J/AJ/149/22 Astrometry of Pluto from 1930-1951 observations (Buie+, 2015)
Astrometry of Pluto from 1930-1951 observations: the Lampland plate collection.
Buie M.W., Folkner W.M.
<Astron. J., 149, 22 (2015)>
=2015AJ....149...22B 2015AJ....149...22B
ADC_Keywords: Minor planets ; Positional data
Keywords: astrometry - ephemerides - Kuiper belt objects: individual: Pluto -
planets and satellites: individual: Pluto
Abstract:
We present a new analysis of 843 photographic plates of Pluto taken by
Carl Lampland at Lowell Observatory from 1930-1951. This large
collection of plates contains useful astrometric information that
improves our knowledge of Pluto's orbit. This improvement provides
critical support to the impending flyby of Pluto by New Horizons. New
Horizons can do inbound navigation of the system to improve its
targeting. This navigation is capable of nearly eliminating the
sky-plane errors but can do little to constrain the time of closest
approach. Thus the focus on this work was to better determine Pluto's
heliocentric distance and to determine the uncertainty on that
distance with a particular eye to eliminating systematic errors that
might have been previously unrecognized. This work adds 596 new
astrometric measurements based on the USNO CCD Astrograph Catalog 4.
With the addition of these data the uncertainty of the estimated
heliocentric position of Pluto in Developmental Ephemerides 432
(DE432) is at the level of 1000km. This new analysis gives us more
confidence that these estimations are accurate and are sufficient to
support a successful flyby of Pluto by New Horizons.
Description:
We present a new analysis of 843 photographic plates of Pluto taken by
Carl Lampland at Lowell Observatory from 1930-1951.
All of the Lampland plates were taken with the Lowell Observatory
40inch reflector. This facility was located on the main observatory
grounds in Flagstaff. The telescope was an f/6 reflector with a
Newtonian optical design.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 97 596 Pluto astrometry
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See also:
VI/88 : Ephemerides of Pluto (PLUTO95) (Chapront+ 1995)
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
J/A+A/570/A86 : Pluto astrometry from 19yrs observations
(Benedetti-Rossi+, 2014)
J/A+A/553/A14 : Pluto's observations between 1997 and 2010 (Beauvalet+, 2013)
J/A+A/515/A32 : Pluto, Charon, Nix, Hydra occultations 2008-15 (Assafin+ 2010)
J/A+A/486/613 : Observation of Pluto (Veiga+, 2008)
J/A+A/383/1054 : Astrometry of Pluto and Saturn in 1995-2001 (Rapaport+, 2002)
J/A+AS/118/105 : Pluto 1991-1994 observations (Ryl'kov+, 1996)
http://www.lowell.edu/ : Lowell Observatory
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- File File name of the archived scan image at
Lowell Observatory (1)
14- 23 A10 "Y:M:D" Obs.date UTC date of the middle of the exposure
25- 32 A8 "h:m:s" Obs.time UTC time of the middle of the exposure
34- 35 I2 h RAh Hour of Right Ascension (J2000) (2)
37- 38 I2 min RAm Minute of Right Ascension (J2000) (2)
40- 45 F6.3 s RAs Second of Right Ascension (J2000) (2)
47- 51 F5.3 s e_RAs 1σ uncertainty in RAs (Pluto only) (3)
53 A1 --- DE- Sign of the Declination (J2000) (2)
54- 55 I2 deg DEd Degree of Declination (J2000) (2)
57- 58 I2 arcmin DEm Arcminute of Declination (J2000) (2)
60- 64 F5.2 arcsec DEs Arcsecond of Declination (J2000) (2)
66- 69 F4.2 arcsec e_DEs 1σ uncertainty in DEs (Pluto only) (3)
71- 75 F5.3 --- xchi2 Unweighted χ2 of ξ fit (4)
77- 81 F5.3 --- echi2 Unweighted χ2 of η fit (4)
83- 87 F5.3 arcsec x0Err 1σ uncertainty of ξ zero-point (5)
89- 93 F5.3 arcsec e0Err 1σ uncertainty of η zero-point (5)
95- 97 I3 --- Nstars [32/458] Number of catalog sources used in
the local fit in the region of interest
around Pluto
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Note (1): Named for the UT date of the night of observation, followed by the
plate number during the night. Note that the first pass processing had not
yet discovered the date confusion in some of the nights and had used the
date listed in the log book for each of plate identification. Most of the
time this leads to a date that is one day earlier. This point is mentioned
since both epochs of scans are saved in the archives at Lowell Observatory.
Note (2): All measurements are topocentric positions based on UCAC4 catalog
(Zacharias et al. 2012, cat. I/322) positions corrected for proper motion
to the epoch of each plate. The observatory location was on the main Lowell
Observatory campus. The position of the observatory was measured in the
center on top of the dome to be N 35° 12.182', W 111°39.988',
2225m on the WGS84 datum.
Note (3): These uncertainties estimate the errors in the measured position of
Pluto and do not include any contribution from errors in the plate solution
or the underlying catalog errors.
Note (4): The unweighted χ2 for the fit in each tangent plane axis divided
by the number of stars (provide the relative quality of the astrometric
fit). These values are also equivalent to the rms of the post-fit residuals
in arcseconds.
Note (5): Formal uncertainty on the constant term of the ξ and η fits.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 30-Jan-2015