Bright Comets Research Articles

Dust properties and their variations in comet C/2013 X1 (PANSTARRS)

Context. We analyze the results of photometric monitoring of comet C/2013 X1 (PANSTARRS) from December 2015 until January 2016 obtained within B, V, and R Johnson–Cousins filters. Aims. The main objective is to investigate the dust coma and to obtain the physical characteristics of its dust particles. Methods. We analyzed our observations using model-agglomerated debris particles, and we constrained the microphysical properties of the dust in comet C/2013 X1 (PANSTARRS) on the pre-outburst and post-outburst epochs. Moreover, we applied a geometrical model to the images processed by digital filters to estimate the rotational period of the nucleus. Results. Our campaign revealed a sharp increase in the comet brightness on January 1, 2016. The B − V and V − R colors calculated within an aperture size of 17 000 km appear to be mostly red, except for the outburst date. The dust production (A f ρ proxy) and normalized spectral gradient S′ (B − R) dramatically changed on January 2 as compared to what was seen in December 2015. According to this model, the C/2013 X1 coma was populated by 70% organic-matter particles by volume and by two types of silicate particles together, constituting the other 30%. One type of silicate particles was composed of Mg-rich silicates, whereas the other type was composed of both Mg-rich and Fe-poor silicates. Using the geometrical model, we estimate the nucleus rotational period to be (24.02 ± 0.02) h. We interpret the observed coma morphology by two jet structures, one structure that formed by the near-pole active area at a latitude of (85+5−3)°, and the other structure formed by an active area at a latitude of (+40 ± 5)°.

Determination of bolometric albedo based on spectroscopic measurements for selected dust analogues and its impact on the change of cometary brightness during its outburst

The paper presents the results of spectroscopic measurements for selected dust analogues, based on which change in cometary brightness was determined. In the first part of the article, we present the results of laboratory measurements of hemispherical albedo for selected dust analogues using a Cary 5000 spectrometer with an integrating sphere. In the case of this system and the tested samples, the obtained hemispherical albedo values ranged from 0.35 ± 0.07% to 41.58 ± 0.07%. The obtained measurement results were used to determine the bolometric albedo and geometric albedo. For the analogue consisting of charcoal, the Bond albedo was equal to AB(charcoal) = 2.15%, whereas the geometric albedo was equal to pv(charcoal) = 6.76%. The second part of the paper presents an analytical method allowing us to calculate the amplitude of the change of cometary brightness during the outburst. The calculations show that the upper value of the amplitude is 6.5 magnitudes, which is within the medium range amplitude of the outburst. Calculations have shown that as the bolometric albedo increases for a given agglomerate porosity, the temperature decreases, which determines a smaller sublimation flux, which translates into a larger change in the cometary brightness.

New measurements of the hemispherical albedo of cometary analogues: Influence on the amplitude of the change of cometary brightness during its outburst

The paper presents new experimental results of measurements of the hemispherical albedo of a potential comet analogue and an analysis of its influence on the change in the cometary brightness. Measurements of the spectral properties of the tested analogues were performed using a Cary 5000 spectrometer in the wavelength range from 200 to 2500 nm. Two samples were used as a dust analogue: a mixture of sand and ash (sample A) and a mixture of sand and charcoal (sample B), respectively. The obtained hemispherical albedo values for the tested samples ranged from 1.20% to 32.25%. In particular, for sample B, the obtained hemispherical albedo values are comparable to the actual reflectance for comet 67P. Based on the obtained spectral properties of the tested samples, a thermodynamic model of cometary activity was developed and used, among others, to calculate the power absorbed by the tested analogue and the sublimation flux occurring through the porous structure of the fine-grained dust present on the cometary surface. The obtained results were used to calculate the change in the cometary brightness during its outburst, the upper limit of which was equal to 5.36 magnitude.

Explanation of the Anomalous Outburst Activity of Comet 29P/Schwassmann–Wachmann 1: The Hypothesis about the Existence of Large Satellites

We explain the anomalous outburst activity of comet 29P/Schwassmann–Wachmann 1 by the existence of satellites touching the surface of the comet nucleus at the pericenters of their orbits. It is assumed that the satellites move in eccentric orbits and a large amount of dust, the reflection of light from which causes periodic outbursts in brightness (BAA 2023), is ejected as a result of their collisions with the dust layer of the nucleus. Depending on the depth of penetration of the satellites into the dust layer, outbursts in comet brightness of various intensities occur. An improvement of the comet orbit by invoking positional observations allows the preferred direction of the ejection of material to be determined from the photocenter offset, which we interpret as the direction of the velocity vector of the largest satellite at the pericenter. The results of our numerical simulations of the ejection and subsequent motion of dust particles caused by the contact of the satellite with the dust layer of the comet nucleus explain the formation of the structures observed in the comet: the dust jets and their mirror symmetry as well as the extent of the region of material ejection from the surface of the comet nucleus.

Long-term monitoring of comet 29P/Schwassmann–Wachmann from the Lulin Observatory

Abstract Multi-band photometric monitoring of comet 29P/Schwassmann–Wachmann 1 was conducted with the standard Johnson–Cousins filter set. Observations extended from 2018 July to 2021 December. The comet was detected to show at least 12 relatively large outbursts, during which its brightness increased by 1.5 to 5 mag as measured through a 5″ aperture. The outbursts resulted in a clear variation of the cometary brightness profile. The derived slopes of the surface brightness profiles showed a significant variation with time from a shallower slope to a steeper one at the beginning of each outburst and then slowly returning to pre-outburst values. There did not seem to be any obvious change in the color indices as the outbursts occurred. However, for the quadruple outbursts in late September of 2021, we could confidently spot a change in the color of the comet, indicating that the color indices seem to be less than the mean values, especially in the B − V term. Dust production derived by using the dust production rate parameter, Afρ, from the R-band photometry measurements shows the outburst to be accompanied by a large increasing trend. Using a simple model and the derived outflow velocity of 0.11 km s−1 from the expanding shell features, an estimated lower limit of 1.0 × 108 kg up to 2.7 × 109 kg of dust was released during the quadruple outbursts by using a specific dust size of 1 μm.

Imaging of exocomets with infrared interferometry

Active comets have been detected in several exoplanetary systems, although so far only indirectly, when the dust or gas in the extended coma has transited in front of the stellar disk. The large optical surface and relatively high temperature of an active cometary coma also makes it suitable to study with direct imaging, but the angular separation is generally too small to be reachable with present-day facilities. However, future imaging facilities with the ability to detect terrestrial planets in the habitable zones of nearby systems will also be sensitive to exocomets in such systems. Here we examine several aspects of exocomet imaging, particularly in the context of the Large Interferometer for Exoplanets (LIFE), which is a proposed space mission for infrared imaging and spectroscopy through nulling interferometry. We study what capabilities LIFE would have for acquiring imaging and spectroscopy of exocomets, based on simulations of the LIFE performance as well as statistical properties of exocomets that have recently been deduced from transit surveys. We find that for systems with extreme cometary activities such as β Pictoris, sufficiently bright comets may be so abundant that they overcrowd the LIFE inner field of view. More nearby and moderately active systems such as є Eridani or Fomalhaut may turn out to be optimal targets. If the exocomets have strong silicate emission features, such as in comet Hale-Bopp, it may become possible to study the mineralogy of individual exocometary bodies. We also discuss the possibility of exocomets as false positives for planets, with recent deep imaging of α Centauri as one hypothetical example. Such contaminants could be common, primarily among young debris disk stars, but should be rare among the main sequence population. We discuss strategies to mitigate the risk of any such false positives.

The influence of the porosity of dust particles on the amplitude of the change in the brightness of a comet

ABSTRACT The paper presents a new approach to determining the change in the brightness of a comet during an outburst. It was investigated how the porosity of the dust particle translates into an increase in comet brightness during an outburst. It has been shown that the greater the porosity of a given particle, the greater the scattering efficiency, which directly translates into a greater amplitude of the change in the cometary brightness. In the case of dense aggregates with porosity ψ = 0.05, the brightness rate varies from −0.74 to −4.24 mag. In the case of porous agglomerates, the porosity of which is in the range from 0.30 to 0.90, the brightness change ranges from −0.91 to −6.66 mag.

Prediction of cometary OH maser emission in 1.6 GHz frequency band based on optical brightness

Cometary OH maser emission evaluation was carried out to identify potentially bright comets for which OH maser emission were detectable in 1.6 GHz frequency range using Irbene RT-32 radio telescope. The evaluation model was based on the results of more than 3320 comets observations using data from optical and radio observations. Using the evaluation model, the correlation between optical brightness and radio flux density and correlation between flux density and OH production models was analyzed. In the research a prediction neural network model prototype was created to predict the comet brightness value in optical frequency range, based on the analyzed results from obtained correlation and characteristics of the comet. Based on the prediction model, the comet C/2021 A1 (Leonard) was observed in 1.6 GHz frequency band using Irbene RT-32 radio telescope. Spectral analysis using Fourier transform was applied to radio astronomical data from multiple observations related to weak cometary OH maser detection.

Кометите – I част

The appearance of a bright comet is one of the most beautiful astronomical phenomena, attracting the attention of professionals and amateur astronomers, as well as the media around the world. Bright comets are relatively rare events – occurring only several times in a human life, which is why they are recorded as important events in the history of astronomy, as well as in human history in general. This article provides a chronological overview of all the brighter comets that appeared in the last half century. Their photographs, taken by Bulgarian professional and amateur astronomers, are displayed.

Emission from HCN and CH3OH in comets

Aims. The aim of this work is to characterise HCN and CH3OH emission from recent comets. Methods. We used the Onsala 20-m telescope to search for millimetre transitions of HCN towards a sample of 11 recent and mostly bright comets in the period from December 2016 to November 2019. Also, CH3OH was searched for in two comets. The HCN sample includes the interstellar comet 2I/Borisov. For the short-period comet 46P/Wirtanen, we were able to monitor the variation of HCN emission over a time-span of about one month. We performed radiative transfer modelling for the observed molecular emission by also including time-dependent effects due to the outgassing of molecules. Results. HCN was detected in six comets. Two of these are short-period comets and four are long-period. Six methanol transitions were detected in 46P/Wirtanen, enabling us to determine the gas kinetic temperature. From the observations, we determined the molecular production rates using time-dependent radiative transfer modelling. For five comets, we were able to determine that the HCN mixing ratios lie near 0.1% using contemporary water production rates, ${Q_{{{\rm{H}}_2}{\rm{O}}}}$, taken from other studies. This HCN mixing ratio was also found to be typical in our monitoring observations of 46P/Wirtanen but here we notice deviations of up to 0.2% on a daily timescale which could indicate short-time changes in outgassing activity. From our radiative transfer modelling of cometary comae, we find that time-dependent effects on the HCN level populations are of the order of 5–15% when ${Q_{{{\rm{H}}_2}{\rm{O}}}}$ is around 2 × 1028 mol s−1. The effects may be stronger for comets with lower ${Q_{{{\rm{H}}_2}{\rm{O}}}}$. The exact details of the time-dependent effects depend on the amount of neutral and electron collisions, radiative pumping, and molecular parameters such as the spontaneous rate coefficient.

Solar Wind Velocities at Comets C/2011 L4 Pan‐STARRS and C/2013 R1 Lovejoy Derived Using a New Image Analysis Technique

AbstractThe ion tails of bright comets have long been considered as a natural tracers of the solar wind (SW) near these objects. Studies of comets and their ion tails allow inexpensive monitoring of key SW structures in the inner heliosphere, much of which is otherwise only accessible by in situ SW spacecraft measurements. Here, we present a novel technique to mine the rich archive of amateur, professional and spacecraft observations of cometary ion tails. To demonstrate this, we focus on Near‐Sun comet C/2011 L4 (Pan‐STARRS) during Carrington Rotations (CR) 2134 and 2135 and comet C/2013 R1 (Lovejoy) during CR 2118. We outline the technique’s shortcomings, including its geometric limitations, and present a catalog of radial SW velocities derived in the near‐comet environment and information on the heliospheric conditions inferred from the measured SW. Complementary measurements, derived from folding ion rays and a velocity profile map built from consecutive images, are provided as an alternative means of quantifying the SW ‐cometary ionosphere interaction. We find that comets are generally good indicators of SW structure, but the quality of the results is strongly dependent on the observing geometry.

The rise time of the change of cometary brightness during its outburst

The paper presents a new method for determining the change in the brightness of a comet during an outburst in which particles are ejected into the coma at a uniform rate, i.e. via a long-lived jet. In the proposed approach, the mass flow rate by a jet and the time it takes to increase the brightness of the comet play key roles. Absolute values adopted for H2O ice and CO2 ice were taken from measurements by Rosetta of the jets observed on 67P/Churyumov–Gerasimenko. These two parameters significantly affect the amplitude of the change in the brightness of a comet during its outburst. The performed numerical calculations concern a hypothetical comet from the Jupiter family for which it was assumed that its sublimation activity was controlled by the sublimation of water ice and carbon dioxide. Based on numerical simulations, it was shown that the difference between the change in brightness for H2O ice and CO2 ice is about −3.4 magnitude for the same fraction of the area that is active and the same mass flow rate. This value corresponds to the rise time of the amplitude of the brightness change t = 3 h. In addition, it should be emphasized that this difference is a consequence of thermodynamic parameters, such as the speed of sublimating gas molecules, the sublimation rate of given ice, which determine the numerical values of the individual scattering cross-sections C(t1) and C(t2).

Leveraging the ALMA Atacama Compact Array for Cometary Science: An Interferometric Survey of Comet C/2015 ER61 (PanSTARRS) and Evidence for a Distributed Source of Carbon Monosulfide

Abstract We report the first survey of molecular emission from cometary volatiles using standalone Atacama Compact Array (ACA) observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) toward comet C/2015 ER61 (PanSTARRS) carried out on UT 2017 April 11 and 15, shortly after its April 4 outburst. These measurements of HCN, CS, CH3OH, H2CO, and HNC (along with continuum emission from dust) probed the inner coma of C/2015 ER61, revealing asymmetric outgassing and discerning parent from daughter/distributed source species. This work presents spectrally integrated flux maps, autocorrelation spectra, production rates, and parent scale lengths for each molecule and a stringent upper limit for CO. HCN is consistent with direct nucleus release in C/2015 ER61, whereas CS, H2CO, HNC, and potentially CH3OH are associated with distributed sources in the coma. Adopting a Haser model, parent scale lengths determined for H2CO (L p ∼ 2200 km) and HNC (L p ∼ 3300 km) are consistent with previous work in comets, whereas significant extended source production (L p ∼ 2000 km) is indicated for CS, suggesting production from an unknown parent in the coma. The continuum presents a point-source distribution with a flux density implying an excessively large nucleus, inconsistent with other estimates of the nucleus size. It is best explained by the thermal emission of slowly moving outburst ejectas, with total mass 5–8 × 1010 kg. These results demonstrate the power of the ACA for revealing the abundances, spatial distributions, and locations of molecular production for volatiles in moderately bright comets such as C/2015 ER61.

A NEW AND IMPROVED ORBIT FOR COMET C/1558 P1

The bright comet C/1558 P1 was seen only from early August to mid-September 1558. Previous orbits for it were calculated based on a limited number of observations and failed to represent all observational reports. By including observations from Asian historical sources and from an additional European treatise a new orbit is calculated that now represents the observational data in a more satisfactory manner.

Activity of the Jupiter co-orbital comet P/2019 LD2(ATLAS) observed with OSIRIS at the 10.4 m GTC

Context.The existence of comets with heliocentric orbital periods close to that of Jupiter (i.e., co-orbitals) has been known for some time. Comet 295P/LINEAR (2002 AR2) is a well-known quasi-satellite of Jupiter. However, their orbits are not long-term stable, and they may eventually experience flybys with Jupiter at very close range, close enough to trigger tidal disruptions like the one suffered by comet Shoemaker-Levy 9 in 1992.Aims.Our aim was to study the observed activity and the dynamical evolution of the Jupiter transient co-orbital comet P/2019 LD2(ATLAS) and its dynamical evolution.Methods.We present results of an observational study of P/2019 LD2carried out with the 10.4 m Gran Telescopio Canarias (GTC) that includes image analyses using a Monte Carlo dust tail fitting code to characterize its level of cometary activity, and spectroscopic studies to search for gas emission. We also presentN-body simulations to explore its past, present, and future orbital evolution.Results.Images of P/2019 LD2obtained on May 16, 2020, show a conspicuous coma and tail, but the spectrum obtained on May 17, 2020, does not exhibit any evidence of CN, C2, or C3emission. The comet brightness in a 2.6′′ aperture diameter isr′ = 19.34 ± 0.02 mag, with colors (g′−r′) = 0.78 ± 0.03, (r′−i′) = 0.31 ± 0.03, and (i′−z′) = 0.26 ± 0.03. The temporal dependence of the dust loss rate of P/2019 LD2can be parameterized by a Gaussian function having a full width at half maximum of 350 days, with a maximum dust mass loss rate of 60 kg s−1reached on August 15, 2019. The total dust loss rate from the beginning of activity until the GTC observation date (May 16, 2020) is estimated at 1.9 × 109kg. Comet P/2019 LD2is now an ephemeral co-orbital of Jupiter, following what looks like a short arc of a quasi-satellite cycle that started in 2017 and will end in 2028. On January 23, 2063, it will experience a very close encounter with Jupiter at perhaps 0.016 au; its probability of escaping the solar system during the next 0.5 Myr is estimated to be 0.53 ± 0.03.Conclusions.Photometry and tail model results show that P/2019 LD2is a kilometer-sized object, in the size range of the Jupiter-family comets, with a typical comet-like activity most likely linked to sublimation of crystalline water ice and clathrates. Its origin is still an open question. Our numerical studies give a probability of this comet having been captured from interstellar space during the last 0.5 Myr of 0.49 ± 0.02 (average and standard deviation), 0.67 ± 0.06 during the last 1 Myr, 0.83 ± 0.06 over 3 Myr, and 0.91 ± 0.09 during the last 5 Myr.

The influence of the size of ice–dust particles on the amplitude of the change in the brightness of a comet caused by an outburst

ABSTRACTThis paper presents a new approach to analysing the brightness change of a Jupiter family comet. We assume that the coma contains particles composed of water ice, carbonaceous, and silicate dust. Different sizes of dust particles were taken into account following the adopted size distribution. From an analysis of modern space missions, it is clear that the sizes of the dominant coma particles at the time of the outburst are in the order of micrometres to centimetres. However, most of these particles have dimensions that are comparable to the wavelength of electromagnetic radiation coming from the Sun. In the case of dust particles, four groups were distinguished depending on their dimensions. The performed calculations show that the particle size significantly influences the change of the cometary brightness, i.e. the scattering efficiency of the incident sunlight that occurs on the particle. The conducted numerical simulations show that the changes in the brightness of the comet oscillate approximately from −8 to −1 mag. This means that we can talk about outbursts, the amplitudes of which are most often observed.

The role of astronomical silicates during a cometary outburst ⋆ ⋆University of Rzeszów, Poland.

This paper presents a new approach to analyzing the change of cometary brightness. In our considerations, we assume that astronomical silicates (dust agglomerates) and gas are present in the coma. This assumption is a consequence of the analysis of the result observed during the Rosetta mission to comet 67P/Churyumov-Gerasimenko (abbreviated 67P/Ch-G). The dimensions of these agglomerates can be up to several centimeters. However, the large ones are few compared to particles with dimensions of several micrometers. This paper presents the results of calculations on the change in hypothetical comet brightness as a result of its outburst. The calculations take into account the percentage of carbonaceous particles and silicates rich in magnesium.

Surfaces of (Nearly) Dormant Comets and the Recent History of the Quadrantid Meteor Shower

Abstract The parent of the Quadrantid meteor shower is the inactive solar system small body (196256) 2003 EH1. EH1 has likely only gone dormant in the past few hundred years, and may be related to the bright comet C/1490 Y1. Compared with the other best-studied inactive meteor shower parent (3200) Phaethon, EH1 has received comparatively minimal characterization of its surface properties. We present the first reflectance spectrum and additional photometry of EH1, as well as new spectra of the nuclei of three nearly dormant comets P/2006 HR30 (Siding Spring), 364P/Pan-STARRS, and 249P/LINEAR for comparison. We also present new short-term high-resolution orbital integrations of these bodies for context. EH1s spectrum is red in color below 0.8 μm in between C and D types, consistent with previous photometric measurements, but is blue beyond 0.8 μm until at least 1.02 μm. 249P and 364P have both red slopes consistent with C taxonomic types and HR30 has a classic comet nucleus D-type slope. If the downturn in EH1’s spectrum is due to an absorption feature, magnetite and olivine are plausible candidates, but more data are needed. 249P and 364P have similar recent and historical dynamical evolutions in addition to their similar surface properties. We discuss the interrelation between the dynamical histories and modern surfaces of these four objects and suggest avenues for further study to better constrain how the Quadrantids and Geminids were created.

Orbit determination just from historical observations? Test case: The comet of AD 760 is identified as 1P/Halley

Recent advances in techniques of critical close reading of historical texts can now be applied to records of pre-telescopic celestial observations – allowing significant progress for analyzing and solving orbits of past comets: here, as a blueprint test case, we exemplify our method by solving the orbit of the comet in AD 760 only with historical observations and then identify it with 1P/Halley. A detailed eyewitness record with drawing of a comet in AD 760 in the Syriac Chronicle of Zuqnīn (finished AD 775/6) was not yet included in the study of its orbit – the Chinese reports alone do not yield a sufficient number of dated positions. We analyze the Syriac and Chinese sources with critical methods for quantitative astronomical usage, we also consider a few further records from the Mediterranean and West Asian area. With our conservatively derived dated positions we can determine the best fitting Keplerian orbital solution by least squares fitting yielding the orbital elements (χred2 < 2 based on 1 million runs); the parameter ranges for non-periodic solutions and highly eccentric periodic solutions are consistent with each other. The allowed parameter ranges for perihelion distance and inclination are sufficiently small to identify the comet with 1P/Halley. Although 1P/Halley is the only comet, where the telescopic orbit is credibly linked to pre-telescopic returns, e.g. to AD 760, our identification confirms claims from extrapolating telescopic observations backward in time – here independently based on historical data. In particular, we obtained a precise perihelion time (760 May 19.1 ± 1.7). The inferior conjunction between comet and Sun as on the previously published orbit (760 May 31.9, Yeomans and Kiang, 1981) is shifted by about one day compared to our new orbit (June 1.8), only the new one is consistent with the last observation (June 1.0) before conjunction as reported in the Chronicle of Zuqnīn. Such a precision would be most critical for studying non-gravitational forces on comets. By studying the comet's brightness evolution, we also compute its absolute brightness and activity parameter for AD 760 and found indications that the comet was quite dusty that year. As the last return before a close encounter with Earth in AD 837, the AD 760 perihelion is particularly important for extrapolation further back in time (at AD 837 and AD 800, Yeomans and Kiang, 1981 had to introduce corrections in their standard orbit). Our improved methods developed in a multidisciplinary cooperation offer possibilities also to solve more orbits and to identify more comets from the rich and widespread pre-telescopic transmissions.

ON TWO SEVENTEENTH CENTURY PERSIAN PAINTINGS DEPICTING COMETS OR FIREBALLS: A CORRECTION

In a recent issue of the <italic>Journal of Astronomical History and Heritage</italic> I looked into two seventeenth century Persian paintings depicting tailed objects (comets or possibly fireballs) in the sky (Kapoor, 2019). One of these, the painting by Muhammad Zaman, has a date inscribed at the lower left as 'sana 7'. Elsewhere, the date has been interpreted as the seventh year of the reign of the Mughal Emperor Aurangzeb (r. CE 1658-1707). Two bright comets, one in December 1664 (C/1664 W1) and another in April 1665 (C/1665 F1), had appeared during the Emperor's seventh regnal year and it was suggested by others that the comet of December 1664 could be the one portrayed by Zaman. In my work, I had inadvertently considered that the seventh regnal year ended on 24 July 1664, which therefore ruled out either of the comets, but since the recorded date of the coronation was 1 <italic>Dhu l-Qa'da</italic> 1068 AH (31 July 1658 CE Greg), Aurangzeb's seventh regnal year should be 1 <italic>Dhu l-Qa'da</italic> 1074-29 <italic>Shawwal</italic> 1075 A.H. (≡26 May 1664-15 May 1665), which revives the suggestion that the comet of December 1664 or of April 1665 was the one portrayed by Zaman. The December 1664 comet rose in the morning in the S-E during its best-view dates, while the April 1665 comet remained a morning object through its visible phase. I have computed ephemerides of the comets and compared their positions in the sky with respect to some bright stars that also were observed on the best-view dates. A late night or early morning skywatcher in Isfahan would have seen the comets rise in the S-E, or, in the N-E, but their respective orientations in the sky would have been the opposite to that portrayed in Zaman's painting where the tailed form is shown headed S-W, suggestive of an evening apparition. While the period of Aurangzeb's seventh regnal year stands corrected, this does not affect the inferences and the conclusions drawn in Kapoor (2019).