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We present the deepest color–magnitude diagram (CMD) for NGC 205 in the F606W (≈ V ) and F814W (≈ I ) filters. Our archival Hubble Space Telescope/Advanced Camera for Surveys field is centered ∼3 $\mathop{.}\limits^{{\rm{^{\prime} }}}$ 8 northwest of the galaxy's center. The CMD shows the canonical features of a predominantly intermediate-to-old age stellar population. Among other features, the CMD reveals a prominent red clump as well as a blue horizontal branch. Notably absent is any significant signature of a young main sequence typically produced by a stellar population with an age less than a few Gyr. From the magnitude of the red-giant-branch tip, we derive a distance modulus of ( m − M ) _o = 24.66 ± 0.05. When compared with α -enhanced theoretical isochrones, the color distribution of the red giant branch stars yields a peak metallicity value of [Fe/H] = −0.51 ± 0.10. Our photometry also reveals a sample of 479 RR Lyrae variable stars (443 ab-type and 36 c-type). Utilizing equations that relate the periods and amplitudes to the metallicities of these stars, we find a mean 〈[Fe/H]〉 = −1.45 ± 0.02 on the Zinn & West scale for the purely old stellar population in NGC 205. The quoted uncertainty represents the standard error of the mean abundance value is consistent with that of the six genuine old globular clusters in NGC 205.

In this paper we study the joint determination of source and background flux for point sources as observed by digital array detectors. We explicitly compute the two-dimensional Cramér–Rao absolute lower bound (CRLB) as well as the performance bounds for high-dimensional implicit estimators from a generalized Taylor expansion. This later approach allows us to obtain computable prescriptions for the bias and variance of the joint estimators. We compare these prescriptions with empirical results from numerical simulations in the case of the weighted least squares estimator (introducing an improved version, denoted stochastic weighted least-squares) as well as with the maximum likelihood estimator, finding excellent agreement. We demonstrate that these estimators provide quasi-unbiased joint estimations of the flux and background, with a variance that approaches the CRLB very tightly and are, hence, optimal, unlike the case of sequential estimation used commonly in astronomical photometry which is sub-optimal. We compare our predictions with numerical simulations of realistic observations, as well as with observations of a bona fide non-variable stellar source observed with TESS, and compare it to the results from the sequential estimation of background and flux, confirming our theoretical expectations. Our practical estimators can be used as benchmarks for general photometric pipelines, or for applications that require maximum precision and accuracy in absolute photometry. [ABSTRACT FROM AUTHOR]

The Zwicky Transient Facility is a time-domain optical survey that has substantially increased our ability to observe and construct massive catalogs of astronomical objects by use of its 47 square degree camera that can observe in multiple filters. However the telescope’s i-band filter suffers from significant atmospheric fringes that reduce photometric precision, especially for faint sources and in multi-epoch co-additions. Here we present a method for constructing models of these atmospheric fringes using Principal Component Analysis that can be used to identify and remove these artifacts from contaminated images. In addition, we present the Uniform Background Indicator as a quantitative measurement of the reduced correlated background noise and photometric error present after removing fringes. We conclude by evaluating the effect of our method on measuring faint sources through the injection and recovery of artificial stars in both single-image epochs and co-additions. Our method for constructing atmospheric fringe models and applying those models to produce cleaned images is available for public download in the open source Python package fringez (https://github.com/MichaelMedford/fringez).

Precision measurements in astronomy require stringent control of systematics such as those arising from imperfect correction of sensor effects. In this work, we develop a parametric method to model the wavelength dependence of pixel response nonuniformity (PRNU) for a laser-annealed backside-illuminated charge-coupled device. The model accurately reproduces the PRNU patterns of flat-field images taken at nine wavelengths from 290 to 950 nm, leaving the rms residuals no more than 0.2% in most cases. By removing the large-scale nonuniformity in the flat fields, the rms residuals are further reduced. This model fitting approach gives more accurate predictions of the PRNU than cubic-spline interpolation does with fewer free parameters. It can be applied to make PRNU corrections for individual objects according to their spectral energy distribution to reduce the photometry errors caused by the wavelength-dependent PRNU, if sub-percent level precision is required.

Photometric observations were made with standard filters in four observatories for 10 contact binary systems. We analyzed the orbital period variations of the systems and found that six of them show long-term changes. The increase in the orbital period of the J07, N65, and PU Vir systems is caused by mass transfer, and the reduction in the orbital period of the J05, LO Psc, and N49 systems is caused by the combination of angular momentum loss and mass transfer. The first light-curve analysis was performed with the PHysics Of Eclipsing BinariEs Python code and Markov Chain Monte Carlo. We discussed the accuracy of photometric mass ratio estimates for contact binary systems with total and partial eclipses compared to spectroscopic results. We also compared our mass ratio findings to a recent method that estimates mass ratios from the light curve’s third derivative. Then, we also discussed this new mass ratio estimate method for photometric data. The systems’ positions were displayed in 18 empirical parameter relationships. According to the light-curve analysis and estimation of absolute parameters, systems BE Mus, J07, J08, N49, and N65 are A subtypes, and the others are W subtypes.

We present cosmological analysis of 12 nearby ( z < 0.06) Type IIP supernovae (SNe IIP) observed with the ROTSE-IIIb telescope. To achieve precise photometry, we present a new image-differencing technique that is implemented for the first time on the ROTSE SN photometry pipeline. With this method, we find up to a 20% increase in the detection efficiency and significant reduction in residual rms scatter of the SN lightcurves when compared to the previous pipeline performance. We use the published optical spectra and broadband photometry of well-studied SNe IIP to establish temporal models for ejecta velocity and photospheric temperature evolution for our SNe IIP population. This study yields measurements that are competitive with other methods even when the data are limited to a single epoch during the photospheric phase of SNe IIP. Using the fully reduced ROTSE photometry and optical spectra, we apply these models to the respective photometric epochs for each SN in the ROTSE IIP sample. This facilitates the use of the Expanding Photosphere Method (EPM) to obtain distance estimates to their respective host galaxies. We then perform cosmological parameter fitting using these EPM distances, from which we measure the Hubble constant to be ${72.9}_{-4.3}^{+5.7}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ , which is consistent with the standard ΛCDM model values derived using other independent techniques.

We performed secular monitoring broadband photometric observations on Jupiter Family Comets (JFCs) 68P/Klemola and 78P/Gehrels 2 from 2018 November to 2020 March with the Yaoan High Precision Telescope. Our main purpose is to study the dust activity, coma properties, and dynamical history of the two comets and analyze the activity evolution of 78P/Gehrels 2 in the recent past. We use aperture photometry to obtain the magnitude and the A (0) f ρ values from the R band observations. The maximum A (0) f ρ values we recorded for 68P/Klemola and 78P/Gehrels 2 are 339.7 ± 4.4 cm and 1028.1 ± 13.3 cm, respectively, showing that the activity of 68P/Klemola is of middle level while 78P/Gehrels 2 is one of the most active JFCs. The mean color of 78P/Gehrels 2 is ( B − V ) = 0.88 ± 0.02 and ( V − R ) = 0.27 ± 0.02. Dynamical history analysis suggests that 78P/Gehrels 2 could have actually resided in this region for a long time in the past 1 Myr, though it recently migrated into the inner solar system. The high activity of 78P/Gehrels 2 reported in the past three perihelion passages could be attributed to the perihelion distance decl. from 2.3 to 2.0 au before 1997 that boosted the water-ice sublimation rate and formed new active regions. The activity decl. over recent apparitions could be attributed to the reformation of the dust mantle.

James Webb Space Telescope (JWST) observations have been demonstrated to be efficient in detecting multiple stellar populations in globular clusters (GCs) in the low-mass regime of M dwarfs. We present an overview, and first results, of different projects that can be explored by using the JWST observations gathered under program GO2560 for 47 Tucanae, the first program entirely devoted to the investigation of multiple populations in very-low-mass stars, which includes spectroscopic data for the faintest GC stars for which spectra are available. Our color–magnitude diagram (CMD) shows some substructures for ultracool stars, including gaps and breaks in slope. In particular, we observe both a gap and a minimum in the F322W2 luminosity function less than 1 mag apart, and discuss which it could be associated with the H-burning limit. We detect stars fainter than this minimum, very likely brown dwarfs. We corroborate the ubiquity of the multiple populations across different masses, from ∼0.1 M _⊙ up to red giants (∼0.8 M _⊙ ). The oxygen range inferred for the M dwarfs, both from the CMD and from the spectra of two M dwarfs associated with different populations, is similar to that observed for giants. We have not detected any difference between the fractions of stars in distinct populations across stellar masses ≳ 0.1 M _⊙ . This work demonstrates the JWST's capability in uncovering multiple populations within M dwarfs and illustrates the possibility to analyze very-low-mass stars in GCs approaching the H-burning limit and the brown-dwarf sequence.

New BVR photometric and high-resolution spectroscopic observations of V505 Lac are presented with Transiting Exoplanet Survey Satellite (TESS) photometric data. The orbital period has experienced a secular decrease during the past 16 yr. A clear anticorrelation in the primary and secondary eclipse timing variation (PSETV) obtained from the TESS data is also identified. A double-lined radial velocity (RV) curve is secured, and the effective temperatures of the less- and more-massive stars (Stars 1 and 2, respectively) are measured. Using a spectral subtraction technique, excess emissions are detected in the time-series Ca ii H and K and H α lines for Star 2. Simultaneous analysis of the light and RV curves using the Wilson–Devinney (WD) code reveals that V505 Lac is a photospherically and chromospherically active W-subtype contact binary system. The component-star masses and radii are determined to an accuracy of approximately 1%. The WD spot model is individually applied to 221 light curves segmented from the TESS data so as to derive the spot parameters of a cool spot on Star 2. The combined variations in both longitude and colatitude among the spot parameters appear to be strongly associated with those of both the anticorrelation in the PSETV and the O’Connell effect in the TESS light curves. Robust negative linear relationships between the PSETV anticorrelation size and the O’Connell effect magnitude are found for the first time. Mass–radius, mass–luminosity, and mass ratio–mass diagrams of contact binaries, along with the mass ratio frequency distribution, are presented in an attempt to elucidate the evolutionary characteristics of these systems.

We use a multilevel perceptron (MLP) neural network to obtain photometry of saturated stars in the All-Sky Automated Survey for Supernovae (ASAS-SN). The MLP can obtain fairly unbiased photometry for stars from g ≃ 4 to 14 mag, particularly compared to the dispersion (15%–85% 1 σ range around the median) of 0.12 mag for saturated ( g < 11.5 mag) stars. More importantly, the light curve of a nonvariable saturated star has a median dispersion of only 0.037 mag. The MLP light curves are, in many cases, spectacularly better than those provided by the standard ASAS-SN pipelines. While the network was trained on g -band data from only one of ASAS-SN’s 20 cameras, initial experiments suggest that it can be used for any camera and the older ASAS-SN V -band data as well. The dominant problems seem to be associated with correctable issues in the ASAS-SN data reduction pipeline for saturated stars more than the MLP itself. The method is publicly available as a light-curve option on ASAS-SN Sky Patrol v1.0.

We empirically assess estimates from v3.0 of the James Webb Space Telescope NIRCam Exposure Time Calculator (ETC) using observations of resolved stars in Local Group targets taken as part of the Resolved Stellar Populations Early Release Science (ERS) Program. For bright stars, we find that (i) purely Poissonian estimates of the signal-to-noise ratio (SNR) are in good agreement between the ETC and observations, but nonideal effects (e.g., flat-field uncertainties) are the current limiting factor in the photometric precision that can be achieved; (ii) source position offsets, relative to the detector pixels, have a large impact on the ETC saturation predictions and introducing subpixel dithers in the observation design can improve the saturation limits by up to ∼1 mag. For faint stars, for which the sky dominates the error budget, we find that the choice in the ETC extraction strategy (e.g., aperture size relative to point-spread function size) can affect the exposure time estimates by up to a factor of 5. We provide guidelines for configuring the ETC aperture photometry to produce SNR predictions in line with the ERS data. Finally, we quantify the effects of crowding on the SNRs over a large dynamic range in stellar density and provide guidelines for approximating the effects of crowding on SNRs predicted by the ETC.

• A simultaneous multi-color survey for GEO is performed. • 1697 objects with g'r'i' measurements are obtained. • Cluster behavior and color evolution are discussed. Optical surveys play significant roles in space object monitoring and catalog, especially for some unique high-altitude regions like the Geosynchronous Earth Orbit (GEO) region. For object classes identification and space environment models development, besides the orbits additional information like physical properties are required. Non-resolving observation techniques like color photometry can provide such knowledge. Here simultaneous surveys for GEO region in g'r'i' bands were performed utilizing the CHanging Event Survey (CHES) system of Purple Mountain Observatory. Based on the large amounts of images, the object detection, catalog correlation and multi-color photometry are performed consecutively. Due to the extremely wide field of view of CHES system, the simultaneous multi-band information of 1697 objects is obtained. The distribution and clustering behavior of their color indexes are preliminarily investigated, and the evolution of color with launch age is also analyzed. It is demonstrated that even for the same object class the distribution of color index may be different, and for various objects of the same class multiple clusters of color index are found. It indicates that the color photometry can help to classify object classes and provide useful information for correlating new observations with catalog. [ABSTRACT FROM AUTHOR]

We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite as TOI-588 b. HIP 33609 b is a large ( R _b = ${1.580}_{-0.070}^{+0.074}$ R _J ) brown dwarf on a highly eccentric ( e = ${0.560}_{-0.031}^{+0.029}$ ) orbit with a 39 days period. The host star is a bright ( V = 7.3 mag), T _eff = 10,400 ${}_{-660}^{+800}$ K star with a mass of M _* = ${2.383}_{-0.095}^{+0.10}$ M _⊙ and radius of R _* = ${1.863}_{-0.082}^{+0.087}$ R _⊙ , making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M _b = ${68.0}_{-7.1}^{+7.4}$ M _J as well as the host star's rotation rate ( $v\sin {i}_{* }=55.6\pm 1.8$ km s ^−1 ). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 ± 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models.

Given its large plate scale of 21″ pixel ^−1 , analyses of data from the Transiting Exoplanet Survey Satellite (TESS) space telescope must be wary of source confusion from blended light curves, which creates the potential to attribute observed photometric variability to the wrong astrophysical source. We explore the impact of light curve contamination on the detection of fast yellow pulsating supergiant (FYPS) stars as a case study to demonstrate the importance of confirming the source of detected signals in the TESS pixel data. While some of the FYPS signals have already been attributed to contamination from nearby eclipsing binaries, others are suggested to be intrinsic to the supergiant stars. In this work, we carry out a detailed analysis of the TESS pixel data to fit the source locations of the dominant signals reported for 17 FYPS stars with the Python package TESS _ localize . We are able to reproduce the detections of these signals for 14 of these sources, obtaining consistent source locations for four. Three of these originate from contaminants, while the signal reported for BZ Tuc is likely a spurious frequency introduced to the light curve of this 127 day Cepheid by the data processing pipeline. Other signals are not significant enough to be localized with our methods, or have long periods that are difficult to analyze given other TESS systematics. Since no localizable signals hold up as intrinsic pulsation frequencies of the supergiant targets, we argue that unambiguous detection of pulsational variability should be obtained before FYPS are considered a new class of pulsator.

Comet 60P/Tsuchinshan is a Jupiter family comet. Since the discovery of 60P/Tsuchinshan, little research for cometary activity has been conducted on this comet, though it has returned to perihelion several times. To study the physical properties and activity characteristic of 60P/Tsuchinshan during its 2018–2019 apparition, we observed 60P/Tsuchinshan with broadband B , V , and R filters from 2018 November to 2019 March by using the 80 cm Yaoan High Precision Telescope at Yaoan Station of Purple Mountain Observatory, Chinese Academy of Sciences. Morphological analysis and photometric studies of 60P/Tsuchinshan were performed. The color indices, Af ρ values, and dust production rates of 60P/Tsuchinshan were obtained. Morphological analysis showed that the comet was active and several images showed a spiral structure in the inner coma; this structure is regardless of the enhancement methods and cannot be explained by the rotation of 60P. The Af ρ curve showed that the peak activity of 60P/Tsuchinshan was at about 10 days after perihelion. Compared to other Jupiter family comets at similar heliocentric distances, we found that 60P/Tsuchinshan was a very active comet. Dynamical analysis showed that 60P/Tsuchinshan’s perihelion distance was reduced from 1.77 to 1.62 au due to the close encounter with Jupiter that occurred on 2008 December 20; this may increase its activity in the next apparition.

The Transiting Exoplanet Survey Satellite (TESS) has an exceptionally large plate scale of 21″ px ^−1 , causing most TESS light curves to record the blended light of multiple stars. This creates a danger of misattributing variability observed by TESS to the wrong source, which would invalidate any analysis. We developed a method that can localize the origin of variability on the sky to better than one fifth of a pixel. Given measured frequencies of variability (e.g., from periodogram analysis), we show that the best-fit sinusoid amplitudes to raw light curves extracted from each pixel are distributed in the same way as light from the variable source. The primary assumption of this method is that other nearby stars are not variable at the same frequencies. Essentially, we are using the high frequency resolution of TESS to overcome limitations from its low spatial resolution. We have implemented our method in an open-source Python package, TESS _ localize ( http://github.com/Higgins00/TESS-Localize ), that determines the location of a variable source on the sky and the most likely Gaia source given TESS pixel data and a set of observed frequencies of variability. Our method utilizes models of the TESS pixel response function, and we characterize systematics in the residuals of fitting these models to data. We find that even stars more than three pixels outside a photometric aperture can produce significant contaminant signals in the extracted light curves. Given the ubiquity of source blending in TESS light curves, verifying the source of observed variability should be a standard step in TESS analyses.

We present a study of the structural properties and metallicity distribution of the nearby peculiar galaxy NGC 3077. Using data from our survey of the M81 Group with the Hyper Suprime-Cam on board the Subaru Telescope, we construct deep color–magnitude diagrams that are used to probe the old red giant branch (RGB) population of NGC 3077. We map these stars out to and beyond the nominal tidal radius, which allows us to derive the structural properties and stellar content of the peripheral regions. We show that NGC 3077 has an extended stellar halo and pronounced “S-shaped” tidal tails that diverge from the radial profile of the inner region. The average metallicity of the old population in NGC 3077 is estimated from individual RGBs to be [M/H] = −0.98 ± 0.26, which decreases with the distance from the galaxy center as [M/H] = −0.17 dex ${R}_{h}^{-1}$ . The metallicity of the S-shaped structure is similar to that of the regions lying at r ∼ 4 × R _h ( ∼ 30 kpc), indicating that the stellar constituents of the tidal tails have come from the outer envelope of NGC 3077. These results suggest that this peculiar galaxy was probably a rather normal dwarf elliptical galaxy before the tidal interaction with M81 and M82. We also examine the evidence in our data set for the six recently reported ultrafaint dwarf candidates around NGC 3077. We recover a spatial overdensity of sources coinciding with only one of these.

Flux is one of the most fundamental parameters in astrophysics, and aperture photometry and point-spread function (PSF) photometry are commonly used methods to obtain the flux. With the continuous development of astronomical equipment that has generated massive data, researchers have to find more effective methods to obtain stellar fluxes. However, current photometric software such as SExtractor are very sensitive to the configuration parameters and are difficult to configure. We propose a new photometric model based on deep learning called sf-convolutional neural network (CNN) to extract aperture fluxes and PSF fluxes. For the simulated data including 5727 stars, the experimental results show that sf-CNN can predict fluxes better than SExtractor. The mean absolute error (MAE) values of sf-CNN and SExtractor for predicting PSF fluxes are 0.0034 and 0.0134, respectively. On the 6293 mixed stars in DECam Legacy Survey Data Release (DR) 9, the MAE values of the predicted PSF fluxes are 0.0075 and 0.0177, respectively. The PSF accuracy of the sf-CNN model is significantly higher than that of SExtractor. Additionally, the MAE values of the predicted aperture fluxes on 6215 mixed stars and 1341 blends of stars in Sloan Digital Sky Survey DR 12 illustrate that the accuracy of sf-CNN is still the highest. Meanwhile, the results indicate that sf-CNN outperforms VGG16 and ResNet50. Furthermore, sf-CNN is 100–200 times faster than Photutils on RTX 3070 GPU and 20–40 times faster than Photutils on I7 12700 CPU. sf-CNN can calculate fluxes efficiently and accurately only by setting a few parameters and may thus become a fundamental tool for the era of big data in astronomy.

Time-domain astronomy has emerged as a vibrant research field in recent years, focusing on celestial objects that exhibit variable magnitudes or positions. Given the urgency of conducting follow-up observations for such objects, the development of an algorithm capable of detecting them and determining their magnitudes and positions has become imperative. Leveraging the advancements in deep neural networks, we present PNet, an end-to-end framework designed not only to detect celestial objects and extract their magnitudes and positions, but also to estimate the photometric uncertainty. PNet comprises two essential steps. First, it detects stars and retrieves their positions, magnitudes, and calibrated magnitudes. Subsequently, in the second phase, PNet estimates the uncertainty associated with the photometry results, serving as a valuable reference for the light-curve classification algorithm. Our algorithm has been tested using both simulated and real observation data, demonstrating the ability of PNet to deliver consistent and reliable outcomes. Integration of PNet into data-processing pipelines for time-domain astronomy holds significant potential for enhancing response speed and improving the detection capabilities for celestial objects with variable positions and magnitudes.

We present the results of new time-series photometric observations of 29 pre–white dwarf stars of PG 1159 spectral type, carried out in the years 2014–2022. For the majority of stars, a median noise level in Fourier amplitude spectra of 0.5–1.0 mmag was achieved. This allowed the detection of pulsations in the central star of planetary nebula A72 (Abell 72), consistent with g modes excited in GW Vir stars, and variability in RX J0122.9–7521 that could be due to pulsations, binarity, or rotation. For the remaining stars from the sample that were not observed to vary, we placed upper limits for variability. After combination with literature data, our results place the fraction of pulsating PG 1159 stars within the GW Vir instability strip at 36%. An updated list of all known PG 1159 stars is provided, containing astrometric measurements from the recent Gaia DR3 data, as well as information on physical parameters, variability, and nitrogen content. Those data are used to calculate luminosities for all PG 1159 stars to place the whole sample on the theoretical Hertzsprung–Russell diagram for the first time in that way. The pulsating stars are discussed as a group, and arguments are given that the traditional separation of GW Vir pulsators in “DOV” and “PNNV” stars is misleading and should not be used.

BL Lacertae is a key monitoring target of the 1.26 m National Astronomical Observatory–Guangzhou University Infrared/Optical telescope. Within the monitored duration from 2020 September 4 to 2022 September 28, we report 13,948 observations at the g , r , and i bands ( g band: 4498, r band: 4866, i band: 4584). (1) In the monitored duration, this source is located in a very bright and variable state. The maximum variabilities are Δ m _g = 2.013 ± 0.073 mag at g band, Δ m _r = 1.900 ± 0.049 mag at r band, and Δ m _i = 2.279 ± 0.089 mag at i band. (2) Among the gri intraday lightcurves, there are 104 portions of data sets displaying intraday variabilities (IDVs), with the IDV timescales (Δ T ) being in the range of 15.84–375.84 minutes and the biggest variable value Δ m = 0.430 ± 0.041 mag. (3) The distributions of Δ T show frequency-dependent behavior, and with the frequency increasing, Δ T tend to be shorter. The variable rates ( $V=\tfrac{{\rm{\Delta }}m}{{\rm{\Delta }}T}$ ) from the g band are more intense than the values ( V _r ) from the r band, but are more stable than the values ( V _i ) from the i band. (4) On three days (2020 September 7, 2020 September 19, and 2022 September 7), we find the intraday periodic oscillations, whose periods are around 150 minutes, 232 minutes, and 150 minutes, respectively, and which might come from the source “flickering.” (5) Based on the distributions between flux densities ( F _gri ) and spectral indices ( α ), they show the bluer-when-brighter behaviors and some uneven locations, which should come from the ministructures of the jet, the shock-induced particle acceleration, or magnetic reconnection in the jet.

(155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005–2021, to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions ( λ = 116.°6, β = −53.°6) and ( λ = 300.°3, β = −55.°4), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon’s pole orientation. We also present a refined sidereal period of P _sid = 5.234246 ± 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04–0.37 kg s ^−1 for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.

We use our new light curves, along with historical data, to determine the rotation state, photometric properties, and convex shape models of the targets of the Lucy mission (3548) Eurybates and (21900) Orus. We determine a retrograde spin for both targets, with sidereal rotation periods of 8.7027283 ± 0.0000029 h and 13.486190 ± 0.000017 h, respectively. The phase curves of both objects are nearly linear in the phase-angle range observable from Earth and lack a pronounced opposition effect. Unsupervised classification of these phase curves by the Penttilä et al. tool suggests that Eurybates and Orus belong to the C and D taxonomic types, respectively, thereby independently confirming past classifications based on their spectral slope. Time-resolved color-index measurements show no systematic color variations correlated with rotation for either target at the 1% level, suggesting that no variegation is present on a hemispherical scale for any of the objects. Comparison of the shape models with stellar occultation data available for the two objects from the program by Buie et al. allows us to resolve the longitude ambiguity of the orientations of the spin axes and derive unique pole solutions for both targets. Furthermore, scaling the shape models to match the occultation chords produces accurate sizes and geometric albedos for both objects. The derived surface-equivalent spherical diameters are D _s = 69.3 ± 1.4 km and D _s = 60.5 ± 0.9 km for Eurybates and Orus, respectively, while the geometric albedo in the H , G _1 , G _2 system is p _V ( H , G _1 , G _2 ) = 0.044 ± 0.003 and p _V ( H , G _1 , G _2 ) = 0.040 ± 0.002 for Eurybates and Orus, respectively.

In 2018, Jewitt identified the “The Trojan Color Conundrum,” namely that Neptune's Trojan asteroids (NTs) had no ultrared members, unlike the the nearby Kuiper Belt. Since then, numerous ultrared NTs have been discovered, seemingly resolving this conundrum. However, it is still unclear whether or not the Kuiper Belt has a color distribution consistent with the NT population, as would be expected if it were the source population. In this work, we present a new photometric survey of 15 out of 31 NTs. We utilized the Sloan $g^{\prime} r^{\prime} i^{\prime} z^{\prime} $ filters on the IMACS f/4 instrument, which is mounted on the 6.5 m Baade telescope. In this survey, we identify four NTs as being ultrared using a principal component analysis. This result brings the ratio of red to ultrared NTs to 7.75:1, more consistent with the corresponding trans-Neptunian object ratio of 4–11:1. We also identify three targets as being blue (nearly solar) in color. Such objects may be C-type surfaces, but we see more of these blue NTs than has been observed in the Kuiper Belt. Finally, we show that there are hints of a color-absolute magnitude (H) correlation, with larger H (smaller sized, lower albedo) tending to be more red, but more data are needed to confirm this result. The origin of such a correlation remains an open question that will be addressed by future observations of the surface composition of these targets and their rotational properties.

Precise multi-color CCD-derived photometric data were obtained from EH Cnc at two sites during 2010, 2014 and 2018 wherein each epoch used a different instrument. This has provided a unique opportunity to investigate parameter uncertainty following Roche modeling of light curves optimized by differential corrections using the Wilson–Devinney code. Furthermore, new radial velocity data from EH Cnc presented in this study for the first time has produced absolute physical and geometric parameters for this A-subtype W UMa-type variable. Analysis of eclipse timing data confirms the presence of sinusoidal-like excursions in the eclipse timing residuals. We address whether these are due to magnetic activity cycles, the so-called "Applegate effect", or related to a light-time effect (LiTE) resulting from the presence of a third gravitationally bound cool low mass white dwarf. A model using the PAdova & TRieste Stellar Evolution Code (PARSEC) has provided valuable insight about the evolutionary history of EH Cnc as a trinary system. [ABSTRACT FROM AUTHOR]

We present a by-product of our long term photometric monitoring of cataclysmic variables. 2MASS J18024395 +4003309 = VSX J180243.9 +400331 was discovered in the field of the intermediate polar V1323 Her observed using the Korean 1-m telescope located at Mt. Lemmon, USA. An analysis of the two-color VR CCD observations of this variable covers all the phase intervals for the first time. The light curves show this object can be classified as an Algol-type variable with tidally distorted components, and an asymmetry of the maxima (the O’Connell effect). The periodogram analysis confirms the cycle numbering of Andronov et al. (2012) and for the initial approximation, the ephemeris is used as follows: Min I. BJD = 2456074.4904+0.3348837E . For phenomenological modeling, we used the trigonometric polynomial approximation of statistically optimal degree, and a recent method “NAV” (“New Algol Variable”) using local specific shapes for the eclipse. Methodological aspects and estimates of the physical parameters based on analysis of phenomenological parameters are presented. As results of our phenomenological model, we obtained for the inclination i=90°, M1=0.745M◉, M2=0.854M◉, M=M1+M2=1.599M◉, the orbital separation a=1.65·109m=2.37R◉ and relative radii r1=R1/a=0.314 and r2=R2/a=0.360. These estimates may be used as preliminary starting values for further modeling using extended physical models based on the Wilson & Devinney (1971) code and it's extensions

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In this paper, we have presented the observational result for the photometric quality of main telescopes in Gimhae Astronomical Observatory. Also we performed the observation of searching new minor planets as competitive work in public observatories. The observation was carried out using 60cm telescope of Gimhae Astronomical Observatory on 2007 January 13. And, Schüler BVI filters and 1K CCD camera (AP8p) were used. To define the quality of CCD photometry, we observed the region of well-known standard stars in the open cluster M67. From observed data, The transformation coefficients and airmass coefficients were obtained, and the accuracy of CCD photometry was investigated. From PSF photometry, we obtained the color-magnitude diagram of M67, and considered the useful magnitude limit and the physical properties of M67. This method can be successfully used to confirm the photometric quality of main telescope in public observatories. To investigate the detection possibility of unknown object as astroid, we observed the near area of the opposition in the ecliptic plane. And we discussed the result. Our result show that it can be possible to detect minor planets in solar system brighter than V ˜18.3mag. and it can carry out photometric study brighter than V~16mag. in Gimhae Astronomical Observatory. These results imply that the public observatories can make the research work.

Results of 6 nights of CCD VR photometry of the nova-like variable V603 Aquilae (Nova Aquilae 1918) obtained at the Mallorcian 35-cm telescope in July 2004 are reported. The ephemeris for the superhump maximum is Max.HJD=2453213.60546(96) +0.14813(10)E. The waves with 3.9d, 1.4d, 0.135d are statistically significant, which may be interpreted as the negative superhump-orbital, the beat periods (negative superhump - positive superhump) and the negative superhump with low amplitude, respectively. Another possible time-scale is 0.8d, which has no coincidence with the beat periods. Quasi-periodic oscillations with an effective period of 18 minutes have been detected, which are close to 15.6 minutes reported by some authors. Their effective semi-amplitudes are 0.045m and 0.051m for V and R, respectively. This corresponds to the 0.12 mag excess in the color index V-R as compared with the mean color, which can be understood as the pulsed emission in the hotter inner parts of the accretion disk, similar to that observed in TT Ari and MV Lyr.

The accuracy of CCD observations obtained at the Korean 1.8 m telescope has been studied. Seventeen comparison stars in the vicinity of the cataclysmic variable BG CMi have been measured. The ``artificial" star has been used instead of the ``control" star, what made possible to increase accuracy estimates by a factor of 1.3-2.1 times for ``good" and ``cloudy" nights, respectively. The algorithm of iterative determination of accuracy and weights of few comparison stars contributing to the artificial star, has been presented. The accuracy estimates for 13-mag stars are around 0.002 m mag for exposure times of 30 sec.

We present BV CCD photometry of metal-rich globular cluster M71. Based on our color-magnitude diagram (CMD), we derive the distance to M71 using a sample of Hipparcos subdwarfs of similar metallicity. Our distance modulus is (m-M)V=13.46(± 0.17). CMD comparison was also made between M71 and 47 Tuc. We confirm that there exists a significant age difference(> 2 billion years) in spite of their similarity in metallicity.

We briefly describe a method of organizing all the star field exposures taken in a complete CCD observational run. By a “CommandLog” (to be published in J. Astron. Data) one can organize all the observations and process them within IRAF in an orderly, automated manner to arrive at stellar photometry calibrated into a standard photometric system (in our case, Strömvil). During the course of this processing we determine the error of the flat and try to correct it.

The results of the first testing of a new CCD camera of the Molėtai Observatory are given. The linearity and the flat field corrections of good accuracy are determined by using shifted star field exposures.

The AZT-8 70-cm telescope of the Crimean Astrophysical Observatory was upgraded in the early 2000s. Obsolete pieces of equipment of the telescope were replaced and new ones were developed. The creation of a special control program has enabled the telescope to be pointed at objects automatically. As a result, it has become much easier to control the telescope and the efficiency of using the observing time has increased significantly. [ABSTRACT FROM AUTHOR]

A semi-automated photometric telescope built at the Skalnate Pleso Observatory is described. In December 2000, the 0.3-m f/5 Zeiss astrograph was replaced by a 0.61-m f/4.3 mirror telescope equipped with a CCD camera. The observing programme is created to conform to the photometry of asteroids which are suspected to be of binary nature; photometry of NEAs and MBAs; a long-term photometry for theoretical modelling of the shape of asteroids; and photometry and astrometry of active comets and asteroids. Some results concerning the binary character of the asteroids are described in the paper. [ABSTRACT FROM AUTHOR]

Photometric analysis of BVR C light curves of newly discovered eclipsing binary GSC 0008-00901 is presented. The orbital period is improved to 0.28948(11) days. Photometric parameters are determined as well. The analysis yielded to conclusion that system is an over-contact binary of W UMa type with components not in thermal contact. The light curves from 2005 show the presence of a spot on the surface of one of the components, while light curves from 2006 are not affected by maculation. [ABSTRACT FROM AUTHOR]

Photometric observations of the variable star EP Lyr were performed with a CCD photometer during the observing season of 2002. Analysis of these observations together with published data has confirmed the mean period of the main variability cycle P = 83.d248 over almost 100 years. The periodicity of the variations in the main cycle is investigated on the basis of O-C diagrams. The time scale of its variations ranges from 1–2 to 8–20 thousand days. [ABSTRACT FROM AUTHOR]

Photometric observations of the variable star TX Oph were performed with CCD photometers during the observing seasons of 1999, 2000, and 2002. Analysis of these observations together with published data has confirmed the mean period of the main variability cycle P = 135d. 2613 over almost 70 years. A secondary cycle with a period of about 10–12 thousand days has also been found. [ABSTRACT FROM AUTHOR]

Three selected asteroids, numbered 58, 360 and405, were observed during 2000at Yunnan Observatory, China. Thenew lightcurves are presented inthis paper. The synodic period of (58)Concordia is estimated as 9.90 ± 0.01hfor the first time. The synodic period of (405) Thia derived from ourobservation is 9.96 ± 0.01h, which is slightly different from the previousresult. For 360, we obtained the synodic period of 6.18 ± 0.02h which isconsistent with previous values. Additionally, the BV and UB-colourindexes for the three asteriods were also determined. [ABSTRACT FROM AUTHOR]