get_last_an_time does not work with a datetime object as input

[adybbroe]

Code Sample, a minimal, complete, and verifiable piece of code

# Your code here
from pyorbital.orbital import Orbital
from datetime import datetime

tlefile = "./aws_2022.tle"
aws1 = Orbital("AWS-1", tle_file=tlefile)

dtobj = datetime(2022, 3, 9, 7, 30)
aws1.get_lonlatalt(dtobj)

Problem description

get_last_an_time does not work with a datetime object as input, as otherwise indicated in the documentation. It seem to require a numpy datetime64 object instead?

If mysat is my Orbital object for a given platform name and TLE file, and dtobjis a datetime object (my utc time) then: mysat.get_last_an_time(dtobj) does not work! See below Traceback.

But mysat.get_last_an_time(np.datetime64(dtobj)) works.

Expected Output

Method should just work providing a datetime object

Actual Result, Traceback if applicable

~/usr/src/forks/pyorbital/pyorbital/orbital.py in get_last_an_time(self, utc_time)
    170         dt = np.timedelta64(10, 'm')
    171         t_old = utc_time
--> 172         t_new = t_old - dt
    173         pos0, vel0 = self.get_position(t_old, normalize=False)
    174         pos1, vel1 = self.get_position(t_new, normalize=False)

UFuncTypeError: ufunc 'subtract' cannot use operands with types dtype('O') and dtype('<m8[m]')

Versions of Python, package at hand and relevant dependencies

• Python 3.9
• Latets pyorbital main branch

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