This page is useful when you work with astronomy-style Julian day numbers or need to compare them with standard calendar dates. It handles both directions in one input box depending on whether you paste a numeric Julian value or a readable date.
The current behavior is intentionally simple: numeric input is treated as a Julian day number and converted to ISO output, while non-numeric input is parsed as a date and converted into a Julian day number with fixed decimal formatting.
You get either a UTC ISO string from a Julian value or a formatted Julian day number from a date input. That makes the page practical for quick comparisons, but not a specialist astronomy package.
| Example | Value |
|---|---|
| Input | Either a numeric Julian day value or a readable date string. |
| Output | Either ISO date output or a Julian day number, depending on input type. |
It is not a full astronomy toolkit with advanced calendars or domain-specific conventions. It is a practical browser-side Julian conversion helper.
Numeric input is treated as a Julian day number; other input is treated as a date.
It returns an ISO string.
It is useful when you need a quick bridge between Julian day values and standard date output.
Convert between Julian day numbers and ISO date output.