PHPackages                             mjaschen/astrotools - PHPackages - PHPackages  [Skip to content](#main-content)[PHPackages](/)[Directory](/)[Categories](/categories)[Trending](/trending)[Leaderboard](/leaderboard)[Changelog](/changelog)[Analyze](/analyze)[Collections](/collections)[Log in](/login)[Sign up](/register)

1. [Directory](/)
2. /
3. [Utility & Helpers](/categories/utility)
4. /
5. mjaschen/astrotools

ActiveLibrary[Utility & Helpers](/categories/utility)

mjaschen/astrotools
===================

General Purpose Astronomy Library for PHP

1.0.0(5y ago)4953[1 issues](https://github.com/mjaschen/astrotools/issues)MITPHPPHP >=7.3

Since Mar 6Pushed 5y ago2 watchersCompare

[ Source](https://github.com/mjaschen/astrotools)[ Packagist](https://packagist.org/packages/mjaschen/astrotools)[ Docs](https://github.com/mjaschen/astrotools)[ RSS](/packages/mjaschen-astrotools/feed)WikiDiscussions main Synced 1mo ago

READMEChangelog (1)Dependencies (6)Versions (5)Used By (0)

Astrotools
==========

[](#astrotools)

Astrotools is a general purpose PHP library for astronomy.

Requirements
------------

[](#requirements)

- PHP >= 7.3
- *bcmath* extension

### Older PHP versions

[](#older-php-versions)

- 0.1.x branch supports PHP >= 7.0
- 0.0.x branch supports PHP 5.4 - 5.6. For details see the next section.

Installation
------------

[](#installation)

```
composer require mjaschen/astrotools
```

### PHP 7.0, PHP 7.1, PHP 7.2

[](#php-70-php-71-php-72)

If you need to use Astrotools with PHP 7.0, 7.1 or 7.2 just require version 0.1:

```
composer require mjaschen/astrotools:^0.1.0
```

Please keep in mind, that the 0.1.x branch is no longer maintained and won't get any updates.

### PHP 5

[](#php-5)

If you need to use Astrotools with PHP 5.4, 5.5, or 5.6, just require version 0.0.2:

```
composer require mjaschen/astrotools:0.0.2
```

Please keep in mind, that the 0.0.x branch is no longer maintained and won't get any updates.

Features
--------

[](#features)

- Julian day calculation (forward/reverse)
- Sidereal time calculation (GMST, local sidereal time)
- Date of Easter calculation
- Time helper

Why not use PHP's calendar extension?
-------------------------------------

[](#why-not-use-phps-calendar-extension)

Some implemented features (e.g. calculation of Julian day or Date of Easter) are already provided by PHP's [calendar](http://php.net/manual/en/ref.calendar.php) extension.

These functions come with some problems, e.g. `easter_date()` can only calculate the Date of Easter for the timerange of unix timestamps (1970 January 1 to somewhere around 2037/2038).

Usage Examples
--------------

[](#usage-examples)

### Calculation of the Julian day from Date/Time

[](#calculation-of-the-julian-day-from-datetime)

```
use Astrotools\Time\JulianDay;

$timestamp = new \DateTime('2015-02-25 12:01:36', new \DateTimeZone('Europe/Berlin'));
$jd = JulianDay::fromDateTime($timestamp);

echo $jd->getValue();
```

The code above produces the output shown below:

```
2459283.3831366

```

### Calculation of Date/Time from Julian day

[](#calculation-of-datetime-from-julian-day)

```
use Astrotools\Time\JulianDay;

$jd = new JulianDay(2451545.0);

var_dump($jd->getDateTime());
```

The code above produces the output shown below:

```
class DateTime#10 (3) {
  public $date =>
  string(26) "2000-01-01 12:00:00.000000"
  public $timezone_type =>
  int(3)
  public $timezone =>
  string(3) "UTC"
}

```

### Calculation of sidereal time for a given Date/Time

[](#calculation-of-sidereal-time-for-a-given-datetime)

#### Greenwich sidereal time

[](#greenwich-sidereal-time)

```
use Astrotools\Time\SiderealTime;

$dt = new \DateTime('2007-12-25 00:00:00', new \DateTimeZone('UTC'));
$st = new SiderealTime($dt);

echo $st->getSiderealTime();
```

The code above produces the output shown below:

```
6.2086583333

```

#### Local sidereal time

[](#local-sidereal-time)

Local sidereal time for Berlin, Germany (longitude = 13.5 degrees east):

```
use Astrotools\Time\SiderealTime;

$dt = new \DateTime('2007-12-25 20:00:00', new \DateTimeZone('UTC'));
$st = new SiderealTime($dt);

echo $st->getLocalSiderealTime(13.5);
```

The code above produces the output shown below:

```
3.1634161794

```

### Time helper

[](#time-helper)

#### Convert hours, minutes, and seconds to decimal time

[](#convert-hours-minutes-and-seconds-to-decimal-time)

```
use Astrotools\Helper\Time;

$time = Time::fromTime(6, 42, 23.1337);

echo $time->getValue();
```

The code above produces the output shown below:

```
6.7064260278

```

#### Convert decimal time to hours, minutes, and seconds

[](#convert-decimal-time-to-hours-minutes-and-seconds)

```
use Astrotools\Helper\Time;

$time = new Time(6.7064260278);

printf('%02d:%02d:%02.4f', $time->getHour(), $time->getMinute(), $time->getSecond());
```

The code above produces the output shown below:

```
06:42:23.1337

```

#### Convert between time and hour angle

[](#convert-between-time-and-hour-angle)

```
use Astrotools\Helper\Time;

$time = Time::fromTime(6, 42, 23.1337);

echo $time->getHourAngle() . PHP_EOL;

echo Time::fromHourAngle(275)->getValue();
```

The code above produces the output shown below:

```
100.596390417
18.333333333333

```

### Date of Easter Calculation

[](#date-of-easter-calculation)

```
use Astrotools\Time\DateOfEaster;

$doe = new DateOfEaster(2000);

echo $doe->getDate()->format('Y-m-d');
```

The code above produces the output shown below:

```
2000-04-23

```

### Calculation of ΔT

[](#calculation-of-δt)

There exist multiple methods to get the value of ΔT for a given (decimal) year. One can lookup the value in [tables](http://maia.usno.navy.mil/) and interpolate it for the wanted date or calculate it using [polynomial expressions](http://eclipse.gsfc.nasa.gov/SEcat5/deltatpoly.html).

*Astrotools* currently provides the calculation of ΔT with polynomial expressions. Reasonably accurate values are provided for the timespan between the years -500 and 2150.

```