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E
P H E M E R I S P R I M A
MOTVS
COMETAE NOVISSIMI
mense
Aprilis 1665,
z
z
where it is assumed
that the Comet’s
maximum declination
on the ecliptic in the Northern hemisphere
is 26:30 degrees;
that the intersection
with the ecliptic, in Gemini
is 5°:35 – descending node;
that the Perigee
near to the maximum latitude in Pisces
is 3°:43;
that the equivalent daily motion from the
Perigee is of 8 parts,
therefore the minimum distance of the Comet
from Earth is 100.
The Comet nears the Perigee
on April 4th at hours 1
after midnight.
Comparison with the observations
of its first apparition carried out
at hours 4 after midnight in Rome
Giovanni Domenico Cassini
astronomer of the Archiginnasio of Bologna. |
Distance the Comet covered
throughout the sky ...
The Comet, now moving rapidly towards the conjunction
with the Sun, will reach the Sun on
22 April morning,
once its latitude becomes 15°.
It will be possible to observe it at dawn at a height of 13°.
It will rise 1h
1/3 before Sunrise:
it will show between the star at the apex of the Triangulum (Triangle),
approx. 2° and the vertical of the luminous Belt of Andromeda, once
it sets in the Northern Hemisphere.
During late mid April, it will start setting
after Sunset; however, Western people
will not be able to see it at Sunset,
as its height at Sunset will not exceed 6°.
And again, for sure, at Sunset, during mid
May. But at the beginning of the month
of May its height, at Sunrise, will be 10° and it will rise 42 minutes
before Sunrise; therefore it will be seen
for all the month faintly, except at the month’s end,
when it will start rising 1h ½ before Sunrise and will rise 15°
½ before sunrise; it will be seen above Pleiades.
For all the month of June it will be possible
to observe it in an adequate way during morning hours,
as on day 10, at Sunrise it will be 21° high; on day 20 it will be
27° high; and at the end of the month
it will be 34°. It will rise with Pleiades,
and it will remain stationary there for the whole month. At that time,
it will be seven times higher above Earth than at the beginning of April
and it will be observable in this position, by naked eye, for a long time
and for even a longer time, if a telescope is used.
Distance the Comet covered
throughout the sky ...
This new Comet will be seen for nearly all
the month of March; therefore the
distance will be found out on the date of the day of the following Perigee
( 4 April at dawn)
and after finding the days of [March and] April that are equally distant
from the day of the Perigee. Here, in fact, the Comet (in the periods that
precede and follow the Perigee, both having a same time interval) is equally
distant from the Perigee and from the limit of maximum Latitude; in both
places it has nearly the same Latitude.
In such an instance the Comet will at last
appear clear in the month of March, the
extreme of Sagittarius, hence Capricorn and Aquarius, after covering the
Northern Latitude, reaching Serpentarius
through Antinous, Heculeous and Petasous, where
it was seen for the first time, even though it could have been seen much
earlier if it had not been hidden to observation by the clouds or by the
shining of the Moon.
Motion will continue through the Southern wing
of Andromeda, and through the Northern Head of Pisces, between
Triangulum and Aries, through
the section of Taurus and up to Pleiades,
where this apparition will find its end: a motion similar
to that of the Comet observed by Tychone
in 1577.
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