LUNAR LASER RANGING OBSERVATIONS FROM 1969 TO 21 DECEMBER 2024

Introduction

The POLAC team collected the LLR observations made between 1969 and the 21th of December 2024 by the LLR tracking stations and stocked them in files in the standard format MINI (see below) according to the stations and the periods of observation. These data were then converted into the form of "VO tables" (Virtual Observatory tables) to facilitate the statistic and graphic processing by software developed for the needs of the astronomers (as Topcat for example).

LLR Reflectors

• Apollo 11 installed in July 1969.
• Luna17 (Lunokhod 1) installed in November 1970, lost in 1971 and found again in 2010.
• Apollo 14 installed in February1971.
• Apollo 15 installed in August 1971.
• Luna 21 (Lunokod 2) installed in January 1973.

LLR Stations

• McDonald observatory (Texas) operational since 1969.
• Grasse-Calern observatory (OCA - ex CERGA) operational since 1984.
• Haleakala observatory (LURE, Maui, Hawaii) operational from 1984 to 1990.
• Matera observatory (Italy) operational since 2003.
• Apache Point observatory (APOLLO, New Mexico) operational since 2006.

Sources of the collected LLR observations

• Files "ARCH": files called "Archives" given to POLAC directly by the CERGA in 1997 or via e-mails from Grasse and McDonald after 1997, and also from colleagues of the ILRS.


• Files "GSFC": files available on the server CDDIS (Crustal Dynamics Data Information System): https://cddis.gsfc.nasa.gov/archive/.


• Files "DGFI" (Deutsches Geodaticshes Forshung Institut): files available on the server : ftp://edc.dgfi.tum.de/pub/slr/data/.


• Files "APOL": files produced by the APOLLO team (Apache Point Observatory Lunar Laser ranging Operation): http://physics.ucsd.edu/~tmurphy/apollo/.

Formats of the LLR observations

• Format "ZN" from 1969 to 1986.
• Format "MINI" since 1987 (see below).
• Format "CSTG" since 1997 (Coordination Space Techniques for Geodesy-Geodynamics).
• Format "CRD" since 2010 (Consolidated laser Ranging Data format).

MINI Format

	Col 01-01		Index of the format : code 5
	Col 02-02		Laser color : green (1), red (2)
	Col 03-10		Date of the launch: YYYYMMDD
	Col 11-23		Time of the launch (UTC): HHMMSSsssssss (100 ns)
	Col 24-37		Light Time: 2sssssssssssss (0.1 ps)
	Col 38-38		Index of the LLR reflector
			0 Apollo 11
			1 Lunokhod 1
			2 Apollo 14
			3 Apollo 15
			4 Lunokhod 2
	Col 39-43		Index of the LLR station
			71110 McDonald 2.70
			71111 McDonald MLRS1
			71112 McDonald MLRS2
			01910 Grasse
			56610 Haleakala
			07941 Matera
			70610 Apache Point Observatory
	Col 44-46		Number of returns
	Col 47-52		Estimation of the uncertainty (0.1 ps)
	Col 53-55		Estimation of the Signal/Noise ratio(0.1)
	Col 56-56		Code of the quality of the observation (1 character)
	Col 57-62		Atmospheric Pressure at the ground (0.01 mbar)
	Col 63-66		Temperature at the ground (0.1 degré Celsius)
	Col 67-68		Humidity at the ground (%)
	Col 69-73		Wavelength of the laser beam (0.1 nm)
	Col 74-74		Code of the version of the file (1 character)
	Col 75-78		Duration of the firing session (second)

A field has been added for specifying of the origin of the data:

	Col 81-89		Code of the source and the format of the observation (9 characters)

How the LLR observations were collected

The archives given by the LLR team of the CERGA in 1997 (observations of Grasse, McDonald and Haleakala) were completed by the observations sent directly by e-mail from Grasse and McDonald during the subsequent years before the format CSTG came into use. Then, all the data from the ILRS data centers were collected as well as those of the OCA and APOLLO web sites. Also added were some observations given by colleagues of the ILRS analysis centers. All these observations were converted to the format MINI and then verified by looking for the obvious wrong values and then correcting them whenever the correction was evident or cancelling the observation if not. Only very few corrections or suppressions were made. Furthermore, the observations were sorted out in chronological order and the duplications eliminated (identical observations from different sources).

List of files of LLR observations

OMCD6985.DAT		Observations McDonald Tel 2.7m		1969-1985		3604 obs.
OMCD8388.DAT		Observations McDonald MLRS1		1983-1988		631 obs.
OMCD8815.DAT		Observations McDonald MLRS2		1988-2015		3670 obs.
OGRA8486.DAT		Observations Grasse (Rubis)		1984-1986		1188 obs.
OGRA8705.DAT		Observations Grasse (YAG)		1987-2005		8324 obs.
OGRA0924.DAT		Observations Grasse (MeO)		2009-2024		11921 obs.
OHAL8490.DAT		Observations Haleakala		1984-1990		770 obs.
OMAT0324.DAT		Observations Matera		2003-2024		11921 obs.
OAPO0624.DAT		Observations Apache Point		2006-2024		4195 obs.
OWET1824.DAT		Observations Wettzell		2018-2024		326 obs.
TOTALOBS6924.DAT		All observations		1969-2024		35064 obs.

VO Tables et Topcat sofware

All the LLR observations which are in the file TOTALOBS6924.DAT (ascii) were converted into the form of "VO tables" and put in the file TOTALOBS6924.xml. This new file can be operated by the software that uses the VO standard such as Topcat available at the site:

http://www.star.bris.ac.uk/~mbt/topcat/

TOPCAT (Tool for OPerations on Catalogues And Tables) is an interactive tool with many possibilities for displaying the data, analysing it, making statics it and plotting graphics.
The description of the characteristics of the file TOTALOBS6924.xml given by Topcat is given in the following window.



A graphical application of Topcat is given below
It shows the evolution of the number of returns by normal point between 1969 and 2010 for all the stations and reflectors.



Barache C., Bouquillon S., Bourgoin A., Carlucci T. & Francou G.
Paris Observatory Lunar Analysis Centre
Observatoire de Paris (SYRTE) - CNRS UMR 8630

June 2025