most beneficial for this initiative, since it is very likely that this community will be a big user of the facility. Purely based on economics we can demonstrate that the OMI can be a strong economic generator for this area who could boost it’s almost non-existent economy. We believe that anywhere from $10-$30 million could be generated annually in terms of economic spin-off if the right amenities in association with the OMI were present.