THE MHO: AN IMAGING SUPERSTAR
The Madawaska Highlands Observatory is a Canadian effort. The focus is on designing
and building a state-of-the-art imaging platform. All of our efforts
have gone into optimizing every aspect of the imaging equation.
This includes choosing the best southerly site in Canada, one
with an exceptionably dark sky and good seeing, on the highest
possible elevation.
An state-of-the-art dome design is used to optimize the local
seeing. The dome constructed of carbon fibre sandwich core is
ultra light but very strong and rigid. It is elevated 3 metres
above ground level to minimize ground turbulence. The dome shape
is a 3/4 sphere to optimize air flow and the slit is a top roll-over
to lessen the air drag on the dome.
The telescope uses several innovative designs and advanced materials
to produce the best possible image quality. This includes the
use of an open back cellular mirror. This topology produces a
very low mass mirror that can be vented from the back. This will
ensure that the mirror has the best possible local seeing for
minimizing the boundary layer above the optical surface. The key
is to maintain the mirror at ambient temperature. The optical
tube assembly (OTA) is made of carbon fibre sandwich core (CFSC)
a material that is lighter aluminum yet very rigid. In addition
the CFSC has exceptionally low thermal coefficient similar to
that of the Borofloat mirror. Extensive baffling is used throughout
the optical design to maximize contrast.
The camera uses the largest monolithic CCD in the world with
over 110 million pixels. The chip is almost 4" across and
has exceptional specifications, such as very high quantum efficiency,
high transfer rate, negligible dark noise, low read noise, etc.
The amazingly large 5 degree² field of view is fully corrected
with triplet lens. The u', g', r', i', z' and Hα filters
will be used because they have a high bandpass and for standardization.
To top off the list of highlights is the use of active optics.
With a fixed primary, the device moves the prime focus imaging
train and is able to continuously achieve accurate collimation
throughout the entire sky. The hexapod is able to tip/tilt, move
laterally, rotate and focus. It has repeatable accuracy of 1 micron
with an X,Y range of some +/-2" and Z range of +/-1"!
The telescope uses a high performance one tyne equatorial fork
mount that employs 40" friction drive wheels in both RA and
DEC. This will yield exceptional pointing accuracy and high precision
tracking.
The Madawaska Highlands Observatory is slated to produce some truly spectacular imaging
that will surely rival images produced by even the Polamar 48"
Schmidt camera. Quite possibly it will be the best imaging telescope
in the world open to nonprofessionals.
For example the Madawaska Highlands Observatory could do a tricolor image of the Andromeda
galaxy, M31 to the 25th magnitude in about 3 hours! M31 is some
4 degrees wide so two images of M31 are required yielding a field
of 4.4º x 2.22º. Since the dark noise is negligible
no dark frames are required.
KEY IMAGING SPECIFICATIONS
- 5 deg² Field of View.
- 1.0" FWHM expected seeing.
- 10580 x 10560 pixels image size.
- 0.76"/pixel image scale.
- 80,000 e- full well depth.
- 370-1000 nm useful spectral range
- u', g', r', i', z' + L +wL filters.
- 4u/6u centre/edge spot 80% 4-lens fully corrected image
- 16 seconds full image download @1 MHz
- 1.6 seconds download @10 MHz
- 4 e- read noise @1 MHz
- 18e- read noise @10 MHz
- 94% quantum efficiency
- 16-bit Quantization
- Back illuminated thinned UV enhanced coatings
- -100ºC Cryo-Tiger Cooling
- 1e-/pix/hr dark noise
- 21.82 mag/arcsec2 sky brightness
- One arm fork equatorial mount with zenith tracking
- 25th magnitude stars in 2000 seconds, s/n=3, r'
Next: 5 degrees²
FOV
|
