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Compilation of Spitzer Space Telescope Observations of Near-Earth Objects
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README.rst

SpitzerNEOs - The Full Dataset

This repository contains flux density measurements, as well as diameter and albedo estimates, for the majority (if not all) Near-Earth Objects that were ever observed with the Spitzer Space Telescope and serves as a backup for the official SpitzerNEOs website. The resulting data set contains 2204 diameter and albedo estimates for 2132 different objects.

The data compiled here are publicly available. If you use the data, please cite Trilling et al. 2010 and Trilling et al. 2016.

Near-Earth Objects

Near Earth Objects (NEOs) are small Solar System bodies whose orbits bring them close to the Earth's orbit. NEOs lie at the intersection of Solar System evolution science, space exploration, and civil defense. They are compositional and dynamical tracers from elsewhere in the Solar System; the study of NEOs allows us to probe environmental conditions throughout the Solar System and the history of our planetary system, and provides a template for analyzing the evolution of planetary disks around other stars. NEOs are the parent bodies of meteorites, one of our key sources of detailed knowledge about the Solar System's development, and NEO studies are the essential context for this work. The space exploration of NEOs is primarily carried out through robotic spacecraft (NEAR, Hayabusa, Chang'e 2, Hayabusa-2, OSIRIS-REx). Energetically, some NEOs are easier to reach with spacecraft than the Earth's moon, and NEOs offer countless targets with a range of physical properties and histories. Finally, NEOs are a civil defense matter: the impact threat from NEOs is real, as demonstrated in Chelyabinsk, Russia, in February, 2013. Understanding the number and properties of NEOs affects our planning strategies, international cooperation, and overall risk assessment.

NEOs typically have daytime temperatures around 250 K. Hence, their thermal emission at 4.5 μm is almost always significantly larger than their reflected light. We can therefore employ a thermal model to derive NEO diameters and albedos. This makes the Spitzer Space Telescope the most powerful NEO characterization telescope ever built, reaching 3σ sensitivities of ~1.5 μJy in 10,000 seconds, and able to observe thousands of NEOs.

Observing Programs

The majority of observations in this data set stem from three major observing campaigns summarized below. The data set is supplemented by data from smaller projects.

  • ExploreNEOs is a Spitzer Cycle 6 Exploration Science program which was carried out between 2009 July and 2011 November. It was composed of a total of 599 AORs and obtained observations in both the 3.6 and 4.5 μm bands. All observations and modeling are complete and in the database. The Spitzer program IDs are 60012, 61010, 61011, 61012, and 61013. The project is described in Trilling et al. 2010.
  • NEOSurvey (Program ID 11002) is a Spitzer Cycle 11 Exploration Science program which was carried out between 2015 February to 2016 September. It was composed of a total of 570 AORs and obtained observations in the 4.5 μm band. All observations and modeling are complete and in the database. The project is described in Trilling et al. 2016.
  • NEOLegacy (Program ID 13006) is a Spitzer Cycle 13 Frontier Legacy Science program which was begun in 2016 October and is still executing. As of 2018 March, a total of 714 AORs have executed and are in the database. IRAC photometry is obtained at 4.5 μm. Observations are scheduled through 2018 September.

These three major observing campaigns were awarded a total of almost 3,000~hrs of Spitzer observing time.

For a full list of related publications, please refer to this page.

Data Set

The data set contains 2204 observations of 2132 different NEOs. The total elapsed time of these observations amounts to

Absolute Magnitude Histogram

The distribution of absolute magnitudes across the three main surveys.

Albedo vs. Diameter Plot

The distribution of geometric albedos vs. diameters in the three main surveys.

Data is provided in the form of a csv file that can be easily read in, e.g., using Python Pandas:

>>> import pandas as pd
>>> data = pd.read_csv('spitzerneos.csv')

For each observation, the following fields are provided:

Field Field Name Data Type Data Unit
desig MPC Designation text  
number MPC Number integer  
name Target Name text  
survey Spitzer Survey text  
ra Target RA at Midtime (J2000) float deg
dec Target Dec at Midtime (J2000) float deg
vmag Predicted Target V Magnitude float mag
heldist Heliocentric Distance at Midtime float au
obsdist Distance from Spitzer at Midtime float au
alpha Solar Phase Angle at Midtime float deg
elong Solar Elongation at Midtime float deg
glxlon Galactic Longitude at Midtime float deg
glxlat Galactic Latitude at Midtime float deg
ra3sig 3 sigma Uncertainty in RA float arcsec
dec3sig 3 sigma Uncertainty in Dec float arcsec
midtime Observation Midtime (UT) text ISO
midtimejd Observation Midtime (UT) float JD
aorkey Observation AOR Key integer  
framet Frame Time float s
totalt Total Integration Time float s
elapsed Total Elapsed Time float s
a Semi-Major Axis float au
e Eccentricity float  
node Ascending Node float deg
argper Argument of the Periapsis float deg
period Orbital Period float yr
absmag Absolute Magnitude in V float mag
absmagsig 1 sigma Uncertainty float mag
slopepar Photometric Slope Parameter (H-G) float  
ch1 IRAC CH1 Flux Density float μjy
ch1err CH1 Flux Density Uncertainty float μjy
ch1snr CH1 Signal-to-Noise Ration float  
ch2 IRAC CH2 Flux Density float μjy
ch2err CH2 Flux Density Uncertainty float μjy
ch2snr CH2 Signal-to-Noise Ration float  
notes Data Reduction Notes text  
diam Volume-equ. Spherical Diameter float km
d1sigl Diameter 1 sigma Interval Bottom float km
d1sigu Diameter 1 sigma Interval Top float km
d3sigl Diameter 3 sigma Interval Bottom float km
d3sigu Diameter 3 sigma Interval Top float km
pv Geometric Albedo (V-Band) float  
pv1sigl Albedo 1 sigma Interval Bottom float  
pv1sigu Albedo 1 sigma Interval Top float  
pv3sigl Albedo 3 sigma Interval Bottom float  
pv3sigu Albedo 3 sigma Interval Top float  
eta Infrared Beaming Parameter float  
eta1sigl Eta 1 sigma Interval Bottom float  
eta1sigu Eta 1 sigma Interval Top float  
eta3sigl Eta 3 sigma Interval Bottom float  
eta3sigu Eta 3 sigma Interval Top float  
reflsol CH2 Reflected Solar Fraction float  

Note that the data provided reflect the information that were used in the thermal modeling. Orbital properties or absolute magnitude measurements might be outdated at the time of reading this. Also, some information are not available for all observations.

Acknowledgements

This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through awards issued by JPL/Caltech.

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