X.1. Introduction

As in the last years, the Ephemerides of Minor Planets for 2015 are prepared by the IAA RAS only in the electronic form. Distribution of the EMP-2015 is accomplished via Internet or through sending compact disks (CD) by mail.

As compared with period before 2012, the substantial changes are introduced in the process of preparing of the EMP. Orbital elements of all numbered planets have been determined in IAA all over again on the ground of available observations in the catalog of the Minor Planet Center. Some changes have been introduced in the procedure of taking into account for perturbations. More detailed information on orbital elements used in the present volume of EMP and their accuracy is given in section "Information on new orbital elements".

The data on CD for 2015 embrace information on elements and ephemerides for 390514 numbered objects as of March 16, 2014. The form of representation of these data is traditional. Orbital data and ephemerides for several dwarf planets defined by the resolution of 26th General Assembly of the IAU are also included in the volume. Besides, the volume contains special Table of elements of all numbered near-Earth asteroids (NEAs). Two more additional Tables contain orbital elements of Centaurs and transneptunian objects and those of some unusual asteroids. Ephemerides of NEAs and unusual asteroids covering near-opposition intervals and intervals of close approaches to the Earth are also given.

Data are presented as PDF files (see http://www.ipa.nw.ru/PAGE/DEPFUND/LSBSS/EMP/2015/emp2015.html) . They can be displayed/printed by a variety of applications, in particular by Acrobat Reader.

The volume of the EMP for 2015 (the sixty ninth of publication) contains:

a) information on new orbital elements;

b) orbital elements of 390514 minor planets numbered as of March 16, 2014 and dates of their oppositions in 2015;

c) special Table of orbital elements of all near-Earth asteroids (NEAs) numbered as of March 16, 2014 and dates of their oppositions in 2015;

d) special Table of orbital elements of Centaurs and transneptunian objects and dates of their oppositions in 2015;

e) special Table of orbital elements of some unusual minor planets (Jupiter-crossers, Jupiter-approachers and some Mars-crossers) and dates of their oppositions in 2015;

f) osculating elements of perturbing planets;

g) minor planet lightcurve parameters;

h) ambiguoes periods of lightcurves;

i) binary asteroid lightcurves;

j) binary asteroid parameters;

k) non-principal axis rotation (tumbling) asteroids;

l) asteroid spin axes;

m) list of all minor planets in order of opposition dates in 2015;

n) opposition ephemerides for 2015;

o) ephemerides of NEAs and some unusual minor planets;

p) status of minor planet observations as of March 16, 2014;

q) positions of the antisun and the Moon;

r) information on the “Updated Ephemerides of Minor Planets” service;

s) information on the AMPLE package.

In conformity with the resolution of IAU Commission 20 (New Delhi, November 1985, the Minor Planet Circulars 10193 - 10194), the so-called H, G magnitude system for minor planets is used in the EMP. A formula for the prediction of the apparent magnitude is

V = 5 log(rΔ)+ H – 2.5 log[(1–G) Φ1 + G Φ2], (1)

where r and Δ are the heliocentric and geocentric distances, respectively, H is the absolute magnitude (in the V band unless otherwise specified) at solar phase angle β=0(degrees), G is termed the slope parameter, and Φ1, Φ2 are two phase functions given by the expressions:

Φ1=exp{–A1[tan(β/2)]^B1},

Φ2=exp{–A2[tan(β/2)]^B2},

A1=3.33, A2=1.87, B1=0.63, B2=1.22.

The formula (1) predicts the observed opposition surge and the non-linear drop off in brightness at large phase angles, and is valid for 0< β <120 (degrees).

H and G are fundamental photometric parameters for each minor planet. They are related to the previously used absolute magnitude B(1,0) and the phase coefficient. In particular, conversion from the B band of the old system to the V band of the new system is conveniently carried out using the approximate relationship
H=B(1,0)–1 mag.

Further details have been given by E.Bowell, B.Hapke, D.Domingue, K.Lumme, J.Peltoniemi, and A.W.Harris in "Asteroids II" (eds. R.P.Binzel, T.Gehrels and M.S.Matthews), p.524-556, Univ. of Arizona Press, Tucson, 1989).

The magnitudes in the present volume of EMP are based on those values of H and G which were published in MPC 28103 - 28116 and in subsequent issues. The parameters for the first 3200 minor planets were determined mainly by E.F. Tedesco (Jet Propulsion Laboratory, U.S.A.). For almost all remaining minor planets the H value were determined by G.V.Williams (Harvard-Smithsonian Center for Astrophysics, U.S.A.).