adsabs/AstroCLIMB huggingface dataset:
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: The 2 × 2 binned, flight-derived bias frame for rolling shutter, 30× gain (DRACO_bias_rolling_30x_n20C_20220113). Each column has its own bias level, and the two halves of the detector behave slightly differently. This image is displayed with the image origin at the lower left (flipped to match the scene an observer looking out the DRACO boresight would see). Detector A (bottom in this view) has a higher bias level than detector B (top in this view). The image is linearly stretched between DN levels of 200 and 350. See Figure 28 for the histogram of this bias frame.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: The predicted (25 TID, approximately double what was expected for DART in flight) and measured (0 TID) dark current as a function of temperature for the BAE CIS2521F FPA. The predicted values were extrapolated from the measured values using the doubling temperature reported by the vendor (∼6°C). In flight, DRACO nominally operated at −20°C and exposure times were ≤94 ms. The read noise was predicted to be <0.1 electrons pixel–1 s–1 in flight.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: Comparison of ground and flight rolling shutter binned bias levels for all four gain settings. The histograms exhibit a shift, with flight levels consistently a few DN lower than ground levels. The shift is likely due to the thermal configuration difference between ground and flight setups.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: The mean bias signal of the full detector (binned pixels) vs. time for rolling shutter, 30× gain images taken in flight on 2022 June 7. The bias signal exhibits a cyclical behavior, with an amplitude of ∼0.15 DN and a period of ∼3.5 minutes, that is related to the temperature of the detector. The solid black line shows the mean value, and the dashed lines show ± one standard deviation from that mean.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: Residual bias (global shutter) and bias (rolling shutter) levels vs. temperature as measured from ground characterization images. DN levels were multiplied by 2 to convert the values measured in the unbinned ground images to binned pixel values to enable a direct comparison to flight results (e.g., first paragraphs of Section 5). The residual bias global shutter images are effectively noise.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Example images displayed to users during the data cleaning process. (A) Initial brightness data vs. LPA. (B) Median-smoothed data using smoothing kernel parameters. (C) Spline fit to the median-smoothed data. (D) Initial data points with an overlay of spline fit sampled at the data’s LPA values. (E) Residuals between the spline fit and the lightcurve data points. 3σ clipped points are shown in red. (F) Cleaned data shown in black with red points showing 24 out of 745 data points that were removed (∼3% of the data set).
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Example data of Intelsat-901 (26824) from 2020 January 30. This format is used for presenting the results of the GEO satellite spectral atlas. (Left) Median reflectance spectrum using data from the entire night of observations normalized to unity at 700 nm. Vertical bars represent phase-induced variations in the spectra throughout the night. (Right) Lightcurve of target brightness vs. phase angle. This is a more traditional method of GEO satellite characterization, which is also provided by the zeroth-order point source data.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Comparison of the full-night median spectra for three satellites in an orbital cluster. Vertical bars represent phase variations in the spectra. The three targets are different satellite bus types, which aids in being able to differentiate their spectra. DirecTV 12 and DirecTV 15 were observed 2020 May 18 while SES 3 was observed the following night to reduce the seasonal variations.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Typical uncertainty in reflectance measurements as a function of the wavelength. The uncertainty at 700 nm is zero because it is the normalization wavelength.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Examples of the top nine bus types observed in this study listed as bus name (satellite example name): (a) SSL-1300 (Wildblue 1); (b) BSS-702 (XM 4); (c) Eurostar-3000 (DirecTV 15); (d) Star-2 (Sky Mexico 1); (e) A2100 (AMC-10); (f) DHF-4 (Venesat 1); (g) BSS-601 (GOES 15); (h) Arsat (Arsat 2); (i) Spacebus 4000 (SGDC 1). All images were obtained from G. Krebs (2024).
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Comparison of full-night median spectra for four satellites of the Eurostar-3000 bus type. All objects were observed in 2021 April to reduce any potential seasonal variations.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Example subimage of slitless spectrometer data. The target solar analog star is in the center and other, fainter stars can be seen—each with their own spectrum. A circular zeroth-order point source is produced with spectra on either side. The grating is blazed, so more energy goes into the first order on the right of the point source. Only the blazed order is visible for fainter stars in the background, which is also the case for the GEO satellite targets.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Traditional lightcurve characterization (left) and SPM (right) of DirecTV 5 (27426) from 2021 February 6 UTC. These plots show feature consistency between both analyses as well as enhanced features more prominent in the SPMs.
Paper: Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects
Authors: Adam Battle, Vishnu Reddy, Roberto Furfaro, Tanner Campbell
Figure caption: Flowchart of data processing and cleaning pipeline.
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: Comparison of the temperature–pressure profiles produced by three archival remote-sensing measurements: Voyager 2 radio occultations, Voyager 2 UV stellar and solar occultations, and Earth-based stellar occultations. The radio occultations are shown in black in the lower atmosphere. The H87-retrieved temperatures from the Voyager UV occultations are shown with green and red circles, connected by thermal gradients. The S93 models fit to the H87 data are shown with red, green, and navy dotted lines. Five profiles from Earth-based stellar occultations (U0, U13, U14, U15, U17b) are shown, as well as the globally averaged temperature from a sixth occultation (U149). The U0 occultation is shown in blue with shaded 1σ uncertainty. Note the large discrepancy between the Earth-based temperatures and Voyager 2 temperatures, especially at the 10−3 mbar pressure level.
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: Average of profiles from Figure 2, across altitudes/pressures that have at least 15 profiles. The 1σ uncertainty region is calculated as the sample standard deviation. (a) Temperature–pressure average profile; (b) temperature–altitude average profile. The individual profiles shown in Figure 2 show lots of detailed structures, but these average out, leading to a gradually warming profile with altitude (decreasing pressure).
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: Reprocessed Earth-based stellar occultation profiles with shaded 1σ uncertainty regions for two selected profiles that are representative of the rest. (a) Temperature–pressure profiles; (b) temperature–altitude profiles, where altitude is above the 1 bar pressure level. We note the similarities between the U13, U14, U15, U16, and U17b occultations, which were all observed within a 1 yr span. Almost all the profiles overlap within the uncertainty regions at the top and then diverge toward the middle of the profiles. While they each show detailed structure and local temperature maxima and minima, taken in aggregate, they indicate a gradual warming with altitude (decreasing pressure).
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: Temperature vs. year, where color indicates latitude and 1σ uncertainties in temperature are shown. The sunspot count is shown in a dotted line on the right y-axis. Each panel shows the temperatures in Figure 4 at a given pressure, where the pressure is indicated in the upper right corner. There is no clear and compelling trend from this figure.
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: The reprocessed temperature profiles from Figure 2(a), with the color mapped to the date of observation, as indicated in the color bar and legend. The 1σ uncertainty regions for the U0 ingress and egress are provided as a representative uncertainty. There appears to be a weak warming trend, with counterexamples, which we explore in Figures 5 and 6.
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption:  The topmost figure shows the observed light curves (black) compared with the simulated Voyager 2 light curves (red, magenta, blue, green, orange) and their residuals below. The second figure from the top is a table of results of applying the AD test of normality to each set of residuals. We use these as the primary results from which to draw conclusions. The third figure from the top is the 10 quantile–quantile plots, showing how the residuals compare to a normal distribution, with the 99.99% confidence lines in dashed red. The bottommost figure contains 10 empirical distribution functions, each of which compares the distribution of the residuals near the occultation to many baseline residuals.
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: Same as Figure A1.
Paper: The Upper Atmosphere of Uranus from Stellar Occultations. II. Revised Temperatures in the Upper Stratosphere and Lower Thermosphere
Authors: William R. Saunders, Michael J. Person, Paul Withers, Richard G. French, Chanita Tubthong
Figure caption: The top left panel lists some of the basic information about the event: the observatory, the primary aperture, the central wavelength, the interval of observations, the S/N per scale height, the impact parameter, and the latitude. The top right panel contains the results of the thermal gradient model fit. The middle left panel is the primary inversion results, separated into ingress and egress, with uncertainty regions, and compared with the originally published results, where available. The middle right panel shows the geometry of the occultation as viewed from the observer, with the green circle representing the star’s starting position projected onto Uranus and the red square representing the ending position. The bottommost panel shows the normalized light curve in black with the thermal gradient model overlaid in blue and the isothermal light curve overlaid in red.
Paper: Grain Size Effects on Visible and Near-infrared (0.35–2.5 μm) Laboratory Spectra of Rare Meteorite Classes
Authors: K. I. Ridenhour, V. Reddy, A. Battle, D. Cantillo, N. C. Pearson, J. A. Sanchez
Figure caption: VNIR spectra of grain sizes for NWA 6685, which is classified as a lodranite. The normalized reflectance has a different x-axis because of the excessive noise around 0.35 μm and 2.50 μm for the 500–1000 μm grain size. The normalized reflectance x-axis starts at 0.45 μm and ends at 2.30 μm.
Paper: Grain Size Effects on Visible and Near-infrared (0.35–2.5 μm) Laboratory Spectra of Rare Meteorite Classes
Authors: K. I. Ridenhour, V. Reddy, A. Battle, D. Cantillo, N. C. Pearson, J. A. Sanchez
Figure caption: VNIR spectra for the slabs of Dhofar 125, NWA 6685, NWA 753, and Eagle. These four were grouped together owing to their spectra being relatively flat.
Paper: Grain Size Effects on Visible and Near-infrared (0.35–2.5 μm) Laboratory Spectra of Rare Meteorite Classes
Authors: K. I. Ridenhour, V. Reddy, A. Battle, D. Cantillo, N. C. Pearson, J. A. Sanchez
Figure caption: VNIR spectra of slabs for NWA 4024, Fukang, and Almahata Sitta.
Paper: Grain Size Effects on Visible and Near-infrared (0.35–2.5 μm) Laboratory Spectra of Rare Meteorite Classes
Authors: K. I. Ridenhour, V. Reddy, A. Battle, D. Cantillo, N. C. Pearson, J. A. Sanchez
Figure caption: VNIR spectra of slabs for NWA 6370, Norton County, Oued Namous 001 (O.N. 001), and Abee.
Paper: Grain Size Effects on Visible and Near-infrared (0.35–2.5 μm) Laboratory Spectra of Rare Meteorite Classes
Authors: K. I. Ridenhour, V. Reddy, A. Battle, D. Cantillo, N. C. Pearson, J. A. Sanchez
Figure caption: VNIR spectra of grain sizes for NWA 6370, which is classified as a mesosiderite.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: A sample of the 512 × 512 pixel DRACO images taken during the Final Phase. Didymos/Dimorphos north is to the upper right corner in the images. (a) The final image to contain Dimorphos and all of the sunlit terrain of Didymos was acquired 2 minutes 41 s before impact at 4.9 m pixel scale (dart_0401929891_00057). Dimorphos is 173 m across its long axis; (b) The final image to contain all of Dimorphos, including the dark side, was acquired 12 s before impact at 37 cm pixel scale (dart_0401930039_14119); (c) The final full image of Dimorphos’s surface was acquired 1.8 s before impact at 5.5 cm pixel scale (dart_0401930049_43695). The impact site is at the center of the image between three large boulders. (d) The final, partial DRACO image was acquired 0.9 s before impact at 2.6 cm pixel scale (dart_0401930050_41838).
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: The DRACO telescope MTF measured out to the optical cutoff frequency, as calculated from the wavefront error in Figure 18 and the system MTF at 40 cycles mm−1 (20% unbinned; 12.6% binned) as measured from the Ronchi ruling image in Figure 20. The telescope-only curve is the average of tangential and sagittal curves. The red lines indicate the value of the telescope-only MTF (35%) at 40 cycles mm−1. Note the suppression of the mid-spatial frequencies from the secondary obscuration.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: Left: a 100 × 100 pixel window of an image of the Ronchi ruling. The modulation was measured using the best contrast of the image. Right: a profile taken perpendicular to the ruling, from lower left to upper right of the image window. The sampling frequency of 40 cycles mm−1 was measured as the distance between the peaks along the profile. The modulation was calculated from the best contrast of the image.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: ConOps for Vega observations. The black square is the DRACO FOV, shown centered on position 7. The star represents Vega. The blue circles show the locations of the 13 spots DRACO was pointed to relative to Vega. Light-blue circles positioned Vega outside the DRACO FOV; dark-blue circles show locations where Vega was inside the DRACO FOV. Black arrows show the paths taken while slewing between these positions. The black circle shows the size of the pointing deadband for these observations relative to the DRACO FOV. The dotted line indicates the division between detectors A and B.
Paper: Calibration and In-flight Performance of DART’s Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)
Authors: Carolyn M. Ernst, R. Terik Daly, Zachary J. Fletcher, Kyle J. Ryan, Andrew F. Cheng, Syau-Yun W. Hsieh, Tony L. Farnham, Carolyn A. Sawyer, Allison K. Glantzberg, Olivier S. Barnouin, Harold A. Weaver, Dmitriy L. Bekker, Nancy L. Chabot, Raymond C. Espiritu, Joseph Dickman, Jacob M. Greenberg, Derek A. Lewis, Bryan J. Maas, Declan M. Mages, Hari Nair, Tyler W. Nelson, Luis M. Rodriguez, Brian P. Rush, Ronald D. Smith, C. Dany Waller
Figure caption: Portion of DRACO image dart_0394397965_43919_01 centered on Jupiter taken during a test of the SMART Nav system on 2022 July 1. Two brightness and contrast stretches, made to optimize Jupiter (left, a linear stretch from 10 to 1600 DN) and its moons (middle, a linear stretch from 0 to 100 DN), respectively, were combined to form the composite view at right (subtle artifacts around Jupiter result from the method used to make the composite). Jupiter’s north pole is toward the upper right corner. From upper left to lower right across each image are Ganymede, Jupiter, Europa, Io, and Callisto.