ASTEROID LIGHTCURVE DATA BASE (LCDB) Revised 2017 February 3 ============================================================================== PDS Note This readme file was supplied by the authors as documentation for the Asteroid Lightcurve Data Base (LCDB) dated Feb. 3, 2017. It is included with the PDS data set Asteroid Lightcurve Derived Data V1.0 (urn:nasa:pds:ast_lightcurve_derived_parameters::1.0) which is based on the LCDB of this date. The data files themselves have been modified to conform to PDS requirements and the peer review liens, so some details in this document are no longer applicable. Changes include: - Not all the LCDB data files were included in the PDS archive. - Some data columns were removed for the PDS archive, in particular the "convenience columns" of H, G, diameter, and albedo, which are archived elsewhere in the PDS. - Additional target identification columns were added to the tables. - Filename extensions were changed to meet PDS requirements. This document itself has been edited by PDS to meet PDS document requirements and to fix minor typos. ============================================================================= ******************************************************************************* SPECIAL NOTICES ******************************************************************************* See Section 5 "SPARSE DATA AND WIDE-FIELD SURVEYS" Please review the column mappings for ALL tables. A number of mappings were modified for the 2017 February release. The Min/Max Amplitude values in the Summary table are based only on detail lines that have a U >= 2- ratings. If the U code is empty or U <= 1+, the detail line min/max amplitudes are not considered. Added "Numbers of Interest" section (6.0.0) ******************************************************************************* 1.0.0 INTRODUCTION -------------------------------------------------------------------------------- The Asteroid Lightcurve Data Base (LCDB) is a set of files generated from a dBase IV data base that includes information directly and indirectly obtained from observations made to determine the period and/or amplitude of asteroid lightcurves. The information is taken from numerous journals and other sources. It's main purpose is to provide a central location for basic information about asteroid rotation rates and related information that can be used in statistical studies involving a few or many parameters. Some of the data are obtained directly from the observations while other data are inferred or calculated based on orbital characteristics, assumed class, etc. Sections below explain in detail which data are direct and indirectly obtained and, for the latter, their derivation. N.B. Even direct data should be confirmed by reference to the original works whenever possible. Indirect data are provided for information purposes only. They should NOT be used in critical studies. 1.1.0 AUTHOR INFORMATION ------------------------- These data files are maintained by Brian D. Warner (Palmer Divide Observatory/ MoreData!), Alan Harris (MoreData!), and Petr Pravec (Astronomical Institute, Czech Republic). For basic information on the database or updated versions of the report files, contact: Brian D. Warner Center for Solar System Studies / MoreData! 446 Sycamore Ave. Eaton, CO 80615 brian@MinorPlanetObserver.com For more theoretical details and discussions, contact Alan Harris MoreData! 4603 Orange Knoll Ave. La Canada, CA 91011 USA harrisaw@att.net 1.2.0 DISCLAIMER ----------------- We have made every attempt to keep the data up to date and correct. However, we know that there is the possibility for omissions or errors. Please let us know of any corrections or additions by sending email to one of the below. Brian D. Warner brian@MinorPlanetObserver.com Alan Harris harrisaw@att.net 2.0.0 DATA FILES -------------------------------------------------------------------------------- The data files in this release consist of two primary sets. The general files and the Binary Asteroid files provided by Petr Pravec, Astronomical Institute, Czech Republic. 2.0.1 AVAILABILITY OF RAW DATA FILES ------------------------------------- The raw databases files are not available since they are in a proprietary format. We can, on a limited basis, provide CSV files generated from the database files. Contact the authors detailing the reasons for needing the files and if there are any special requirements to be considered. 2.1.0 GENERAL FILES -------------------- README.TXT This file of introductory information. LC_DETAILS The lightcurve data file, with data from individual references LC_SUMMARY Summary data, one line per asteroid, no references. LC_REFERENCES Reference list to all published lightcurve data. LC_AMBIGUOUS Separate summary/detail file for asteroids with ambiguous periods. LC_BINARY Separate summary/detail file for binary asteroids LC_NPA Separate summary/detail file for "tumbling" asteroids LC_SPINAXIS Separate summary/detail file for asteroids with spin axis results 2.1.1 SPIN AXIS CATALOGS ------------------------- As noted above, the LC_SPINAXIS file stores information about the spin axis properties (ecliptic coordinates and sidereal periods). A more complete and thorough catalog is maintained by Kryszczynka et al at the Poznan Observatory in Poland. That catalog can be accessed via http://vesta.astro.amu.edu.pl/Science/Asteroids/ Josef Durech also maintains a list of spin axis solutions, with shape models and data files. His site is at http://astro.troja.mff.cuni.cz/projects/asteroids3D/ 2.2.0 BINARY ASTEROID FILES ---------------------------- The following files are maintained by Petr Pravec. These files are considerably more detailed than what's in LC_BINARY and so are better suited for critical studies. BINARY_README.TXT Separate README pertaining the binary asteroid BINASTD_PUB.TXT The best estimates of compiled parameters BINASTE_PUB.TXT Uncertainties of the estimates in BINASTD_PUB.TXT BINASTM_PUB.TXT References and notes for the compiled estimates BINASTR_PUB.TXT Information on each of the estimates, e.g., their derivation These files are available at http://www.asu.cas.cz/~asteroid/binastdata.htm 2.2.1 ABOUT BINARY DATA ------------------------ The data in the LC_BINARY file are by no means exhaustive. They are meant to provide a quick overview of the primary period and amplitude as well as a secondary period and, if available, amplitude. The secondary period may be due to rotation of the secondary or the orbit of the secondary if it is tidally locked with the primary. The reader is urged to consult the original journal articles for more complete details. A good summary page with links to those journal references is the web site run by by Wm. Robert Johnston http://www.johnstonsarchive.net/astro/asteroidmoons.html 3.0.0 LCDB DATA -------------------------------------------------------------------------------- The original lightcurve database was a simple text file with a structure that tried to minimize disk space requirements. That served well for many years. However, the rapidly growing number of lightcurves being reported as well as the file's format not being able to accommodate some data prompted a change starting in mid-2006. The foremost change was converting to a relational database that includes numerous tables and has SQL search capabilities. This allows for not only easier maintenance of the database but for generating reports in a new way that are more informative, complete, and constant in formatting. The format of the LCDATPUB, LCSUMPUB and LCREF files has changed from previous years. Very small changes were made again for the 2008 release that may require additional work on parsing programs. The sections below provide the new formatting for each field. This should make rewriting old parsing programs, or new ones, fairly straightforward. 3.1.0 DIRECT DATA ------------------ Data that is obtained directly from photometric observations includes 1. Rotation period (usually synodic). 2. Amplitude. 3. Absolute magnitude, H, and phase slope parameter, G, when determined by using reduced magnitude versus phase angle data. 4. Binarity due to mutual events, i.e., occultations and eclipses. In such cases, the rotation period of the primary and orbital period of the satellite and the amplitude of the primary lightcurve are the usual direct results. The size ratio can be computed from the depth of the events. For more details on binary lightcurve analysis, see Pravec et al., 2006, Icarus 181, 63-93. 5. Color indices. 6. Diameter if based on stellar occultation or adaptive optics/radar. Radar diameters can also be considered indirect, depending on how the diameter was determined. 7. Taxonomic class. 3.1.1 SYNODIC VERSUS SIDEREAL PERIOD ------------------------------------- The synodic period depends on viewing aspect and the rate of motion of the asteroid across the sky. An expression for the magnitude of the expected difference between the sidereal period and synodic period based on the Phase Angle Bisector (PAB) is DeltaP = [d(PAB)/dt] * P^2 Where DeltaP difference between synodic and sidereal periods, in units of the rotation period (usually hours). [d(PAB)/dt] angular rate of change in the Phase Angle Bisector in inverse units of the rotation period, e.g., in units of cycles/hour P the synodic rotation period of the asteroid in the same units of time e.g., hours/cycle For example, assume an asteroid with a rotation period of 8 hours observed when the PAB is changing by 0.05 deg/day (typical for an main-belt asteroid at opposition), then the sidereal-synodic difference is DeltaP = [0.05 / 360.0 / 24.0] * (8 ^ 2) = 0.00037 hr. cycles / hour hours^2/cycles^2 hours / cycle The synodic-sidereal difference can be either positive or negative, and can exceed the value given by this expression for near-polar aspects, but the expression gives a reasonable estimate of the magnitude of the expected difference. In most cases, the period given in the summary and details lines are synodic and not sidereal. An 'S' flag (see notes below) indicates that the period is sidereal. There are many entries in both tables that do not carry the 'S' flag when they should. This is part of the legacy nature of the data after converting the files to the new data base, i.e., the old format did not allow for indicating the period was one type or another. We hope to update these and other legacy values that now have qualifying flags in future versions. For most studies, the difference between sidereal and synodic period is not significant. 3.1.2 INDIRECT DATA -------------------- Indirect data is that obtained by calculation and/or assumption. N.B. THESE DATA ARE PROVIDED FOR CONVENIENCE ONLY, AND SHOULD NOT BE USED FOR STATISTICAL STUDIES, NOR ASSUMED TO BE ACCURATE AND CURRENT. 1. Diameter, H, and albedo (Pv, Pr, etc.). The relationship between H, diameter, and albedo is: D = (1329km) * 10.0^(-0.2*H) / sqrt(albedo) or logD (km) = 3.1235 - 0.2H - (0.5 * log(albedo)). (See Pravec and Harris, 2007. Icarus 190, 250-259). The value of H is usually known, though not always accurately, based on photometric observations. If direct data are available for D and/or Pv, then the above relationships can be used to derive a missing quantity. Data from the SIMPS study (Tedesco, E.F., Noah, P.V., Price, S.D.: 2004, IRAS Minor Planet Survey. IRAS-A-FPA-3-RDR-IMPS-V6.0. NASA Planetary Data System) is used when available and no overriding data are available. If a newer value of H than that used by SIMPS is available, the diameter and albedo are re-computed based on Harris and Harris (1997, Icarus 126, 450-454). If the diameter was based on an assumed albedo and H is revised, the albedo is held constant and the diameter re-computed using the above formulae. If the diameter was determined by radar, resolved imagery, etc. and a new H is available, the diameter is held constant and the albedo is re-computed. 2. Taxonomic Class, orbital class, and albedo These three values can have a complex relationship when the class and albedo are not directly obtained. When spectroscopic or other data are available that can determine the taxonomic class exactly but no direct albedo data are available, the albedo can be assumed. This albedo can, in turn, be used to find the estimated diameter and/or H if those quantities are not directly known. Flags in the Summary table indicate the source of these fields, including if they are assumed based on a combination of available data. The table below shows the assumed values used barring any direct data. The family/group is based on orbital parameters. These are mostly for informational purposes only since the definition for some groups or families is "fuzzy", at best. Note the distinction between a family and group. A family is a set of asteroids with a common parent body. A group is a set of asteroids with common orbital characteristics. Members of a family will almost always be in the same group, but members of a group may not necessarily be of the same family. Group/Family Orbit parameters Class pv NOTES -------------------------------------------------------------------------------------------------- Baptistina Bottke el al C 0.057 Centaur 5.5 < a <= 30 C 0.057 Centaur Comet Centaur w/comet behavior C 0.057 9 Comet-like orbit Q > 5.0 C 0.057 4 Comet exhibits coma and/or tail C 0.057 Eos 2.99 < a < 3.03, 0.01 < e < 0.13, 8 < i < 12 S 0.14 Erigone 2.32 < a < 2.40, 0.15 < e < 0.22, 4 < i < 6 C 0.057 Eunomia 2.53 < a < 2.72, 0.08 < e < 0.22, 11 < i < 16 S 0.21 Flora 2.15 < a < 2.35, 0.03 < e < 0.23, 1.5 < i < 8 S 0.24 Hungaria 1.78 < a < 2.0, e < 0.18, 16 < i < 34 ES 0.3 1 Karin Nesvorny, private communications S 0.26 Koronis 2.83 < 2.91, e < 0.11, i <= 3.5 S 0.24 Main belt - inner a < 2.6 S 0.20 5 Main belt - inner comet a < 2.6 C 0.057 9 Main belt - middle 2.6 < a < 2.7 SC 0.10 Main belt - middle comet 2.6 < a < 2.7 SC 0.10 9 Main belt - outer 2.7 < a < 5.0 C 0.057 Main belt - outer comet 2.7 < a < 5.0 C 0.057 9 Mars crosser 1.3 < q < 1.668, Q < 5.0 S 0.20 5 NEA (Apollo/Aten/Amor) q < 1.3 S 0.20 5 NEA (comet) q < 1.3 C 0.057 9 Nysa 2.4 < a < 2.5, 0.12 < e < 0.21, 1.3 < i < 4.3 S 0.20 6 Phocaea 2.25 < a < 2.5, e >= 0.1, 18 < i < 32 S 0.23 Planet Satellite 7 Themis 3.08 < a < 3.24, 0.09 < e < 0.25, i <= 3 S 0.08 TNO/KBO a > 30 C 0.1 Trojan - Jupiter 5.05 < a < 5.4 C 0.057 Trojan - Mars similar to Mars S 0.20 5 Trojan - Neptune similar to Neptune C 0.057 Trojan - Saturn similar to Saturn C 0.057 2 Trojan - Uranus similar to Uranus C 0.057 2 Vestoid 2.26 < a < 2.48, 0.03 < e < 0.16, 5 < i < 8.3 S 0.20 3 NOTES ----- 1 Pv = 0.3 is a compromise value when no taxonomic information is available, since the Hungarias are both a family (common parent, E/X class, pv = 0.4) and group (similar orbits, S class, Pv = 0.20). 2 None known and not likely due to perturbations by giant planets, both interior and exterior. 3 Higher albedo (0.4) assigned only if in V class determined (SMASS, etc). Otherwise, class is 'S' and Pv = 0.20 on presumption that the object shares orbital characteristics but not parent body. 4 Barring any other classification that meets Q > 5, the orbit is classified as "comet-like." 5 The default Pv = 0.20 ± 0.07 for S-type objects was derived from the geometric mean of all S-type objects in the LCDB with known albedos (usually SIMPS). 6 The Nysa orbital space is polluted by a large portion of objects that are not true members of the Nsya-Hertha family and even then, the true members are heterogeneous in nature. For this reason, we elected to treat the Nysa space the same as other unassociated inner main belt objects by using a default of S class and Pv = 0.20. 7 The Planet satellite group includes small and distant natural satellites of the major planets, e.g., Himalia Jupiter VI. They are included since a number of these smaller bodies resemble asteroids in size and rotational properties. 9 Several orbital groups have been given a "comet" subclass. This is for objects within the given orbital class that have shown cometary activity, e.g., so-called "main belt comets." The Comet class is reserved for "true" comets, e.g., P/Encke and the Comet-like orbit class is still reserved for objects that have very elongated orbits but have shown no signs of cometary activity. These "comet" subclasses are given default taxonomic class of 'C' and albedo of 0.057. Bottke, W.F., Vokrouhlicky, D., Nesvorny, D. (2007). Nature 449, 48-53, and private communications. 3. Color Index applied to H Color index is not generally assumed or entered into the LCDB. However, some times the value of H was found in a photometric band other than V, e.g., Cousins R. In that case, and if the value is used to override the H given by SIMPS or the MPCORB file (Minor Planet Center) in the Summary line, H is transformed to the V band. When the color index is not directly available, these values are used to transform the measured H value V-R 0.45 B-V 0.80 V-r' 0.23 When such a transform is used in the Summary line, whether or not based on an assumed value, the H value has the 'T' (transformed) flag. 4.0.0 LCDB FILE DESCRIPTIONS -------------------------------------------------------------------------------- The following sections describe the specific files that are part of the LCDB release, not including the Binary files from Petr Pravec. A column map is provided for each report that is part of the release. In addition, sub-sections describe the meaning of the flags that qualify various fields in the report. 4.0.1. FILE STANDARDS ---------------------- All files are simple ASCII text with Windows (PC) line terminators (CRLF). Unless stated otherwise, all files are single-space delimited, i.e., there is a one-character blank column between the end of one field and the start of the next. 4.1.0 LC_SUMMMARY AND LC_DETAILS ------------------------------- These are the primary files in the LCDB release. Both have the same column mapping. They show both direct and indirect data, the most important being the direct data of lightcurve period and amplitude along with our assessment of the quality of the period solution. The latter is expressed by the U code, which is described in detail below. In the LCDETAILS file, a Summary line is followed by one or more Details lines. The Summary line is our best determination of the primary information for a given object based on the data in the Details lines. For example, where several periods are available, the Summary line uses the one that we consider the most likely to be correct. Sometimes that value may be an average of the available values. The Details lines differ in formatting only in that the number and name of the asteroid are replaced by a "short reference" name that will be found in the LC_REFERENCES references file. 4.1.1 MULTIPLE DETAILS TABLE ENTRIES ------------------------------------- In some cases, there is more than one detail line under a given asteroid with the same publication reference. This is deliberate in order to allow statistical studies of lightcurve amplitude versus phase versus class (albedo). For example, if a single publication reports the lightcurve behavior for an asteroid where the synodic period and/or amplitude of the curve changed significantly during the course of the observations, the DETAILS table will include an appropriate number of entries. Those entries will "split out" the results so that the period and/or amplitude can be tied to a specific (though maybe only approximate) set of PAB or Phase values. A good example would be a paper reporting observations of an NEA asteroid over several weeks where the amplitude of the curve when from 1.1 to 0.3 magnitudes over the range of observations. In most cases, splitting the results into distinct sets was not difficult, e.g., the asteroid was observed on one night at one-week intervals. In some cases, the split was not so distinct. In this case, compromises were made in order to avoid having an excess of multiple entries while still retaining sufficient resolution of the variations versus time. A variation on the above is if the author(s) forced the data from several blocks of dates to fit a fixed period solution. Here, the period will be the same for all entries, though the amplitude may change. In this case, the period is left blank. The U code is assigned for each lightcurve based on the presumption that the fixed period is correct, i.e., it is based on the quality of the fit of the data to the presumed period. The main point of interest is the amplitude for the reasons given above. Other information that was derived based on the given block of data, e.g., a value for H, G, or a color index, will be included within that Details record as well so that it's clear which block of data was used to derive the given values. 4.1.2 U (QUALITY) CODE ----------------------- The U code provides our assessment of the quality of the period solution, not necessarily of the data per se. The uniqueness of the solution, while an important factor, is not the sole consideration in making an assessment. Depending on the specifics for a given asteroid, a good period solution can be obtained by using a large amount of lesser quality data about as well as using less data that is of higher quality. Many factors come into play making the assessment. The table below gives the general outline of the criteria used, going from highest to lowest rating. 3 The lightcurve is completely unambiguous in terms of period, i.e., there are no cycle ambiguities or possible solutions with single, triple, or other number of extrema. The coverage of the entire rotation phase is to the degree than any remaining small gaps can be confidently interpolated. 3- A unique period determination, but possibly some moderate gaps in coverage, enough so that interpolation of the entire curve is not certain, but not enough to allow any other solution. 2+ It is unlikely but not impossible that the period is in error due to cycle counts or alternate numbers of extrema per cycle, and no more than moderate gaps in coverage (as in U = 3-). 2 Result based on less than full coverage, so that the period may be wrong by 30 percent or so. Also, a quality of 2 is used to note results where an ambiguity exists as to the number of extrema per cycle or the number of elapsed cycles between lightcurves. Hence the result may be wrong by an integer ratio. 2- Period and total amplitude not firmly established. For example, a single night coverage of about half a cycle including a maximum and minimum, but not enough to actually derive an accurate period. This is the minimum reliability code that we accept for statistical analysis. 1+ Similar to U = 2-, but with less amplitude so that it is not absolutely certain that the variations are true rotational variation and not due to noise, etc. 1 May be completely wrong. What is interpreted as rotational variation may be just noise, calibration error, etc. 1- Probably wrong. A lightcurve that may be completely wrong (as in U = 1) but, in addition, the claimed period is very unlikely, e.g., a large object with a claim of P < 2h. 0 Result later proven incorrect. This appears only on records of individual observations. It is important to keep in mind that U = 0 does not necessarily mean that the data for a given lightcurve are of low quality. The only interpretation that should be inferred is that the -reported solution- has been determined, perhaps from subsequent data, to be incorrect so that not even the loose constraints of U = 1 or U = 2 can be used. For the most part, U = 0 will be used very sparingly and the previous U rating (unless 3) will be retained to avoid the false impression that the data are of limited or no use. N.B. Until the intermediate release in 2008 November, the LCDB also used a value of '4' for the U code, which indicated that a pole solution had been reported. This is no longer the case since, in the past, there have been cases where a 4 was assigned because there was a pole solution given but the best available period solution was no better than 2. The period solution quality is now independent of any pole solution. A separate "Pole" flag in the Summary and Details reports is used to indicate that a pole solution has been reported. The LC_SPINAXIS_PUB file includes more details and its own quality code assignment. Assignment of the refined ratings using a + or - is a work in progress as we catch up with almost 20 years of data entry. Therefore, not all U code ratings will match what we would give under current rules and are subject to change. If a summary line contains U = 3 it should be understood that, by implication, any detail lines with U < 3 are superceded in terms of period determination. We will generally retain the U rating assigned to a prior U < 3 result if the period derived lies close within its uncertainty range to the later adopted U = 3 period, as an indicator of the quality of the observations reported. In the case where U < 3 in the summary line, then one or more detail lines may be assigned U = 0, but only if it is firmly established that, while we cannot say for certain what is the correct period, we can say with certainty that the period claimed in the reference is wrong (i.e., discordant with subsequent data). Some Details lines, and even some Summary, may not contain a U code rating. This is deliberate and can be for several reasons. 1. The available data do not include a lightcurve, therefore, it is not possible to give a rating to the curve. In some cases, where the results are reported by observers whose standard of work is known to be of sufficient quality, we may assign an interim U code, usually 2, until a lightcurve or the data are available. 2. In the case where several results are published for a given object in the same reference, we will assign a U code rating for the "best" available data and include only new information for that given Details record, e.g., see section 4.1.1, "Multiple Details Table Entries." There are instances when data are available they do not reasonably define a period or even constrain a range in which the period lies. In addition, the data may not be able to provide any reasonable indication of the amplitude. In these cases, the entry in the Details record will have the reference to the work and blank U code rating and no period or amplitude. The Summary line may also have no period and/or amplitude as well as U = . This occurs when none of the Detail lines, even if they have some or all of the information, is deemed insufficiently reliable so as to put the information in the Summary line. This is done to show that there are data available for the object but that they may be of very limited use. 4.1.3 LCSUMMARY AND LCDETAILS COLUMN MAPS ------------------------------------------ LC_SUMMARY --------- Field Header Format Pos Notes ------------------------------------------------------------------------------------- Number NUMBER I7 1-7 Blank if no MPC assigned number Name NAME A30 9-38 Name Desig DESIG A20 40-59 Primary designation H H F5.2 61-65 Adopted H (V absolute magnitude) G G F6.3 67-72 Adopted G (phase slope parameter: H-G system) Diameter DIAMETER F8.3 74-81 Adopted Diameter (km) Albedo ALBEDO F6.4 83-88 Adopted Albedo PFlag A1 90 Period qualifier PDescrip PDESCRIP A15 92-106 Description of period if PFlag = 'D' Period PERIOD F13.8 108-120 Period, in hours AmpFlag A1 122 Amplitude flag AmpMin AMIN F4.2 124-127 Minimum amplitude of a range AmpMax AMAX F4.2 129-132 Maximum amplitude of a range OR amplitude if no range U U A2 134-135 Lightcurve Quality Notes NOTES A5 137-141 Qualifying flags for lightcurve record Pole P A1 143 Y/N Y = Pole position reported in spin axis table Binary B A1 145 N = No; ? = Suspected; B = Binary; M = Multiple SparseData S A1 147 Y/N Y = Results based on sparse data survey WideField W A1 149 Y/N Y = Results based on wide-field survey The Min/Max Amplitude values in the Summary table are based only on detail lines that have a U >= 2- ratings. If the U code is empty or U <= 1+, the detail line min/max amplitudes are not considered. LC_DETAILS ---------- Field Header Format Pos Notes ------------------------------------------------------------------------------------- Number NUMBER I7 1-7 Blank if no MPC assigned number Name NAME A30 9-38 Name Desig DESIG A20 40-59 Primary designation HBand A2 61-62 Color band for H (see notes) H H F5.2 64-68 Reported H (absolute magnitude) HErr HERR F4.2 70-73 Reported H error G G F6.3 75-80 Reported G (phase slope parameter: H-G system) GErr GERR F5.3 82-86 Reported G error Diameter DIAMETER F8.3 88-95 Reported diameter (km) DiaErr DIAERR F7.3 97-103 Reported diameter error (km) Albedo ALBDEO F6.4 105-110 Reported albedo AlbedoError ALBERR F6.4 112-117 Reported albedo error PFlag A1 119 Period qualifier PDescrip PDESCRIP A15 121-135 Description of period if PFlag = 'D' Period PERIOD F13.8 137-149 Period (hours) PErr PERR F13.8 151-163 Period error (hours) AmpFlag A1 165 Amplitude flag AmpMin AMIN F4.2 167-170 Minimum amplitude of a range AmpMax AMAX F4.2 172-175 Maximum amplitude of a range OR amplitude if no range AmpErr AERR F4.2 177-180 Amplitude error (mag; for AmpMax) U U A2 182-183 Lightcurve Quality Notes NOTES A5 185-189 Qualifying flags for lightcurve record Pole P A1 191 Y/N Y = Pole position reported in spin axis table Binary B A1 193 N - No; ? = Suspected; B = Binary; M = Multiple SparseData S A1 195 Y/N Y = Results based on sparse data survey WideField W A1 197 Y/N Y = Results based on wide-field survey ShortRef SHORTREF A30 199-228 Short reference from LC_REFERENCES file NOTES: The values for H, G, Diameter, and albedo may have been measured, calculated (e.g., Diameter from H and albedo), or assumed. For IR surveys, e.g., WISE, the H value was often assumed based on the value from the MPCORB file or some other source. Another possible case is a value for H determined using an assumed value for G. H Color Band ------------ This indicates the color band in which the value for H was found Blank Johnson V B Johnson B V Johnson V R Cousins R I Cousins I SU Sloan u' SG Sloan g' SR Sloan r' SI Sloan i' SZ Sloan z' 4.1.4 FIELD (FLAG) CODES USED IN SUMMARY AND DETAIL LINES ---------------------------------------------------------- The flags appear in the data field immediately before the value they qualify. In most cases, they are a single character. AMPFLAG (Amplitude Flag) ------------------------ Blank NONE < Less than > Greater than PFLAG (Period Flag) ------------------- Blank NONE < Less than > Greater than D No numerical value, see P DESC field description S Sidereal period, default is no flag and synodic period U Uncertain, not the same as ambiguous where one or additional periods are reported. For example, the data did not allow finding a definite period and so the author(s) reported a "best guess." NOTES (single letter flag(s)) ----------------------------- Blank NONE ? Usually tied with 'T' or 'A' flags to indicate uncertainty - Tied with T flag. See notes below. X is an integer, e.g., 3 for a trimodal curve (three min/max per rotation) or 4 quadrimodal curve (four min/max per rotation), etc. A Ambiguous period (see LC_AMBIGUOUS_PUB.TXT for details) D Period determined by us that differs from that given in the original publication E Occultation observation (usually when reporting a diameter) H Space telescope observations (optical) I IR/Thermal observations (e.g., Spitzer) M Polarimetric observation N No lightcurve published O Adaptive optics observation P Photographic photometry R Radar observation S Spectroscopic T Tumbling (NPA rotation - see LC_NPA_PUB.TXT for details and notes below) V Visual photometry The 'A' and 'T' notes flags are used to call the reader's attention to the LC_AMBIGUOUS or LC_NPA reports, respectively. They should not be taken as stand- alone information. Instead, consider them footnote numbers in the body of a main text. The other reports (and original references) are the actual footnotes. The A flag does not appear in the Summary line unless the Summary line value itself represents an ambiguous solution, i.e., just because a Details line may report an ambiguous period does not mean that the Summary period is also ambiguous. The T flag currently has four possible qualifiers: Blank The asteroid has a PAR < -1, i.e., it is definitely tumbling. Example: T ? Possible tumbler. There is some evidence that the asteroid might be a tumbler. It may carry a PAR = 0 to -1. See the discussion for the LC_NPA_PUB table for the meaning of the PAR codes. Example: T? 0 The tumbling damping time scale (see Pravec 2005, Icarus) is long enough that tumbling might be expected, but observations are not sufficient to substantiate either tumbling or not tumbling, PAR = 0. Example: T0 - The tumbling damping time scale is long enough that tumbling might be expected, but observations indicate that the object is NOT tumbling, i.e., PAR >= 1. Example: T- + The tumbling damping time scale is short enough that tumbling would not seem likely, however observations indicate that it may be tumbling or actually is tumbling. PAR = < 0. Example: T+ We include the expanded tumbling notes to call attention to what we consider to be an important aspect in the study of YORP spin up/down theories. This is done by making known any asteroids that are or are strongly believed to be tumbling as well as those that should be and aren't or are and shouldn't be. The W flag is included so that those doing statistical studies can include or exclude the results from these surveys. Such surveys can introduce significant biases by "cherry picking" the best results from a large pool and so skew overall rotational statistics. See the paper by Warner and Harris (2011, Icarus). 4.1.5 DATA SUITABLE FOR ROTATION RATE STUDIES ---------------------------------------------- As noted in Warner et al. (2009, Icarus 202, 134-146), only those objects with a U code of 2- or greater in the LC_SUMMARY file, i.e., U = 2-, 2, 2+, 3-, or 3, should be used for rotational rate studies and, unless there is a specific reason otherwise, the summary line period should be used instead of one of the periods in the details table. 4.2.0 LC_AMBIGUOUS (AMBIGUOUS PERIODS) -------------------------------------------------------------------------------- This file includes any record where the Notes flag for a Summary and/or Detail line indicates an ambiguous period. There is not always a direct cross-connection between the Summary and Details entries. For example, it's possible to have a Summary line without the ambiguous period flag but one or more of the Details lines to have the flag. In this case, we judge that the ambiguity has been resolved by subsequent observations, but retain the ambiguous flag in the detail line for historical accuracy. In turn, if the Summary line is flagged as ambiguous, this does not mean that any of the Details lines are also flagged as such. In that case, it means that no one solution sufficiently stands out and so the one that is reported on the Summary line is considered to be only the most probable solution. The first line for a given object is the Summary line, which contains the number and name of the object and the adopted period and amplitude. As noted above, the Details lines(s) may not agree with the Summary line. 4.2.1 LC_AMBIGUOUS COLUMN MAPPING -------------------------------------- Field Format Pos Notes -------------------------------------------------------------------------------- Number I7 1-7 MPC assigned number. Blank if none. Name A30 9-38 Name of object. Desig A20 40-59 Primary designation ShortRef A30 61-90 Publication reference. Notes A5 92-96 Qualifying flags for summary and detail lines. See the NOTES description in section 4.1.4. Period F13.8 98-110 Adopted period from Summary table AmpMax F4.2 112-115 Adopted maximum amplitude from Summary table Period2 F13.8 117-129 Second possible period. Amp2 F4.2 131-134 Amplitude for second period. Period3 F13.8 136-148 Third possible period. Amp3 F4.2 150-153 Amplitude for third period. Period4 F13.8 155-167 Fourth possible period. Amp4 F4.2 169-172 Amplitude for fourth period. Period5 F13.8 174-186 Fifth possible period. Amp5 F4.2 188-191 Amplitude for fifth period. 4.3.0 LC_BINARY (BINARY ASTEROIDS) -------------------------------------------------------------------------------- This file includes those asteroids that are known or suspected binaries. This is not meant to be a comprehensive compilation of data for binary asteroids. Visit the URL given in section 2.2.0 for a page that provides more details as well as links to the original journal articles. The Summary line gives the number (if any) and name of the object as well as the adopted period and amplitude. The Details table lists core data, including the type of binary. There are three broad categories: Fully-asynchronous (Binary Type Flag: A) Example: 1509 Esclangona The satellite's rotation period is different from its orbital period. In this case, the orbital period is given along with the independent rotation period and lightcurve amplitude of the satellite, if available. Singly-asynchronous (Binary Type Flag: S) Example: 5905 Johnson The satellite's rotation period and orbital period are the same, i.e., they are tidally-locked, but different from the primary's spin period. In this case, only an orbital period is given. The lightcurve may be flat or bowed between events. If flat, the presumption is that the satellite is nearly spheroidal and the rotation is still tidally-locked to the orbit. If the lightcurve shows an overall "bowed" shaped, this is presumed to indicate a significantly elongated satellite. Fully-synchronous (Binary Type Flag: F) Example: Pluto/Charon, 90 Antiope The rotation period of the primary and satellite are the same and is the same as the orbital period of the satellite. In this case, the primary rotation period and lightcurve amplitude is given and matches the orbital period of the two bodies. No secondary period is given. Undetermined (Binary Type Flag: U) Usually reserved for binaries discovered by imaging with Hubble or very-large ground-based telescopes. In most cases, the orbital parameters are not or very poorly known and there are no lightcurves to determine the actual type of binary, e.g., if the satellite is tidally locked to its orbital period. In some asynchronous systems, it is not always possible to determine with certainty which of the two is the primary and which is the secondary in such systems. In these cases, we are forced to give the period and amplitude of one body as that of the "primary" and the other period and amplitude as that of the "secondary" when, in fact, the roles may be reversed from our selection. Only the detail line of the binary report includes the type flag. It may be followed by '?' to indicate that the object is suspected to be binary but definitive proof was lacking. For multiple systems and in _most_ cases, the satellite information is for the first one discovered. In some cases, e.g., 3749 Balam, the first discovery was for a satellite with a long orbital period of 1920 hours. It is assumed that the satellite's rotation is not equal to the orbital period. A second satellite was found that has a rotation period that is tidally-locked to its orbital period of about 33.4 hours. The Details lines also give the primary rotation period and amplitude and secondary/orbital periods/amplitudes as appropriate. If available the estimated effective diameter ratio (Ds/Dp) is given, as are the ratio of the semi-major axis of the satellite orbit to the diameter of the primary (A/Dp). The Ds/Dp ratio is a minimum in most cases since total eclipses were not seen in the satellite's lightcurve. As of this time, there is no flag to indicate which of the values are minimums and those that are more definitive. 4.3.1 LC_BINARY COLUMN MAPPING ----------------------------------- Field Format Pos Notes -------------------------------------------------------------------------------- Number I7 1-7 MPC assigned number. Blank if none. Name A30 9-38 Name of asteroid Desig A20 40-59 Primary designation ShortRef A30 61-90 Short reference from LC_REFERENCES file. Flag A1 92 Summary/Details ? = Suspected B = confirmed binary M = multiple Type A1 94 Details only F = Fully-synchronous S = Singly-asynchronous A = Fully-asynchronous U = Undetermined/uncertain Period F13.8 96-108 Primary rotation period Amp1 F4.2 110-113 Maximum amplitude of primary lightcurve Period2 F13.8 115-127 Secondary period (usually for satellite of fully-asynchronous system) Amp2 F4.2 129-132 Secondary amplitude (not mutual events) POrb F13.8 134-146 Orbital period (satellite in type A or of both in type F) Ds/Dp F4.2 148-151 Ratio of effective diameters satellite/primary A/Dp F6.3 153-158 Ratio of semi-major axis to primary diameter 4.4.0 LC_SPINAXIS (POLE SOLUTIONS) -------------------------------------------- This file includes a summary line and associated details line(s) for any asteroid for which spin axis information has been reported. See section 2.1.1, "Spin Axis Catalogs" for additional resources and references. The Summary line gives the number (if any) and name of the object along with the adopted period and amplitude. The Details line gives the additional information such as publication reference, quality rating, period, and pole solutions. 4.4.1 Q (QUALITY) RATING ------------------------- The Q value gives our assessment of the quality of the pole solution. It is adopted from the rating system used in Kryszczynska et al. (2007, Icarus 192, 223-237). 0 Either wrong or very uncertain determination 1 Possible but not certain pole determination. This will most often appear when a limited number of data sets is used, especially if methods other than lightcurve inversion are involved. 2 Good determination, based on large dataset. The solution consists of one or two solutions (and possibly their 180° mirrors). If two solutions, they may differ in both longitude and latitude but not by the simple 180° mirror. 3 Very good determination, based on large dataset, an ambiguity of about 180° in pole longitude might appear. 4 Excellent determination, pole position confirmed by methods based on independent datasets (for example, lightcurves and radar data, lightcurves and spacecraft fly-by). P A prograde rotation has been determined but no specific pole position has been determined. This will be followed by a 0 or 1, indicating the quality of the determination. R A retrograde rotation has been determined by no specific pole position has been determined. This will be followed by a 0 or 1, indicating the quality of the determination. If the Q value is blank, the given pole solution has not yet been reviewed under the new rating system. 4.4.2 LC_SPINAXIS COLUMN MAPPING ------------------------------------- Field Format Pos Notes -------------------------------------------------------------------------------- Number I7 1-7 MPC assigned number. Blank if none. Name A30 9-38 Name of asteroid Desig A20 40-59 Primary designation ShortRef A30 61-90 Short reference from LC_REFERENCES file. Quality A2 92-93 Summary: U rating for given synodic period Details: Quality of best or "synthesis" Period F13.8 95-107 Adopted period from Summary table (Summary) Period of pole solution (usually sidereal) AmpMax F4.2 109-112 Adopted maximum amplitude from summary line L1 F5.1 114-118 Ecliptic longitude of first solution. B1 F5.1 120-124 Ecliptic latitude of first solution. L2 F5.1 126-130 Ecliptic longitude of second solution. B2 F5.1 132-136 Ecliptic latitude of second solution. L3 F5.1 138-142 Ecliptic longitude of third solution. B3 F5.1 144-148 Ecliptic latitude of third solution. L4 F5.1 150-154 Ecliptic longitude of fourth solution. B4 F5.1 156-160 Ecliptic latitude of fourth solution. SidPeriod F13.8 162-174 Sidereal period of spin axis solution. ShapeModel A1 176 Y/N; Y = Shape model reported. 4.5.0 LC_NPA (NON-PRINCIPAL AXIS ROTATION - TUMBLING) --------------------------------------------------------------- This file includes a Summary line and associated Detail line(s) for any asteroid for which NPA (tumbling) data has been reported. 4.5.1 PAR RATING ---------------- The PAR rating is adopted from Pravec et al, Icarus 173, 108-131. Those asteroids where we believe the claims of NPA are not justified are not included in the NPA table, nor are they given an entry in the NOTES field of the Summary and/or Details tables. Instead a special entry is made in the "free-form" NOTESEX field of the appropriate table and so appear in the LC_NOTESEX file. Following is a brief description of the PAR codes. See the Pravec paper for a more detailed explanation. -4 Physical model of the NPA rotation constructed -3 NPA rotation reliably detected with the two periods resolved. There may be some ambiguities in one or both periods. -2 NPA rotation detected based on deviations from a single period but the second period is not resolved. -1 NPA rotation possible, i.e., deviations from a single period are seen, but not conclusively. 0 Insufficient data to determine if rotation is PA or NPA +1 PA rotation is consistent with the data but coverage is insufficient. +2 PA rotation likely, or deviations from PA are small with some overlapping data fitting a PA rotation period. +3 PA rotation quite likely +4 PA spin vector obtained. Entries with a positive number are rare and used when the asteroid was thought to be tumbling but further examination showed it was likely in PA rotation, or when the damping time to PA rotation is sufficiently long that the given asteroid would more likely be in NPA than PA rotation. 4.5.2 LC_NPA COLUMN MAPPING -------------------------------- Field Format Pos Notes -------------------------------------------------------------------------------- Number I7 1-7 MPC assigned number. Blank if none. Name A30 9-38 Name of asteroid Desig A20 40-59 Primary designation ShortRef A30 61-90 Short reference from LC_REFERENCES file. PAR A2 92-93 NPA Probability rating. Period F13.8 95-107 Adopted period ("primary" period) AmpMax F4.2 109-112 Adopted maximum amplitude ("primary" period) Period2 F13.8 114-126 Secondary period. Amp2 F4.2 128-131 Secondary period amplitude. 4.6.0 LC_REFERENCES (REFERENCES) ---------------------------------- The LCREF.TXT file contains the complete literature citation for each reference in the data file. The left column gives the "shorthand" form as it appears in the table. On the right is the proper full citation, listing all authors, year, journal, volume and page numbers. 4.6.1 LC_REF COLUMN MAPPING ---------------------------- Field Format Pos Notes -------------------------------------------------------------------------------- EntryFlag A1 1 * New record since last release ShortRef A30 3-32 Primary author and year BibCode A19 34-52 19-character BibCode Citation A1024 54-80 Full citation. This can span multiple lines. The first line always starts in column 54. The second and subsequent lines start in column 56 (two space indent) to make the file more readable. All lines go to a maximum of column 80. N.B. Initials for names are packed, e.g., Warner, B.D. and not Warner, B. D. 5.0.0 WIDE-FIELD SURVEYS AND SPARSE DATA SETS -------------------------------------------------------------------------------- 5.1.0 WIDE-FIELD SURVEYS ------------------------- Since about 2012, several papers have been published that made use of the Palomar Transit Factory survey. The combined papers have added more than 10,000 new asteroids to the LCDB. The first two papers, Polishook 2012b and Chang 2014b, produced a manageable number of lightcurves, meaning that each one was reviewed by the LCDB authors and a U code assigned. More recent papers, e.g., Waszczak 2015 and Chang 2015, produced thousands of "reliable" lightcurves. For these two papers, and those likely to follow, it is not possible to review each lightcurve. As a result, the LCDB authors adopted the policy of assigning U = 2 to any lightcurve from the two later papers above where the original authors claimed to have found a reliable period. The Waszczak paper found a number of periods that were not considered reliable. These were assigned U = 1 in the LCDB. Where no period was reported, what information that was available, e.g., amplitude, was entered and no U code was assigned. Over time, at least some individual entries will be reviewed and, if necessary, the summary line will be updated. It should be noted that the Waszczak paper reported observations on more than 50,000 asteroids but found less than 10,000 "reliable" periods, or about a 16% success rate. The Chang 2015 paper had about a 27% success rate. As a result, statistical studies should use the wide-field data with some caution since they have likely introduced substantial biases, e.g., against super-fast or super-slow rotators, tumblers, binary objects, and, probably most significantly, against objects with low amplitudes, i.e., A < ~0.10-0.12 mag. For a detailed look at these issues, the reader is referred to Warner, B.D., Harris, A.W. (2011) "Using sparse photometric data sets for asteroid lightcurve studies." Icarus 216, 610-624. Harris, A.W., Pravec, P., Warner, B.D. (2012) "Looking a gift horse in the mouth: Evaluation of wide-field asteroid photometric surveys." Icarus 221, 226-235. The LCDB authors anticipate having to handle the results based on similar large surveys in the future. These will be handled on a case-by-case basis. 5.2.0 SPARSE DATA SETS ----------------------- Sparse data sets differ from their wide-field counterparts in that they are generally the result of surveys such as the Catalina Sky Survey, i.e., 2-5 data points a night on a few nights each lunation over several years. A more extensive example is the Lowell Lightcurve Database (Bowell et al., 2014) that includes hundreds of observations for some asteroid over 10-15 years. These sparse data sets can be used exclusively in shape modeling and spin axis studies (e.g., Durech et al., 2016). If a period and/or spin axis is generated by the use of sparse data _only_, the SPARSEDATA field will be set to TRUE in the details and/or summary record. Depending on the number of data points involved, the result may be given a U rating of 2 even though the NOTES flag will include 'N' for no published lightcurve. If the sole period result, the value is included on the summary line, which will also have the SPARSEDATA field set along with the U rating field. In those cases where sparse data are combined with dense lightcurves, the sparse data field will NOT be set but, as above, the result may be given a U rating and 'N' in the in NOTES field and, if the only period result, migrated to the summary line. 6.0.0 NUMBERS OF INTEREST ---------------------------------------------------------------------------- The numbers presented here are as of 2017 February 3. 6.0.1 ORPHAN RECORDS --------------------- "Orphan" records are in the Summary table only. They are from publications that did not report any observations towards finding a lightcurve period and/or amplitude. Some examples are most of the IR survey papers (WISE, AKARI, SPITZER) that reported diameter and diameter. Others include those reporting only color indices or taxonomic classification. These records are added to the Summary line so that if, in the future, a lightcurve is reported, the other information will be "on the record" and so be included as part of the LCDB reports. No orphaned records were included in the production of the publicly released files. 6.1.0 SUMAMRY TABLE - OVERVIEW -------------------------------- Total Records: 316113 Non-Orphan: 19296 WideField: 14178 (detail source is from a WF survey) SparseData: 125 (detail source is from a SparseData survey) U >= 1-: 17766* U >= 2-: 16049 * This is the number of entries in the LC_SUMMARY table and so excludes summary lines where no period, amplitude, or U code was given. These "no data" lines are included to show that some lightcurve data are available but they were insufficient to make even an approximate guess of the period and/or amplitude. Pole: 1098 (could be just "retrograde vs. prograde" Tumblers: 397 Binaries: 337 (256 with 'B' or 'M', i.e., considered confirmed) 6.1.0 SUMMARY TABLE: U >= 2- ONLY ------------------------------------ NEA: 1026 Binary: 73 (7%, includes 'B', 'M', and '?') Pole: 30 (3%) Hungaria: 445 Binary: 48 (11%, includes 'B', 'M', and '?') Pole: 30 (7%) Hilda: 114 Binary: 0 Pole: 8 Jupiter Trojans: 338 Binary: 3 Pole: 3 6.1.1 SUMAMRY TABLE: U >= 2- ONLY; MIN/MAX VALUES --------------------------------------------------- Shortest Period: 0.0068295 h (24.6 s); 2010 JL88 Longest Period: 1880 h (78.33 days); (162058) 1997 AE12 Smallest Diameter: 0.003 km; 2010 WA, 2006 RH120 Largest Diameter: 2700 km; (136199) Eris Based on AmpMax value -------------------------- Largest Amplitude: 2.3 mag; 2010 XM56, (1865) Cerberus Average Amp: 0.47 mag Amp 0.01-0.10: 454 ( 84 Wide/Sparse, 18%) Amp 0.11-0.20: 2188 ( 866 Wide/Sparse, 40%) Amp 0.21-0.30: 2470 (1333 Wide/Sparse, 54%) Amp 0.31-0.40: 2377 (1430 Wide/Sparse, 60%) Amp 0.41-0.50: 2087 (1463 Wide/Sparse, 70%) Amp 0.51-0.75: 4128 (3200 Wide/Sparse, 78%) Amp 0.76-1.00: 1754 (1264 Wide/Sparse, 72%) Amp 1.01-1.50: 426 ( 185 Wide/Sparse, 43%) Amp > 1.50: 37 ( 5 Wide/Sparse, 13%) 6.2.0 DETAILS TABLE - OVERVIEW ------------------------------- The numbers for the tumbler and binary subsets are going to be higher than reflected in the Summary table totals. This just indicates that not every suspected binary or tumbler was "good enough" to make it to the summary line. All numbers in each subset include multiple entries for a given asteroid. Total Records: 443497 WideField: 14584 SparseData: 12269 U >= 1-: 27883 U >= 2-: 25095 Pole: 2056 Tumblers: 484 Binaries: 667 (507 with 'B' or 'M') References ---------- Pravec et al., 2006, Icarus 181,63-93. Pravec and Harris, 2007. Icarus 190, 250-259. Tedesco, E.F., Noah, P.V., Price, S.D.: 2004, IRAS Minor Planet Survey. IRAS-A-FPA-3-RDR-IMPS-V6.0. NASA Planetary Data System. Harris and Harris 1997, Icarus 126, 450-454. Bottke, W.F., Vokrouhlicky, D., Nesvorny, D. (2007). Nature 449, 48-53. Warner et al. 2009, Icarus 202, 134-146. Kryszczynska et al. 2007, Icarus 192, 223-237. Pravec et al. 2005, Icarus 173, 108-131. Polishook, D.; Ofek, E.O.; Waszczak, A.; Kulkarni, S.R.; et al. 2012, MNRAS 421, 2094-2108. Chang, C.-K.; Waszczak, A.; Lin, H.-W.; Ip, W.-H.; et al. 2014, Ap. J. Letters 791, L35. Waszczak, A.; Chang, C.-K.; Ofeck, E.O.; Laher, F.; et al. 2015, Astron. J. 150, A75. Chang, C.K.; Ip, W.-H.; Lin, H.-W.; Cheng, Y.C.; et al. 2015, Astrophys. J. Supp. Ser. 219, A27. Warner, B.D., Harris, A.W. 2011, Using sparse photometric data sets for asteroid lightcurve studies, Icarus 216, 610-624. Harris, A.W., Pravec, P., Warner, B.D. 2012, Looking a gift horse in the mouth: Evaluation of wide-field asteroid photometric surveys, Icarus 221, 226-235. Durech, J.; Hanus, J.; Oszkiewsicz, D.; Vanco, R. 2016, Astron. Astrophys. 587, A48.