On the Zero Point Constant of the Bolometric Correction Scale

Arbitrariness attributed to the zero point constant of the V band bolometric corrections (BCV) and its relation to “bolometric magnitude of a star ought to be brighter than its visual magnitude” and “bolometric corrections must always be negative” was investigated. The falsehood of the second assertion became noticeable to us after IAU 2015 General Assembly Resolution B2, where the zero point constant of bolometric magnitude scale was decided to have a definite value CBol(W) = 71.197 425 ... . Since the zero point constant of the BCV scale could be written as C2 = CBol − CV, where CV is the zero point constant of the visual magnitudes in the basic definition BCV = MBol − MV = mbol − mV, and CBol > CV, the zero point constant (C2) of the BCV scale cannot be arbitrary anymore; rather, it must be a definite positive number obtained from the two definite positive numbers. The two conditions C2 > 0 and 0 < BCV < C2 are also sufficient for LV < L, a similar case to negative BCV numbers, which means that “bolometric corrections are not always negative”. In sum it becomes apparent that the first assertion is misleading causing one to understand bolometric corrections must always be negative, which is not necessarily true.

Performance Analysis of Space Surveillance Using Space Based Optical Sensors

This paper aims to describe the analysis of the performance of an electro-optical space-based sensor for space surveillance purposes and space debris detection in the geostationary (GEO) ring. Such sensor is considered to be operating on a dawn–dusk Sun-synchronous, circular low Earth orbit at an altitude of 630 Km, while its optical characteristics have been taken from those of the Space-Based Visible (SBV) sensor. Two main simulations have been carried out through the use of the MATLAB software. The first simulation deals with the detection capability of the sensor, which is discussed in terms of detectable visual magnitude when the target of the observation is a diffuse sphere orbiting in the geostationary (GEO) orbit; its minimum detectable size is then determined. In addition, the relative geometry between the Sun, the sensor and the target has also been studied along with the configurations which can limit the visibility of the sensor over the target. The second simulation has been used to evaluate the performance of the sensor in terms of number of detectable GEO targets and duration of the observation when a certain pointing strategy is adopted. In such strategy, two SBV-like sensors are placed on the same orbit, thus creating a constellation in which each sensor points towards a fixed location in the inertial space. These locations have been chosen to be the geosynchronous pinch points.

Babylonian observations of a unique planetary configuration

In this paper, we discuss Babylonian observations of a “massing of the planets” reported in two Astronomical Diaries, BM 32562 and BM 46051. This extremely rare astronomical phenomenon was observed in Babylon between 20 and 30 March 185 BC shortly before sunrise when all five planets were simultaneously visible for about 10 to 15 min close to the horizon in the eastern morning sky. These two observational texts are not only interesting as records of an extremely rare planetary configuration, but also because (1) the observers appear to be confused by the presence of all planets simultaneously and mix them up in their reports, and (2) the two reports of the same observations are so different that we are forced to conclude that they were carried out by two different observers. There is an additional astronomical event which makes this planetary configuration even more unique: the exact conjunction of the planets Mars and Jupiter in the afternoon of 25 March 185 BC. An exact conjunction, where two planets are so close together that they appear as one object in the sky, is also extremely rare. Although this exact conjunction between Mars and Jupiter occurred during the day so that it was not observable, it was correctly predicted by the Babylonian scholars: a remarkable achievement and a nice illustration of their astronomical craftsmanship. Finally, our study clearly exposes one of the limitations of Babylonian naked-eye astronomy. When first appearances of the planets Mercury, Mars and Saturn are expected around the same date, it is nearly impossible to correctly identify them because their expected positions are only approximately known while they have about the same visual magnitude so that they become visible at about the same altitude above the horizon.

Parker Solar Probe Observations of a Dust Trail in the Orbit of 3200 Phaethon

<p>We present details on the first white-light detection of a dust trail following the orbit of asteroid 3200 Phaethon, seen in images recorded by the Wide-field Imager for Parker Solar Probe (WISPR) instrument on the NASA Parker Solar Probe (PSP) mission. In this talk we will present a brief introduction to the PSP mission and the WISPR instrument. We will then show observations returned by WISPR in multiple perihelion 'encounters' that clearly show a diffuse dust trail perfectly aligned with the perihelion portion of the orbit of 3200 Phaethon, recorded while the asteroid itself was near aphelion. We will discuss the physical parameters that we have derived for the dust trail, including its visual magnitude, surface brightness and mass. We also speculate on the relationship of this trail to the Geminid meteor shower, of which Phaethon is assumed to be the parent, and demonstrate why the trail has not been detected visually until now, despite a number of dedicated observing campaigns. We also hope to present initial analyses of the most recent set of WISPR observations (January 2020), where we anticipate the trail should again be visible in the WISPR observations.</p>

A new method of determining brightness and size of cometary nuclei

ABSTRACT This paper presents a new method of determining the brightness and size of cometary nuclei that has been applied to the following 32 observed comets: 2P/Encke, 29P/Schwassmann-Wachmann 1, 102P/Shoemaker 1, 103P/Hartley 2, 168P/Hergenrother, 189P/NEAT, 260P/McNaught, 315P/LONEOS, P/2012 NJ (La Sagra), P/2013 J2 (McNaught), C/2006 S3 (LONEOS), C/2009 P1 (Garradd), C/2010 S1 (LINEAR), C/2010 X1 (Elenin), C/2011 J2 (LINEAR), C/2011 L4 (PANSTARRS), C/2011 W3 (Lovejoy), C/2012 F6 (Lemmon), C/2012 J1 (Catalina), C/2012 K1 (PANSTARRS), C/2012 S1 (ISON), C/2013 R1 (Lovejoy), C/2013 US10 (Catalina), C/2014 B1 (Schwartz), C/2014 E2 (Jacques), C/2014 Q2 (Lovejoy), C/2015 F4 (Jacques), C/2015 V2 (Johnson), C/2015 ER61 (PANSTARRS), C/2015 VL62 (Lemmon-Yeung-PANSTARRS), C/2016 A8 (LINEAR), and C/2017 O1 (ASASSN). The method consists in fitting the exponential decay function to the measured coma brightness in the aperture radius range from 0.5 to 2 pixels, and extrapolating this function to 0 pixels to obtain nuclear brightness. The R-band absolute nuclear magnitude RN(1, 1, 0), and the logarithm of the nucleus diameter DN expressed in kilometres, follow a linear dependence with the absolute total visual magnitude H. This dependence is of the form RN(1, 1, 0) = 12.5943 + 0.648H, and log DN[km] = 1.2415 − 0.13H. Comet 2P/Encke does not fit this dependence due to its high nuclear density of 800 kg m−3 (Sosa & Fernández 2009). The mean bulk density of the observed comets (except 2P/Encke) is 453 ± 29 kg m−3. The accuracy of the method in determining the brightness of comet nuclei at a level of 1σ is 8 per cent.

HD 2685 b: a hot Jupiter orbiting an early F-type star detected by TESS

We report on the confirmation of a transiting giant planet around the relatively hot (Teff = 6801 ± 76 K) star HD 2685, whose transit signal was detected in Sector 1 data of NASA’s TESS mission. We confirmed the planetary nature of the transit signal using Doppler velocimetric measurements with CHIRON, CORALIE, and FEROS, as well as using photometric data obtained with the Chilean-Hungarian Automated Telescope and the Las Cumbres Observatory. From the joint analysis of photometry and radial velocities, we derived the following parameters for HD 2685 b: P = 4.12688−0.00004+0.00005 days, e = 0.091−0.047+0.039, MP = 1.17 ± 0.12 MJ, and RP =1.44 ± 0.05 RJ. This system is a typical example of an inflated transiting hot Jupiter in a low-eccentricity orbit. Based on the apparent visual magnitude (V = 9.6 mag) of the host star, this is one of the brightest known stars hosting a transiting hot Jupiter, and it is a good example of the upcoming systems that will be detected by TESS during the two-year primary mission. This is also an excellent target for future ground- and space-based atmospheric characterization as well as a good candidate for measuring the projected spin-orbit misalignment angle through the Rossiter–McLaughlin effect.

Applications of visual magnitude in forest planning: A case study

Recent impacts from the Mountain Pine Beetle epidemic, the lack of available timber in areas of lower elevation, and the reduction in back-country timber has pushed forest operations into publicly significant and visible landscapes. When these become the stage for operations they can be a source of public backlash. These kinds of landscapes are carefully protected by governments, yet, this protection may reduce timber availability. We have developed a new GIS-based tool to aid planners in designing harvests in these areas. Our tool is applied to three case studies in British Columbia to showcase how it can reduce planning time, increase timber availability and limit the negative visible effects of operations.