Документ взят из кэша поисковой машины. Адрес оригинального документа : http://zebu.uoregon.edu/messier/m81.txt Дата изменения: Thu Apr 28 21:14:51 1994 Дата индексирования: Mon Oct 1 21:33:19 2012 Кодировка: Поисковые слова: comet

M81 is one of the classic grand design spiral arm galaxies.
It has a substantial bulge and rather anemic star formation
in its disk. In fact, its overall properties are rather
similar to M31. Its angular size is 21x10 minutes of arc making
it a favorite target for amateur scopes. Hubble Space Telescope
OBSERvations have detected Cepheid Variables in the some fields
on the outskirts of M81 and thus M81 is a fundamental calibrator
of the Extragalactic Distance Scale. This exposure is taken through
a blue filter using re-imaging optics on a 52-inch telescope.
The scale is about 2.35 arcseconds per pixel. The exposure time
was 30 seconds.

The image of the Supernova field in M81 was obtained in spring of
1993 at the Pine Mountain Observatory using a Lynxx PC CCD camera
at the prime focus of the 32-inch telescope.

The Ultraviolet Image of M81 comes from the Ultraviolet Imaging Telescope
which is flown on the Shuttle. The next UIT mission will be in January
of 1995. Note how well the spiral structure is defined in the UV (since
only hot massive stars contribute). This really shows the grand-design
nature of the spiral structure in M81.