共查询到20条相似文献，搜索用时 24 毫秒
1.
《New Astronomy》2016
High accuracy scanned sunspot drawings handwritten characters recognition is an issue of critical importance to analyze sunspots movement and store them in the database. This paper presents a robust deep learning method for scanned sunspot drawings handwritten characters recognition. The convolution neural network (CNN) is one algorithm of deep learning which is truly successful in training of multi-layer network structure. CNN is used to train recognition model of handwritten character images which are extracted from the original sunspot drawings. We demonstrate the advantages of the proposed method on sunspot drawings provided by Chinese Academy Yunnan Observatory and obtain the daily full-disc sunspot numbers and sunspot areas from the sunspot drawings. The experimental results show that the proposed method achieves a high recognition accurate rate. 相似文献
2.
R. Arlt 《Solar physics》2008,247(2):399-410
Original drawings by J.C. Staudacher made in the period of 1749 – 1796 were digitized. The drawings provide information about
the size of the sunspots and are therefore useful for analyses sensitive to sunspot area rather than Wolf numbers. The total
sunspot area as a function of time is shown for the observing period. The sunspot areas measured do not support the proposition
of a weak, “lost” cycle between cycles 4 and 5. We also evaluate the usefulness of the drawings for the determination of sunspot
positions for future studies. 相似文献
3.
T. Baranyi L. Gyori A. Ludmány H. E. Coffey 《Monthly notices of the Royal Astronomical Society》2001,323(1):223-230
Sunspot area measurements play an important role in the studies of sunspot groups and variations in solar irradiance. However, the measured areas may be burdened with systematic and random errors, which may affect the results in these fields. Mainly the total solar irradiance models can be improved by using more precise area data. In order to choose the most appropriate area data for a given study or create a homogeneous composite area data base, there is a need to compare the sunspot areas provided by different observatories. In this study we statistically investigated all the available corrected sunspot area data bases for the years 1986 and 1987. We find that the photographic data bases are in good agreement with each other but there are important systematic differences between the photographic and sunspot drawings data bases. We give the characteristic parameters for the systematic and random errors as well as the possible reasons for them. 相似文献
4.
5.
Sunspot records in the seventeenth century provide important information on the solar activity before the Maunder minimum, yielding reliable sunspot indices and the solar butterfly diagram. Galilei’s letters to Cardinal Francesco Barberini and Marcus Welser contain daily solar observations on 3?–?11 May, 2 June?–?8 July, and 19?–?21 August 1612. These historical archives do not provide the time of observation, which results in uncertainty in the sunspot coordinates. To obtain them, we present a method that minimizes the discrepancy between the sunspot latitudes. We provide areas and heliographic coordinates of 82 sunspot groups. In contrast to Sheiner’s butterfly diagram, we found only one sunspot group near the Equator. This provides a higher reliability of Galilei’s drawings. Large sunspot groups are found to emerge at the same longitude in the northern hemisphere from 3 May to 21 August, which indicates an active longitude. 相似文献
6.
We address recent concerns that the sunspot-area measurements performed by the United States Air Force (USAF) Solar Observing Optical Network (SOON) have been underestimating sunspot areas. We examine briefly the history of SOON, and we perform an analysis of a three-decade time series of SOON measurements. By remeasuring USAF sunspot areas, we find that sunspot areas are being underestimated by between 8% and 17% due to the measuring techniques employed by SOON analysts. In particular, the SOON practice of rounding down limb-area correction factors results in some individual regions having areas reported by up to 50% less than their true values. This does not, however, account for the full discrepancy in sunspot areas between SOON and other observatories, which, in recent years, may be as high as a 50% discrepancy. 相似文献
7.
Although W. Brunner began to weight sunspot counts (from 1926), using a method whereby larger spots were counted more than once, he compensated for the weighting by not counting enough smaller spots in order to maintain the same reduction factor (0.6) as was used by his predecessor A. Wolfer to reduce the count to R. Wolf’s original scale, so that the weighting did not have any effect on the scale of the sunspot number. In 1947, M. Waldmeier formalized the weighting (on a scale from 1 to 5) of the sunspot count made at Zurich and its auxiliary station Locarno. This explicit counting method, when followed, inflates the relative sunspot number over that which corresponds to the scale set by Wolfer (and matched by Brunner). Recounting some 60,000 sunspots on drawings from the reference station Locarno shows that the number of sunspots reported was “over counted” by \({\approx}\,44~\%\) on average, leading to an inflation (measured by an effective weight factor) in excess of 1.2 for high solar activity. In a double-blind parallel counting by the Locarno observer M. Cagnotti, we determined that Svalgaard’s count closely matches that of Cagnotti, allowing us to determine from direct observation the daily weight factor for spots since 2003 (and sporadically before). The effective total inflation turns out to have two sources: a major one (15?–?18 %) caused by weighting of spots, and a minor source (4?–?5 %) caused by the introduction of the Zürich classification of sunspot groups which increases the group count by 7?–?8 % and the relative sunspot number by about half that. We find that a simple empirical equation (depending on the activity level) fits the observed factors well, and use that fit to estimate the weighting inflation factor for each month back to the introduction of effective inflation in 1947 and thus to be able to correct for the over-counts and to reduce sunspot counting to the Wolfer method in use from 1894 onwards. 相似文献
8.
Most of our knowledge about the Sun's activity cycle arises from sunspot observations over the last centuries since telescopes have been used for astronomy. The German astronomer Gustav Spörer observed almost daily the Sun from 1861 until the beginning of 1894 and assembled a 33‐year collection of sunspot data covering a total of 445 solar rotation periods. These sunspot drawings were carefully placed on an equidistant grid of heliographic longitude and latitude for each rotation period, which were then copied to copper plates for a lithographic reproduction of the drawings in astronomical journals. In this article, we describe in detail the process of capturing these data as digital images, correcting for various effects of the aging print materials, and preparing the data for contemporary scientific analysis based on advanced image processing techniques. With the processed data we create a butterfly diagram aggregating sunspot areas, and we present methods to measure the size of sunspots (umbra and penumbra) and to determine tilt angles of active regions. A probability density function of the sunspot area is computed, which conforms to contemporary data after rescaling. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
T. Baranyi 《Solar physics》2018,293(10):142
We investigate the spatial and temporal variation of sunspot group areas reported by the Greenwich Photoheliographic Results (GPR), the Solar Optical Observing Network (SOON), the Kislovodsk Mountain Astronomical Station (KMAS), and the Debrecen Photoheliographic Data (DPD) databases. We identify improved correction factors for reconciling these individual records to a common scale. Our results show that the DPD sunspot group areas are stable over the studied interval (1974?–?2014). We find an improved fit between GPR and DPD sunspot group areas when using a correction factor such that \(\mathrm{GPR} = 0.975(\pm 0.006) \times \mathrm{DPD}\), independent of the position of the sunspot group on the solar disk. We also find that the scale of KMAS sunspot group areas fits that of DPD well, but has a small position-dependent trend near the limb. However, in order to set SOON sunspot group area records onto the scale of DPD, we find that there is a need for a multivariate correction factor. This multivariate correction factor has a value ranging between 1.1 and 1.9 and is dependent upon the time of the SOON observation, the distance of the group from disk center, and the observatory within the SOON network. Finally, we provide further context to the systematic bias in SOON sunspot group area observations toward lower values relative to those recorded in the GPR and DPD databases that has previously been reported in the literature. We have identified the two main contributors to the SOON area deficit; some penumbral parts are unobserved, and the spot areas are underestimated. Our analysis is vital for studies that require stable, long-term solar activity records such as solar irradiance models that estimate irradiance reduction from records of sunspot group numbers, areas, and locations. 相似文献
10.
In the 19th century De la Rue, Stewart, and Loewy carried out a compilation of drawings and photographs of the solar sunspots in the period 1832–1868. From these drawings and photographs, they determined fortnightly values of the sunspot areas. In this work, monthly values of the sunspot areas for the period 1832–1868 are calculated and the reliability of these data in terms of the solar activity indices is discussed. 相似文献
11.
Zdeněk Kopal 《Earth, Moon, and Planets》1969,1(1):59-66
The aim of the present paper is to give a brief account of the history of lunar mapping in the pre-telescopic era, and that immediately following the discovery of the telescope. It is pointed out that the first (and also last) extant map of the Moon based on naked-eye observations was prepared some time before 1603 by William Gilbert - discoverer of the terrestrial magnetism - though it was published only posthumously in 1651. Moreover, the recently unearthed drawings of the Moon by Thomas Harriott in England based on telescope observations between 1609 and 1610 are in no way inferior (if not otherwise) than those published by Galileo Galilei at the same time. As G. C. La Galla's drawings of the Moon published in Venice in 1612 are in reality identical with those of Galileo, the third independent contribution to lunar mapping was made by P. Christoph Scheiner in Germany between 1611 and 1613; preceding those by C. Malapert (1916) or Gassendi and Mellan more than twenty years later. 相似文献
12.
When drawing up a database for sunspots from a large collection of white-light films, a need for the automation of the process arises. The concepts used at the automation of the area measurements of sunspots are described. As an example, sunspot groups NOAA 5521 and 5528 are processed and the areas obtained are compared to the measurements published in the literature. Similar values are obtained, except umbral areas published by Steinegger et al. (1996) which are significantly larger than ours. We find that the differences may be attributed to the fact that the definition proposed by Steinegger et al. (1996) for the penumbra–umbra border of a sunspot is not equivalent to those used for the measurements of others of the umbral area. 相似文献
13.
Christian Horrebow and his colleagues of Copenhagen, Denmark, actively observed sunspots from 1761 to 1777. These observations were examined by Thiele in 1859 and by d'Arrest in 1873 with markedly different conclusions. Thiele reported nearly twice as many sunspot groups as d'Arrest. To resolve this discrepancy, we have reexamined Horrebow's original notebooks. We find slightly more sunspot groups then did d'Arrest. Thiele apparently called individual sunspots sunspot groups, so he would call a bipolar group two groups. d'Arrest seems to have missed counting some of the smaller sunspot groups. A correct interpretation of Horrebow's observations is required in efforts to reconstruct solar activity. Wolf gave a sunspot number for 1769 of 106.1. On the basis of our re-examination of Horrebow's drawings and other observers, we deduce a sunspot number of about 80.5 for 1769. 相似文献
14.
We perform a nonlinear study of the short-term correlation properties of the solar activity (daily range) in order to reveal
their long-life variations. We estimate the lifetime of the high-frequency component of a Markov-type signal when the high-frequency
component is modulated by a slowly varying multiplicative factor. This treatment is applied to different series of solar activity:
Wolf Sunspot numbers (WSN), Sunspot Group numbers (SGN), and Royal Greenwich Observatory (RGO) sunspot group series. We obtain
that all the lifetime estimates exhibit similar temporal variations that agree with the variations of the sunspot lifetimes
directly measured from the RGO data and those of the sunspot areas. An increase of lifetimes by a factor 1.4 is observed from
1915 to 1940. At the same time, a stable ratio is observed between the sunspot group’s maximal area and the lifetime, confirming
the Gnevyshev–Waldmeier-type relationship. The analysis identifies also time intervals where the homogeneity of the different
time series may be questioned. 相似文献
15.
16.
Ksenia Tlatova Andrey Tlatov Alexei Pevtsov Kalevi Mursula Valeria Vasil’eva Elina Heikkinen Luca Bertello Alexander Pevtsov Ilpo Virtanen Nina Karachik 《Solar physics》2018,293(8):118
We use recently digitized sunspot drawings from Mount Wilson Observatory to investigate the latitudinal dependence of tilt angles of active regions and its change with solar cycle. The drawings cover the period from 1917 to present and contain information as regards polarity and strength of magnetic field in sunspots. We identified clusters of sunspots of same polarity, and used these clusters to form “bipole pairs”. The orientation of these bipole pairs was used to measure their tilts. We find that the latitudinal profile of tilts does not monotonically increase with latitude as most previous studies assumed, but instead, it shows a clear maximum at about 25?–?30 degree latitudes. Functional dependence of tilt (\(\gamma\)) on latitude (\(\varphi\)) was found to be \(\gamma= (0.20\pm0.08) \sin(2.80 \varphi) + (-0.00\pm0.06)\). We also find that latitudinal dependence of tilts varies from one solar cycle to another, but larger tilts do not seem to result in stronger solar cycles. Finally, we find the presence of a systematic offset in tilt of active regions (non-zero tilts at the equator), with odd cycles exhibiting negative offset and even cycles showing the positive offset. 相似文献
17.
Full-disk white light images of the Sun have been digitized, calibrated, and examined to determine objective sunspot areas for the early part of the operation of the Solar Maximum Mission satellite. We find that published sunspot areas determined from synoptic programs compare favorably with our digital areas. The mean residual between published areas and our digital areas is approximately 80 millionths of a hemisphere. The largest residual found is 642 millionths on April 1980 for Hale No. 16752. 相似文献
18.
V. M. S. Carrasco J. M. Vaquero M. C. Gallego A. Lourenço T. Barata J. M. Fernandes 《Solar physics》2018,293(11):153
A sunspot catalogue was published by the Coimbra Astronomical Observatory (Portugal), which is now called the Geophysical and Astronomical Observatory of the University of Coimbra, for the period 1929?–?1941. We digitalised data included in that catalogue and provide a machine-readable version. We show the reconstructions for the (total and hemispheric) sunspot number index and sunspot area according to this catalogue and compare it with the sunspot number index (version 2) and the Balmaceda sunspot area series (Balmaceda et al. in J. Geophys. Res.114, A07104, 2009). Moreover, we also compared the Coimbra catalogue with records made at the Royal Greenwich Observatory. The results demonstrate that the historical catalogue compiled by the Coimbra Astronomical Observatory contains reliable sunspot data and can therefore be considered for studies about solar activity. 相似文献
19.
R. Arlt 《Solar physics》2009,255(1):143-153
Digitized images of the drawings by J.C. Staudacher were used to determine sunspot positions for the period 1749 – 1796. From
the entire set of drawings, 6285 sunspot positions were obtained for a total of 999 days. Various methods have been applied
to find the orientation of the solar disk, which is not given for the vast majority of the drawings by Staudacher. Heliographic
latitudes and longitudes in the Carrington rotation frame were determined. The resulting butterfly diagram shows a highly-populated
Equator during the first two cycles (cycles 0 and 1 in the usual counting since 1749). An intermediate period is cycle 2,
whereas cycles 3 and 4 show a typical butterfly shape. A tentative explanation may be the transient dominance of a quadrupolar
magnetic field during the first two cycles. 相似文献
20.
The ratio of penumbral to umbral area of sunspots is an important topic for solar and geophysical studies. Hathaway (Solar Phys.286, 347, 2013) found a curious behaviour in this parameter for small sunspot groups (areas smaller than 100 millionths of solar hemisphere, msh) using records from Royal Greenwich Observatory (RGO). Hathaway showed that the penumbra–umbra ratio decreased smoothly from more than 7 in 1905 to lower than 3 by 1930 and then increased to almost 8 in 1961. Thus, Hathaway proposed the existence of a secular variation in the penumbra–umbra area ratio. In order to confirm that secular variation, we employ data of the sunspot catalogue published by the Coimbra Astronomical Observatory (COI) for the period 1929?–?1941. Our results disagree with the penumbra–umbra ratio found by Hathaway for that period. However, the behaviour of this ratio for large (areas greater or equal than 100 msh) and small groups registered in COI during 1929?–?1941 is similar to data available from RGO for the periods 1874?–?1914 and 1950?–?1976. Nevertheless, while the average values and time evolution of the ratio in large groups are similar those for small groups according to the Coimbra data (1929?–?1941) it is not analogous for RGO data for the same period. We also found that the behaviour of the penumbra–umbra area ratio for smaller groups in both observatories is significantly different. The main difference between the area measurements made in Coimbra and RGO is associated with the umbra measurements. We would like to stress that the two observatories used different methods of observation and while in COI both methodology and instruments did not change during the study period, some changes were carried out in RGO that could have affected measurements of umbra and penumbra. These facts illustrate the importance of the careful recovery of past solar data. 相似文献