NEOWISE REACTIVATION MISSION YEAR ONE: PRELIMINARY ASTEROID DIAMETERS AND ALBEDOS

Sizes and albedos of asteroids are basic quantities that can be used to answer a range of scientific questions. A significant number of diameter measurements produce a size–frequency distribution, which can constrain models of asteroid formation and evolution (Zellner 1979; Gradie & Tedesco 1982; Bus & Binzel 2002; Tedesco et al. 2002; Masiero et al. 2011). Asteroid albedos aid the identification of collisional family members (Carruba et al. 2013; Masiero et al. 2013, 2015; Walsh et al. 2013; Milani et al. 2014), and allow for basic characterization of asteroid composition (Mainzer et al. 2011c; Grav et al. 2012a; Masiero et al. 2014).

Most observations of asteroids are made in visible wavelengths, where flux is dependent on both size and albedo. Observations in other wavelengths, such as the infrared (e.g., Hansen 1976; Cruikshank 1977; Lebofsky et al. 1978; Morrison & Lebofsky 1979; Delbó et al. 2003, 2011; Wolters et al. 2005, 2008; Matter et al. 2011; Müller et al. 2012, 2013) or radio (e.g., Ostro et al. 2002; Benner et al. 2015), are needed to determine these quantities precisely. At present, well-determined diameters and albedos have been measured for less than a quarter of known asteroids.

The infrared NEOWISE project (Mainzer et al. 2011a) has measured diameters and albedos for ∼20% of the known asteroid population, the majority of these measurements to date (Grav et al. 2011, 2012c; Mainzer et al. 2011b, 2012, 2015; Masiero et al. 2011, 2012; Bauer et al. 2013). Here, we expand the number of asteroids characterized by NEOWISE, deriving diameters and albedos for asteroids detected by NEOWISE between 2013 December 13 and 2014 December 13 during the first year of the Reactivation mission.

The NEOWISE mission uses the Wide-field Infrared Survey Explorer (WISE) spacecraft, which images the entire sky using freeze-frame scanning from a Sun-synchronous polar orbit (Wright et al. 2010; Cutri et al. 2012). WISE is equipped with a 50 cm telescope and four 1024 × 1024 pixel focal plane array detectors that simultaneously image the same 47 × 47 arcmin field of view in 3.4, 4.6, 12, and 22 μm bands, all originally cooled by solid hydrogen cryogen. WISE scans the sky between the ecliptic poles continuously during its 95 minute orbit. A tertiary scan mirror freezes the sky on the focal planes for 11 s while the detectors are read out, producing a sequence of adjacent images with 7.7 s exposure times in the 3.4 and 4.6 μm bands and 8.8 s in the 12 and 22 μm bands. The orbit precesses at an average rate of approximately one degree per day, so that the full sky is covered in six months.

WISE was launched on 2009 December 14 and began surveying on 2010 January 7. WISE scanned the sky 1.5 times during the 9.5 months while it was cooled by its hydrogen cryogen. After the hydrogen was depleted, the survey continued as NEOWISE until 2011 February 1, using the 3.4 and 4.6 μm detectors that operated at near full sensitivity with purely passive cooling. During the additional four months of "post-cryo" operations, coverage of the entire inner Main Asteroid Belt was completed, along with a second complete coverage of the sky. WISE/NEOWISE was placed into hibernation in 2011 mid-February. In this mode, the solar panels were held facing the Sun and the telescope pointed toward the north ecliptic pole. The telescope viewed the Earth during half of each orbit, resulting in some heating.

The WISE spacecraft was brought out of hibernation in 2013 September and renamed NEOWISE to continue its mission to discover, track, and characterize asteroids through ∼2017 (Mainzer et al. 2014). The telescope was restored to near zenith pointing, which enabled the optics and focal planes to cool passively back to ∼74 K. Survey operations resumed on 2013 December 13, with the 3.4 and 4.6 μm detectors operating at a sensitivity comparable to that during the original WISE cryogen survey (Cutri et al. 2015). The NEOWISE moniker, an acronym of near-Earth object WISE, encompasses both the archiving of individual images to allow for the detection of transient objects, and the extensions of the mission beyond WISE's original 9-month lifetime.

NEOWISE uses the same survey and observing strategy as the original WISE mission (Wright et al. 2010). The majority of each orbit is devoted to observations, with only brief breaks for data transmission and momentum unloading. The spacecraft carries a body-fixed antenna, and therefore must reorient itself to communicate with the Tracking and Data Relay Satellite System, which relays the data to Earth. Data transmission is timed to only interrupt survey coverage near the ecliptic poles, which are observed frequently. Momentum unloading, which can result in streaked images, is also completed at this time.

Data processing for NEOWISE uses the WISE Science Data System (Cutri et al. 2015), which performs instrumental, photometric, and astrometric calibration for each individual set of 3.4 and 4.6 μm exposures obtained by the spacecraft, and detects and characterizes sources on each exposure. The calibrated images and the database of positions and fluxes of sources extracted from those images for the first year of NEOWISE survey observations were released in 2015 March (Cutri et al. 2015).

The WISE Moving Object Pipeline System (WMOPS; Cutri et al. 2012) identifies sources that display motion between the different observations of the same region on the sky. WMOPS uses the extracted source lists from sets of images to first identify and filter out sources that appear stationary between individual exposures, and then links non-stationary detections into sets that exhibit physically plausible motion on the sky. Generally, objects within 70 AU of the Sun move quickly enough to be detected by WMOPS (Mainzer et al. 2011a, see also Bauer et al. 2013). Those candidate moving objects that are not associated with known asteroids, comets, planets, or planetary satellites are verified individually by NEOWISE scientists. A minimum of five independent detections are required for a tracklet (a set of position/time pairs) to be considered reliable. Tracklets for each verified new candidate object and previously known solar system objects are reported to the IAU Minor Planet Center (MPC) three times per week. The MPC performs initial orbit determination, associates the NEOWISE tracklets with known objects, and archives the NEOWISE astrometry and times in its observation database.

Candidates confirmed by the MPC to be possible new near-Earth-objects (NEOs) are posted to their NEO Confirmation page for prompt follow-up observations by ground-based observers. Rapid follow-up is essential for NEOWISE NEO candidates because the NEOWISE arcs are usually short, and the asteroid's projected positional uncertainties grow quickly, making reliable recovery difficult after 2–3 weeks. To ensure prompt follow-up, NEOWISE observations are reported to the MPC less than three days after observations on board the spacecraft. A NEOWISE candidate discovery has a minimum of five observations over ∼3 hr, although typical objects have ∼12 observations spanning ∼1.5 days.

Targets observed by NEOWISE can pose unique challenges to ground-based follow-up observers. NEOWISE's orbit allows observations to be made at all declinations, and observing is independent of lunar phase. Ground-based observers are limited to a fixed declination range, and must sometimes deal with light from the moon and terrestrial weather, which can preclude observations. Moreover, NEOWISE discoveries are frequently extremely dark (see Figure 5), often requiring 2–4 m class telescopes to detect them at low solar elongations.

Observers around the globe (including both amateurs and professionals) have contributed essential follow-up observations, which are defined here as an observation of an object within 15 days of its first observation on board the spacecraft. Significant contributors of follow-up observations are given in Figure 1. The Spacewatch Project (McMillan 2007) contributes a large share of recoveries in the northern hemisphere. The Las Cumbres Observatory Global Telescope (LCOGT) Network of robotically operated queue-scheduled telescopes (Brown et al. 2013) has been an extremely useful resource for securing detections when weather is poor at a particular site. Additionally, the group led by D. Tholen using the University of Hawaii 2.2 m and Canada–France–Hawaii 4 m telescopes has successfully detected the targets with the faintest optical magnitudes in the northern hemisphere (e.g., Tholen et al. 2014). The NEOWISE team was awarded time with the DECam instrument on the Cerro Tololo Inter-American Observatory 4 m telescope, which has proven invaluable for the recovery of low albedo objects at extreme declinations in the southern hemisphere.

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We present diameters and albedos for 201 near-Earth asteroids (NEAs) and 7755 Main Belt and Mars-crossing asteroids detected in the first year of reactivation, between 2013 December 13 and 2014 December 13. This includes the 38 NEAs discovered by NEOWISE during those dates.

2.1. Observations

2.2. Near-Earth Thermal Model (NEATM)

We used the NEATM of Harris (1998), following the implementation of Mainzer et al. (2011b, 2012) for NEAs and Masiero et al. (2011, 2012) for MBAs and Mars crossers. These results supersede those published in Mainzer et al. (2014). NEATM is a simple but effective method for determining effective spherical diameters and albedos (when corresponding visible light observations are available). This model makes several assumptions, including a spherical, non-rotating body, with a simple temperature distribution:

$$\begin{eqnarray}&&T(\theta )={T}_{\mathrm{max}}{\mathrm{cos}}^{1/4}(\theta )\quad \mathrm{for}\quad 0\leqslant \theta \leqslant \pi /2\end{eqnarray} \tag{ 1 }$$

where θ is the angular distance from the sub-solar point. T_max is the subsolar temperature, defined as:

$$\begin{eqnarray}&&{T}_{\mathrm{max}}={\left(\displaystyle \frac{(1-A)S}{\eta \epsilon \sigma }\right)}^{1/4}\end{eqnarray} \tag{ 2 }$$

where A is the bolometric Bond albedo, S is the solar flux at the asteroid, η is termed the beaming parameter, is the emissivity, and σ is the Stefan–Boltzmann constant. The beaming parameter η accounts for any deviation between the actual asteroid and the model. Changes in η can account for a host of factors, including non-spherical shapes, the presence of satellites, variations in surface roughness or thermal inertia, uncertainties in emissivity, high rates of spin, changes in surface temperature distributions due to spin pole location, or the imprecise assumption that the object's night-side has zero thermal emission (a factor that is most relevant for objects observed at high phase angles). Some of these factors that are accounted for in the beaming parameter are degenerate. For example, a slow-rotating object will have a heat distribution similar to a faster rotating object that has a lower thermal inertia. For this simple model, beaming accounts for the changes in temperature distribution due to these effects that cannot be otherwise separated.

Observations were divided into apparitions of 10 days, and the NEATM model was fitted to each individual apparition. These shorter apparitions allowed for fits to widely spaced apparitions or, for NEAs, over changing phase angles. Given that the NEOWISE observational cadence generally results in an object being detected over ∼1.5 days, sometimes with an additional epoch of observations ∼3–6 months later, we chose to divide observations separated by >10 days for separate fitting to account for large changes in object distances and viewing geometries.

NEATM spheres were approximated by a faceted polygon with 800 facets. Individual facet temperature was determined following Equation (1), and then color corrected following Wright et al. (2010). Observed thermal flux for each facet was computed, as was flux from reflected sunlight. The integrated flux from the object was determined, accounting for viewing geometry, to produce a model magnitude. A least-squares fitting routine compared modeled to observed magnitudes, and iterated on diameter, albedo, and beaming parameter until a best fit was found.

Geometric optical albedo p_V was computed using absolute magnitude H and slope parameter G, using values supplied in MPCORB.dat by the MPC. Inaccurate H and G values will result in inaccurate p_V fits. Work by Williams (2012) and Pravec et al. (2012) found systematic H offsets that vary as a function of H magnitude in data reported to the MPC. As albedo measurements depend on H and G values, errors in measurement of those values will propagate to derived albedos.

NEATM requires at least one of the NEOWISE wavelengths to be dominated by thermally emitted light. Some outer main-belt objects observed by NEOWISE were too cold to have thermally dominated emission at 3.4 or 4.6 μm, and therefore diameters and albedos for those objects are not reported in this paper. The proportion of reflected versus thermally emitted light for NEAs and inner MBAs can be seen in the spectral energy distribution plots shown in Figure 2. The proportion of thermally emitted flux depends on albedo, which means that for colder, outer MBAs it is unclear if a wavelength is thermally dominated until after the fit was performed. Comparison of those results to NEOWISE fits using 12 μm images and radar data confirmed that the thermal fits were poor, so we did not include results that had more than 25% reflected light in the 4.6 μm band.

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We assumed that η was equal to the average value for the object's population, as determined by Mainzer et al. (2011b) or Masiero et al. (2011), respectively. For NEAs, this meant η = 1.4 ± 0.5; for all other asteroids in this paper, η = 0.95 ± 0.25. As shown in Masiero et al. (2011), although the average η for the main belt is 1.0, the peak of the histogram is located closer to 0.95, so this value was adopted in this work.

Following the average values determined by Mainzer et al. (2011b) and Masiero et al. (2011), the ratio of infrared to visible albedo p_IR/p_V was initially set to 1.6 ± 1.0 for NEAs and 1.5 ± 0.5 for Mars-crossers and MBAs. Additionally, it was assumed that the albedos of each band were equal, or p_{3.4 μm} = p_{4.6 μm}. Although this may be a poor assumption for objects with red slopes (Grav et al. 2012b), it is necessary to prevent over fitting of the data.

2.3. Uncertainties

Uncertainties on d, p_V, and η (when η was a free parameter) were determined using a Monte Carlo method. Measured NEOWISE magnitudes, H, and G were randomly adjusted within their errors, and the resultant model values of d, p_V, and (in appropriate cases) η, were compared to the best-fit values. This process was repeated 25 times for each object, and the resultant errors are the weighted standard deviation of the Monte Carlo trials. The errors quoted in the tables below only include the random component measured through this MC method, not the systematic offset.

Systematic errors were computed by comparing the match between diameters derived in this work to radar-derived diameters for the same objects. Albedos were derived from the radar diameters using the equation

$$\begin{eqnarray}&&d=\displaystyle \frac{1329}{\sqrt{{p}_{V}}}{10}^{-H/5}\end{eqnarray} \tag{ 3 }$$

where d is the diameter in kilometers (for more information, see Harris & Lagerros 2002).

2.4. Objects without Visible-wavelength Detections

2.5. NEAs

Results are divided into four tables. As diameters were calculated using different parameters for the NEAs vs the MBAs and Mars-crossing asteroids, results for these two groups are presented separately. Results are further subdivided between objects that were characterized previously by the NEOWISE team, and objects that were not. This is because previously published values likely used the fully cryogenic 12 and 22 μm wavelengths, and therefore can derive diameters more accurately, to within 10%. Researchers looking for the best-constrained diameter and albedo measurements should consult previously published work (Mainzer et al. 2011b, 2012; Masiero et al. 2011, 2012). However, for those researchers who are interested in diameters and albedos derived from additional epochs of data provided by the Year One Reactivation results, we also include the diameters derived for objects using these new data.

Tables 2 and 3 contain the fit diameters and albedos for 173 new and 28 previously characterized NEAs, respectively. Tables 4 and 5 contain the fit diameters and albedos for 1176 new and 6579 previously characterized MBAs and Mars crossing asteroids, respectively. Several objects were observed at multiple apparitions; in these cases, results are presented for each apparition.

Table 2.  Measured Diameters (d) and albedos (p_V) of Near-Earth Objects Not Previously Characterized Using NEOWISE Data

Name	Packed	H	G	d (km)	pV	η	W2 amp.	${n}_{W1}$	${n}_{W2}$
1566	01566	16.90	0.15	1.03 ± 0.04	0.29 ± 0.05	1.40 ± 0.00	0.24	5	7
1580	01580	14.50	0.15	8.55 ± 5.23	0.04 ± 0.08	1.40 ± 0.52	0.34	0	12
1620	01620	15.60	0.15	1.87 ± 0.05	0.29 ± 0.04	1.40 ± 0.00	0.89	14	14
1862	01862	16.25	0.09	1.40 ± 0.04	0.29 ± 0.04	1.40 ± 0.00	0.41	10	10
1862	01862	16.25	0.09	1.26 ± 0.04	0.35 ± 0.05	1.40 ± 0.00	0.84	10	10
1917	01917	13.90	0.15	4.99 ± 0.14	0.20 ± 0.03	1.40 ± 0.00	0.58	14	14
1943	01943	15.75	0.15	2.34 ± 0.05	0.16 ± 0.02	1.40 ± 0.00	0.22	30	31
1943	01943	15.75	0.15	2.30 ± 0.04	0.17 ± 0.02	1.40 ± 0.00	0.29	171	172
1943	01943	15.75	0.15	2.28 ± 0.05	0.17 ± 0.03	1.40 ± 0.00	0.54	14	15
2062	02062	16.80	0.15	0.80 ± 0.03	0.52 ± 0.10	1.40 ± 0.00	0.82	32	36
3288	03288	15.20	0.15	2.49 ± 0.07	0.24 ± 0.04	1.40 ± 0.00	1.40	11	11
4954	04954	12.60	0.15	9.56 ± 0.24	0.18 ± 0.03	1.40 ± 0.00	1.06	8	8
5381	05381	16.50	0.15	0.91 ± 0.05	0.54 ± 0.07	1.40 ± 0.00	0.49	10	10
5381	05381	16.50	0.15	0.94 ± 0.04	0.51 ± 0.06	1.40 ± 0.00	0.17	13	13
6053	06053	14.90	0.15	3.72 ± 0.08	0.14 ± 0.02	1.40 ± 0.00	0.21	11	11
7025	07025	18.30	0.15	0.50 ± 0.17	0.34 ± 0.23	1.40 ± 0.52	0.58	0	4
7889	07889	15.20	0.15	1.68 ± 0.07	0.52 ± 0.06	1.40 ± 0.00	0.45	8	8
8567	08567	15.30	0.15	2.93 ± 0.07	0.16 ± 0.03	1.40 ± 0.00	0.42	25	26
13651	13651	17.60	0.15	0.56 ± 0.02	0.51 ± 0.11	1.40 ± 0.00	1.22	11	11
35107	35107	16.80	0.15	0.91 ± 0.03	0.41 ± 0.05	1.40 ± 0.00	0.25	10	10
35107	35107	16.80	0.15	1.10 ± 0.28	0.28 ± 0.16	1.40 ± 0.37	0.45	0	14
39572	39572	16.50	0.15	1.55 ± 0.66	0.18 ± 0.16	1.40 ± 0.47	0.42	0	8
39796	39796	15.70	0.15	2.13 ± 0.59	0.20 ± 0.20	1.40 ± 0.39	0.69	0	16
53430	53430	16.60	0.15	1.23 ± 0.32	0.27 ± 0.15	1.40 ± 0.37	1.14	0	5
54686	54686	16.50	0.15	1.35 ± 0.46	0.24 ± 0.19	1.40 ± 0.47	1.02	0	10
55532	55532	16.10	0.15	1.31 ± 0.04	0.38 ± 0.06	1.40 ± 0.00	0.22	6	6
68063	68063	15.50	0.15	2.30 ± 0.07	0.21 ± 0.04	1.40 ± 0.00	0.38	24	24
68267	68267	16.90	0.15	0.88 ± 0.04	0.40 ± 0.05	1.40 ± 0.00	0.29	13	15
68348	68348	14.20	0.15	3.51 ± 0.13	0.30 ± 0.05	1.40 ± 0.00	0.46	12	12
68548	68548	16.50	0.15	1.18 ± 0.04	0.32 ± 0.04	1.40 ± 0.00	0.24	8	10
68548	68548	16.50	0.15	1.24 ± 0.04	0.29 ± 0.03	1.40 ± 0.00	0.55	23	24
85182	85182	17.10	0.15	1.03 ± 0.37	0.24 ± 0.19	1.40 ± 0.49	0.69	0	9
85774	85774	19.20	0.15	0.94 ± 0.01	0.04 ± 0.01	1.40 ± 0.00	0.90	11	11
86819	86819	17.40	0.15	0.80 ± 0.27	0.30 ± 0.22	1.40 ± 0.46	0.79	0	7
86829	86829	15.90	0.15	1.43 ± 0.05	0.37 ± 0.05	1.40 ± 0.00	0.33	14	14
87309	87309	17.60	0.15	0.57 ± 0.16	0.50 ± 0.23	1.40 ± 0.47	0.67	0	10
88213	88213	19.70	0.15	0.91 ± 0.42	0.03 ± 0.03	1.40 ± 0.51	0.66	0	6
89355	89355	15.60	0.15	2.04 ± 0.05	0.25 ± 0.03	1.40 ± 0.00	1.19	30	31
90075	90075	15.20	0.15	2.23 ± 0.08	0.29 ± 0.04	1.40 ± 0.00	0.73	12	12
99248	99248	16.30	0.15	1.12 ± 0.04	0.43 ± 0.06	1.40 ± 0.00	0.29	7	8
99248	99248	16.30	0.15	1.14 ± 0.37	0.41 ± 0.28	1.40 ± 0.48	0.48	0	8
137099	D7099	18.20	0.15	0.56 ± 0.02	0.29 ± 0.04	1.40 ± 0.00	0.65	6	6
138127	D8127	17.10	0.15	0.75 ± 0.02	0.45 ± 0.06	1.40 ± 0.00	0.17	7	7
138947	D8947	18.70	0.15	0.45 ± 0.12	0.29 ± 0.28	1.40 ± 0.46	0.46	0	9
142781	E2781	16.10	0.15	1.59 ± 0.05	0.25 ± 0.04	1.40 ± 0.00	0.15	14	14
142781	E2781	16.10	0.15	2.01 ± 0.74	0.16 ± 0.15	1.40 ± 0.44	0.85	0	15
142781	E2781	16.10	0.15	2.03 ± 0.77	0.16 ± 0.09	1.40 ± 0.40	0.45	0	9
143624	E3624	15.90	0.15	2.14 ± 0.04	0.17 ± 0.03	1.40 ± 0.00	0.32	9	9
143624	E3624	15.90	0.15	2.23 ± 1.08	0.15 ± 0.17	1.40 ± 0.53	0.82	0	8
154276	F4276	17.60	0.15	1.06 ± 0.35	0.14 ± 0.17	1.40 ± 0.43	0.29	0	5
159454	F9454	17.90	0.15	0.58 ± 0.02	0.37 ± 0.04	1.40 ± 0.00	0.30	6	6
159560	F9560	17.00	0.15	1.10 ± 0.47	0.24 ± 0.23	1.40 ± 0.54	1.16	0	87
159560	F9560	17.00	0.15	1.16 ± 0.30	0.21 ± 0.21	1.40 ± 0.39	0.53	0	13
159857	F9857	15.40	0.15	3.07 ± 1.32	0.13 ± 0.16	1.40 ± 0.45	0.34	0	5
162058	G2058	17.80	0.15	0.85 ± 0.01	0.19 ± 0.02	1.40 ± 0.00	0.34	26	27
162058	G2058	17.80	0.15	0.85 ± 0.28	0.19 ± 0.14	1.40 ± 0.44	0.87	0	31
162080	G2080	19.80	0.15	0.78 ± 0.06	0.04 ± 0.01	1.40 ± 0.11	1.39	4	4
162080	G2080	19.80	0.15	0.82 ± 0.33	0.03 ± 0.07	1.40 ± 0.49	0.99	0	13
162116	G2116	19.30	0.15	0.54 ± 0.17	0.12 ± 0.08	1.40 ± 0.40	0.47	0	7
162567	G2567	19.90	0.15	0.33 ± 0.01	0.17 ± 0.03	1.40 ± 0.00	0.20	6	6
162741	G2741	17.30	0.15	3.95 ± 0.04	0.01 ± 0.00	1.40 ± 0.00	0.22	6	6
162980	G2980	16.70	0.15	0.79 ± 0.04	0.66 ± 0.13	1.40 ± 0.00	0.40	8	8
163818	G3818	18.40	0.15	0.39 ± 0.02	0.52 ± 0.06	1.40 ± 0.00	0.33	7	7
172034	H2034	17.80	0.15	0.63 ± 0.02	0.34 ± 0.05	1.40 ± 0.00	1.05	16	16
190166	J0166	17.10	0.15	1.01 ± 0.03	0.25 ± 0.04	1.40 ± 0.00	0.92	6	7
190166	J0166	17.10	0.15	1.05 ± 0.02	0.23 ± 0.03	1.40 ± 0.00	0.68	12	12
209924	K9924	16.10	0.15	1.86 ± 0.71	0.19 ± 0.12	1.40 ± 0.44	0.40	0	7
211871	L1871	18.80	0.15	0.41 ± 0.01	0.32 ± 0.05	1.40 ± 0.00	0.28	5	7
214088	L4088	15.20	0.15	2.42 ± 0.06	0.25 ± 0.03	1.40 ± 0.00	0.63	8	8
215588	L5588	19.50	0.15	0.49 ± 0.16	0.12 ± 0.12	1.40 ± 0.44	0.57	0	5
215757	L5757	17.70	0.15	0.78 ± 0.27	0.24 ± 0.17	1.40 ± 0.48	0.47	0	11
235086	N5086	17.50	0.15	1.02 ± 0.40	0.17 ± 0.18	1.40 ± 0.51	1.04	0	60
235086	N5086	17.50	0.15	1.02 ± 0.32	0.17 ± 0.11	1.40 ± 0.38	1.64	0	32
235086	N5086	17.50	0.15	1.08 ± 0.33	0.15 ± 0.12	1.40 ± 0.38	0.85	0	29
242450	O2450	14.70	0.15	2.54 ± 0.10	0.36 ± 0.13	1.40 ± 0.00	0.41	11	11
242450	O2450	14.70	0.15	2.91 ± 0.08	0.27 ± 0.04	1.40 ± 0.00	0.83	13	14
250620	P0620	18.00	0.15	0.65 ± 0.14	0.26 ± 0.13	1.40 ± 0.33	0.29	0	4
267337	Q7337	18.00	0.15	0.44 ± 0.10	0.58 ± 0.25	1.40 ± 0.43	0.21	0	4
269690	Q9690	18.40	0.15	0.89 ± 0.43	0.10 ± 0.11	1.40 ± 0.59	0.31	0	7
271480	R1480	17.50	0.15	0.71 ± 0.22	0.35 ± 0.22	1.40 ± 0.48	0.82	0	6
274138	R4138	17.80	0.15	0.75 ± 0.02	0.24 ± 0.03	1.40 ± 0.00	0.48	7	7
275976	R5976	16.30	0.15	1.86 ± 0.04	0.15 ± 0.03	1.40 ± 0.00	1.01	5	5
275976	R5976	16.30	0.15	2.38 ± 0.03	0.09 ± 0.01	1.40 ± 0.00	1.11	15	16
276274	R6274	17.20	0.15	1.53 ± 0.71	0.10 ± 0.17	1.40 ± 0.52	0.91	0	5
276468	R6468	17.90	0.15	1.03 ± 0.37	0.11 ± 0.14	1.40 ± 0.42	0.36	0	5
285944	S5944	16.50	0.15	1.04 ± 0.04	0.41 ± 0.03	1.40 ± 0.00	0.16	10	10
285944	S5944	16.50	0.15	1.40 ± 0.43	0.23 ± 0.19	1.40 ± 0.41	0.51	0	29
297418	T7418	18.60	0.15	0.41 ± 0.02	0.39 ± 0.05	1.40 ± 0.00	0.93	5	5
299582	T9582	18.00	0.15	0.62 ± 0.02	0.29 ± 0.03	1.40 ± 0.00	0.31	7	7
303174	U3174	16.70	0.15	1.50 ± 0.03	0.16 ± 0.03	1.40 ± 0.00	0.65	21	23
304330	U4330	18.90	0.15	0.61 ± 0.01	0.13 ± 0.02	1.40 ± 0.00	0.13	11	11
304330	U4330	18.90	0.15	0.78 ± 0.01	0.08 ± 0.01	1.40 ± 0.00	0.23	12	12
322763	W2763	16.90	0.15	1.25 ± 0.03	0.20 ± 0.04	1.40 ± 0.00	0.27	12	13
326388	W6388	18.20	0.15	1.26 ± 0.57	0.06 ± 0.12	1.40 ± 0.52	0.33	0	8
334673	X4673	17.90	0.15	0.57 ± 0.22	0.38 ± 0.25	1.40 ± 0.60	0.67	0	11
349219	Y9219	18.20	0.15	0.58 ± 0.15	0.27 ± 0.23	1.40 ± 0.41	0.58	0	14
363505	a3505	18.10	0.15	1.90 ± 0.05	0.03 ± 0.01	1.40 ± 0.03	0.66	12	12
368184	a8184	19.50	0.15	0.38 ± 0.12	0.19 ± 0.19	1.40 ± 0.46	0.54	0	25
369264	a9264	16.30	0.15	1.51 ± 0.47	0.23 ± 0.20	1.40 ± 0.42	0.65	0	7
377732	b7732	17.00	0.15	0.95 ± 0.03	0.31 ± 0.05	1.40 ± 0.00	0.62	5	5
377732	b7732	17.00	0.15	0.99 ± 0.03	0.29 ± 0.03	1.40 ± 0.00	0.16	5	5
381677	c1677	18.40	0.15	0.47 ± 0.01	0.35 ± 0.05	1.40 ± 0.00	0.92	19	19
381677	c1677	18.40	0.15	0.44 ± 0.16	0.40 ± 0.21	1.40 ± 0.54	0.47	0	5
387733	c7733	18.90	0.15	0.34 ± 0.01	0.41 ± 0.06	1.40 ± 0.00	0.22	11	11
387733	c7733	18.90	0.15	0.32 ± 0.09	0.47 ± 0.25	1.40 ± 0.46	0.37	0	5
387746	c7746	20.00	0.15	0.37 ± 0.01	0.13 ± 0.02	1.40 ± 0.00	0.23	5	6
388838	c8838	19.50	0.15	0.36 ± 0.01	0.21 ± 0.04	1.40 ± 0.00	0.61	18	18
388838	c8838	19.50	0.15	0.38 ± 0.01	0.20 ± 0.02	1.40 ± 0.00	0.24	12	12
389694	c9694	18.20	0.15	0.45 ± 0.02	0.46 ± 0.06	1.40 ± 0.00	0.22	4	5
391211	d1211	18.50	0.15	0.41 ± 0.09	0.42 ± 0.23	1.40 ± 0.38	0.85	0	17
393359	d3359	19.20	0.15	0.77 ± 0.33	0.06 ± 0.11	1.40 ± 0.52	0.51	0	30
393569	d3569	20.20	0.15	0.55 ± 0.01	0.05 ± 0.01	1.40 ± 0.00	0.22	13	14
399433	d9433	18.60	0.15	1.34 ± 0.56	0.04 ± 0.09	1.40 ± 0.49	0.24	0	10
399433	d9433	18.60	0.15	1.76 ± 0.89	0.02 ± 0.05	1.40 ± 0.53	0.16	0	9
406952	e6952	17.10	0.15	0.77 ± 0.21	0.43 ± 0.23	1.40 ± 0.44	0.64	0	5
408751	e8751	19.00	0.15	0.40 ± 0.01	0.28 ± 0.03	1.40 ± 0.00	0.84	68	69
409256	e9256	18.20	0.15	1.89 ± 0.68	0.03 ± 0.04	1.40 ± 0.40	0.84	0	4
409836	e9836	18.10	0.15	0.55 ± 0.19	0.33 ± 0.25	1.40 ± 0.49	1.78	0	14
410088	f0088	18.10	0.15	1.03 ± 0.01	0.10 ± 0.02	1.40 ± 0.00	0.14	9	10
410778	f0778	18.10	0.15	1.46 ± 0.57	0.05 ± 0.03	1.40 ± 0.41	0.38	0	6
411201	f1201	17.80	0.15	0.66 ± 0.01	0.31 ± 0.05	1.40 ± 0.00	1.45	12	15
411611	f1611	18.80	0.15	0.36 ± 0.10	0.41 ± 0.21	1.40 ± 0.43	0.81	0	31
413038	f3038	16.90	0.15	1.24 ± 0.03	0.20 ± 0.04	1.40 ± 0.00	1.19	22	23
413038	f3038	16.90	0.15	1.01 ± 0.04	0.30 ± 0.04	1.40 ± 0.00	1.79	23	25
413192	f3192	16.80	0.15	3.96 ± 1.84	0.02 ± 0.05	1.40 ± 0.47	0.62	0	18
413421	f3421	18.30	0.15	1.90 ± 0.78	0.02 ± 0.02	1.40 ± 0.41	1.39	0	23
413820	f3820	19.80	0.15	0.66 ± 0.26	0.05 ± 0.04	1.40 ± 0.46	0.97	0	36
414286	f4286	18.60	0.15	0.37 ± 0.08	0.47 ± 0.19	1.40 ± 0.38	0.54	0	27
414286	f4286	18.60	0.15	0.40 ± 0.09	0.40 ± 0.24	1.40 ± 0.40	0.71	0	29
418797	f8797	19.40	0.15	0.70 ± 0.29	0.06 ± 0.07	1.40 ± 0.50	0.32	0	7
418929	f8929	17.00	0.15	1.43 ± 0.02	0.14 ± 0.03	1.40 ± 0.00	0.54	48	49
419624	f9624	20.50	0.15	0.34 ± 0.14	0.09 ± 0.17	1.40 ± 0.50	0.57	0	18
419624	f9624	20.50	0.15	0.36 ± 0.13	0.09 ± 0.14	1.40 ± 0.46	0.46	0	6
419880	f9880	19.60	0.15	0.98 ± 0.06	0.03 ± 0.01	1.40 ± 0.08	0.20	6	6
2000 AG205	K00AK5G	19.70	0.15	0.95 ± 0.01	0.03 ± 0.00	1.40 ± 0.00	0.79	12	14
2002 XS40	K02X40S	20.10	0.15	0.76 ± 0.03	0.03 ± 0.00	1.40 ± 0.05	0.18	14	14
2003 CC11	K03C11C	19.10	0.15	1.13 ± 0.51	0.03 ± 0.10	1.40 ± 0.53	0.49	0	16
2003 SS214	K03SL4S	20.10	0.15	0.86 ± 0.25	0.02 ± 0.02	1.40 ± 0.35	0.75	0	16
2004 BZ74	K04B74Z	18.10	0.15	0.96 ± 0.02	0.11 ± 0.02	1.40 ± 0.00	0.65	4	5
2004 MX2	K04M02X	19.30	0.15	1.26 ± 0.08	0.02 ± 0.00	1.40 ± 0.09	0.35	9	9
2004 TG10	K04T10G	19.40	0.15	1.32 ± 0.61	0.02 ± 0.04	1.40 ± 0.51	0.64	0	8
2005 LS3	K05L03S	19.50	0.15	0.38 ± 0.10	0.19 ± 0.12	1.40 ± 0.38	0.64	0	7
2006 BB27	K06B27B	20.00	0.15	0.22 ± 0.05	0.38 ± 0.21	1.40 ± 0.38	0.98	0	5
2007 BG	K07B00G	19.50	0.15	0.31 ± 0.11	0.24 ± 0.19	1.40 ± 0.51	0.38	3	5
2007 RU10	K07R10U	19.10	0.15	0.92 ± 0.37	0.05 ± 0.06	1.40 ± 0.47	0.31	0	9
2008 QS11	K08Q11S	19.90	0.15	0.45 ± 0.01	0.09 ± 0.01	1.40 ± 0.00	0.33	9	11
2009 ND1	K09N01D	17.10	0.15	2.50 ± 0.95	0.04 ± 0.04	1.40 ± 0.39	0.70	0	11
2010 OQ1	K10O01Q	19.00	0.15	0.54 ± 0.21	0.15 ± 0.14	1.40 ± 0.51	0.47	0	8
2011 CQ4	K11C04Q	18.40	0.15	0.66 ± 0.02	0.18 ± 0.02	1.40 ± 0.00	0.29	5	7
2012 DN	K12D00N	18.10	0.15	2.77 ± 1.05	0.01 ± 0.03	1.40 ± 0.38	0.42	0	7
2013 PX6	K13P06X	18.40	0.15	1.65 ± 0.03	0.03 ± 0.00	1.40 ± 0.02	0.19	9	10
2013 WT44	K13W44T	19.30	0.15	0.65 ± 0.01	0.08 ± 0.02	1.40 ± 0.00	0.31	6	6
2013 WU44	K13W44U	21.00	0.15	0.29 ± 0.13	0.09 ± 0.19	1.40 ± 0.61	0.26	0	8
2013 YZ13	K13Y13Z	19.60	0.15	0.31 ± 0.10	0.27 ± 0.19	1.40 ± 0.46	0.07	0	6
2013 YP139	K13YD9P	21.60	0.15	0.40 ± 0.03	0.03 ± 0.01	1.09 ± 0.07	0.25	6	6
2014 AA33	K14A33A	19.30	0.15	0.79 ± 0.04	0.05 ± 0.01	1.40 ± 0.06	0.19	4	4
2014 AQ46	K14A46Q	20.10	0.15	0.59 ± 0.29	0.05 ± 0.11	1.40 ± 0.60	0.47	0	17
2014 AA53	K14A53A	19.80	0.15	0.70 ± 0.27	0.04 ± 0.06	1.40 ± 0.47	0.50	0	13
2014 BG60	K14B60G	20.10	0.15	0.67 ± 0.25	0.04 ± 0.08	1.40 ± 0.46	1.30	0	163
2014 BE63	K14B63E	23.20	0.15	0.36 ± 0.13	0.01 ± 0.00	1.40 ± 0.46	0.42	0	5
2014 CY4	K14C04Y	21.10	0.15	0.57 ± 0.25	0.02 ± 0.04	1.40 ± 0.52	0.35	0	5
2014 DC10	K14D10C	20.10	0.15	0.89 ± 0.01	0.02 ± 0.00	1.40 ± 0.00	0.90	9	10
2014 ED	K14E00D	19.30	0.15	0.49 ± 0.13	0.14 ± 0.14	1.40 ± 0.39	0.57	0	6
2014 EN45	K14E45N	21.20	0.15	0.37 ± 0.13	0.04 ± 0.01	0.75 ± 0.24	0.16	12	12
2014 EZ48	K14E48Z	18.80	0.15	0.45 ± 0.01	0.26 ± 0.04	1.40 ± 0.00	1.10	5	6
2014 EZ48	K14E48Z	18.80	0.15	0.44 ± 0.11	0.27 ± 0.21	1.40 ± 0.38	0.47	0	6
2014 EQ49	K14E49Q	21.80	0.15	0.38 ± 0.13	0.02 ± 0.03	1.40 ± 0.42	0.42	0	5
2014 ER49	K14E49R	18.60	0.15	0.46 ± 0.15	0.30 ± 0.26	1.40 ± 0.49	0.51	0	9
2014 HE3	K14H03E	19.90	0.15	0.56 ± 0.15	0.06 ± 0.04	1.40 ± 0.34	0.18	0	5
2014 HQ124	K14HC4Q	18.90	0.15	0.41 ± 0.17	0.29 ± 0.22	1.40 ± 0.57	0.80	0	10
2014 HF177	K14HH7F	19.70	0.15	0.25 ± 0.01	0.36 ± 0.06	1.40 ± 0.00	0.39	10	12
2014 JL25	K14J25L	23.00	0.15	0.23 ± 0.06	0.02 ± 0.03	1.40 ± 0.34	0.68	0	5
2014 JH57	K14J57H	16.60	0.15	4.61 ± 0.03	0.02 ± 0.00	1.40 ± 0.00	0.11	6	6
2014 JH57	K14J57H	16.60	0.15	6.79 ± 3.81	0.01 ± 0.03	1.40 ± 0.47	0.30	0	5
2014 JN57	K14J57N	20.70	0.15	0.27 ± 0.10	0.12 ± 0.10	1.40 ± 0.47	0.69	0	4
2014 KX99	K14K99X	18.20	0.15	1.72 ± 0.68	0.03 ± 0.05	1.40 ± 0.46	0.43	0	9
2014 LQ25	K14L25Q	20.00	0.15	0.94 ± 0.32	0.02 ± 0.01	1.40 ± 0.37	0.48	0	5
2014 LR26	K14L26R	18.50	0.15	2.08 ± 0.90	0.02 ± 0.03	1.40 ± 0.46	0.65	0	6
2014 MQ18	K14M18Q	15.60	0.15	5.27 ± 3.50	0.04 ± 0.07	1.40 ± 0.52	0.54	0	8
2014 NB39	K14N39B	19.50	0.15	1.08 ± 0.15	0.02 ± 0.02	1.40 ± 0.18	0.08	7	7
2014 NE52	K14N52E	17.90	0.15	0.70 ± 0.22	0.25 ± 0.27	1.40 ± 0.47	0.66	0	9
2014 NC64	K14N64C	20.50	0.15	0.50 ± 0.19	0.04 ± 0.02	0.82 ± 0.29	0.64	5	6
2014 NM64	K14N64M	22.60	0.15	0.33 ± 0.12	0.01 ± 0.02	1.40 ± 0.44	0.82	0	25
2014 OY1	K14O01Y	19.10	0.15	0.60 ± 0.21	0.11 ± 0.09	1.40 ± 0.43	0.30	0	6
2014 OZ1	K14O01Z	21.00	0.15	0.73 ± 0.29	0.01 ± 0.03	1.40 ± 0.49	0.38	0	21
2014 PC68	K14P68C	20.40	0.15	0.56 ± 0.20	0.04 ± 0.04	1.40 ± 0.43	0.39	0	8
2014 PF68	K14P68F	18.20	0.15	3.33 ± 2.06	0.01 ± 0.01	1.20 ± 0.48	0.60	0	12
2014 QK433	K14Qh3K	18.30	0.15	1.78 ± 0.75	0.03 ± 0.06	1.40 ± 0.47	0.79	0	10
2014 RH12	K14R12H	23.50	0.15	0.09 ± 0.04	0.09 ± 0.11	1.40 ± 0.54	0.75	0	10
2014 RL12	K14R12L	17.90	0.15	0.69 ± 0.02	0.25 ± 0.03	1.40 ± 0.00	0.31	5	5
2014 RL12	K14R12L	17.90	0.15	0.61 ± 0.17	0.33 ± 0.19	1.40 ± 0.42	0.83	0	6
2014 SR339	K14SX9R	18.60	0.15	0.97 ± 0.37	0.07 ± 0.07	1.40 ± 0.46	0.69	0	13
2014 TW57	K14T57W	20.10	0.15	0.47 ± 0.01	0.07 ± 0.02	1.40 ± 0.00	0.76	4	6
2014 TF64	K14T64F	20.10	0.15	0.70 ± 0.20	0.03 ± 0.03	1.40 ± 0.35	0.33	0	5
2014 TJ64	K14T64J	21.30	0.15	0.52 ± 0.20	0.02 ± 0.02	1.40 ± 0.47	0.46	0	31
2014 TJ64	K14T64J	21.30	0.15	0.52 ± 0.23	0.02 ± 0.03	1.40 ± 0.54	0.55	0	14
2014 UG176	K14UH6G	21.50	0.15	0.42 ± 0.12	0.03 ± 0.03	1.40 ± 0.39	0.17	0	8
2014 US192	K14UJ2S	18.70	0.15	0.87 ± 0.01	0.08 ± 0.01	1.40 ± 0.00	0.25	5	5
2014 UF206	K14UK6F	18.80	0.15	1.63 ± 0.79	0.02 ± 0.04	1.40 ± 0.49	0.62	0	17
2014 UH210	K14UL0H	21.10	0.15	0.40 ± 0.16	0.04 ± 0.06	1.40 ± 0.47	0.76	0	5
2014 VP35	K14V35P	22.70	0.15	0.12 ± 0.05	0.10 ± 0.10	1.40 ± 0.53	0.36	0	6
2014 WJ70	K14W70J	17.60	0.15	2.92 ± 1.21	0.02 ± 0.04	1.40 ± 0.44	0.62	0	27
2014 XQ7	K14X07Q	20.60	0.15	0.65 ± 0.29	0.02 ± 0.05	1.40 ± 0.55	0.83	0	8
2014 XX7	K14X07X	19.80	0.15	1.20 ± 0.38	0.01 ± 0.02	1.40 ± 0.36	0.43	0	6
2014 XX31	K14X31X	17.60	0.15	1.35 ± 0.49	0.09 ± 0.15	1.40 ± 0.43	0.42	0	8

Note. Magnitude H, slope parameter G, and beaming η used are given. The numbers of observations used in the 3.4 μm (${n}_{W1}$) and 4.6 μm (${n}_{W2}$) wavelengths are also reported, along with the amplitude of the 4.6 μm light curve (W2 amp.).

Machine-readable versions of the table is available.

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Table 4.  Measured Diameters (d) and Albedos (p_V) of MBAs and Mars Crossers Not Previously Characterized Using NEOWISE Data

Name	Packed	H	G	d (km)	pV	η	W2 Amp.	nW1	nW2
21	00021	7.35	0.11	99.47 ± 27.12	0.16 ± 0.12	0.95 ± 0.19	0.27	10	10
65	00065	6.62	0.01	276.58 ± 74.49	0.06 ± 0.04	0.95 ± 0.17	0.09	8	10
69	00069	7.05	0.19	131.07 ± 32.19	0.19 ± 0.07	0.95 ± 0.18	0.09	14	14
74	00074	8.66	0.15	111.87 ± 46.38	0.04 ± 0.03	0.95 ± 0.23	0.26	3	4
74	00074	8.66	0.15	105.13 ± 29.95	0.05 ± 0.02	0.95 ± 0.16	0.24	9	9
140	00140	8.34	0.15	82.63 ± 20.19	0.09 ± 0.07	0.95 ± 0.18	0.37	7	7
144	00144	7.91	0.17	131.36 ± 33.30	0.05 ± 0.01	0.95 ± 0.17	0.31	10	10
147	00147	8.70	0.15	144.68 ± 47.63	0.03 ± 0.02	0.95 ± 0.19	0.11	6	6
147	00147	8.70	0.15	119.59 ± 37.39	0.04 ± 0.02	0.95 ± 0.18	0.20	9	9
160	00160	9.08	0.15	69.62 ± 13.23	0.07 ± 0.04	0.95 ± 0.14	0.58	20	21
212	00212	8.28	0.15	132.58 ± 48.48	0.05 ± 0.03	0.95 ± 0.20	0.16	5	5
212	00212	8.28	0.15	129.09 ± 40.48	0.05 ± 0.04	0.95 ± 0.19	0.17	7	7
253	00253	10.30	0.15	50.35 ± 17.16	0.04 ± 0.02	0.95 ± 0.24	0.43	16	16
284	00284	10.05	0.11	54.47 ± 20.59	0.04 ± 0.03	0.95 ± 0.23	0.21	11	11
284	00284	10.05	0.11	56.81 ± 15.15	0.04 $\pm$ 0.01	0.95 $\pm$ 0.16	0.25	23	23

Note. Objects in this table do not have previously published diameters and albedos by the NEOWISE team. Beaming η, H, G, the amplitude of the 4.6 μm light curve (W2 amp.), and the numbers of observations used in the 3.4 μm (n_W1) and 4.6 μm (n_W2) wavelengths are also reported. For a small (<1%) fraction of objects, diameter fits could not reproduce optical magnitudes for a realistic range of albedos. This may be due to a large light curve amplitude, uncertainty in G slope values used to derive H magnitudes, or other reasons noted in Mainzer et al. (2011b, 2012), Masiero et al. (2011, 2012). These objects are marked with a † in the name column. Objects without reported albedos did not have measured H values, see text for details. Only the first 15 lines are shown.

Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.

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Results were compared to previous work by the NEOWISE team (Mainzer et al. 2011b, 2012; Masiero et al. 2011, 2012). Figure 3 shows the comparison between diameter and albedo measurements of MBAs. As observed in Masiero et al. (2011), asteroids in the Main Belt group into bright and dark types, with a greater fraction of bright objects found in the inner regions of the belt. Objects that were also modeled with the thermophysical model of Wright (2007) are given in Table 6.

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When possible, derived diameters were compared to diameter measurements made from radar data. Radar-derived diameters are ideal for this purpose, as they are derived via an independent method (Benner et al. 2015). This comparison is shown in Figure 4. Although the histograms in the figure are not perfectly Gaussian, a best-fit Gaussian to their forms gives fitted σ values, which indicates a 14% relative accuracy in diameter, and a 29% relative accuracy in albedo. These values are consistent with previous NEOWISE 3-band data results (Mainzer et al. 2012; Masiero et al. 2012). From this comparison to radar-derived diameters and previous work, we conclude that diameters are determined to an accuracy of ∼20% or better. If good-quality H magnitudes are available, albedos can be determined to within ∼40% or better.

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Roughly 3% of objects in this work have significantly different derived diameters than previously published NEOWISE values. It is possible that some of these objects are elongated. NEOWISE collects a sparsely sampled lightcurve for each object, and for example, it is possible that the prime mission happened to observe one of these objects in a more edge-on shape, whereas the reactivation observations tended to observe a wider side of the object. Alternatively, changes in viewing geometry between epochs could result in different diameter measurements; a pole-on viewing geometry could have a larger cross section than a geometry aligned with the plane of the equator.

For a small (<1%) fraction of objects, diameter fits could not reproduce optical magnitudes for a realistic range of albedos. This may be due to a large light curve amplitude (see column W2 amp. for the amplitude of the 3.4 μm band light curve, though note that this is a sparsely sampled light curve), uncertainty in G slope values used to derive H magnitudes, or other reasons noted in Mainzer et al. (2011b, 2012), Masiero et al. (2011, 2012). Poor-quality H values can drive albedo fits to extremes; therefore very low (∼0.01) measurements may be signs of this phenomenon.

We have plotted the diameters and albedos of NEOWISE Year One Reactivation discoveries, along with all NEAs detected by NEOWISE (Figure 5). The trend observed in Mainzer et al. (2014) is also present here: NEOWISE tends to discover darker NEAs than optical surveys. This is a direct consequence of the infrared wavelengths that NEOWISE employs.

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3.1. NHATS Targets

We present preliminary diameters and albedos for 7956 asteroids observed in the first year of the NEOWISE Reactivation mission. Five of these objects are NHATS targets. Future work by the NEOWISE team includes preliminary characterization results from the continuing mission.

Uncertainties on d and p_V are consistent with the errors measured during the initial post-cryo mission. NEOWISE is expected to maintain this pace of detection and NEO discovery for the extent of its mission, currently expected to run through 2017. These results demonstrate the power of infrared survey telescopes to characterize basic physical parameters for large numbers of small bodies.

C.R.N. was partially supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory (JPL), administered by Oak Ridge Associated Universities through a contract with NASA. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and JPL/California Institute of Technology, funded by NASA. This publication also makes use of data products from NEOWISE, which is a project of the JPL/California Institute of Technology, funded by the Planetary Science Division of NASA. This research has made use of the NASA/IPAC Infrared Science Archive. The JPL High-Performance Computing Facility used for our simulations is supported by the JPL Office of the CIO.

This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cienti´fico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovacão, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Enérgeticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule (ETH) Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l'Espai (IEEC/CSIC), the Institut de Fi´sica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University.

This work makes use of observations from the LCOGT network.

Follow-up included observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministrio da Cincia, Tecnologia e Inovao (Brazil) and Ministerio de Ciencia, Tecnologa e Innovacin Productiva (Argentina).

We thank the anonymous referee for their thoughtful and thorough consideration of our manuscript.