What's in a Name?

There is some confusion about the exactly what’s stored in the ALCDEF database. It is often referred to as “the asteroid lightcurve database”, which happens to be the long-established name for the real asteroid lightcurve database (LCDB; Warner et al., 2009).

The LCDB stores the results of data analysis, e.g., rotation periods, taxonomic class, spin axis/shape models, and so on. It does not store the original data used to do that analysis.

On the other hand, the ALCDEF database (call it “ALK-def”) stores only raw asteroid time-series photometry.

Simplifying ALCDEF

To upload data from the main ALCDEF page requires that the metadata and data follow the ALCDEF standard. Programs such as MPO Canopus, written by the author, include provisions for writing such files from the original data. However, many other programs do not and there is a wealth of legacy data that might also be uploaded if there were a simpler format.

In mid-2015, the Simple-ALCDEF (S-ALCDEF) standard was introduced. In its simplest form, S-ALCDEF requires only four lines other than the data lines. For example, assuming all the data in the file are for the same asteroid (bold text highlights the four lines),

            #First night
            STARTBLOCK
            STARTDATA
            2457210.698517|+18.377|+0.121
            2457210.700769|+18.489|+0.136
            2457210.703026|+18.354|+0.121
            ...
            ENDDATA
            ENDBLOCK
            

            #Second Night
            STARTBLOCK
            STARTDATA
            2457210.776946|+17.375|+0.055
            2457210.777695|+17.419|+0.058
            ...
            ENDDATA
            ENDBLOCK
            

Lines preceded by the hashtag (#) are ignored. The hashtag can also be embedded in a line. Starting with the hashtag, it and all characters after it on that line are ignored, making it possible to include a comment about a specific line in the file.

More details about S-ALCDEF can be found in the ALCDEF documentation. The S-ALCDEF page is found at http://alcdef.org/alcdef_SimpleUpload.php

Redundancy! Redundancy!

The ALCDEF and S-ALCDEF standards and MPC web site provide a straight-forward way to archive raw asteroid time-series data that are readily available and critical to researchers. However, the ALCDEF database is far from universally-accepted and used.

For example, all data presented in articles in Astronomy and Astrophysics must be archived in the Centre de Donnée astronoimiques de Stransbourg (Lub, 2015; CDS, Strasbourg Astronomical Data Center). This is not going to change nor should it do so. It’s also unlikely that a researcher is going to prepare his data for more than one archive database, even though in this case there may not be significant differences in the files submitted to CDS and ALCDEF; it might be something for those submitting to CDS (or ALCDEF) to consider.

There are many other repositories of raw data, many on private web sites or in the computer equivalent of “dusty filing cabinets.” It’s hoped that the introduction of S-ALCDEF will encourage even more submissions to the system.

While a single universally-accepted repository is preferable, a minimum number, each with long-term stability that extends beyond those who currently own and/or maintain it, is a good alternative and is encouraged.

References

Chang, C.-K., Ip, W.-H., Lin, H.-W., Cheng, Y.-C., Ngeow, C.-C., Yang, T.-C., Waszczak, A., Kulkarni, S.R., Levitan, D., Sesar, B., Laher, R., Surace, J., Prince, T.A. (2015). “Asteroid Spin-rate Study Using the Intermediate Palomar Transient Factory.” Ap. J. Suppl. Ser. 219, A27.

Chang, C.-H.; Lin, H.-W.; Ip, W.-H.; Chen, W.-P.; Yeh, T.C., Chambers, K.C., Magnier, E.A., Huber, M.E., Flewelling, H.A., Waters, C.Z., Wainscoat, R.J., Schultz, A.S.B. (2019). “Searching for Super-Fast Rotators Using the Pan-STARRS 1.” ArXiv:1901.08719.

Hanuš, J., Brož, M., Durech, J., Warner, B. D., Brinsfield, J., Durkee, R., Higgins, D., Koff, R. A., Oey, J., Pilcher, F., Stephens, R., Strabla, L. P., Ulisse, Q., Girelli, R. (2013). “An anisotropic distribution of spin vectors in asteroid families.” Astron. Astrophys. 559, A134.

Lagerkvist, C.-I., Magnusson, P., Belskaya, I., Erikson, A., Dahlgren, M., Barucci, M.A. (1993). “Asteroid Photometric Catalog, Third Update.” Uppsala Astronomical Observatory, Uppsala.

Lub, J. (2015). “Editorial.” Astron. Astrophys. 581, E1.

Magnusson, P., Lagerkvist, C.-I., Dahlgren, M., Erikson, A. (1993). “The Uppsala Asteroid Database.” in ACM 1993, Proceedings of the 160th International Astronomical Union. (A. Milani, M. Di Martino, A. Cellino, eds). pp 471-476. Kluwer Academic Publishers.

NASA (2011). Update to Uppsala Asteroid Database. Planetary Data Systems catalog EAR-A-3-DDR-APC-LIGHTCURVE-V1.1. Available on-line

Piironen, J., Lakgerkvist, C.-I., Torppa, J., Kaasalainen, M., Warner B. (2001). “Standard Asteroid Photometric Catalog.” DPS Meeting #33. B.A.A.S. 33, 1562.

Pravec, P., Harris, A. W., Vokrouhlický, D., Warner, B. D., Kušnirák, P., Hornoch, K., Pray, D. P., Higgins, D., Oey, J., Galád, A., Gajdoš, Š., Kornoš, L., Világi, J., Husárik, M., Krugly, Yu. N., Shevchenko, V., Chiorny, V., Gaftonyuk, N., Cooney, W. R., Gross, J., Terrell, D., Stephens, R. D., Dyvig, R., Reddy, V., Ries, J. G., Colas, F., Lecacheux, J., Durkee, R., Masi, G., Koff, R. A., Goncalves, R. (2008). “Spin rate distribution of small asteroids.” Icarus 197, 497-504.

Rubincam, D.P. (2000). “Relative Spin-up and Spin-down of Small Asteroids.” Icarus 148, 2-11.

Stephens, R.D., Warner, B.D., Harris, A.W. (2010). “A Proposed Standard for Reporting Asteroid Lightcurve Data.” DPS meeting #42. B.A.A.S. 42, 1035.

Tonry, J.L., Denneau, L., Heinze, A.N., Stalder, B., Smith, K.W., Smartt, S.J., Stubbs, C.W., Weiland, H.J., Rest, A. (2018). “ATLAS: A High-cadence All-sky Survey System.” PASP 130, 064505.

Warner, B.D., Harris, A.W., Pravec, P. (2009). “The Asteroid Lightcurve Database.” Icarus 202, 134-146. Updated 2019 February.
http://www.minorplanet.info/lightcurvedatabase.html

Waszczak, A.; Chang, C.-K.; Ofek, E.O.; Laher, R.; Masci, F.; Levitan, D.; Surace, J.; Cheng, Y.-C.; Ip, W.-H.; Kinoshita, D.; Helou, G.; Prince, T.A.; Kulkarni, S. (2015). “Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry.” Astron. J. 150, A75.