Color Changes for the Surface of 6478 Gault (??) Submitted to Apjl

Draft version August 3, 2020 Typeset using LATEX twocolumn style in AASTeX63

Color changes for the Surface of 6478 Gault (??)

1 2 2 3 4 5 1 Remington Cantelas, Karen J. Meech, Jan T. Kleyna, Erica Bufanda, Alan Fitzsimmons, James Bauer, 2 2 2 6 2 2 Larry Denneau, Robert Weryk, Jacqueline V. Keane, Olivier R. Hainaut, and Richard J. Wainscoat

1 3 University of Central Florida, 4111 Libra Drive, Orlando, FL 32816, USA 2 4 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA 3 5 Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 USA 4 6 Astrophysics Research Centre, Queen’s University Belfast, Belfast BT7 1NN, UK 5 7 University of Maryland, Dept. of Astronomy, College Park, MD 20742-2421 USA 6 8 European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei M¨unchen,Germany

9 Submitted to ApJL

10 ABSTRACT

11 (6478) Gault is a main belt asteroid in the Phocaea Family which was discovered to have activity in

12 January 2019, and precovery images reveal it has been consistently active since at least September 2013.

13 Gault’s activity is believed to be caused by it being a fast rotator near the asteroid break-up limit. We

14 have collected images and photometry from several telescopes dating back several apparitions. Using

15 this data we attempt to produce a reliable rotational light curve and conﬁrm Gault’s rotation period.

16 We also investigate possible color variations on the surface of the asteroid by measuring it’s spectral

17 reﬂectivity over the course of 7 months between January and August 2019. These color variations would

18 imply that Gault’s activity is either revealing new fresh material unaﬀected by long-term radiation

19 from the Sun, or Gault’s surface is composed of a mineralogy we would not typically expect for an

20 asteroid of it’s class. Confirming these color variations could have significant implications in the field

21 of space weathering and would also be notable since color variations on an asteroids surface have not

22 been observed from the ground before.

23 Keywords: minor planets, asteroids: individual ((6478) Gault) — planets and satellites: dynamical

24 evolution and stability

25 1. INTRODUCTION 43 impact events, rotational breakup, thermal fracture, and

44 “rubbing binaries” (Jewitt 2012). 26 On January 5th 2019, the ATLAS sky survey de- 45 Determining Gault’s asteroid type will give us insight 27 tected activity around the main belt asteroid (6478) 46 into what the object might be made of and may help 28 Gault. Further investigation showed the development of 47 constrain likely sources of activity. For instance, most 29 three separate tails: the first appearing on October 28 48 cometary activity is associated with volatile sublimation 30 2018, the second on December 31 2018, and the third on 49 caused by ices in the object sublimating due to heat- 31 February 10 2019 (Jewitt et al. 2019). Looking back at 50 ing from the Sun. This type of activity is more likely 32 existing NOAO DECam images, Chandler et al.(2019) 51 to occur on primitive C-type asteroids which are gen- 33 found that activity in the asteroid had been consistent 52 erally thought to have formed farther out in the aster- 34 since at least 2013. These discoveries make Gault a rare 53 oid belt where temperatures are cooler and volatiles are 35 new member of a small group of active asteroids. 54 more likely to condense. Furthermore, objects under- 36 Active asteroids are defined as objects that exhibit 55 going volatile sublimation show more activity near per- 37 comet-like behavior, have semi-major axes within the 56 ihelion and less during aphelion. In the case of Gault, 38 orbit of Jupiter, and a Tisserand parameter of Tj > 3 57 the brightness due to activity varies along it’s orbit, but 39 (Jewitt et al. 2015). There are only ∼ 20 known active 58 this brightness has no correlation to Gault’s distance 40 asteroids, 16 of which are C-type and 4 are S-type (Je- 59 from the Sun (Chandler et al. 2019). Optical reflectance 41 witt 2012). Activity on these asteroids can be caused by 60 spectra showed no gas in Gault’s tail (Jewitt et al. 2019). 42 a variety of phenomena, including: volatile sublimation, 2

61 This evidence argues against volatile sublimation as the Table 1. Observations

62 main cause for Gault’s activity. 00 63 Gault is a member of the Phocaea family (Nesvorny Telescope Detector Gain RN /pix

64 2015), made up mostly of S-type objects and the ATLAS STA-1600 2.0 11.0 1.86 65 low albedo, presumed C-type, Tamara sub-family (No- Gemini GMOS 2.27 3.32 0.161 66 vakovi´cet al. 2017). Color observations from early 2019 CFHT Megacam 1.634 3.00 0.187 67 suggested that Gault was most likely a C-type asteroid PanSTARRS GPC1 1.256 7.462 0.260 68 (Kleyna et al. 2019; Hui et al. 2019; Lee 2019; Jewitt VLT FORS2 0.8 2.7 0.126 69 et al. 2019). Later, visible and near-Infrared spectra

70 taken in March and April of 2019, after activity had de- 112 (ATLAS), the All Sky Automated Survey for Super- 71 creased, suggested instead that Gault was very clearly 113 Novae (ASAS-SN) and the Very Large Telescope (VLT). 72 an S-type, observing the two distinct 1µm and 2µm ab- 114 All images, with the exception of VLT and Gemini im- 73 sorptions bands associated with silicates (Marsset et al. 115 ages, were reduced using our pipeline. To photometri- 74 2019). Curiously, Marsset et al.(2019) also found that 116 cally calibrate the data we calculated a photometric zero 75 the color had changed significantly, from a very blue- 117 point for each image using the Pan-STARRS, SDSS and 76 sloped Q-type spectra on March 31 2019 to a typical 118 Gaia2 catalogs and published color corrections to trans- 77 red S-type spectra on April 8 2019. Carbognani & Buz- 119 late photometric bands (Magnier et al. 2016; Chambers 78 zoni(2020) found a similar blue color shift on April 15, 120 et al. 2016). The information from the image head- 79 2019 using optical photometry. 121 ers was used to download orbital elements from the 80 One suggested mechanism for activity on Gault is 122 Minor Planet Center and the computed object loca- 81 rotational breakup caused by the Yarkovsky–OKeefe– 123 tion was used to determine which object in the frame 82 Radzievskii–Paddack (YORP) effect. Asteroids absorb 124 corresponded to the target. Terapix tools (SExtractor 83 sunlight and re-emit it as thermal radiation, and over 125 (Bertin & Arnouts 1996)) were used to produce multi- 84 long periods time the momentum from this radiation can 126 aperture and automatic aperture target photometry for 85 gradually speed up an asteroid’s rotation until the ap- 127 several of the data sets. A full description of the pipeline 86 parent surface gravity is zero (Bottke et al. 2006). This 128 is given in Meech et al.(2017). Gemini data was reduced 87 can trigger disruption or landslide events that would re- 129 using the new Gemini DRAGONS reduction software. 88 lease dust at a near zero velocity which would get swept 130 For all telescopes except VLT we photometrically cal- 89 away by solar radiation pressure, hence producing a tail. 131 ibrate our images by calculating a zero point for each 90 Several dust dynamical models confirm this, finding that 132 image using the Pan-STARRS database and published 91 the dust in Gault’s tail has a low ejection velocity (Je- 133 color corrections to translate photometric bands. The 92 witt et al. 2019; Hui et al. 2019; Kleyna et al. 2019; 134 photometry is shown in Figure7. 93 Moreno et al. 2019; Ye et al. 2019). Kleyna et al.(2019) 135 Photometry was done using the IRAF software to de- 94 has proposed a ∼ 2 hour rotation period, which is near 136 termine the best aperture size for each set of data. For 95 the limit of a body with some internal cohesion (Holsap- 137 faint objects this is done by finding the curve of growth 96 ple 2007; Chang et al. 2019). Other studies have been 138 for an unsaturated star in the image and determining 97 unable to confirm this rotation period, but this is mostly 139 the aperture at which most light is collected with the 98 due to the effect of dust masking around Gault making 140 least amount of sky. In addition, smaller aperture sizes 99 it difficult to detect a brightness variation from the ro- 141 can decrease the amount of contribution coming from 100 tating nucleus (Kleyna et al. 2019; Jewitt et al. 2019; Ye 142 the dust cloud surrounding an object and increase the 101 et al. 2019; Sanchez et al. 2019; Moreno et al. 2019). 143 contribution from the nucleus. This technique could al- 102 In this paper, we will be looking at data from before 144 leviate the effects of dusk masking on our light curve 103 and after Gault’s 2019 period of activity to try to deter- 145 and reveal periodic rotational variabilities which were 104 mine it’s rotation period. We will also be looking deeper 146 not found in previous studies. 105 into Gault’s colors to find out what mechanisms might

106 be causing such drastic color variations. 147 2.1. Very Large Telescope

148 The ESO Science Archive contains a set of 436 images 107 2. OBSERVATIONS AND DATA REDUCTION 149 (taken for program 2102.C-5038, by Drahus et al) from

108 Data for (6478) Gault was obtained using the Pan- 150 2019 March 4. To increase time resolution with a short

109 STARRS1 telescope, the Canada-France-Hawaii Tele- 151 exposure time of 20s, only a subarray of each image

110 scope (CFHT), the Gemini North Telescope, the As- 152 was read out to save read out time. The small FOV

111 teroid Terrestrial-impact Last Alert System telescopes 153 (Fig.1) did not have enough calibration stars to produce 3

Table 2. Gault Colors (g 0-r 0) 0.59 ± 0.0025 (r 0-i 0) 0.24 ± 0.0027 (i 0-z 0) −0.12 ± 0.0026 Note—We are still trying to ﬁgure out if the z-band measurements are real, so (i 0-z 0) shouldn’t be trusted at this point.

187 signature through the Elixir pipeline (Magnier & Cuil-

188 landre 2004), and calibrated with our pipeline.

th Figure 1. Image of Gault taken on March 4 2019 using 189 2.4. Pan-STARRS the Very Large Telescope. North is up, East is to the left. 190 You need to ﬁll in the description of the PanSTARRS 3.50 × 20. As you can see, there are very few stars to use for the photometric calibration. 191 data.

192 2.5. William Herschel Telescope 154 a reliable zero point using ours pipeline, therefore we 193 KJM - Alan will be joining the paper and provide 155 performed manual differential photometry on this data 194 his spectrum (See6). “For info the data was taken on 156 set. The same field stars were not present throughout 195 the night of 11 March last year, 2×900 sec spectra with 157 all 436 images, therefore the set was broken into five 196 the WHT. Theres a bit of extra noise from cosmics/ 158 batches. Each batch contained at least one field star 197 sky emission I can clean up, that was a quick reduction 159 from the previous one in order to normalize the images 198 where I skipped those steps to get the spectrum out.” 160 to one another. 199 RC- Currently working on a table of photometry 161 The seeing over the course of the night significantly

162 degraded, as shown in Figure3. We used small aper- 200 3. ANALYSIS 00 163 tures (2 radius) to maximize brightness changes due 201 The photometry from the various telescopes was color 164 to rotation, but small apertures also makes this data 0 202 corrected to SDSS r using the following ﬁlter conver- 165 susceptible to changes caused by seeing variability. To 203 sions. 166 minimize the eﬀect of the worsening seeing on our rota- For the ATLAS telescopes we used the conversions 167 tional analysis, we removed images taken with a seeing described in Tonry et al.(2018): 00 168 over >1 which excluded all images taken after 4.7 UT. r = 0.35(0.73(g − r) + o) + 0.65o (1)

169 2.2. Gemini North 2 2 2 2 0 0 170 A set of 47 images with exposure times of 90 s were σr0 = σo + (0.2555σ(g −r )) + 0.01 (2)

171 taken of Gault using the Gemini North GMOS imager 172 on 2019 January 14, also collected by Michal Drahus. r = 0.35c + 0.65(c − 0.73(g − r)) (3) 173 Similar to the VLT data, the Gemini images were mea- 00 174 sured using diﬀerential photometry through a 2 radius 2 2 2 2 σr0 = σc + (0.4745σ(g0−r0)) + 0.01 (4) 175 aperture to correct for varying cloud cover throughout

176 the night. The observing conditions that night were not 204 For the Kron-Cousins ﬁlter system we used the con-

177 ideal, with cloud coverage and image quality in the 70%- 205 versions described in Lupton(2005):

178 ile and sky background in the 80%-ile. r = R + 0.2936(r − i) + 0.1439 (5)

179 2.3. Canada-France-Hawaii Telescope r = V + 0.5784(g − r) − 0.0038 − (g − r) (6) 180 A set of 148 SDSS g, r, i, z CFHT images, each of 120

181 s duration, were taken on 13 nights between January 6, 206 For the Pan-STARRS ﬁlter system we used the con-

182 2019 and August 14, 2019 using the MegaCam wide-ﬁeld 207 versions described in Tonry et al.(2012): 00 183 imager with a plate scale of 0.185 /pixel. An additional

184 six 60 s SDSS g,r,i images were collected on June 17, 0 0 0 0 0 2 r = gP 1 + 0.011 − 0.875(g − r ) + 0.015(g − r ) , 185 2020. The data were obtained using queue service ob- 2 2 0.5 σr0 = (0.006 + σ ) 186 serving and were processed to remove the instrumental gp1 (7) 4

r0 = r − 0.001 + 0.006(g0 − r0) + 0.002(g0 − r0)2, P 1 (8) 2 2 0.5 σr0 = (0.002 + σrp1)

0 0 0 0 0 r = iP 1 + (r − i ) − 0.004 + 0.014(g − r )− (9) 0 0 2 2 2 0.5 0.001(g − r ) , σr0 = (0.003 + σip1)

0 0 0 0 0 r = zP 1 + (r − z ) + 0.013 − 0.040(g − r )+ (10) 0 0 2 2 2 0.5 0.001(g − r ) σr0 = (0.009 + σzp1)

0 0 0 0 0 2 r = wP 1 − 0.018 − 0.118(g − r ) + 0.091(g − r ) 2 2 0.5 σr0 = (0.012 + σwp1) (11) Figure 2. Top Figure: Seeing recorded by DIMM on the night of January 14th, 2019. Bottom Figure: Rotational

208 3.1. Rotation Period light curve from Gemini North Telescope images taken on January 14, 2019. During this time, Gault was still very 209 Using the Gemini North and VLT data, we performed active so this data set may be impacted by dust masking. 210 an analysis of Gault’s light curve to determine it’s ro- Just to note: for this data set I used the wrong zero point, so 211 tation period. To minimize contribution from the dust the magnitude values are wrong, but the curve itself is still 00 212 coma we used a small 2 aperture radius. The rotational correct. Currently in the process of going back and ﬁxing this. 213 light curves for Gemini and VLT are shown in Figures

214 2 and3 respectively. Period analysis was done using

215 Peranso 2.60 (Paunzen & Vanmunster 2016), which in-

216 corporates the Fourier Analysis of Light Curves (FALC)

217 and a variety of other period search algorithms. The

218 Gemini data showed signatures at ∼1 hr (shown in Fig-

219 ure4, but no period signatures were found in the VLT

220 data. The Gemini result is consistent with a two-peaked

221 ∼2 hour rotation period, in agreement with the rotation

222 period found by Kleyna et al.(2019) and the ∼2 hr

223 breakup limit.

224 However, similar to Kleyna et al.(2019), phasing the

225 data does not reveal any obvious light curve. This sug-

226 gests that any period signatures have a low amplitude,

227 expected in objects where coma contributes most of the

228 ﬂux (ex. Hsieh et al.(2011)). To test the dust contri-

229 bution for our data, we performed an exercise to calcu-

230 late the nucleus radius of Gault with an assumed albedo

231 of 13%, comparing the calculated nucleus size on days Figure 3. Top Figure: Seeing recorded by DIMM on the 232 where Gault was active to days when Gault was less night of March 4th 2019. At ∼3 UT, the seeing begins to 233 active. The results of this exercise are shown in Table rapidly degrade. Due to the bad seeing we excluded all im- 234 3. On the day the Gemini data was taken the calcu- ages taken after 4.7 UT from our rotation analysis. Bottom 235 lated nucleus size was almost 1 km larger than expected, Figure: Rotational light curve from Very Large Telescope 236 therefore the nucleus was only contributing a fraction of images taken on March 4, 2019. Activity was still present

237 the light on this night. during this time. This data set also had some problems in

238 Unfortunately, due to the bad seeing nearly half of the the photometry, so do I have to back and ﬁx this set as well.

239 VLT data had to be excluded from our rotation anal-

240 ysis, and this could have been a signiﬁcant factor in 242 observations. Despite the fact that the seeing for the

241 Peranso’s inability to ﬁnd a rotation period with these 243 data-points we kept were relatively good, the shortened 5

Table 3. Calculated Nucleus Radius Date Telescope r [au] ∆ [au] α [deg] mag ﬁlt Nuc Rad [km] 1/14/2019 ATLAS 2.46 1.77 19.5 17.67 r 2.88 3/30/2019 CFHT 2.3 1.43 15.41 17.34 r 2.19 6/17/2019 CFHT 2.06 1.94 29.28 18.79 r 1.88 7/1/2020 Gemini 2.09 1.81 29.17 18.66 r 1.88

244 window of time to ∼2.5 hours makes it difficult to find 261 Within our data Gault showed significant color varia-

245 periodic variations. Seeing variations and a short obser- 262 tions. The raw CFHT images were scrutinized critically

246 vation window likewise aﬀect the Gemini observations. 263 to ensure that these color variations were real, check-

264 ing to see if the images were reduced properly and that

265 Gault was not over any ﬁeld stars that may have been 200 266 contributing any brightness. After correcting for several

267 issues in our CFHT data, the variations did not disap-

150 268 pear leading us to believe that these color changes on 269 Gault are real measurements.

270 In most observations Gault displayed spectra consis- 100 271 tent with C and S type material, both of which are con-

FALC Periodogram Power Periodogram FALC 272 p = 1.2627 sistent with color inconsistencies previously reported in p = 1.1347 p = 1.1745 Gemini 50 273 the literature (see Sec1). Shockingly, on June 2 and 1.0 1.1 1.2 1.3 1.4 Time or Period (Hours) 274 July 3 2019 Gault had a steep red sloped spectra that 275 is typically associated with D-type asteroids and comet Figure 4. The calculated FALC analysis period curve for 276 colors measured from in-situ space missions RC - Is there the Gemini data set, shown as Spectral Density Values vs 277 a source I can use for this statement?. Spectral changes Time, with the blue dashed lines indicating possible rotation 278 do not appear to be associated with time, and are likely periods. These three spectral peaks suggest a rotation period of ∼2 hours 279 not due to some currently ongoing process like space 280 weathering. Rather, the random nature of the changes

281 suggest that Gault’s surface is spectrally heterogeneous.

247 3.2. Spectral Reflectivity 1.9 248 In order to calculate the spectral reflectivity of Gault 1.8 D Type (1143 Odysseus) 249 over time we normalized the reflectance of each filter to C Type (1 Ceres) 250 the g band using the following: 1.7 S Type (42 Isis) D Type – Jun/July −0.4(m −m ) 1.6 C Type – 8/12 10 λ λ S Type – 2/6, 3/12, 3/31 Rλ = (12) 10−0.4(mo−mo ) 1.5 1.4

h i0.5 1.3 σR = 0.921R σ 2 + σ 2 + σ 2 + σ 2 (13) mλ mλ mo mo 1.2 Normalized Reflectivity Normalized 251 where Rλ is the reflectance, mλ is the magnitude of the 1.1 252 object in filter λ, and mg is the magnitude of the object 1.0 253 in the reference filter, which is g in this case. The mλ (6478) Gault Spectral Reflectivity 254 and the mo are the solar magnitudes in the respective 0.9 0.4 0.5 0.6 0.7 0.8 0.9 1.0 255 filters. For the SDSS filters we use g = 5.12±0.02, r 1 µ 256 = 4.69±0.03, i = 4.57±0.03, and z = 4.60±0.03 . Wavelength [ m] 257 Gault’s spectral reflectivity was calculated using Figure 5. Spectral reflectivity of Gault between February 258 CFHT measurements in the SDSS g, r, i, z filters taken 6, 2019 and August 12, 2019. Reflectances are normalized to 259 over a six month period between February and August g. 260 of 2019. Resulting reflectivities are shown in Figure5.

1 http://www.sdss.org/dr12/algorithms/ugrizvegasun/ 282 3.3. Activity 6

312 3.4. Dust Production

313 To determine whether or not Gault is currently ac-

314 tive we used 4 20s Gemini North images taken on July

315 1st, 2020 to approximate the upper limit of Gault’s dust

316 production. The images were reduced with the same

317 method described in Section 2.2 and were subsequently

318 ﬂattened and stacked. Using this stacked image we mea-

319 sured the surface brightness proﬁles of our object and

320 two reference stars. To ﬁnd the upper limit on the dust

321 production we subtracted the average normalized stellar

322 proﬁle from the proﬁle of Gault, which should produce

323 a value of zero and an associated error. The 3σ of this

324 error can be used to ﬁnd the maximum ﬂux that could

325 have been contributed by an undetected coma. This flux Figure 6. Gault spectrum taken on 2019 March 11 using 326 can be found using the following equation from Meech the WHT showing that the dust is consistent with S-type 327 & Weaver(1996): asteroid surfaces.change ”col2” to WHT spectrum - erica - 2 also make the font larger - y axis can be chopped from like S πagr pvQφ F = 2 2 (14) .75 to 1.8 2r ∆ vgr RC - This is isn’t my plot, I think Alan Fitzsimmons is clean- 328 where S is the solar flux through the bandpass [W ing up this data more. −2 329 m ], agr [m] the grain radius, pv the grain albedo, Q [kg −1 330 s ] the dust production rate, φ the projected size of the 283 All the photometry was plotted by apparition into the −1 331 aperture [m], vgr [m s ] the grain velocity, and r is in 284 heliocentric light curves in Figures7. We plotted this 332 au and ∆ in m. If an empirical Bobrovnikoff relation for 285 data against a model of the brightness of the bare nu- 333 the terminal grain velocities is assumed (Bobrovnikoff 286 cleus as the object goes around the Sun taking into ac- −0.5 0 334 1954), vgr = vbob = 600 r , and φ = ∆ φ / 206265 287 count any brightness variations due to the comet’s or- 0 00 335 where φ is the angular size of the aperture ( ), then for 288 bital parameters such as phase, true anomaly, geocentric 336 a given observed flux, the dust production will vary as 289 distance, and heliocentric distance. Gault only became

290 an object of interest recently due to the discovery of ac- Q ∝ r1.5∆ (15) 291 tivity in Jan 2019, therefore none of our model parame-

292 ters are constrained. In the model we used the following 337 Comparing the surface brightness profile of Gault to 293 assumptions based off of known values from other minor 338 that of the averaged normalized field stars, it’s clear that 294 bodies (Meech et al. 2017): emissivity, =0.9, nucleus 339 Gault has a wider psf than the averaged stars, indicating −1 295 phase function, β=0.04 mag deg , coma phase func- 340 that Gault is slightly active. Taking into consideration −1 296 tion, β =0.03 mag deg , nucleus density, ρ =2000 kg 00 c N 341 the average seeing of ∼0. 5, the dust production was −3 297 m , and an average dust size of 5 µm. After testing −3 −4 342 approximated to be ∼ 10 − 10 kg/s. We obtain 298 several different model-free parameters we found that a 343 this result despite the fact that visually Gault appears 299 radius of 1.75 km and an albedo of 0.15 provided the 344 stellar with no tail. 300 best fit for our data. This size is consistent with the di-

301 ameter of 3.96 ± 22% km found by Sanchez et al.(2019) 345 4. DISCUSSION 302 using WISE data. RC - Gerbs should be sending us sizes 346 Similar to previous studies, we were unable to deter- 303 measured with WISE data. 347 mine rotation period for Gault, mostly due to the effect 304 In the most recent apparition, between October 2018 348 of dust masking and the unreliability of data caused by 305 and April 2021, CFHT data starts to deviate and be- 349 bad observing conditions. It’s become evident from all 306 come brighter than the curve in July 2019 at TA = -70 350 attempts that it’s not possible to find a conclusive ro- 307 and August 2019 at TA = -58. After stacking the CFHT 351 tational light curve of Gault during a period of activity. 308 images from July 2019, we found that Gault was expe- 352 It’s vital that future attempts to prove Gault’s rotation 309 riencing activity during this time, months after it was 353 take observations during an inactive period for the ob- 310 believed that activity had slowed down. This activity is 354 ject. Gault’s activity isn’t driven by sublimation, which 311 seen by the two tails in Figure8. 355 makes it very difficult to predict inactivity and plan ob-

356 servations. Comparing the periods of activity found by 7

Gault-Helio.pdf

Figure 7. Heliocentric light curve for Gault over two apparitions between April 2014-2021. The vertical dashed lines show the known periods of activity. The active periods are not correlated with distance from the Sun.

357 Chandler et al.(2019) to the photometry collected in 364 of 2019 around TA = −70, when Gault was becoming

358 Figure7 reveals that while activity on Gault is typically 365 fainter after it’s peak in January 2019.

359 found when Gault’s appears brightest to Earth, these 366 Despite these frequent bursts of activity, we do have

360 periods of brightness are due to orbital geometry are 367 evidence that Gault is not perpetually active, it’s most

361 not responsible for the activity. The lack of a correla- 368 notable inactivity being right now. Using our maximum

362 tion between Gault’s orbit and it’s activity is further 369 dust production limit we found that Gault is currently −4 363 exempliﬁed with a clear tail being discovered in July 370 producing very little dust, only about 10 kg/s and

371 is inactive. Considering the unpredictability of Gault’s 8

Figure 8. Gault activity found on July 3, 2019. North is up and East is right. Left image is 4.40 × 30 and the right image is 1.750 × 1.40. The red arrows point the two tails.

Figure 9. On the left is plotted the surface brightness proﬁle of Gault and it’s reference stars. On the right is Gault’s dust production, measured on July 1st 2020

372 activity, it’s diﬃcult to say when Gault will become ac- 384 groups have also reported broad-band color changes at

373 tive again and when that activity will slow down after 385 optical wavelengths between 2019 Jan. and April con-

374 that. Knowing that right now Gault is inactive means 386 sistent with asteroidal C and S type colors.

375 it is urgent that we attempt to study it now without the 387 Marsset et al.(2019) proposed Gault’s heterogenous

376 contribution of dust, before it become active again. 388 surface colors were caused by the removal of space

377 The surface shows signiﬁcant color variations over a 6- 389 weathered material that exposed bluer fresh (unweath-

378 month period Between 2019 February and August. The 390 ered) material. Space weathering is a process whereby

379 optical spectral reﬂectivities seen from our CFHT data 391 cosmic rays interact with surface minerals aﬀecting their

380 as shown in Fig.5, are consistent with S and C-type 392 optical properties. The eﬀect is strongly dependent on

381 mineralogies seen by other observers, however, the re- 393 mineral composition. Inner solar system minerals found

382 ﬂectivity seen in 2019 Jun/July was very red, consistent 394 on S-type asteroids, rich in olivine and pyroxene, tend

383 with outer solar system organic-rich material. Several 395 to redden and darken as iron is deposited on the surface 9

396 from vaporization of material (Clark et al. 2002). The 418 impacts. Most of the zodiacal dust in the solar system

397 surface of asteroid 433 Eros shows fresher unweathered 419 is produced from Jupiter family comets (Nesvorn´yet al.

398 surface material as the dusty surface moved downslope 420 2010) and this material could accrete on asteroid sur-

399 in an impact crater. More volatile-rich spectrally ﬂat 421 faces.

400 compositions found on C-type surfaces in the outer as-

401 teroid belt get bluer and darker as they weather (Kaluna

402 et al. 2016), due in part to polymerization and fragmen- 422 5. ACKNOWLEDGMENTS 403 tation of organics (Thompson et al. 2020).

404 The red slope seen in 2019 June and July, if conﬁrmed, 423 RC acknowledges support from the National Science

405 is extremely interesting because small bodies typically 424 Foundation (NSF) Research Experience for Undergrad-

406 don’t exhibit signiﬁcant large-scale color variation across 425 uate program at the Institute for Astronomy, Univer-

407 the surface. The Dawn spacecraft observations of the 426 sity of Hawai‘i at M¯anoa,funded through NSF grant

408 asteroid Vesta revealed a surface with the highest color 427 6104374. We acknowledge the following supporting

409 and albedo variation of any other asteroid. The spectral 428 grants: KJM: NSF award AST1617015, and HST pro-

410 reﬂectivity of Vesta is dominated by the 0.9 and 2.0 µm 429 gram GO/DD-15678 from NASA through STScI, oper-

411 absorptions from pyroxene. Vesta at 263.5 km radius 430 ated by AURA under NASA contract NAS 5-26555; AF:

412 is large enough to have diﬀerentiated and the surface 431 UK STFC grant ST/P0003094/1. This work uses data

413 pyroxene is a product of igneous activity. This is in- 432 from the ATLAS project, funded through NASA grants

414 consistent with the dark carbonaceous material seen on 433 NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575,

415 the surface. Reddy et al.(2012) proposed that the dark 434 with the IfA at the University of Hawai’i, and with con-

416 material could have been delivered by a carbonaceous 435 tributions from the Queen’s University Belfast, STScI,

417 chondrite impactor, or alternatively, by micrometeorite 436 and the South African Astronomical Observatory.

REFERENCES

437 Bertin, E., & Arnouts, S. 1996, A&AS, 117, 393 462 Kleyna, J. T., Hainaut, O. R., Meech, K. J., et al. 2019,

438 Bobrovnikoﬀ, N. T. 1954, AJ, 59, 356 463 ApJL, 874, L20

439 Bottke, Jr., W. F., Vokrouhlick´y,D., Rubincam, D. P., & 464 Lee, C.-H. 2019, AJ, 158, 92

440 Nesvorn´y,D. 2006, Annual Review of Earth and 465 Lupton, R. 2005, Transformations between SDSS

441 Planetary Sciences, 34, 157 466 magnitudes and UBVRcIc, http://classic.sdss.org/dr4

442 Carbognani, A., & Buzzoni, A. 2020, MNRAS, 493, 70 467 /algorithms/sdssUBVRITransform.html, ,

443 Chambers, K. C., Magnier, E. A., Metcalfe, N., et al. 2016, 468 Magnier, E. A., & Cuillandre, J. C. 2004, PASP, 116, 449

444 ArXiv e-prints, arXiv:1612.05560 469 Magnier, E. A., Schlaﬂy, E. F., Finkbeiner, D. P., et al.

445 Chandler, C. O., Kueny, J., Gustafsson, A., et al. 2019, 470 2016, ArXiv e-prints, arXiv:1612.05242

446 ApJL, 877, L12 471 Marsset, M., DeMeo, F., Sonka, A., et al. 2019, ApJL, 882,

447 Chang, C.-K., Lin, H.-W., Ip, W.-H., et al. 2019, arXiv 472 L2

448 e-prints, arXiv:1901.08719 473 Meech, K. J., & Weaver, H. A. 1996, Earth Moon and

449 Clark, B. E., Hapke, B., Pieters, C., & Britt, D. 2002, 474 Planets, 72, 119

450 Asteroid Space Weathering and Regolith Evolution, 475 Meech, K. J., Weryk, R., Micheli, M., et al. 2017, Nature,

451 585–599 476 552, 378

452 Holsapple, K. A. 2007, Icarus, 187, 500 477 Moreno, F., Jehin, E., Licandro, J., et al. 2019, A&A, 624,

453 Hsieh, H. H., Ishiguro, M., Lacerda, P., & Jewitt, D. 2011, 478 L14

454 AJ, 142, 29 479 Nesvorny, D. 2015, NASA Planetary Data System,

455 Hui, M.-T., Kim, Y., & Gao, X. 2019, MNRAS, 488, L143 480 EAR-A-VARGBDET-5-NESVORNYFAM-V3.0

456 Jewitt, D. 2012, AJ, 143, 66 481 Nesvorn´y,D., Jenniskens, P., Levison, H. F., et al. 2010,

457 Jewitt, D., Hsieh, H., & Agarwal, J. 2015, Asteroids IV 482 ApJ, 713, 816

458 (Tucson, University of Arizona Press), 221–241 483 Novakovi´c,B., Tsirvoulis, G., Granvik, M., & Todovi´c,A.

459 Jewitt, D., Kim, Y., Luu, J., et al. 2019, ApJL, 876, L19 484 2017, AJ, 153, 266

460 Kaluna, H. M., Masiero, J. R., & Meech, K. J. 2016, Icarus, 485 Paunzen, E., & Vanmunster, T. 2016, Astronomische

461 264, 62 486 Nachrichten, 337, 239 10

487 Reddy, V., Le Corre, L., O’Brien, D. P., et al. 2012, Icarus, 495 Tonry, J. L., Denneau, L., Heinze, A. N., et al. 2018, PASP,

488 221, 544 496 130, 064505 489 Sanchez, J. A., Reddy, V., Thirouin, A., et al. 2019, ApJL,

490 881, L6 497 Ye, Q., Kelley, M. S. P., Bodewits, D., et al. 2019, ApJL, 491 Thompson, M. S., Morris, R. V., Clemett, S. J., et al. 2020,

492 Icarus, 346, 113775 498 874, L16

493 Tonry, J. L., Stubbs, C. W., Lykke, K. R., et al. 2012, ApJ,

494 750, 99 11 d σ 0.030 0.068 0.031 0.060 0.067 0.125 0.094 0.026 0.040 0.026 0.034 0.023 0.037 0.070 0.046 0.117 0.110 0.071 0.071 0.090 0.025 0.057 0.028 0.034 0.078 0.160 0.047 0.064 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mag r σ 0.030 16.554 0.090 19.354 0.050 18.204 0.090 18.919 0.090 19.431 0.190 19.570 0.120 19.109 0.060 18.012 0.040 17.744 0.060 18.194 0.100 18.356 0.050 18.254 0.060 18.424 0.090 18.561 0.060 18.615 0.140 19.364 0.110 19.673 0.070 18.773 0.070 18.623 0.120 18.785 0.050 17.803 0.060 17.957 0.040 17.593 0.070 18.677 0.110 19.472 0.160 20.413 0.040 18.715 0.100 19.151 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Filt mag c TA continued b α Table 4 b ∆ . Observing Geometry and Photometry b r Table 4 a UTDate JD Pan-STARRS 6/15/20099/6/2010 4998.03711/17/2010 1.862 5446.1271/8/2011 5518.919 1.0071/26/2011 2.591 23.096 2.683 2.258 5570.8182/17/2011 1.777 -7.784 22.692 5588.714 10.4061/8/2012 2.726 137.762 5610.773 153.131 2.736 2.133 r2/23/2012 2.351 18.722 z 2.745 5935.062 r2/27/2012 16.550 20.582 163.553 2.638 5981.995 18.900 167.0793/29/2012 2.469 21.031 18.190 5985.877 i 2.374 1.859 171.3943/30/2012 z 1.413 20.748 6016.770 2.366 18.760 4/9/2012 -121.502 7.445 y 1.399 6017.804 19.050 2.2994/10/2012 -109.736 6.817 y 1.433 19.360 2.296 6027.8624/19/2012 15.794 -108.720 g 1.439 6028.818 18.590 -100.3724/21/2012 2.274 16.199 i 6037.730 18.250 2.272 1.500 -100.0846/4/2012 z 1.507 19.836 6039.752 2.252 17.500 6/19/2013 y 20.148 -97.254 17.860 1.576 2.247 6083.744 -96.9826/26/2013 22.752 18.100 1.593 6463.107 i -94.4237/20/2013 2.149 23.263 z 6470.076 2.062 2.016 -93.8367/23/2013 18.030 y 1.924 27.962 6494.073 17.970 2.07610/2/2013 29.281 -80.457 1.860 z 6497.056 18.060 2.12810/7/2013 66.977 29.280 1.635 6568.974 18.120 y 2.13410/9/2013 69.368 27.566 1.607 6573.968 z 2.295 18.740 11/22/2013 77.347 27.124 1.298 6575.836 z 2.306 19.330 11/28/2013 78.312 6619.731 3.097 1.322 z 2.310 18.430 12/4/2013 6625.727 5.799 2.403 99.877 1.333 y 18.280 1/23/2014 1.802 101.263 6.779 2.416 6631.742 21.685 18.300 g10/11/2014 1.887 101.778 6681.742 113.386 g 2.428 22.492 17.690 6942.139 1.976 114.903 r 2.522 18.020 r 23.058 2.752 2.722 116.409 17.530 g 2.616 21.201 18.590 21.242 128.392 19.510 z -178.161 w 20.070 z 18.750 18.990 12 d σ 0.137 0.037 0.025 0.039 0.084 0.013 0.023 0.017 0.031 0.016 0.012 0.016 0.015 0.020 0.016 0.081 0.026 0.033 0.020 0.040 0.030 0.054 0.021 0.016 0.016 0.020 0.124 0.092 0.078 0.118 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mag r σ 0.250 20.706 0.070 19.780 0.050 18.012 0.030 17.875 0.080 17.989 0.040 17.296 0.020 17.254 0.030 17.064 0.030 16.593 0.010 16.479 0.020 16.609 0.020 16.823 0.030 17.042 0.040 17.587 0.020 17.550 0.080 18.793 0.050 19.020 0.040 18.840 0.030 18.475 0.100 18.471 0.060 18.572 0.080 19.105 0.030 17.988 0.020 17.548 0.020 17.456 0.030 17.761 0.199 18.829 0.178 19.111 0.126 19.000 0.118 18.407 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Filt mag c TA continued (continued) b α Table 4 Table 4 b ∆ b r a UTDate JD 6/2/20151/9/2016 7176.7513/8/2016 7397.1333/9/2016 2.535 3.064 7456.1163/19/2016 2.075 17.861 2.269 7457.1024/2/2016 1.964 -129.916 25.674 7467.151 1.5294/13/2016 1.962 -68.815 z 29.859 1.946 1.518 7481.0474/19/2016 -47.529 1.409 29.832 7492.094 w 20.920 5/27/2016 1.926 29.337 -47.154 7498.055 1.912 1.274 i 19.790 -43.2916/8/2016 1.183 28.013 7536.107 w 1.9046/19/2016 26.503 17.770 -37.849 y 1.141 1.871 17.910 7548.002 -33.4447/5/2016 25.581 0.997 7559.923 17.610 r -31.0417/16/2016 1.865 21.640 w 1.862 0.998 7575.917 -15.3378/18/2016 17.280 1.019 22.309 i 17.200 7586.8838/26/2016 1.860 23.803 -10.332 z 7619.811 1.862 1.074 16.770 10/28/2016 -5.291 1.127 26.343 7627.766 w 16.250 1.87910/31/2016 28.021 7690.702 1.344 1.491 1.885 i 16.500 9/19/2017 31.366 7693.701 6.139 1.967 1.40810/2/2017 19.978 2.029 31.716 16.360 w 1.972 8016.126 28.731 i10/30/2017 23.276 2.062 16.860 8029.087 i 2.610 49.431 28.37111/7/2017 8057.053 16.800 2.114 w 140.619 2.627 17.340 12/6/2017 21.444 z 2.662 1.989 8066.000 17.680 w 143.3981/10/2018 1.804 19.417 8094.919 18.450 2.672 13.098 149.26412/17/2018 19.070 w 1.779 8129.810 151.112 2.7001/5/2019 11.327 8470.151 w 18.890 1.841 2.726 151.1191/6/2019 i 12.419 2.509 18.520 2.159 8489.103 163.951ATLAS 2.162 19.064 i 17.690 22.803 -126.726 8490.1119/8/2017 2.474 w -122.248 18.370 1.895 w9/14/2017 2.472 2458005.066 19.070 21.143 w 1.8819/26/2017 2458011.056 2.593 -122.006 18.270 20.995 2.602 2.231 17.580 9/30/2017 2458023.015 -99.309 w 2.167 22.538 2.619 2458027.040 22.017 138.225 2.045 17.450 w 2.625 139.529 20.465 2.008 o 17.780 142.106 19.790 o 18.737 142.965 o 18.788 o 18.889 18.255 13 d σ 0.090 0.056 0.063 0.052 0.127 0.056 0.069 0.028 0.040 0.064 0.127 0.039 0.133 0.060 0.048 0.044 0.144 0.071 0.098 0.062 0.070 0.057 0.179 0.137 0.068 0.132 0.136 0.082 0.178 0.048 0.052 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mag r σ 0.123 18.636 0.105 18.661 0.123 18.468 0.122 18.505 0.127 18.898 0.099 18.538 0.091 18.307 0.062 18.427 0.071 18.446 0.111 18.412 0.069 18.898 0.080 18.416 0.133 18.420 0.161 18.707 0.124 18.690 0.107 18.624 0.144 18.810 0.171 18.914 0.181 18.819 0.097 18.714 0.121 19.076 0.086 19.336 0.179 19.180 0.137 18.994 0.170 19.041 0.132 18.519 0.136 18.844 0.116 19.105 0.178 19.123 0.069 18.216 0.091 17.911 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Filt mag c TA continued (continued) b α Table 4 Table 4 b ∆ b r a UTDate JD 10/17/2017 2458044.99410/21/2017 2.648 2458048.97610/27/2017 1.866 2.652 2458054.967 15.97610/29/2017 1.842 2.659 146.758 2458056.938 15.01410/31/2017 1.812 2.662 147.592 2458058.929 13.578 o11/8/2017 1.804 2.664 148.839 13.123 o11/10/2017 2458066.951 1.797 18.646 149.248 2458068.945 2.673 12.681 o11/12/2017 18.507 2.675 1.778 149.660 2458070.935 o11/14/2017 1.776 11.181 18.269 2.677 2458072.928 10.909 151.314 o11/16/2017 1.775 18.402 2.679 151.723 2458074.941 10.68811/20/2017 1.774 18.746 o 2.681 152.131 2458078.951 10.523 o11/22/2017 1.775 2.685 18.312 152.540 2458080.916 10.418 o12/4/2017 1.780 18.007 2.687 152.951 10.397 o12/8/2017 2458092.919 1.784 18.228 153.769 2.698 10.479 c12/10/2017 2458096.887 18.242 1.830 154.170 2458098.887 2.702 c12/12/2017 12.036 18.346 2.703 1.853 2458100.880 156.599 o12/22/2017 1.866 12.815 18.532 2.705 2458110.844 13.232 157.39912/24/2017 1.880 18.429 o 2.713 157.801 2458112.826 13.65512/28/2017 1.960 o 2.714 18.268 158.201 2458116.848 15.780 o1/5/2018 1.979 2.717 18.570 160.193 16.185 o1/9/2018 2.018 18.395 2458124.840 160.590 16.967 c1/11/2018 2.723 18.607 2458128.832 161.390 2.103 o1/13/2018 2458130.830 2.725 19.092 18.343 2.727 2.148 o1/15/2018 2458132.871 18.914 162.975 2.171 18.930 2.7281/17/2018 2458134.870 19.198 18.327 163.764 2.195 o 2.729 164.1592/2/2018 2458136.834 19.452 2.219 o 2.730 18.514 164.5622/6/2018 19.683 o 2458152.827 2.243 18.544 164.9562/10/2018 2.738 19.891 o 2458156.839 18.926 2.447 165.3422/14/2018 2458160.802 2.740 c 20.955 19.028 2.742 2.49912/8/2018 2458164.805 168.484 o 2.551 21.057 19.276 2.74312/10/2018 2458461.097 21.098 169.268 2.604 19.033 o 2458463.124 2.525 170.042 21.082 2.522 2.294 o 18.367 170.825 2.264 22.950 o 22.948 -128.816 18.692 o -128.351 18.933 o 18.971 c 18.115 18.240 14 d σ 0.056 0.037 0.054 0.054 0.088 0.070 0.078 0.035 0.034 0.020 0.026 0.021 0.024 0.021 0.022 0.032 0.059 0.038 0.045 0.033 0.032 0.043 0.025 0.041 0.041 0.035 0.057 0.050 0.019 0.021 0.062 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mag r σ 0.087 18.237 0.058 18.299 0.105 18.188 0.101 18.283 0.121 17.999 0.134 18.108 0.096 17.971 0.081 17.596 0.063 17.682 0.047 17.519 0.049 17.691 0.054 17.512 0.044 17.617 0.079 17.741 0.036 17.669 0.063 17.600 0.145 17.681 0.085 17.650 0.092 17.681 0.042 17.729 0.056 17.571 0.076 17.500 0.047 17.478 0.061 17.528 0.054 17.453 0.043 17.424 0.094 17.468 0.102 17.256 0.032 17.323 0.027 17.310 0.177 17.290 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Filt mag c TA continued (continued) b α Table 4 Table 4 b ∆ b r a UTDate JD 12/16/2018 2458469.08012/18/2018 2.511 2458471.07212/20/2018 2.178 2.508 2458473.059 22.83912/22/2018 2.149 2.504 -126.969 2458475.104 22.76712/23/2018 2.120 2.500 -126.505 2458476.123 o 22.67412/24/2018 2.091 2.498 -126.040 2458477.050 o 22.55912/26/2018 17.983 2.076 2.497 -125.562 2458479.078 o 22.4931/2/2019 18.173 2.063 2.493 -125.322 o 22.4291/3/2019 17.949 2.034 2458486.123 -125.103 o 22.2711/5/2019 18.048 2.480 2458487.079 -124.625 1.935 o1/9/2019 17.795 2.478 2458489.053 21.543 1.922 o1/11/2019 17.717 2.474 -122.953 2458493.055 21.420 1.8951/12/2019 17.901 2458495.033 2.467 -122.724 c 21.151 2.463 1.8421/13/2019 2458496.094 -122.253 1.816 c 20.526 17.664 2.4611/15/2019 2458497.030 20.177 -121.291 o 1.803 18.006 2.459 -120.8131/17/2019 2458499.022 19.980 o 1.791 17.329 2.455 -120.5561/20/2019 2458501.007 c 19.798 1.766 17.505 2.452 -120.3281/22/2019 2458504.040 o 19.394 17.760 1.741 2.446 -119.8441/25/2019 2458506.995 o 18.962 17.318 1.705 2.440 -119.3591/27/2019 2458509.018 o 18.253 17.565 1.671 2.436 -118.6181/29/2019 2458511.006 o 17.499 17.613 1.648 2.432 -117.8902/2/2019 2458513.002 o 16.951 17.321 1.626 2.428 -117.3912/4/2019 o 16.384 17.522 2458517.015 1.606 -116.8982/6/2019 2.420 o 15.791 17.536 2458519.018 1.566 -116.4032/13/2019 2.416 o 17.404 2458521.013 14.522 1.5472/13/2019 2458528.978 2.412 o -115.399 17.679 13.859 2.395 1.5292/17/2019 2458528.995 -114.897 17.535 o 1.468 13.182 2.3952/21/2019 2458532.946 10.385 -114.396 1.468 c 17.342 2.387 -112.3712/25/2019 2458536.966 10.378 o 1.443 17.858 2.379 -112.3663/1/2019 2458540.946 o 9.046 1.422 17.265 2.3703/5/2019 o -111.352 7.862 17.308 2458544.942 1.406 2.362 -110.313 7.026 17.234 2458548.935 o 1.394 2.353 -109.277 o 6.714 17.225 1.386 o -108.231 7.041 17.214 -107.175 17.094 o o 17.117 17.446 15 d σ 0.058 0.021 0.032 0.038 0.128 0.021 0.021 0.020 0.070 0.031 0.058 0.031 0.037 0.165 0.134 0.081 0.049 0.048 0.050 0.055 0.047 0.056 0.063 0.054 0.119 0.105 0.101 0.072 0.059 0.064 0.067 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mag r σ 0.057 17.357 0.050 17.398 0.072 17.411 0.073 17.209 0.128 17.214 0.044 17.273 0.038 17.539 0.058 17.469 0.069 17.623 0.074 17.658 0.057 17.916 0.060 17.829 0.078 17.985 0.165 18.269 0.186 18.409 0.166 18.195 0.087 18.354 0.070 18.238 0.080 18.296 0.145 18.386 0.073 18.496 0.114 18.426 0.114 18.627 0.102 18.647 0.154 18.699 0.150 18.744 0.176 18.553 0.103 19.109 0.077 18.769 0.125 18.726 0.132 18.959 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Filt mag c TA continued (continued) b α Table 4 Table 4 b ∆ b r a UTDate JD 3/9/20193/13/2019 2458552.9443/17/2019 2458556.914 2.345 2.336 1.3843/21/2019 2458560.892 1.385 7.938 2.3283/23/2019 2458564.934 9.214 1.391 -106.112 2.3193/25/2019 2458566.895 10.714 -105.048 1.401 2.315 o -103.9743/27/2019 2458568.886 12.341 o 1.407 2.310 -102.876 17.205 3/29/2019 2458570.884 o 13.143 1.415 17.240 2.306 -102.3404/2/2019 2458572.886 o 13.961 17.245 1.423 2.301 -101.7914/4/2019 o 14.767 16.993 2458576.902 1.432 -101.2434/6/2019 2.293 o 15.570 17.062 2458578.882 1.454 -100.6874/8/2019 2.288 o 16.992 2458580.869 17.122 1.4654/10/2019 2.284 o -99.572 17.395 2458582.873 17.858 1.4784/16/2019 2458584.858 2.279 -99.018 17.358 18.574 2.275 o 1.4914/17/2019 2458590.902 -98.460 1.504 19.269 2.262 c 17.471 4/19/2019 2458591.892 19.934 -97.896 1.550 2.259 o -97.3334/22/2019 2458593.887 18.085 21.782 1.558 2.255 c -95.610 17.764 4/24/2019 2458596.846 22.060 o 1.574 2.248 -95.3264/26/2019 2458598.842 18.090 22.600 o 1.599 17.940 2.244 -94.7504/30/2019 2458600.835 23.347 o 1.616 18.117 2.239 -93.8935/6/2019 2458604.828 23.814 o 1.634 18.207 2.230 -93.3145/7/2019 24.254 2458610.842 o 1.670 18.064 -92.7305/9/2019 2.217 25.050 2458611.817 o 18.135 1.727 -91.5585/10/2019 2.215 2458613.759 o 26.044 18.076 1.7365/14/2019 2458614.799 2.211 -89.774 o 26.184 18.152 2.208 1.7555/15/2019 2458618.850 -89.481 1.765 26.442 18.102 2.199 c5/16/2019 2458619.825 26.571 -88.899 1.805 2.197 c -88.5875/21/2019 2458620.799 18.735 27.012 1.815 2.195 o -87.3625/22/2019 2458625.805 18.874 27.103 o 1.824 2.184 -87.068 18.467 5/25/2019 2458626.809 27.191 o 1.874 18.458 2.181 -86.7695/26/2019 2458629.790 27.556 o 1.884 18.403 2.175 -85.238 2458630.757 27.614 o 1.914 18.614 2.173 -84.927 27.756 o 1.923 18.542 -84.004 27.793 o 18.850 -83.703 o 18.486 o 18.368 18.971 16 d σ 0.065 0.103 0.087 0.111 0.184 0.083 0.163 0.185 0.170 0.151 0.068 0.054 0.046 0.075 0.085 0.075 0.189 0.003 0.001 0.005 0.001 0.002 0.002 0.002 0.004 0.005 0.010 0.004 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± mag r σ 0.112 18.841 0.145 19.024 0.119 18.970 0.137 18.775 0.184 18.997 0.092 18.402 0.163 18.680 0.185 19.018 0.170 18.807 0.151 18.720 0.134 18.907 0.141 18.752 0.129 18.966 0.109 18.804 0.145 18.685 0.188 18.755 0.189 18.578 0.004 17.412 0.005 17.506 0.005 17.335 0.004 17.863 0.004 17.944 0.008 18.880 0.009 18.762 0.008 18.738 0.019 18.876 0.030 19.264 0.008 18.831 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Filt mag c TA continued (continued) b α Table 4 Table 4 b ∆ b r a UTDate JD 5/28/20195/30/2019 2458632.799 2.1686/1/2019 2458634.774 1.943 2.1646/7/2019 27.856 2458636.759 1.963 -83.0676/11/2019 2.159 27.900 2458642.771 1.983 -82.4516/15/2019 2458646.773 2.146 o 27.926 2.137 2.0426/17/2019 2458650.798 -81.825 2.080 c 27.908 18.594 2.1287/17/2019 2458652.762 27.819 -79.921 2.118 19.086 2.124 o -78.6417/23/2019 2458682.760 27.675 2.137 2.061 c -77.340 18.864 4/10/2020 2458688.762 27.585 o 2.393 2.048 -76.7035/4/2020 2458950.113 18.877 24.982 o 2.437 18.845 1.935 -66.6365/20/2020 24.248 2458974.090 o 2.437 18.145 -64.5485/28/2020 2458990.075 1.974 23.031 o 18.528 2.002 2.2895/29/2020 2458998.069 40.871 o 2.172 26.051 18.866 2.0175/30/2020 2458999.077 27.686 50.100 2.108 o 18.655 2.0196/7/2020 2459000.087 56.046 28.337 2.100 2.021 18.568 o6/9/2020 58.952 28.410 2459008.076 2.091 oCFHT 2.037 59.317 28.480 18.531 2459010.094 o 2.024 18.514 2/28/2019 2.041 59.680 28.949 c 2.006 18.662 3/11/2019 2458543.789 62.532 29.041 c 2.364 18.878 3/29/2019 2458554.742 63.242 1.397 2.341 18.698 o3/30/2019 2458572.761 6.741 1.384 2.302 o4/1/2019 2458573.736 -108.534 18.851 8.480 1.432 2.300 gsdss6/1/2019 15.519 -105.630 18.426 2458575.805 1.437 17.972 -100.723 gsdss7/2/2019 2.295 15.904 2458636.753 gsdss 18.066 1.448 -100.4537/4/2019 2.159 18.403 2458667.755 16.706 gsdss 1.9838/11/2019 2.092 18.402 -99.878 2458669.781 27.926 2.2718/13/2019 2458707.740 2.088 gsdss -81.828 26.543 2.011 2.288 18.530 6/17/2020 2458709.738 gsdss -71.748 2.561 26.359 2.007 19.434 2459018.082 21.618 gsdss -71.067 2.573 2.057 19.186 -57.780 21.321 gsdss 1.935 gsdss 19.425 -57.054 29.288 19.387 gsdss 66.039 19.663 rsdss 18.844 17 d σ ± mag r σ ± Filt mag c ◦ TA (continued) b α Table 4 b as described in the text ∆ r b r radius aperture. 00 a UTDate JD Magnitude and error through 5 Magnitude and error converted to SDSS Julian Date -2450000.0 Heliocentric, geocentric distance (au) and phaseTrue angle anomaly (deg). (deg), position along orbit, TA at perihelion=0 d e a b c