Neosurvey 1: Initial Results From the Warm Spitzer Exploration Science Survey of Near-Earth Object Properties

Abstract

Near-Earth objects (NEOs) are small solar system bodies whose orbits bring them close to the Earth's orbit. We are carrying out a Warm Spitzer Cycle11 Exploration Science program entitled NEOSurvey-a fast and efficient fluxlimited survey of 597known NEOs in which we derive a diameter and albedo for each target. The vast majority of our targets are too faint to be observed by NEOWISE, though a small sample has been or will be observed by both observatories, which allows for a cross-check of our mutual results. Our primary goal is to create a large and uniform catalog of NEO properties. We present here the first results from this new program: fluxes and derived diameters and albedos for 80NEOs, together with a description of the overall program and approach, including several updates to our thermal model. The largest source of error in our diameter and albedo solutions, which derive from our single-band thermal emission measurements, is uncertainty in η, the beaming parameter used in our thermal modeling; for albedos, improvements in solar system absolute magnitudes would also help significantly. All data and derived diameters and albedos from this entire program are being posted on a publicly accessible Web page at nearearthobjects.nau.edu .

Spitzer Observations of Interstellar Object 1I/‘Oumuamua

“…The default approach used in our Spitzer NEO program is to derive η from phase angle; Trilling et al (2016) present in some detail the correlation and dispersion in the correlation between those two parameters. In this case, the phase angle of 31 degrees implies η around 1.1.…”

Constraining the Shape Distribution of Near-Earth Objects from Partial Light Curves

“…The observations used in this project were obtained with the Spitzer/IRAC instrument (Fazio et al 2004) as part of the NEO Survey (Program ID 11002), and the NEO Legacy Survey (Program ID 13006) [Trilling et al 2010, Trilling et al 2016]. The observations were carried out using the moving single mode to track the NEO motion, dithering during the observations to remove the effect of bad pixels or heterogenous sensitivity across the array.…”

“…The maximum time for objects in the survey was chosen to be 3 hours, to keep the total time requested within the range allowed by the Spitzer program. For further information on this and the data reduction processes see Trilling et al (2016) and Hora et al (2018).…”

Spitzer Albedos of Near-Earth Objects

“…The target sample considered for this work consists of 1505 NEOs observed with the Spitzer/IRAC instrument (Fazio et al 2004) as part of ExploreNEOs (Trilling et al 2010), NEOSurvey (Trilling et al 2016), and NEOLegacy. This dataset contains all targets observed by these Spitzer surveys as of JD 2457921 (2017-06-16).…”

“…The heliocentric distance (r), geocentric distance (∆), and phase angle (α) for the asteroid are obtained from the NASA JPL Horizons Database 3 at the midpoint time of the Spitzer observation. The resulting H-magnitude (H ), thermal flux (f ), slope parameter (G), and observing geometry of the target (r, ∆, α) are used as inputs in the modified NEATM (Trilling et al 2010(Trilling et al , 2016 to generate an albedo for each target. The distribution is randomly sampled as input for the MC simulation.…”