J/AJ/152/80 Astrometry of Pluto and trans-Neptunian objects (Holman+, 2016)
Observational constraints on Planet Nine: astrometry of Pluto and other
trans-neptunian objects.
Holman M.J., Payne M.J.
<Astron. J., 152, 80-80 (2016)>
=2016AJ....152...80H 2016AJ....152...80H (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Positional data
Keywords: astrometry - ephemerides - Kuiper Belt: general -
Kuiper Belt objects: individual Pluto
Abstract:
We use astrometry of Pluto and other trans-neptunian objects to
constrain the sky location, distance, and mass of the possible
additional planet (Planet Nine) hypothesized by Batygin & Brown. We
find that over broad regions of the sky, the inclusion of a massive,
distant planet degrades the fits to the observations. However, in
other regions, the fits are significantly improved by the addition of
such a planet. Our best fits suggest a planet that is either more
massive or closer than argued for by Batygin & Brown based on the
orbital distribution of distant trans-neptunian objects (or by Fienga
et al. based on range measured to the Cassini spacecraft). The trend
to favor larger and closer perturbing planets is driven by the
residuals to the astrometry of Pluto, remeasured from photographic
plates using modern stellar catalogs, which show a clear trend in
decl. over the course of two decades, that drive a preference for
large perturbations. Although this trend may be the result of
systematic errors of unknown origin in the observations, a possible
resolution is that the decl. trend may be due to perturbations from a
body, in addition to Planet Nine, that is closer to Pluto but less
massive than Planet Nine.
Description:
We decided to build upon the carefully selected data of Buie & Folkner
2015 (Cat. J/AJ/149/22) for our analysis of Pluto. We use the Minor
Planet Center (MPC) astrometry for Trans-Neptunian Objects (TNOs) only.
For Pluto, we include the astrometry from the remeasured Lampland
plates (Buie & Folkner 2015, Cat. J/AJ/149/22); that from a selection
of photographic plates from Pulkovo Observatory that were also
remeasured with modern stellar catalogs (Rylkov et al.
1995A&AT....6..265R 1995A&AT....6..265R); Pluto or Charon positions from recent
occultation measurements of Pluto and Charon (Assafin et al. 2010,
Cat. J/A+A/515/A32 ; Benedetti-Rossi et al. 2014, Cat. J/A+A/570/A86);
and CCD observations from Pico dos Dias Observatory (Benedetti-Rossi
et al. 2014, Cat. J/A+A/570/A86), the USNO's Flagstaff Station (Stone
et al. 2003AJ....126.2060S 2003AJ....126.2060S), and JPL's Table Mountain Observatory
(described in Buie & Folkner 2015, Cat. J/AJ/149/22).
We adopt the uncertainties of Buie & Folkner 2015 (Cat. J/AJ/149/22)
for the Pluto astrometry from Lowell and Pulkovo Observatory. However,
we used significantly smaller astrometric uncertainties for the Pico
do Dias data. We also used somewhat smaller astrometric uncertainties
for the remaining data sets. For the USNO astrometry, we adopt
0.09'' for both R.A. and decl. For the Table Mountain Observatory
astrometry, we adopt 0.07'' and 0.05'' for the R.A. and decl.,
respectively. For the occultation data we adopt 0.05'' and 0.03''
for the R.A. and decl., respectively. The astrometric uncertainties we
adopted result in a χ2 per degree of freedom=1 for the
unperturbed Pluto orbit fits.
We included all TNOs, including Scattered-Disk Objects (SDOs), with
semimajor axes a≳30au for which we could fit reliable orbits. For
these objects, we adopt a fixed astrometric uncertainty of 0.27'',
which results in χ2 per degree of freedom=1 for the ensemble of
TNOs.
We include a total of 6677 observations for Pluto, plus 35646
observations of other TNOs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
obs.dat 98 42238 Observations of Pluto and other trans-neptunian
objects (TNOs) in the standard Minor Planet
Center (MPC) 1992 astrometric format
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
J/AJ/149/22 : Astrometry of Pluto from 1930-1951 observations (Buie+, 2015)
J/A+A/570/A86 : Pluto astrometry from 19yrs obs. (Benedetti-Rossi+, 2014)
J/A+A/515/A32 : Pluto, Charon, Nix, Hydra occultations 2008-15 (Assafin+, 2010)
Byte-by-byte Description of file: obs.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Planet Minor planet number
6- 12 A7 --- Prov Provisional or temporary designation
13 A1 --- Dis [*] Indicates a discovery or new/unidentified
observation
14 A1 --- Code The list of standard codes used for observations
of minor planets is given in each batch of
Minor Planet Centers (MPCs)
15 A1 --- A [A] Adjusted observation flag (2)
16 A1 --- R [CEc] Flag on observation reduced in the J2000.0
system (C, E, or c) (3)
17 A1 --- X [X] Already-filed observation flag (4)
18 A1 --- Bin [ab] Binary flag (a or b)
19- 35 A17 --- Date Date of the observation (YYYY:MM:DD.dddddd)
37- 38 I2 h RAh Hour of Right Ascension (J2000)
40- 41 I2 min RAm Minute of Right Ascension (J2000)
43- 48 F6.3 s RAs Second of Right Ascension (J2000)
49 A1 --- DE- Sign of the Declination (J2000)
50- 51 I2 deg DEd Degree of Declination (J2000)
53- 54 I2 arcmin DEm Arcminute of Declination (J2000)
56- 60 F5.2 arcsec DEs Arcsecond of Declination (J2000)
61- 69 A9 --- ORef Original Minor Planet Center (MPC) discovery
reference (5)
70- 74 F5.2 mag mag [14.7/27.6]? Observed magnitude in Filter
75 A1 --- Flt [CIRVgirwz] Filter used in the observation
(V, R, I, C, g, r, i, z, or w)
76- 81 A6 --- CRef Correct MPC discovery reference
82- 84 A3 --- Obs Observatory code (6)
86- 90 F5.2 arcsec e_RAs Uncertainty in RAs
92- 96 F5.2 arcsec e_DEs Uncertainty in DEs
98 I1 --- Out [0/1] Outlier code (1=point was rejected as an
outlier, 0=included in the final fit)
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Note (2):
A = Observation which have been converted to the J2000.0 system by
rotating B1950.0 coordinates (to indicate that the value has been
adjusted).
Note (3): For the observations reduced in the J2000.0 system this column is used
to indicate how the observation was made. The codes used are defined as
follows:
P = Photographic (default if column is blank);
e = Encoder;
C = CCD;
T = Meridian or transit circle;
M = Micrometer;
V/v = "Roving Observer" observation;
R/r = Radar observation;
S/s = Satellite observation;
c = Corrected-without-republication CCD observation;
E = Occultation-derived observations;
O = Offset observations (used only for observations of natural
satellites);
H = Hipparcos geocentric observations;
N = Normal place;
n = Mini-normal place derived from averaging observations from video
frames.
Note (4): The codes used for already-filed observations are defined as follows:
X = Given originally only to discovery observations that were approximate
or semi-accurate and that had accurate measures corresponding to the
time of discovery: this has been extended to other replaced discovery
observations;
X/x = Observations that are to be suppressed in residual blocks. They are
retained so that there exists an original record of a discovery.
Note (5): Original but outdated & subsequently corrected discovery publication.
Note (6): Lists of observatory codes are published in the Minor Planet Centers
(MPCs).
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 24-Apr-2017