Separation (\(\rho\)) and Position Angle (PA) measurements are reported of 10 pairs which measures where last reported in the WDS +20 years from epoch of observation 2021.066. Measurements were ...obtained by direct imaging and are presented with associated measurement uncertainties, as well as, comparisons to measurements determined from Gaia DR2 & EDR3 and historic data extrapolation at epoch of J2000.0.
Presented here is list of 50 pairs quasi-evenly spaced over the northern sky, and that have Separations and Position Angles accurate at the milli-arcsec, and milli-degree level. These pairs are ...suggested as calibration pairs for lucky imaging observations. This paper is a follow-up to our previous paper regarding southern sky calibration pairs.
Accurate measures of double stars require accurate calibration of the instrument. Here we present a list of 50 pairs, that are quasi-evenly spaced over the southern sky, and that have Separations and ...Position Angles accurate at the milli-arcsec, and milli-degree level. These wide angle pairs are suggested as calibration pairs for lucky imaging observations.
We compared several techniques for calibrating angular separation between wide (>1 arcsec) pairs. These techniques are (i) reference pair calibration using {\alpha} Cen AB orbital parameters, (ii) ...the video drift method, and (iii) the utilisation of an aperture diffraction grating with red filters of different passbands. Separations of 62 pairs were determined using these 3 calibration techniques and compared. It was found that {\alpha} Cen AB and video drift methods are in good agreement. The use of the grating and filter (by measuring fringe spacing) proved unsatisfactory for the broad-band filters, and the use of a narrow band H{\alpha} filter with the grating, resulted in image scales that differed from those obtained using {\alpha} Cen AB reference pair calibration and the video drift method by 0.024 and 0.031 pixel/arcsec (px/arcsec) respectively. A more complete modelling of Fraunhofer diffraction of the H{\alpha} filter and grating produced a difference in image scale of 0.009 px/arcsec. A bias in the diffraction grating method of ~0.1% in the separation of pairs also revealed itself and could not be accounted for. We conclude that calibration against a known pair for which the separation and PA is known with high precision is probably the simplest and best way to undertake image scale calibration.
Measures of 62 Southern Pairs James, Matthew; Letchford, Rod; White, Graeme L ...
arXiv.org,
03/2020
Paper, Journal Article
Odprti dostop
We report lucky imaging observations of 62 pairs at mid-southern declinations sourced from the WDS with separations larger than 4 arc seconds and magnitude less than 10. The measures comprise ...separations and PA calibrated against Alpha Centauri AB and drift scans, presented as weighted means of these two calibration methods, with formal internal uncertainties \delta\rho = 80 mas and \delta PA = 0.056(deg). We also compare our measures against 1) extrapolated historic measures, 2) GAIA DR2 data and 3) measures determined from HIPPARCOS and GAIA observations. Our best estimate of our bias against these 3 databases are \rho \approx 10 \pm 30 mas and PA \approx 0.04 \pm 0.08(deg). These formal uncertainties are consistent with the internal uncertainties of \delta\rho = 80 mas and \delta PA = 0.056(deg). We also report Rectilinear Elements for 61 pairs, Grade 5 Orbital Elements for 5 pairs and suggest 5 pairs as optical doubles (4 of which are new).
We present light curves and flares from a seven day, multi-wavelength observational campaign of AU Mic, a young and active dM1e star with exoplanets and a debris disk. We report on 73 unique flares ...between the X-ray to optical data. We use high-time resolution NUV photometry and soft X-ray (SXR) data from XMM-Newton to study the empirical Neupert effect, which correlates the gradual and impulsive phase flaring emissions. We find that 65% (30 of 46) flares do not follow the Neupert effect, which is three times more excursions than seen in solar flares, and propose a four part Neupert effect classification (Neupert, Quasi-Neupert, Non-Neupert I & II) to explain the multi-wavelength responses. While the SXR emission generally lags behind the NUV as expected from the chromospheric evaporation flare models, the Neupert effect is more prevalent in larger, more impulsive flares. Preliminary flaring rate analysis with X-ray and U-band data suggests that previously estimated energy ratios hold for a collection of flares observed over the same time period, but not necessarily for an individual, multi-wavelength flare. These results imply that one model cannot explain all stellar flares and care should be taken when extrapolating between wavelength regimes. Future work will expand wavelength coverage using radio data to constrain the nonthermal empirical and theoretical Neupert effects to better refine models and bridge the gap between stellar and solar flare physics.
We present measures for 10 pairs in the constellation of Scorpius using a C14 telescope, Lucky Imaging, and the Reduc software. The separations of Alpha Centauri AB, as determined from the orbital ...elements of Pourbaix and Boffin (2016), were used as an image scale and position angle calibrator. Our internal uncertainties are ~0.06 arcsec in rho and ~0.06 degree in PA. There is excellent agreement with historic data extrapolated to epoch of observation (~2018.53), and micro-arcsecond positions from the GAIA database where the differences are ~0.05 arcsec in rho and ~0.15 degrees in PA. In addition, we present rectilinear elements for the 10 Sco pairs and orbital elements for two of them. Ephemera are given for these pairs based on both the rectilinear elements and the orbital elements.
An International Asteroid Search Campaign Miller, J. Patrick; Davis, Jeffrey W.; Holmes, Robert E. ...
Astronomy education review,
02/2008, Letnik:
7, Številka:
1
Journal Article
The International Asteroid Search Campaign (IASC, fondly nicknamed "Isaac") is an Internet-based program for high schools and colleges. Within hours of acquisition, astronomical CCD images are made ...available via the Internet to participating schools around the world. Under the guidance of their teachers, students analyze the images with free software tools, searching for new asteroids and confirmations of near-Earth objects (NEOs). These discoveries are reported to the Minor Planet Center (MPC; Smithsonian Astrophysical Observatory, Harvard), which gives the students published recognition in its MPC circulars. To date, 36 new Main Belt asteroids have been found in one year, and 197 NEOs confirmed. (Contains 11 figures, 5 tables and 1 note.)
Using a global network of small telescopes, we have obtained light curves of Proxima Centauri at 329 observation epochs from 2006 - 2017. The planet Proxima b discovered by Anglada-Escude et al. ...(2016) with an orbital period of 11.186 d has an a priori transit probability of ~1.5%; if it transits, the predicted transit depth is about 5 millimagnitudes. In Blank et al. (2018), we analyzed 96 of our light curves that overlapped with predicted transit ephemerides from previously published tentative transit detections, and found no evidence in our data that would corroborate claims of transits with a period of 11.186 d. Here we broaden our analysis, using 262 high-quality light curves from our data set to search for any periodic transit-like events over a range of periods from 1 - 30 d. We also inject a series of simulated planet transits and find that our data are sufficiently sensitive to have detected transits of 5 millimagnitude depth, with recoverability ranging from ~100% for an orbital period of 1 d to ~20% for an orbital period of 20 d for the parameter spaces tested. Specifically at the 11.186 d period and 5 millimagnitude transit depth, we rule out transits in our data with high confidence. We are able to rule out virtually all transits of other planets at periods shorter than 5 d and depths greater than 3 millimagnitudes; however, we cannot confidently rule out transits at the period of Proxima b due to incomplete orbital phase coverage and a lack of sensitivity to transits shallower than 4 millimagnitudes.
