Time: Basic time functionalities

This notebook illustrates the usage of the montu.Time class in MontuPython.

If you are running this script in Google Colab you need first to install the package and create a directory for saving plots:

[1]:

try:
    from google.colab import drive
    %pip install -Uq montu
except ImportError:
    print("Not running in Colab, skipping installation")
    import plotly.io as pio
    pio.renderers.default = "notebook_connected"
    %load_ext autoreload
    %autoreload 2
# Create folders for figures and temporal files
!mkdir -p ./gallery/ ./montu_dem/

Not running in Colab, skipping installation

[2]:

%matplotlib inline
import montu as mn

MontuPython version 0.50.0. 𓇍𓇋𓇋𓏏𓅓𓊵 𓎛𓎡𓄿𓀭𓎛𓈖𓂝𓎡 (ii-ti m Htp, HkAx Hn'-k)

2. Definition of time and conversion to other scales

Convert dates:

From Gregorian Proleptic to other scales:

[3]:

mtime = mn.Time('-2500-01-01 12:00:00.00',format='iso',scale='utc',calendar='proleptic')
print(mtime)

2501 B.C. 01-01 12:00:00.00 / [hrw 280] I shemu 17:
    Date in ISO format: 2501 B.C. 01-01 12:00:00.00
    Date in proleptic UTC: -2500-01-01 12:00:00.000000
    Date in mixed UTC: -2500-01-22 12:00:00
    Weekday: 2 (monday)
    Date in sothic format: [hrw 280] I shemu 17
    Terrestrial time: tt [seconds]: -142006202700.3
    UTC time: jed [days]: 807954.0
    Delta-t = TT - UTC [seconds]: 59699.7

From Gregorian Mixed to other scales:

[4]:

mtime = mn.Time('-2500-01-22 12:00:00.00',format='iso',scale='utc',calendar='mixed')
print(mtime)

2501 B.C. 01-23 04:34:59.700000 / [hrw 280] I shemu 17:
    Date in ISO format: 2501 B.C. 01-23 04:34:59.700000
    Date in proleptic UTC: -2500-01-23 04:34:59.7
    Date in mixed UTC: -2500-01-22 12:00:00
    Weekday: 2 (monday)
    Date in sothic format: [hrw 280] I shemu 17
    Terrestrial time: tt [seconds]: -142006202700.3
    UTC time: jed [days]: 807954.0
    Delta-t = TT - UTC [seconds]: 59699.7

From Julian day (UTC) to other scales:

[5]:

mtime = mn.Time(807954,format='jd',scale='utc')
print(mtime)

2501 B.C. 01-01 12:00:00.00 / [hrw 280] I shemu 17:
    Date in ISO format: 2501 B.C. 01-01 12:00:00.00
    Date in proleptic UTC: -2500-01-01 12:00:00.000000
    Date in mixed UTC: -2500-01-22 12:00:00
    Weekday: 2 (monday)
    Date in sothic format: [hrw 280] I shemu 17
    Terrestrial time: tt [seconds]: -142006202700.3
    UTC time: jed [days]: 807954.0
    Delta-t = TT - UTC [seconds]: 59699.7

From terrestrial time (TT) to other scales:

[6]:

mtime = mn.Time(0,format='tt',scale='utc')
print(mtime)

2000-01-01 12:00:00.000000 / [hrw 4783] I shemu 13:
    Date in ISO format: 2000-01-01 12:00:00.000000
    Date in proleptic UTC: 2000-01-01 12:00:00.000000
    Date in mixed UTC: 2000-01-01 12:00:00
    Weekday: 7 (saturday)
    Date in sothic format: [hrw 4783] I shemu 13
    Terrestrial time: tt [seconds]: 63.9
    UTC time: jed [days]: 2451545.0
    Delta-t = TT - UTC [seconds]: 63.9

Detailed attributes

The Time objects has many attributes related to the epoch defined.

You may access different attributes using:

[7]:

(mtime.readable.datepro, # Date in gregorian proleptic
 mtime.readable.datemix, # Date in gregorian mixed
 mtime.jed, # Date in Julian Day (utc scale)
 mtime.tt, # Date in ephemerides time (tt scale)
 mtime.et, # Date in ephemerides time (utc scale)
)

[7]:

('2000-01-01 12:00:00.000000', '2000-01-01 12:00:00', 2451545.0, 63.9, 0.0)

A list of attributes are:

[8]:

mtime.__dict__.keys()

[8]:

dict_keys(['readable', 'calendar', 'isjulian', 'deltat', 'bce', 'jed', 'et', 'jtd', 'tt', 'obj_pyephem', 'obj_pyplanet', 'hed', 'htd'])

Here is a detailed explanation of each attribute:

Strings:

readable.datepro: Date in proleptic gregorian (extrapolates gregorian calendar before 1582-10-15).
readable.datemix: Date in mixed calendar (gregorian from 1582-10-15) and julian before.
readable.datespice: Date in SPICE format.
readable.datecan: Egyptian civil (sothic) date, e.g. [hrw 280] I *shemu* 17.

Boolean:

bce: Is date before christ (before current era).
isjulian: Is date a Julian date, i.e. it is a date from before 1582-10-04.

Uniform time-scales:

deltat: Delta-t = TT - UTC.
jtd: Julian day in terrestrial time scale.
tt: Ephemerides time.
jed: Julian day in UTC.
et: Uniform time.

Calendar:

readable.components: Components of date.
readable.year, readable.month, readable.day, readable.hour, readable.minute, readable.second, readable.usecond: Self explanatory.

3. Operations with with objects

You may perform operations between time objects:

[9]:

t1 = mn.Time('[hrw 0] I akhet 1', calendar='sothic')
ts = t1 + 1*mn.YEAR

t1, ts

[9]:

(Time('-2781-07-20 18:48:41.4'/'-2781-07-20 00:00:00'/'[hrw 0] I akhet 1'/JED 705497.5/JTD 705498.2838125),
 Time('-2780-06-26 06:00:29.401952'/'-2780-07-19 06:00:00'/'[hrw 1] I akhet 1'/JED 705862.7503403/JTD 705863.5338125))

[10]:

t2 = mn.Time('[hrw 0] I akhet 2', calendar='sothic')
ts = t2.jed - t1.jed
ts

[10]:

1.0

4. Search dates

[11]:

t = mn.Time('[hrw 0] I akhet 1', calendar='sothic')
t

[11]:

Time('-2781-07-20 18:48:41.4'/'-2781-07-20 00:00:00'/'[hrw 0] I akhet 1'/JED 705497.5/JTD 705498.2838125)

[12]:

t = mn.Time('[-2781] I akhet 1', calendar='sothic')
t

[12]:

Time('-2781-07-20 18:48:41.4'/'-2781-07-20 00:00:00'/'[hrw 0] I akhet 1'/JED 705497.5/JTD 705498.2838125)

[13]:

t = mn.Time('[bce2782] I akhet 1', calendar='sothic')
t

[13]:

Time('-2781-07-20 18:48:41.4'/'-2781-07-20 00:00:00'/'[hrw 0] I akhet 1'/JED 705497.5/JTD 705498.2838125)

[14]:

# t2 = mn.Time('[hrw 0] I akhet 2', calendar='sothic')
# t2 = mn.Time('[bce 2026] I akhet 2', calendar='sothic')
# t2 = mn.Time('[-2025] I akhet 2', calendar='sothic')

[15]:

mn.Time('2026-01-01')

[15]:

Time('2026-01-01 00:00:00.000000'/'2026-01-01 00:00:00'/'[hrw 4809] I shemu 20'/JED 2461041.5/JTD 2461041.5008692)

[16]:

t = mn.Time('[bce 1341] I akhet 1', calendar='sothic')
t

[16]:

Time('-1340-07-24 08:52:13.9'/'-1340-07-24 00:00:00'/'[hrw 1442] I akhet 1'/JED 1231827.5/JTD 1231827.8696053)

[17]:

t = mn.Time('[hrw 1442] I akhet 1', calendar='sothic')
t

[17]:

Time('-1340-07-24 08:52:13.9'/'-1340-07-24 00:00:00'/'[hrw 1442] I akhet 1'/JED 1231827.5/JTD 1231827.8696053)

[18]:

t = mn.Time('[hrw 1442] II peret 12', calendar='sothic')
t

[18]:

Time('-1339-01-01 08:51:53.7'/'-1339-01-01 00:00:00'/'[hrw 1442] II peret 12'/JED 1231988.5/JTD 1231988.8693715)

Powered by MontuPython. For more examples see MontuPython GitHub repo.