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Special Annoucements

Download and review the latest ALCDEF standards PDF.

2024 March 4
The site and standard have been updated to distinguish between Pan-STARRS and Sloan ugriz filters and magbands. "Px" stands for Pan-STARRS wile "Sx" stands for Sloan. Magnitudes based on the ATLAS star catalog (Tonry et al., 2008) are Px

The EPOCH keyword has been deprecated and replaced by EQUINOX. Existing programs that generate EPOCH will still work as will upload files using EPOCH. If using a custom program to read/write ALCDEF files, it should be updated to use EQUINOX.

Simple-ALCDEF Lightcurve Data Upload

  • Change in S-ALCDEF 2.2:
    Single observations in a lightcurve block are no longer allowed. Each lightcurve block must have at least 2, preferably 5 or more, observations.
  • If not named and/or numbered, objects must have an MPC designation. Do not submit data for NEOCP objects or those using a custom designation.
  • View the ALCDEF standards documentation, which describes the data and formatting for the values associated with the keywords in the two data sections.
    An appendix details the requirements for submitting "simple" data.
  • The fields in the Required Data section will apply to all submitted data except for the ALLOWSHARING and SUBMITPDS settings. These can be altered with metadata overrides. All other settings are fixed.
  • The fields in the Base Data section will be applied to all light curve blocks unless their corresponding keywords appear within a given light curve block. This allows, e.g., submitting data for multiple asteroids or filters within the same file.
  • Please limit files to approximately 250 KB or less in order to avoid overloading site resources.

Required Data

Allow Sharing
You must give express permission before your data can be stored and distributed.
Submit to PDS
In addition to Allow Sharing, you must give express permission before your data can be automatically submitted to the NASA PDS in periodic updates.
Contact Name
e.g., J. Q. Astronomer
Contact Info
e.g., email and/or postal address (do not include Contact Name)
Use semicolon to separate names, e.g., J. Q. Astronomer; H. I. S. Assistant
Delimiter      Data columns delimiter
JD Offset  Value required to get full JD (not MJD). See documentation.
Additional information that applies to all observations. Max chars: 400.
Text will be split into COMMENT lines of up to 70 characters each.

Base Data (Can override)

Object Number
Leave blank if not numbered
Object Name
Enter MPC designation if not named.
When a non-zero number and name are given, they must be for the same object, e.g., 5463 Ceres will be rejected.


MPC Code

Observatory/Facility name, e.g., Center for Solar System Studies - Palmer Divide Station
MPC observatory code, e.g., U82
Tools Telescope 
e.g., 0.5-m f/8.1 Ritchey-Chretien
e.g., CCD or FLI-1001E or Apogee Alta
±DDD.dddddd (-180.00 to +180.00)
Negative for Western Hemsphere
±DD.dddddd (-90.00 to +90.00)
Negative for Southern Hemsphere
L-T Correction   If Yes, the correction at mid-time will be added to the output
Reduced Mags   If Yes, the correction at mid-time will be added to the output
P'X' = Pan-STARRS ugriz
S'X' = Sloan ugriz
Mag Band
Mag System

Differ Mags

Diff Zero Mag 
Exposure JD

Exp (sec) 
Enter 0 if mid-time
Revised See ALCDEF documentation before submitting revised data


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