Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPositions of Pluto extracted from digitized Pulkovo photographic plates taken in 1930 - 1960
99
0
0.0
(
0
)
Authors
E.V. Khrutskaya
Ask ChatGPT about the research
No Arabic abstract
We present the results of determination of Plutos positions derived from photographic plates taken in 1930 - 1960. Observations were made with Normal Astrograph at Pulkovo Observatory. Digitization of these plates was performed with high precision scanner at Royal Observatory of Belgium (ROB Digitizer). Mean values of standard errors of plate positions (x,y) lie between 12 and 18 mas. The UCAC4 catalogue was used as an astrometric calibrator. Standard errors of equatorial coordinates obtained are within 85 to 100 mas. Final table contains 63 positions of Pluto referred to the HCRF/UCAC4 frame.
rate research
Read More
Photographic plate archives contain a wealth of information about positions and brightness celestial objects had decades ago. Plate digitization is necessary to make this information accessible, but extracting it is a technical challenge. We develop algorithms used to extract photometry with the accuracy of better than ~0.1m in the magnitude range 13<B<17 from photographic images obtained in 1948-1996 with the 40cm Sternberg institutes astrograph (30x30cm plate size, 10x10deg field of view) and digitized using a flatbed scanner. The extracted photographic lightcurves are used to identify thousands of new high-amplitude (>0.2m) variable stars. The algorithms are implemented in the free software VaST available at http://scan.sai.msu.ru/vast/
We identify 339 known and 316 new variable stars of various types among 250000 lightcurves obtained by digitizing 167 30x30cm photographic plates of the Moscow collection. We use these data to conduct a comprehensive test of 18 statistical characteristics (variability indices) in search for the best general-purpose variability detection statistic. We find that the highest peak on the DFT periodogram, interquartile range, median absolute deviation, and Stetsons L index are the most efficient in recovering variable objects from the set of photographic lightcurves used in our test.
At the Hamburger Sternwarte an effort was started in 2010 with the aim of digitizing its more than 45000 photographic plates and films stored in its plate archives. At the time of writing, more than 31000 plates have already been made available on the Internet for researchers, historians, as well as for the interested public. The digitization process and the Internet presentation of the plates and accompanying hand written material (plate envelopes, logbooks, observer notes) are presented here. To fully exploit the unique photometric and astrometric data, stored on the plates, further processing steps are required including registering the plate to celestial coordinates, masking of the plates, and a calibration of the photo-emulsion darkening curve. To demonstrate the correct functioning of these procedures, historical light curves of two bright BL Lac type active galactic nuclei are extracted. The resulting light curve of the blazar 1ES 1215+303 exhibits a large decrease in the magnitude from $14.25^{+0.07}_{-0.12}$ to $15.94^{+0.09}_{-0.13}$ in about 300 days, which proves the variability in the optical region. Furthermore, we compare the measured magnitudes for the quasar 3C~273 with contemporaneous measurements.
Online Digital Sky Survey (DSS) material is often used to obtain information on newly discovered variable stars for older epochs (e.g. Nova progenitors, flare stars, ...). We present here the results of an investigation of photometry on online digital sky survey material in small fields calibrated by CCD sequences. We compared different source extraction mechanisms and found, that even down near to the sensitivity limit, despite the H-compression used for the online material, photometry with an accuracy better than 0fm1 rms is possible on DSS-II. Our investigation shows that the accuracy depends strongly on the source extraction method. The SuperCOSMOS scans, although retrieved with an higher spatial resolution, do not give us better results. The methods and parameters presented here, allow the user to obtain good plate photometry in small fields down to the Schmidt plate survey limits with a few bright CCD calibrators, which may be calibrated with amateur size telescopes. Especially for the events mentioned above, new field photometry for calibration purposes mostly exists, but the progenitors were not measured photometrically before. Also the follow up whether stellar concentrations are newly detected clusters or similar work may be done without using mid size telescopes. The calibration presented here is a local one for small fields. We show that this method presented here gives higher accuracies than global calibrations of surveys (e.g. GSC-II, SuperCOSMOS and USNO-B)
Context. The 16 Myr old star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a series of complex eclipses in May 2007, interpreted as the transit of a giant Hill sphere filling debris ring system around a secondary companion, J1407b. No other eclipses have since been detected, although other measurements have constrained but not uniquely determined the orbital period of J1407b. Finding another eclipse towards J1407 will help determine the orbital period of the system, the geometry of the proposed ring system and enable planning of further observations to characterize the material within these putative rings. Aims. We carry out a search for other eclipses in photometric data of J1407 with the aim of constraining the orbital period of J1407b. Methods. We present photometry from archival photographic plates from the Harvard DASCH survey, and Bamberg and Sonneberg Observatories, in order to place additional constraints on the orbital period of J1407b by searching for other dimming and eclipse events. Using a visual inspection of all 387 plates and a period-folding algorithm we performed a search for other eclipses in these data sets. Results. We find no other deep eclipses in the data spanning from 1890 to 1990, nor in recent time-series photometry from 2012-2018. Conclusions. We rule out a large fraction of putative orbital periods for J1407b from 5 to 20 years. These limits are still marginally consistent with a large Hill sphere filling ring system surrounding a brown dwarf companion in a bound elliptical orbit about J1407. Issues with the stability of any rings combined with the lack of detection of another eclipse, suggests that J1407b may not be bound to J1407.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
