J/AJ/152/70 Outer Solar System Origins Survey (OSSOS). I. (Bannister+, 2016)
The outer solar system origins survey. I. Design and first-quarter discoveries.
Bannister M.T., Kavelaars J.J., Petit J.-M., Gladman B.J., Gwyn S.D.J.,
Chen Y.-T., Volk K., Alexandersen M., Benecchi S.D., Delsanti A.,
Fraser W.C., Granvik M., Grundy W.M., Guilbert-Lepoutre A., Hestroffer D.,
Ip W.-H., Jakubik M., Jones R.L., Kaib N., Kavelaars C.F., Lacerda P.,
Lawler S., Lehner M.J., Lin H.W., Lister T., Lykawka P.S., Monty S.,
Marsset M., Murray-Clay R., Noll K.S., Parker A., Pike R.E., Rousselot P.,
Rusk D., Schwamb M.E., Shankman C., Sicardy B., Vernazza P., Wang S.-Y.
<Astron. J., 152, 70 (2016)>
=2016AJ....152...70B 2016AJ....152...70B (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Magnitudes ; Surveys
Keywords: Kuiper Belt: general - surveys
Abstract:
We report the discovery, tracking, and detection circumstances for 85
trans-Neptunian objects (TNOs) from the first 42deg2 of the Outer
Solar System Origins Survey. This ongoing r-band solar system survey
uses the 0.9deg2 field of view MegaPrime camera on the 3.6m
Canada-France-Hawaii Telescope. Our orbital elements for these TNOs
are precise to a fractional semimajor axis uncertainty <0.1%. We
achieve this precision in just two oppositions, as compared to the
normal three to five oppositions, via a dense observing cadence and
innovative astrometric technique. These discoveries are free of
ephemeris bias, a first for large trans-Neptunian surveys. We also
provide the necessary information to enable models of TNO orbital
distributions to be tested against our TNO sample. We confirm the
existence of a cold "kernel" of objects within the main cold classical
Kuiper Belt and infer the existence of an extension of the "stirred"
cold classical Kuiper Belt to at least several au beyond the 2:1 mean
motion resonance with Neptune. We find that the population model of
Petit et al. remains a plausible representation of the Kuiper Belt.
The full survey, to be completed in 2017, will provide an exquisitely
characterized sample of important resonant TNO populations, ideal for
testing models of giant planet migration during the early history of
the solar system.
Description:
The Outer Solar System Origins Survey (OSSOS) observations are
acquired in blocks: contiguous patches of sky formed by a layout of
adjoining multiple 0.90deg2 MegaCam fields.
The OSSOS discovery and tracking program uses the Canada-France-Hawaii
Telescope (CFHT) MegaPrime/MegaCam. In 2013 and 2014, the
MegaPrime/MegaCam focal plane was populated by thirty-six 4612*2048
pixel CCDs in a 4 by 9 arrangement, with a 0.96°*0.94°
unvignetted Field Of View (FOV) (0.90deg2) and 0.05'' Full Width at
Half Maximum (FWHM) Image Quality (IQ) variation between center and
edge. The plate scale is 0.184'' per pixel, which is well suited for
sampling the 0.7'' median seeing at Maunakea. We observed our 2013
discovery fields in MegaCam's r.MP9601 filter (564-685nm at 50%
transmission; 81.4% mean transmission) which is similar to the Sloan
Digital Sky Survey (SDSS) r' filter. Our integration length was set at
287s. This exposure length achieves a target depth of mr=24.5 in a
single frame in 0.7'' median CFHT seeing. MegaPrime/MegaCam operates
exclusively as a dark-time queue-mode instrument for CFHT. The OSSOS
project thus has between 10 and 14 potentially observable nights each
month, weather considerations aside. Through CFHT's flexible
queue-schedule system we requested our observations be made in
possibly non-photometric conditions (discussed in Section 3.5) with
0.6''-0.8'' seeing and <0.1mag extinction for discovery, and requested
image quality of 0.8''-1.0'' seeing for follow-up observations. Images
were taken entirely with sidereal guiding and above airmass 1.5. This
aided the quality of the astrometric solution and the point-spread
function, and retained image depth: median extinction on Maunakea is
0.10mag per airmass in this passband.
This paper covers OSSOS blocks that had their discovery observations
in 2013A (2013 is the year that the discovery observations were
successfully made, and A indicates the half-year semester of discovery
opposition; A for Northern spring). Forthcoming papers will cover the
subsequent discovery observations. The 2013A blocks were 13AE,
centered at R.A. 14h20m, decl. -12°52' at discovery, spanning
ecliptic latitude range b=0°-3°, and 13AO, centered at R.A.
15h57m, decl. -12°30' at discovery, spanning ecliptic latitude
range b=6°-9°. The sky locations of the 13A blocks are at
44° and 30° galactic latitude. The 13AE discovery triplets
were taken under some minor (<0.04mag) extinction and with IQ that
ranged from 0.65'' to 0.84''. The 13AO discovery triplets exhibited no
extinction and IQ that ranged from 0.49'' to 0.74''. Subsequent
imaging to track the discoveries was acquired through 2013 August. Not
all discoveries were observed in every lunation due to objects falling
in chip gaps or on background sources on some dates, faint magnitudes,
or variable seeing in the recovery observations. In much of 2013, poor
weather conditions prevented observations in sufficient IQ for us to
recover the faintest objects. To compensate, from 2013 November onward
we used alternative 387s exposures in 0.8±0.1'' seeing for
single-image passes on the block. For the seven February-August
lunations that the blocks were visible in 2014, the 13AE and 13AO
discoveries brighter than the characterization limit (Section 5) were
observed with pointed recoveries; this was possible because the
high-frequency cadence in the discovery year shrank the ephemeris
uncertainty to a tiny fraction of the MegaPrime FOV. A handful of
fainter objects not immediately recovered in the first pointed
recovery images were targeted with spaced triplets of observations in
subsequent lunations until recovery was successful on all of them
(Section 6.1). Generally, two observations per object per lunation
were made.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 244 85 Orbit and discovery properties of the characterized
Outer Solar System Origins Survey (OSSOS) objects
table5.dat 244 19 Orbit and discovery properties of the uncharacterized
Outer Solar System Origins Survey (OSSOS) objects
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
J/A+A/546/A115 : Colors of minor bodies in outer solar system (Hainaut+, 2012)
http://www.minorplanetcenter.net/iau/MPCORB.html : Public catalog at the MPC
http://www.ossos-survey.org/ : OSSOS website
Byte-by-byte Description of file: table[45].dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Pop Orbital population (xxx, cen, sca, cla, res,
or det) (1)
5 A1 --- n_Pop [Nimox] Population subgroup (N, i, m, o, x) (2)
7- 8 I2 --- j [2/18]?=-1 Object is in the j:k resonance
10- 11 I2 --- k [1/11]?=-1 Object is in the j:k resonance
13- 15 A3 --- sh Orbit classification status (I, H, S, or x) (3)
17- 24 A8 --- Object Object identifier (4)
26- 30 F5.2 mag [21.15/24.8] Cleaned mean magnitude during
discovery (mr)
32- 36 F5.3 mag e_ [0.02/0.364] Uncertainty in
38 A1 --- Flt [r] Filter used in observation (r) (5)
40- 44 F5.2 mag HMag [5.27/12.9] Absolute magnitude H in Flt (Hr)
46- 51 F6.3 AU Dist [13.7/57.4] Object distance at discovery (6)
53- 57 F5.3 AU e_Dist [0/8.5] Uncertainty in Dist
59- 60 I2 --- Nobs [3/56] Number of observations
62- 68 F7.4 yr Time [0.0002/13.85] Length of measured orbital arc
70- 74 F5.3 arcsec [0.006/0.185] Mean orbit-fit residual, RA
76- 80 F5.3 arcsec [0/0.202] Mean orbit-fit residual, Dec
82- 86 F5.3 arcsec max-x [0.009/0.669] Maximum orbit-fit residual, RA
88- 92 F5.3 arcsec max-y [0.001/1.169] Maximum orbit-fit residual, Dec
94-103 F10.6 AU a [15.5/149.9] Semimajor axis (6)
105-111 F7.4 AU e_a [0.002/25.5] Uncertainty in a (7)
113-120 F8.6 --- e [0.012/0.76] Orbital eccentricity (6)
122-129 F8.6 --- e_e [0/0.94] Uncertainty in e (7)
131-136 F6.3 deg i [0.5/50.4] Inclination to the ecliptic (6)
138-143 F6.3 deg e_i [0/49.5] Uncertainty in i (7)
145-151 F7.3 deg Omega [25.2/229] Longitude of ascending node Ω
153-159 F7.3 deg e_Omega [0/166.5] Uncertainty in Omega
161-167 F7.3 deg omega [11.9/358.6] Argument of perihelion ω
169-176 F8.3 deg e_omega [0.003/1716.8] Uncertainty in omega
178-187 F10.3 d T0 [7912/107982] Modified Julian Date of
perihelion passage
189-198 F10.3 d e_T0 [2/576875] Uncertainty in T0
200-205 F6.3 h RAh Hour of Right Ascension at mean equinox of
discovery (J2000)
207-213 F7.3 deg DEdeg Declination in decimal degrees at mean equinox
of discovery (J2000)
215-227 F13.5 d Mean Julian Date of discovery
229-232 F4.2 arcsec/h Motion [2.2/8.3] Angular rate of sky motion at
discovery
234-238 F5.3 --- Deff [0.01/0.9] Value of the detection efficiency
function for the motion rate and magnitude of
the object at its discovery
240-244 F5.2 mag mlim [23.9/24.5] Limiting magnitude of discovery
block
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Note (1): Orbital population is defined as follows:
xxx = Unclassified due to uncharacterized status;
cen = Centaur;
sca = Scattering disk object;
cla = Classical belt;
res = In mean-motion resonance;
det = Detached object.
Note (2): Population subgroup for resonant (resonance status is checked for
outer planets) and classical objects is defined as follows:
U = Uranus;
N = Neptune;
i = Inner main belt;
m = Main belt;
o = Outer main belt;
x = No applicable population subgroup;
X = Not checked due to uncharacterized status.
Note (3): Orbit classification status is defined as follows:
I = The orbit classification is currently insecure;
H = The human operator intervened to declare the orbit security status;
S = The orbit classification is secure;
x = Unclassifiable due to uncharacterized status.
Note (4):
Survey designation here based on their OSSOS discovery, with a format:
* u=uncharacterized, and o=Outer Solar System Origins Survey (OSSOS);
* Last digit of the year in which the object was discovered by OSSOS (3-6);
* The block ID letter:
e=Centered at R.A. 14h20m, decl. -12°52' at discovery, spanning
ecliptic latitude range b=0°-3°;
o=Centered at R.A. 15h57m, decl. -12°30' at discovery, spanning
ecliptic latitude range b=6°-9°;
* And the sequential number 01-xx to give unique identifiers;
* PD suffix = Previous Discovery. Some of the Trans-Neptunian Objects
(TNOs) in the OSSOS discovery sample were previously discovered in other
surveys: seven 13AE and one 13AO object link either to one-night
observations from the Canada-France Ecliptic Plane Survey (CFEPS) survey
(Jones et al. 2006Icar..185..508J 2006Icar..185..508J; Kavelaars et al. 2009AJ....137.4917K 2009AJ....137.4917K;
Petit et al. 2011AJ....142..131P 2011AJ....142..131P), or to objects of varying arc length in
the public catalog at the Minor Planet Center (MPC;
http://www.minorplanetcenter.net/iau/MPCORB.html), providing arcs to
objects first observed 9-13 years ago;
* nt suffix = Not observed on more than two nights in the discovery
lunation.
The on-plane 13AE block contains more discoveries (49 Trans-Neptunian
Objects) than in the higher-latitude 13AO block (36 TNOs), due to the cold
classical Kuiper Belt's concentration in the plane.
Note (5): We observed our 2013 discovery fields in MegaCam's r.MP9601 filter
(564-685nm at 50% transmission; 81.4% mean transmission) which is similar
to the Sloan Digital Sky Survey (SDSS) r' filter (see Section 3.5).
Note (6): J2000 ecliptic barycentric coordinates. Full barycentric elements are
available at http://www.ossos-survey.org/. The full heliocentric orbital
elements are available in electronic form from the Minor Planet Center.
Note (7): Uncertainties from the covariant matrix fit of
Bernstein & Khushalani 2000AJ....120.3323B 2000AJ....120.3323B.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 26-Sep-2016