Find Exoplanet Transits

This form calculates observability of exoplanet transits.


Choose an observatory, or choose "manual coordinate entry" at end of list:

  Use UTC  /  Use observatory's local time.

Date window:

Base date for transit list (mm-dd-yyyy or 'today'):

From that date, show transits for the next days.
(Also include transits from the previous days.)


Only show transits with an elevation (in degrees) of at least:

at ingress:     Combine constraints with AND OR.
at egress:

Unspecified elevation constraints default to 0. Constraints are evaluated at night, i.e. to be shown as observable an event has to meet that elevation constraint during nighttime hours.

Ignore all elevation and day/night constraints; show all transits. Useful for space-based observing (but can generate lots of output if no target constraints specified).

Only show transits with a depth of at least millimag.

Only show targets with names matching this string: .
(Not case sensitive; can be a Perl regular expression.)

Target list: database
Single object with ephemeris below (above filters still apply, except depth filters).
Note: to search for a specific target, don't use this. Choose "Known targets" above, then enter the target name above in the box labeled "Only show targets with names matching this string." Use this only if you want to manually enter the ephemeris for some other target (or try an alternate ephemeris for a known target).

RA (J2000):  
Dec (J2000):  
JD (UTC) of mid-transit:  
Period (days):  
Transit duration (hours):  
Target name (for labeling only):  

Show the input ephemeris data used to generate the target list (useful for debugging if a particular target isn't showing up as you expect):

Output format and labeling:

Output results as:
HTML table
CSV file for parsing by script.
CSV file for calendar import. (Save resulting output to a text file, then import into your observing calendar, e.g., import into Google Calendar.)

Day/night definition: start night at Sun altitude of  
The above choice determines both which events are displayed (since part of the transit must be at night), and which parts of an event are color-coded to indicate daytime.

Maximum airmass to show in airmass plots:  
(Current airmass value of 2.4 is elevation of 24.6 degrees.)

This page uses input ephemeris data from, maintained by Jason Wright.

The software producing this page is based on Tapir, created by Eric Jensen.

Last update: March 12, 2017
kielkopf at louisville dot edu