Julian Day Conversion

Many astronomical observations require that the data be presented with Julian Dates. The following charts will display the Julian Date of the first of each month for this and the coming year.

Add 2,400,000 to get the full Julian Day. So, the full Julian Day for July 1st 2016 is 2457570. The Julian Day is a consecutive day count starting on January 1 of the year -4712 (= 4713 B.C.E.).

Julian Days (JD) for 2018:

Add the day of the month to the number shown. Julian Days begin at Greenwich Noon.

January

57784

July

57965

February

57815

August

57996

March

57843

September

58027

April

57874

October

58057

May

57904

November

58088

June

57935

December

58118

Julian Days (JD) for 2019:

Add the day of the month to the number shown. Julian Days begin at Greenwich Noon.

January

58149

July

58330

February

58180

August

58361

March

58208

September

58392

April

58239

October

58422

May

58269

November

58453

June

58300

December

58483

An Easier Way to Calculate JD:

Though you can calculate the JD yourself, we highly recommend you go to the AAVSO site for a direct conversion to Julian Date and decimal. There is an app that allows you to enter the data in either form and convert it. Also, you can find a thorough explanation about Julian Dates and why they are so important..