Potential of Astrographic Plates for Stellar Flare Detection

Fresneau, A.; Argyle, R. W.; Marino, G.; Messina, S.

doi:10.1086/318020

Cited by 10 publications

(11 citation statements)

References 24 publications

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“…1: stars are identified in the image inventory of a plate scanned with APM by the combination of double images. Along with the x, y plate mean coordinates (in mm) and their errors ∆x, ∆y (in microns), an indication of short term magnitude variability ∆m, is also computed for each star: this information is not available from the AC measurements but is usable to search for flare stars (Fresneau et al 2001). The (ξ, η) plate coordinates (in arcmin) for the Tycho-2 stars …”

mentioning

confidence: 99%

Sydney observatory Galactic survey

Fresneau¹,

Vaughan²,

Argyle³

2007

A&A

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Context. First Epoch astrometric and radiometric information of a survey in the optical along the Galactic fourth quadrant is archived for further analysis in the time-domain. Aims. A photographic survey of 1.9 × 10 6 stars down to B-magnitude 14 ± 0.5 along the galactic meridian l = (330 ± 5)• , −64• ≤ b ≤ −7• and along the galactic equator 272• , is provided from century old astrographic plates of Sydney Observatory. Stellar candidates to investigate the Galaxy disk kinematics up to a distance of 1 kpc from the Sun are tentatively selected. Methods. The early data are combined with late epoch observations into a set of 4.8 × 10 5 stars with significant proper motion µ ≥ 0.005 yr −1 and approximate color B − V. The selection effects and the kinematical bias on the stellar system are investigated. F-G stellar candidates with a mean transverse velocity dispersion of 45 km s −1 are suggested. Results. The spin rate of 1 2• pc −1 of the velocity ellipsoid along its long axis is observed over half a thickness of 25 pc of the galactic disk for stars at an estimated distance D ≤ 300 pc from the Sun. Conclusions. A catalogue of 4.8 × 10 5 stars is provided for further investigation of the galactic disk heating by transient spiral wave or by GMC encounter.Key words. surveys -stars: kinematics Retrospective of early astrographic surveysFirst epoch observations used in the proper motion (p.m.) determination of faint stars observed in the Tycho-2 catalogue are based on short exposure plates observed for the Astrographic Catalog (AC) at the beginning of the 20th century over a field of view of 2• × 2 • for each of the 4 × 10 4 AC plates at a scale of 1 mm −1 , proving that photographic observations from the past were indeed durable even at the time of space astrometry (Urban et al. 1998). In order to check the quality of the old plates with a fast measuring machine like APM, used for instance to scan large Schmidt plates (Evans 1992), a set of 104 short exposure plates dating from the late 19th century was selected from the plate vault of Sydney Observatory, archived at Macquarie University.The double exposure technique used in the astrophotographic survey is shown in Fig. 1: stars are identified in the image inventory of a plate scanned with APM by the combination of double images. Along with the x, y plate mean coordinates (in mm) and their errors ∆x, ∆y (in microns), an indication of short term magnitude variability ∆m, is also computed for each star: this information is not available from the AC measurements but is usable to search for flare stars (Fresneau et al. 2001). The (ξ, η) plate coordinates (in arcmin) for the Tycho-2 stars The quality of the best linear unbiased estimation of the set of 12 plate constants (A, B, C, D, E, F and A , B , C , D , E , F ) after the weighted least squares fit is measured by the rms error σ T between the computed and observed equatorial coordinates of the set of Tycho-2 stars (a couple of hundreds per 2 • × 2 • field of view). The same stars are also used to derive a calibrat...

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confidence: 99%

Sydney observatory Galactic survey

Fresneau¹,

Vaughan²,

Argyle³

2007

A&A

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“…Thus, this work is essentially just an exploratory analysis to see what might be extracted from data obtained from a photographic survey that was intended exclusively for charting purposes. Confirmation and understanding of our tentative findings will need follow-up observations (Fresneau et al 2001).…”

Section: Does the Vsc Reveal Any True Interesting Behavior?mentioning

confidence: 65%

“…This is consistent with observations (Gautschy & Saio 1995, 1996. We note that we rediscover that stellar flaring candidates should be searched for in the region (B − V) 0 ≥ 1.2 and M B ≥ 5 (Fresneau et al 2001). We must keep in mind that these are statistical results and merely suggest the types of stars in our sample that appear to be the best candidates for follow up studies.…”

Section: Stellar Variability Information In the Vscmentioning

confidence: 90%

A variability sample catalogue selected from the Sydney Observatory Galactic Survey

Fresneau

Osborn²

2009

A&A

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Context. A set of 55 × 10 3 stars brighter than about B-magnitude 14 and having at least three observations are identified in the Sydney Observatory Galactic Survey, carried out over the years 1892-1932 along the galactic equator section l ∈ [275. Short-term (30 min) and long-term (decades) magnitude variations in the data set are analyzed. Aims. Evidence is sought for a correlation between short-term and long-term variabilities which would identify stars in a non-quiescent phase. Methods. We use a reduced proper motion diagram to classify the stars in our sample into probable dwarfs, giants and other types. The validity of the kinematical classification is checked using objective-prism spectroscopic classification for 10 × 10 3 early-type stars. A search is made for statistical correlations between our variability indicators and physical and kinematical stellar properties. Results. We find that suspected photospheric activity for giant and dwarf stellar candidates is correlated with the time to cross the galactic thin disk. We estimate a significant apparent B-magnitude variation of ±0.25 over the 40 years of photographic observations, and candidates for monitoring for possible photospheric activity at the present time are selected employing a statistical colour-diagram which uses the total proper motion component as a distance indicator. Conclusions. Follow up studies of our tentative findings are suggested. Toward this aim the derived data for the set of 55 × 10 3 stars with variability information is archived as the variability Sample Catalogue. The data for a set of 2.4 × 10 5 stars along the section of the galactic equator l ∈ [275 • , 335 • ], |b| ≤ 7 • , and a set of of 1.7 × 10 5 stars along the section of the galactic meridian 330 • ± 5 • , b ∈ [−64 • , −7 • ] is also archived as a quick-look facility for seeking long-term magnitude changes since the century-old photographic observations were obtained.

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“…The CdC plates continue to be used for proper motion determinations with standard errors of about 100 to 120 mas on the positions according to Rapaport et al (2006), and the positional precision at the mean epoch ranges from 50 to 70 mas according to Ducourant et al (2006), as well as in stellar clusters with astrometric accuracy ranges from 100 to 200 mas (Geffert et al 1996) or discoveries of quick brightness changes (time scales up to 20 min and amplitudes larger than 0.5 mag) in stars with brightness in the photographic range 10-14 mag (Fresneau et al 2001). According to Vicente et al (2007) on the base of the 420 CdC plates, digitized with flatbed scanner, a measuring accuracy of 200 mas is achieved, which demonstrate the potential of this flatbedscanning.…”

Section: The Cdc Plate Potentialmentioning

confidence: 99%

“…The plates are considered to be reasonable firstepoch material for astrometric studies. That was the reason for the digitization of such plate collections in the observatories in Sydney (Fresneau et al 2001(Fresneau et al , 2003(Fresneau et al , 2005(Fresneau et al , 2007, Toulouse (Lamareille et al 2003), Cordoba (Bustos Fierro & Calderon 2003;Calderon et al 2004), Bordeaux Rapaport et al 2006), Uccle (Tsvetkova et al 2007), and San Fernando (Vicente et al 2007). In order to enable the present and future use of the CdC plates we undertook an inventory of the Potsdam…”

Section: Introductionmentioning

confidence: 99%

The Potsdam plates of the Carte du Ciel project: I. Present inventory and plate catalogue

et al. 2009

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We present an inventory ofthe Carte du Ciel (CdC) plates stored in the Astrophysical Institute Potsdam. The Potsdam CdC zone (+32° to +39°) was divided into 1232 areas and about 2200 plates from the first and second epochs were obtained within the framework of the CdC project. At present, only 977 plates (45% of all) are stored in AIP, the others got lost during the Second World War. The plates for the first epoch measurements had been obtained during the period 1893 May– 1900 February. The plates for the second epoch (1913 August–1924 February) can be separated into two time intervals according to the observer and the observing method used: from 1913 August till 1914 July, and from 1916 February to 1924 February. The present work aims to provide online access to the plate information, given in the plate catalogue and is the first step to online access to the plate images digitized with flatbed scanners.

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Potential of Astrographic Plates for Stellar Flare Detection

Cited by 10 publications

References 24 publications

Sydney observatory Galactic survey

Sydney observatory Galactic survey

A variability sample catalogue selected from the Sydney Observatory Galactic Survey

The Potsdam plates of the Carte du Ciel project: I. Present inventory and plate catalogue

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