A WIDE FIELD OF VIEW
The MHO was designed with the widest possible field of view (FOV)
in mind. Of all the specifications the FOV was the strongest driving
force. The reasons are very clear; a wide FOV has the highest
scientific and imaging throughput and thus yield.
If we take one example: supernovae search. The probability of
discovering a supernova is directly related to two key parameters;
limiting magnitude and FOV. In both these categories the MHO has
excellent specifications. Most one metre class and larger telescopes
have narrow fields typically less than 0.5 square degrees as compared
to the MHO's 5 square degrees. In the supernovae search example
the MHO could potentially observe hundreds of thousands of galaxies
during a single deep exposure in one of the larger clusters of
galaxies. And could potentially observe over 1,000,000 galaxies
of the course of an 8 hour night observing with medium exposure
lengths of 5-10 minutes. So you can see the potential of the instrument.
Here are several graphic examples:
The M31 galaxy in Andromeda. The field of M31 is approximately
4 degrees long by 1 degree wide, the MHO could image the entire
galaxy with two side-by-side frames yielding a field of 4.44 x
2.22 degrees² with 0.2 degrees of overlap. The MHO could
reach magnitude 25 in a little under 30 minutes (1.25" FWHM,
r', s/n=3) thus could do the entire galaxy in under on hour, and
about half that time if the seeing is 0.85 arcsec! A tricolor
image would take about 3 hours since no dark frames are required
because of the negligible dark noise (1e-/pix/hr).
M33 the Pinwheel galaxy in nearby Triangulum is well over 1 degree
in size. The MHO can easily image the entire galaxy to 26th magnitude
in about 3 hours (FWHM =1.25", r', s/n=3)).
A final example is the galaxy cluster in Virgo centered around
the giant elliptical galaxy of M87. The area has a very large
number of galaxies certainly tens of thousands if not greater.
A 3 x 3 mosaic with 9 frames covering over 40 square degrees could
be done in 3 hours to magnitude 25 (1.25" FWHM, r', s/n=3)
Such a deep exposure could potentially reveal 1,000,000+ galaxies!
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