Version 11.5, Released September 2018

R.C. Walker

September 17, 2018

SCHED is a program for planning and scheduling Very Long Baseline Array (VLBA), High Sensitivity Array (HSA), Global Very Long Baseline Interferometry (Global VLBI), European VLBI Network (EVN), Long Baseline Array (LBA; Australia), Korean VLBI Network (KVN), VLBI on the Karl G. Jansky Very Large Array (VLA) and other VLBI observations. It writes VEX files that describe the details of an observation and are becoming the near universal format for distribution of schedules to VLBI telescopes and correlators.

This manual describes how to use the program, provides extensive information on all possible inputs, and gives considerable information and advice on many aspects of scheduling VLBI observations. The INTRODUCTION gives an overview of the program and is the only chapter that a new user should read before starting to use the program. The rest of the manual can be treated as a reference to be consulted to answer questions.

Scheduling with SCHED involves creating an input file with a text editor, and then running the program on that file. SCHED creates a variety of output files that provide summary and detailed information to the scheduler and telescope control information for the VLBI station. The easiest way to create an input file is to copy one of the examples and modify it for your particular project. All of the examples are complete, working files. SCHED is not interactive unless plots are being made, in which case there is a convenient, interactive interface to control the plotting. The plotting capabilities should be very useful, especially during proposal writing and while planning observations.

This edition of the manual corresponds to the SCHED version as indicated in the title. Please be sure that you have the latest major version of the code and catalogs to be sure your schedule files are valid. Please check the notes on the current release to be sure that you don’t need a more recent minor release than the one you have (these are usually bug fixes). The distribution files for the latest releases are available on anonymous ftp at in directory pub/sched.

In several places in this manual, there are links to text files that come with the manual. Some browsers just display those files without issue. But, since the files typically don’t have a .txt extension, sometimes the browser won’t display them natively and won’t give an option to do so. I encountered this with Firefox on a Mac. It thinks the .key files are Keynote files. I found an add-on called “open in Browser” that deals with the situation. You can find it with a search.

For general, and NRAO specific, comments and questions, please contact the help desk ( or Amy Mioduszewski. For EVN, Mark IV and non-VLBA VEX format issues, contact Des Small at SCHED was written by Craig Walker of NRAO with significant contributions from Huib van Langevelde, Cormac Reynolds, Antonios Polatidis, Friso Olnon, and Des Small of JIVE, and Franco Tinarelli of CNR in Bologna. Craig Walker retired at the end of 2014 and Amy Mioduszewski is now the main NRAO based SCHED supporter. Des Small and Cormac Reynolds are the main active non-NRAO supporters. Craig will continue a low level of involvement but should not be the first person to contact with issues. The manual is long and has been supported mainly by one person, so, in this period of rapid changes in hardware, please excuse occasional sections that are not entirely up to date.

 0.1 Important Notes - Please check these
 0.2 Links to Manual Sections and to External Information.
 1.1 Overview
 1.2 Keyin Free-format Input
 1.3 SCHED Input and Output Files
 1.4 Examples
 1.5 Plotting
 2.1 Using SCHED for Project Planning
 2.2 Scheduling Tips
 2.3 Recording Systems.
 2.4 Wide Band Observing: RDBE, DBBC, VLBA and Mark IV Modes
 2.5 Spectral Line Observations
 2.6 Reference Pointing
 2.7 Multiple Phase Centers
 2.8 Automatic Insertion of Geodetic Segments
 2.9 Scheduling the VLA
 2.10 Special Concerns for Specific Observatories
 2.11 Single Dish VLBA Observing
 2.12 Configuration Studies
 2.13 Satellite Tracking
3 THE SCHED INPUT FILES (Includes parameter lists)
 3.1 The Schedule File
 3.2 Source Catalog
 3.3 Station Catalog and Locations Catalog
 3.4 Tape Initialization File
 3.5 Frequency Catalog
 3.6 Setup Files
 3.7 Satellite Initialization.
 4.1 Installing SCHED
 4.2 Running SCHED
 4.3 Distribution of Schedule Files
 4.4 Related Programs
 4.5 Release Instructions.
 5.1 Recent Releases
 5.2 Old Releases
 5.3 Wish List
 A.1 Station Codes
 A.2 Historical Notes
 B.1 Old VLA
 B.2 Tape Management
 B.3 Mark III Observations
 B.4 Scheduling Mark II Observations
 B.5 Head Positions and Track Assignments
 B.6 S2
 B.7 Green Bank 140’.
 B.8 Installation on Mac OSX 10.3 in 2003.