Photometric System Research Articles

Optical and near-infrared photometry of 94 type II supernovae from the Carnegie Supernova Project

Type II supernovae (SNe II) mark the endpoint in the lives of hydrogen-rich massive stars. Their large explosion energies and luminosities allow us to measure distances, metallicities, and star formation rates into the distant Universe. To fully exploit their use in answering different astrophysical problems, high-quality low-redshift data sets are required. Such samples are vital to understand the physics of SNe II, but also to serve as calibrators for distinct -- and often lower-quality -- samples. We present $uBgVri$ optical and $YJH$ near-infrared (NIR) photometry for 94 low-redshift SNe II observed by the Carnegie Supernova Project (CSP). A total of 9817 optical and 1872 NIR photometric data points are released, leading to a sample of high-quality SN II light curves during the first sim 150 days post explosion on a well-calibrated photometric system. The sample is presented and its properties are analysed and discussed through comparison to literature events. We also focus on individual SNe II as examples of classically defined subtypes and outlier objects. Making a cut in the plateau decline rate of our sample ($s_2$), a new subsample of fast-declining SNe II is presented. The sample has a median redshift of 0.015, with the nearest event at 0.001 and the most distant at 0.07. At optical wavelengths ($V$), the sample has a median cadence of 4.7 days over the course of a median coverage of 80 days. In the NIR ($J$), the median cadence is 7.2 days over the course of 59 days. The fast-declining subsample is more luminous than the full sample and shows shorter plateau phases. Of the non-standard SNe II highlighted, SN 2009A particularly stands out with a steeply declining then rising light curve, together with what appears to be two superimposed P-Cygni profiles of in its spectra. We outline the significant utility of these data, and finally provide an outlook of future SN II science.

Characterization of developed integrating sphere photometer system for total luminous flux measurements

This research focuses on characterizing a developed integrating sphere photometer system for measuring total luminous flux at the National Institute of Standards (NIS) in Egypt. The research examines factors such as the efficiency of the integrating sphere across different wavelengths, the sphere photometer calibration factor (SPCF), and temperature variations in the photometer system during measurement days. One setup utilizes a spectroradiometer with an uncertainty of 4.7% and a 2.5-meter integrating sphere to measure the spectral responsivity of the sphere photometer. Another setup involves a 2.5-meter big-integrating sphere and NIS-photometer, along with NIS- luminous flux standard lamps calibrated at (NPL) with an uncertainty of 0.8%, to determine the SPCF. The overall uncertainty of the final (SPCF) ranges from 0.03% to 0.05%, while the temperature variation during measurements ranges from 0.045% to 0.07%.

On the use of field RR Lyrae as Galactic probes

Context. The Vera C. Rubin Observatory will start operations in 2025. During its first two years, too few visits per target per band will be available, meaning that the mean magnitude measurements of variable stars will not be precise and thus standard candles such as RR Lyrae (RRL) will not be usable. Light curve templates (LCTs) can be adopted to estimate the mean magnitude of a variable star with a few magnitude measurements, provided that their period (plus the amplitude and reference epoch, depending on how the LCT is applied) is known. The LSST will provide precise RRL periods within the first six months, enabling exploitation of RRLs if LCTs are available. Aims. We aim to build LCTs in the LSST bands to enhance the early science with LSST. Using them will provide a one- to two-year advantage with respect to the classical approach concerning distance measurements. Methods. We collected grί-band data from the ZTF survey and z-band data from DECam to build the LCTs of RRLs. We also adopted synthetic grίz band data in the LSST system from pulsation models, plus SDSS, Gaia and OGLE photometry, inspecting the light amplitude ratios in different photometric systems to provide useful conversions to apply the LCTs. Results. We have built LCTs of RRLs in the grίz bands of the LSST photometric system; for the z band, we could build only fun damental mode RRL LCTs. We quantitatively demonstrated that LCTs built with ZTF and DECam data can be adopted on the LSST photometric system. The LCTs will decrease the uncertainty on distance estimates of RRLs by a factor of at least two with respect to a simple average of the available measurements. Finally, within our tests, we have found a brand new behavior of amplitude ratios in the Large Magellanic Cloud.

NEOROCKS color survey: Final results

Context. Near-Earth objects (NEOs) are the most accessible small Solar System bodies by both spacecrafts and ground-based telescopes. Close encounters of these objects with Earth represent opportunities to characterize their physical and mineralogical properties. They are also a constant threat to humanity due to possible impact events with Earth. In this context, the NEOROCKS project has been financed by the European Union’s Horizon 2020 research and innovation program. Aims. We present the final results on photometry of the NEOROCKS project, with the aim of extending the dataset of surface colors for small NEOs with unknown properties and, when possible, characterizing newly discovered NEOs. Methods. Photometric observations were performed using the 1.2 m telescope at the Haute-Provence observatory (in France) in the BVRI filters of the Johnson-Cousins photometric systems between May 2022 and June 2023. The stability and dynamics of objects from the NEOROCKS database was investigated by numerical integration. Results. We obtained new surface colors for 83 NEOs. Overall, the NEOROCKS color database contains 170 objects. The majority of the objects in the dataset with diameters D<500 m belong to a group of silicate bodies. We estimated the unbalanced percentage between S- and C-type objects as an observational bias due to reflective proprieties of the surface of objects. The average of Lyapunov time of about 100 years is evidence of highly chaotic orbits of objects from the color database of NEOROCKS. Asteroid 2011 OL51 has a reasonable probability of being a parent body contributor to the October Capricornidis meteor shower. Asteroids 2004 HK33, 2022 VV (D-type), 2003 WR21, and 2017 SE1 (A-type) belong to end-member classes and have ΔV<7 km/s; thus, they are possible candidates for in situ investigations.

Small Magellanic Cloud Cepheids Observed with the Hubble Space Telescope Provide a New Anchor for the SH0ES Distance Ladder

We present phase-corrected photometric measurements of 88 Cepheid variables in the core of the Small Magellanic Cloud (SMC), the first sample obtained with the Hubble Space Telescope's (HST) Wide Field Camera 3, in the same homogeneous photometric system as past measurements of all Cepheids on the SH0ES distance ladder. We limit the sample to the inner core and model the geometry to reduce errors in prior studies due to the nontrivial depth of this cloud. Without crowding present in ground-based studies, we obtain an unprecedentedly low dispersion of 0.102 mag for a period–luminosity (P–L) relation in the SMC, approaching the width of the Cepheid instability strip. The new geometric distance to 15 late-type detached eclipsing binaries in the SMC offers a rare opportunity to improve the foundation of the distance ladder, increasing the number of calibrating galaxies from three to four. With the SMC as the only anchor, we find H 0 = 74.1 ± 2.1 km s−1 Mpc−1. Combining these four geometric distances with our HST photometry of SMC Cepheids, we obtain H 0 = 73.17 ± 0.86 km s−1 Mpc−1. By including the SMC in the distance ladder, we also double the range where the metallicity ([Fe/H]) dependence of the Cepheid P–L relation can be calibrated, and we find γ = −0.234 ± 0.052 mag dex−1. Our local measurement of H 0 based on Cepheids and Type Ia supernovae shows a 5.8σ tension with the value inferred from the cosmic microwave background assuming a Lambda cold dark matter (ΛCDM) cosmology, reinforcing the possibility of physics beyond ΛCDM.

The Completeness of Accreting Neutron Star Binary Candidates from the Chinese Space Station Telescope

Abstract A neutron star (NS) has many extreme physical conditions, and one may obtain some important information about an NS via accreting neutron star binary (ANSB) systems. The upcoming Chinese Space Station Telescope (CSST) provides an opportunity to search for a large sample of ANSB candidates. Our goal is to check the completeness of the potential ANSB samples from CSST data. In this paper, we generate some ANSBs and normal binaries under the CSST photometric system by binary evolution and binary population synthesis method and use a machine learning method to train a classification model. Although the Precision (94.56%) of our machine learning model is as high as before study, the Recall is only about 63.29%. The Precision/Recall is mainly determined by the mass transfer rate between the NSs and their companions. In addition, we also find that the completeness of ANSB samples from CSST photometric data by the machine learning method also depends on the companion mass and the age of the system. ANSB candidates with a low initial mass companion star (0.1 M ⊙ to 1 M ⊙) have a relatively high Precision (94.94%) and high Recall (86.32%), whereas ANSB candidates with a higher initial mass companion star (1.1 M ⊙ to 3 M ⊙) have similar Precision (93.88%) and quite low Recall (42.67%). Our results indicate that although the machine learning method may obtain a relatively pure sample of ANSBs, a completeness correction is necessary for one to obtain a complete sample.

Image analysis to evaluate removal of particles from fabric surface

We propose an objective method to quantify the solid-particle removal rate from fabric. The method extracts the ratio ( K/S) λ of light absorption K to scattering S at wavelength λ from fused digital images captured under a stereo photometric system in which illumination is from four directions. Three different white polyester fabrics were contaminated with iron oxide particles. Digital images of the fabrics were obtained before contamination, then before and after cleaning. The ( K/S) λ ratios extracted from images were used in a fabric-detergency formula to determine the solid-particle removal rate. Digital image acquisition conditions were optimized to minimize the effects of fabric structural factors. Our method was faster, more accurate, and cheaper than existing methods. Moreover, it is nondestructive and does not require a tracer. The average accuracy of the proposed method was improved by 44.77% compared with the existing surface reflectance method and by 42.51% compared with the binary image method. Moreover, the accuracy was further increased by calculating ( K/S) λ for a signal that corresponds to the color of the contaminant particles. This method can be used to quantify the effectiveness of self-cleaning textiles and garment-care machines.

The red giant branch tip in the SDSS, PS1, JWST, NGRST, and Euclid photometric systems. Calibration in optical passbands using Gaia DR3 synthetic photometry

The red giant branch tip in the SDSS, PS1, JWST, NGRST, and Euclid photometric systems. Calibration in optical passbands using Gaia DR3 synthetic photometry

A complex node of the cosmic web associated with the massive galaxy cluster MACS J0600.1-2008

ABSTRACT MACS J0600.1-2008 (MACS0600) is an X-ray-luminous, massive galaxy cluster at $z_{\mathrm{d}}=0.43$, studied previously by the REionization LensIng Cluster Survey and ALMA Lensing Cluster Survey projects which revealed a complex, bimodal mass distribution and an intriguing high-redshift object behind it. Here, we report on the results of a combined analysis of the extended strong lensing (SL), X-ray, Sunyaev–Zeldovich (SZ), and galaxy luminosity-density properties of this system. Using new JWST and ground-based Gemini-N and Keck data, we obtain 13 new spectroscopic redshifts of multiply-imaged galaxies and identify 12 new photometric multiple-image systems and candidates, including two multiply-imaged $z\sim 7$ objects. Taking advantage of the larger areal coverage, our analysis reveals an additional bimodal, massive SL structure which we measure spectroscopically to lie adjacent to the cluster and whose existence was implied by previous SL-modelling analyses. While based in part on photometric systems identified in ground-based imaging requiring further verification, our extended SL model suggests that the cluster may have the second-largest critical area and effective Einstein radius observed to date, $A_{\mathrm{crit}}\simeq 2.16\, \mathrm{arcmin}^2$ and $\theta _{\mathrm{E}}=49.7^{\prime \prime }\pm 5.0^{\prime \prime }$ for a source at $z_{\mathrm{s}}=2$, enclosing a total mass of $M(\lt \theta _{\mathrm{E}})=(4.7\pm 0.7)\times 10^{14}\, \mathrm{M}_{\odot }$. These results are also supported by the galaxy luminosity distribution, and the SZ and X-ray data. Yet another, probably related massive cluster structure, discovered in X-rays 5 arcmin (1.7 Mpc) further north, suggests that MACS0600 is part of an even larger filamentary structure. This discovery adds to several recent detections of massive structures around SL galaxy clusters and establishes MACS0600 as a prime target for future high-redshift surveys with JWST.

Characterization of a CMOS camera based film digitization platform for gated x-ray imaging diagnostics at the National Ignition Facility.

Hardened gated x-ray detectors use photographic film as the data recording medium due to its low sensitivity to the high-yield neutron environments at the National Ignition Facility (NIF). The photographic film is digitized with a Photometric Data Systems (PDS) microdensitometer, which measures the film's optical density. The PDS scanner is able to measure a dynamic range of 0-5 OD; however, raster scanning the film is time consuming and maintenance of the instrument is challenging due to legacy technology. Since film usage at NIF is expected to continue in the foreseeable future, a digitization platform that is faster and more maintainable would benefit the NIF's current and future operations. This work presents the characterization of the digital transitions (DT) atom, a CMOS camera-based digitization platform that records film data in a single image capture very quickly and has widely available user support. The preliminary results suggest that the DT atom is able to reconstruct exposures accurately enough to be a competitive alternative to the PDS Scanner.

IoT-based pesticide distribution control system with photometric sensor frameworkIoT-based pesticide distribution control system with photometric sensor framework

The use of pesticides is often given under extreme conditions. The excess use of these pesticides can harm both the farmers directly and the affected environment; this is the impact of the uncontrolled use of pesticides. There is a need for a control system to control the distribution of pesticides on agricultural land. This article seeks to provide a control system design for controlling the distribution of pesticides by utilizing photometric technology integrated with the internet of things (IoT). The control system is designed automatically with a sensing system or an operating record. It is expected to be able to disseminate the correct use of pesticides to achieve production efficiency. This study provides a design of an automatic control system for pesticide distribution IoT-based. We use a photometric sensor to control the pesticide distribution. Future work can be implemented for prototype work due to smart farming to control pesticide distribution automatically.

Accuracy of a new photometric jaw tracking system in the frontal plane at different recording distances: An in-vitro study

ObjectivesTo evaluate the accuracy of a new photometric jaw tracking system (JTS) in recording linear vertical movements in the frontal plane at different distances. MethodsA mandibular plaster cast of a patient was placed on a simulation machine capable of linear movements along two spatial axes. Cyclops JTS (Itaka) was adapted to the plaster cast, while the head frame was attached to the simulation machine. The latter performed five linear movements from 20 to 40 mm in the y-axis; each movement was repeated five times at five different recording distance (380 to 420 mm). The recorded movements were measured and compared with those obtained with a laser Doppler vibrometer (LDV) for accuracy analysis. Data were statistically processed (α = 0.05). ResultsNo statistically significant differences were found between Cyclops and LDV measurements on the y- and z-axes (p = 0.5). Changes in linear vertical motion and distance positions did not affect the accuracy, which remained relatively constant with similar trends and values less than 1 % for each parameter variation. The best condition observed was linear vertical movement of 30 mm at 420 mm (0.010 ± 0.023 mm). ConclusionsCyclops has proven to be an accurate JTS in recording linear vertical movements in the frontal plane at different recording distances. For optimal recordings, the scanner should be placed as close as possible to the markers; excessive vertical movements decreased the accuracy. However, this study has limitations and requires in-vivo confirmations. Clinical significanceThe tested JTS proved accurate in recording linear vertical movements in the frontal plane. However, given the limitations of the study, further investigation under real conditions is needed to support prosthetic and gnathological rehabilitations.

The variable stars in the field of the bulge cluster NGC 6558

ABSTRACT We made a survey of the variable stars in a 13.2 × 13.2 arcmin$^{2}$ centred on the field of the Galactic bulge cluster NGC 6558. A total of 78 variables were found in the field of the cluster. Many of these variables are included in the catalogue of variable stars in Galactic globular clusters (Clement et al. 2001), OGLE or Gaia DR3 data releases. A membership analysis based on the proper motions of Gaia DR3 revealed that many of these variables do not belong to the cluster. We employed the data from the aforementioned surveys and our own data in the VI photometric system to estimate the periods, which along with the light-curves morphology and position in a deferentially dereddened colour–magnitude diagram (CMD), help classifying the variable types. Two new member variables were found; an eclipsing binary (V18) and a semiregular SR/L (V19). In the end, we conclude that only nine variables are likely cluster members. Member variables were used to discuss the mean metallicity and distance of the parental cluster and find the average values.

Adaptive Weighted Data Fusion for Line Structured Light and Photometric Stereo Measurement System.

Line structured light (LSL) measurement systems can obtain high accuracy profiles, but the overall clarity relies greatly on the sampling interval of the scanning process. Photometric stereo (PS), on the other hand, is sensitive to tiny features but has poor geometrical accuracy. Cooperative measurement with these two methods is an effective way to ensure precision and clarity results. In this paper, an LSL-PS cooperative measurement system is brought out. The calibration methods used in the LSL and PS measurement system are given. Then, a data fusion algorithm with adaptive weights is proposed, where an error function that contains the 3D point cloud matching error and normal vector error is established. The weights, which are based on the angles of adjacent normal vectors, are also added to the error function. Afterward, the fusion results can be obtained by solving linear equations. From the experimental results, it can be seen that the proposed method has the advantages of both the LSL and PS methods. The 3D reconstruction results have the merits of high accuracy and high clarity.

The miniJPAS survey: Evolution of luminosity and stellar mass functions of galaxies up to z~0.7

We aim to develop a robust methodology for constraining the luminosity and stellar mass functions (LMFs) of galaxies by solely using photometric measurements from multi-filter imaging surveys. We test the potential of these techniques for determining the evolution of these functions up to $z 0.7$ in the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS), which will image thousands of square degrees in the northern hemisphere with an unprecedented photometric system that includes $54$ narrow band filters. As J-PAS is still an ongoing survey, we used the miniJPAS dataset (a stripe of $1$ deg$^2$ dictated according to the J-PAS strategy) for determining the LMFs of galaxies at $0.05 z 0.7$. Stellar mass and $B$-band luminosity for each of the miniJPAS galaxies are constrained using an updated version of our fitting code for spectral energy distribution, MUlti-Filter FITting (MUFFIT), whose values are based on non-parametric composite stellar population models and the probability distribution functions of the miniJPAS photometric redshifts. Galaxies are classified according to their star formation activity through the stellar mass versus rest-frame colour diagram corrected for extinction (MCDE) and we assign a probability to each source of being a quiescent or star-forming galaxy. Different stellar mass and luminosity completeness limits are set and parametrised as a function of redshift, for setting the limitations of our flux-limited sample ($r_ SDSS 22$) for the determination of the miniJPAS LMFs. The miniJPAS LMFs are parametrised according to Schechter-like functions via a novel maximum likelihood method accounting for uncertainties, degeneracies, probabilities, completeness, and priors. Overall, our results point to a smooth evolution with redshift ($0.05 z 0.7$) of the miniJPAS LMFs, which is in agreement with previous studies. The LMF evolution of star-forming galaxies mainly involve the bright and massive ends of these functions, whereas the LMFs of quiescent galaxies also exhibit a non-negligible evolution in their faint and less massive ends. The cosmic evolution of the global $B$-band luminosity density decreases by $ 0.1$ dex from $z=0.7$ to $0.05$; whereas for quiescent galaxies, this quantity roughly remains constant. In contrast, the stellar mass density increases by $ dex in the same redshift range, where the evolution is mainly driven by quiescent galaxies, owing to an overall increase in the number of this type of galaxy. In turn, this covers the majority and most massive galaxies, namely, $60$--$100$<!PCT!> of galaxies at $ (M_

Effects of Helianthus annuus seeds on antioxidants, lipid profile and serum urea and creatinine in obesity induced rats using high fat diet

High-fat diets have been strongly associated with common metabolic diseases. Clinical practices often link these diseases, such as hyperlipidemia and oxidative stress resulting from the accumulation of reactive oxygen species, to severe conditions like cancer, diabetes, atherosclerosis, and cardiovascular diseases. Managing these conditions is often financially demanding. Helianthus annuus seeds, known to be non-toxic even at doses greater than 5000mg/kg in rats, with an LD50 greater than 5000mg/kg, has demonstrated efficacy in reducing elevated blood sugar levels and BMI in both animal and human studies. Therefore, further research is needed to explore the potential effects of sunflower seeds on antioxidants, lipid profiles, and serum urea and creatinine levels in rats induced with obesity using a high-fat diet. In this study, overnight fasting blood samples were collected to conduct lipid profile tests (HDL, LDL, VLDL, and triglycerides). These tests utilized a photometric system with procedures derived from the Diasys-G Emmany kit and the measurement and precipitation method. The modified Jaffe technique for in-vitro measurement of creatinine in serum was employed to measure urea and creatinine levels. The experiment involved 27 Wistar rats weighing between 350 and 400 grams, randomly divided into 9 groups, with 3 rats in each group. Group 1 served as the control, while groups 2 to 9 were subjected to various conditions: high-fat diets alone for 6 weeks (group 2), high-fat diets with high (5000mg/kg body weight), medium (3000 mg/kg body weight), or low (2000 mg / kg body weight) doses of Helianthus annuus seeds powder for 6 weeks (groups 3, 4, and 5, respectively). Additionally, there were variations in duration and doses in groups 6 to 9, where rats were fed high-fat diets 20 g/ kg / day /rats for 5 weeks and then supplemented with Helianthus annuus seeds powder (5000 mg / kg, 3000 mg / kg and 2000 mg / kg per rat for group 6,7,8 or Metformin 70 mg / kg per rat for group 9) for 1 week. The results revealed a significant (P < 0.05) increase in serum cholesterol, triglyceride, and low-density lipoprotein (LDL) levels in rats across all groups compared to the control. However, all groups supplemented with Helianthus annuus seeds alongside high-fat diets displayed a significantly increased HDL level (P < 0.05) compared to rats fed only high-fat diet alone. Creatinine levels were significantly increased in all Helianthus annuus seeds -supplemented groups compared to the high-fat diet alone, while urea levels showed no significant differences among the groups. Furthermore, rats in all Helianthus annuus seeds -supplemented groups alongside high-fat diets demonstrated a significantly increased glutathione reductase activity (P < 0.05) compared to the control and high-fat diet alone. The study indicated that sunflower seeds significantly bolster antioxidant protection, elevate HDL levels, and increase creatinine levels in rats fed high-fat diets, suggesting potential beneficial effects in mitigating the adverse impacts of high-fat diets on health parameters.

Estimating the Mass of Galactic Components Using Machine Learning Algorithms

The estimation of galactic component masses can be carried out through various approaches that involve a host of assumptions about baryon dynamics or the dark matter model. In contrast, this work introduces an alternative method for predicting the masses of the disk, bulge, stellar, and total mass using the k-nearest neighbours, linear regression, random forest, and neural network (NN) algorithms, reducing the dependence on any particular hypothesis. The ugriz photometric system was selected as the set of input features, and the training was performed using spiral galaxies in Guo’s mock catalogue from the Millennium simulation. In general, all of the algorithms provide good predictions for the galaxy’s mass from 109 M⊙ to 1011 M⊙, corresponding to the central region of the training domain. The NN algorithm showed the best performance. To validate the algorithm, we used the SDSS survey and found that the predictions of disk-dominant galaxies’ masses lie within a 99% confidence level, while galaxies with larger bulges are predicted at a 95% confidence level. The NN also reveals scaling relations between mass components and magnitudes. However, predictions for less luminous galaxies are biased due to observational limitations. Our study demonstrates the efficacy of these methods with the potential for further enhancement through the addition of observational data or galactic dynamics.

Evaluating the Consistency of Cosmological Distances Using Supernova Siblings in the Near-infrared

The study of supernova (SN) siblings, supernovae with the same host galaxy, is an important avenue for understanding and measuring the properties of Type Ia SN Ia light curves (LCs). Thus far, sibling analyses have mainly focused on optical LC data. Considering that LCs in the near-infrared (NIR) are expected to be better standard candles than those in the optical, we carry out the first analysis compiling SN siblings with only NIR data. We perform an extensive literature search of all SN siblings and find six sets of siblings with published NIR photometry. We calibrate each set of siblings ensuring they are on homogeneous photometric systems, fit the LCs with the SALT3-NIR and SNooPy models, and find median absolute differences in μ values between siblings of 0.248 and 0.186 mag, respectively. To evaluate the significance of these differences beyond measurement noise, we run simulations that mimic these LCs and provide an estimate for uncertainty on these median absolute differences of ∼0.052 mag, and we find that, statistically, our analysis rules out the nonexistence of intrinsic scatter in the NIR at the 99% level. When comparing the same sets of SN siblings, we observe a median absolute difference in μ values between siblings of 0.177 mag when using optical data alone as compared to 0.186 mag when using NIR data alone. It is unclear if these results may be due to limited statistics or poor quality NIR data, all of which will be improved with the Nancy Grace Roman Space Telescope.

Prospects of the Multi-channel Photometric Survey Telescope in the Cosmological Application of Type Ia Supernovae

The Multi-channel Photometric Survey Telescope (Mephisto) is a real-time, three-color photometric system designed to capture the color evolution of stars and transients accurately. This telescope system can be crucial in cosmological distance measurements of low-redshift (low-z, z ≲0.1) Type Ia supernovae (SNe Ia). To optimize the capabilities of this instrument, we perform a comprehensive simulation study before its official operation is scheduled to start. By considering the impact of atmospheric extinction, weather conditions, and the lunar phase at the observing site involving the instrumental features, we simulate light curves of SNe Ia obtained by Mephisto. The best strategy in the case of SN Ia cosmology is to take the image at an exposure time of 130 s with a cadence of 3 days. In this condition, Mephisto can obtain hundreds of high-quality SNe Ia to achieve a distance measurement better than 4.5%. Given the on-time spectral classification and monitoring of the Lijiang 2.4 m Telescope at the same observatory, Mephisto, in the whole operation, can significantly enrich the well-calibrated sample of supernovae at low-z and improve the calibration accuracy of high-z SNe Ia.

OSPC: Online Sequential Photometric Calibration

Photometric calibration is essential to many computer vision applications. One of its key benefits is enhancing the performance of Visual SLAM, especially when it depends on a direct method for tracking, such as the standard KLT algorithm. Additionally, it proves valuable in extracting sensor irradiance values from measured intensities, serving as a pre-processing step for a number of vision algorithms such as shape-from-shading. Current photometric calibration systems rely on a joint optimization problem and encounter an ambiguity in the estimates, which can only be resolved using ground truth information. We propose a novel method that solves for photometric parameters using a sequential estimation approach. To enhance the decoupling of CRF and Vignette estimation, we strategically utilize keyframes with high exposure ratios and small displacements for the former, and keyframes with relatively large displacements for the latter. Our proposed method achieves high accuracy in estimating all parameters; furthermore, the formulations are linear and convex, which makes the solution fast and suitable for online applications. Experiments on a Visual Odometry system validate the proposed method and demonstrate its advantages.