Le brocanteur des étoiles

The Gaia satellite was launched Thursday, December 19 , at 10:12 am from Kourou . It must , in 27 days , join the L2 point where , after a period of commissioning, it will observe for 5 years. An interactive tool has been developed SYRTE at the Paris Observatory, to calculate the ephemeris Gaia on its way to L2 and then on its orbit. This tool also allows a field map showing the position of Gaia in the sky for different longitudes and latitudes ( on Earth) and sizes of field observation . This tool is available online: GBOT for Ground-Based Optical Tracking of Gaia .

The idea was launched from the ground to photograph the satellite during its journey to L2 . Its magnitude is unknown , and will be between 12 and 18 , but the tool developed SYRTE will find . Photos can be sent to jordan at ari.uni - heidelberg.de with subject " Gaia in the sky" until 15 January 2014. The best photos will be published by ESA as picture of the week on the website of Gaia.

A question: why have developed this software? As strange as it may seem , a priori , Gaia will need to rely on a network of small telescopes to achieve the incredible precision of a few micro- seconds on its degrees astrometric measurements . In addition to the usual methods of tracking satellites used by the Operations Centre of ESA in Darmstadt ( ESOC ) , the astrometric observation satellite from the ground , will provide valuable data.

Indeed , the orbit covered by Gaia must be known with great precision : 150 m on its position and 2.5 mm / s on its movement. A panel of Analysis Consortium data Gaia (CAPD = Data Processing and Analysis Consortium ) was established as early as 2008 : GBOT for Ground Based Tracking Orbit . The team must provide daily GBOT position Gaia. She trained in observing the WMAP and Planck satellites, themselves also in orbit around the Lagrange point L2 . See also the second part of the orbit and launch page that illustrates how a satellite L2 point follows the Earth in its orbital motion around the Sun.

To this end, the team has developed an infrastructure , methods of observation and treatment dedicated to these very specific observations data. The main telescopes involved are the 2m Liverpool Telescope located on the Canary Island of La Palma and network telescopes "Las Cumbres Global Telescope Optical Network" which includes instruments in Chile , South Africa, Australia and Texas, which adds a telescope of ESO VST Chile. From 2012 , observations radio Very Long Baseline ( VLBI ) were also involved. The tool described above will be used throughout the mission to track Gaia from the ground.

All these activities are coordinated from Heidelberg, with an important participation of the Observatoire de Paris where the data is analyzed and archived . View blog of Martin Altmann (in English) .

COD C10
OBS J.-F. Soulier
MEA J.-F. Soulier
TEL 0.30-m f/3.8 Newtonian reflector + CCD
NET UCAC-4
     JF-GAIA KC2013 12 20.76085 05 40 21.119+13 08 51.37         17.58R      C10 10.7"/min 56°
     JF-GAIA KC2013 12 20.76647 05 40 26.141+13 09 37.64         17.43R      C10 10"/min 55°
     JF-GAIA KC2013 12 20.77203 05 40 30.748+13 10 23.13         17.63R      C10 9.9"/min 54°
     JF-GAIA KC2013 12 20.77730 05 40 34.930+13 11 05.78         17.06R      C10* 9.8"/min    53°
     JF-GAIA KC2013 12 20.78275 05 40 39.094+13 11 49.80         18.07R      C10* 9.7"/min 52°
     JF-GAIA KC2013 12 20.78820 05 40 42.822+13 12 32.93         17.70R      C10 9.4"/min 51°
----- end -----

COD C10
OBS J.-F. Soulier
MEA J.-F. Soulier
TEL 0.30-m f/3.8 Newtonian reflector + CCD
NET UCAC-4
JF-GAIA KC2013 12 20.79982 05 40 50.089+13 14 03.04         17.72R      C10     8.5"/min 42°
JF-GAIA KC2013 12 20.80524 05 40 53.045+13 14 43.82         17.69R      C10 8.45"/min 42°
   JF-GAIA KC2013 12 20.81072 05 40 55.884+13 15 25.03         17.46R      C10 7.8"/min 41°
   JF-GAIA KC2013 12 20.81621 05 40 58.409+13 16 05.72         17.47R      C10 6.8"/min 40°
   JF-GAIA KC2013 12 20.82172 05 41 00.741+13 16 45.96         17.29R      C10 5.8"/min 39°
   JF-GAIA KC2013 12 20.83263 05 41 04.662+13 18 02.21         17.31R      C10*
   JF-GAIA KC2013 12 20.83802 05 41 06.295+13 18 40.27         17.57R      C10 5"/min    36°
   JF-GAIA KC2013 12 20.84332 05 41 07.725+13 19 16.13         17.81R      C10* 4.8"/min 36°
   JF-GAIA KC2013 12 20.84880 05 41 08.906+13 19 52.70         17.75R      C10 4.8"/min 35.5°
----- end -----

is a potential radar target in the next couple of days.
Right now the 3-sigma pointing uncertainties are enormous, but it's possible
that they might shrink enough for us to observe it with radar if
observers can obtain optical astrometry in the next ~14 hours before this
asteroid gets too close to the Sun to observe.

Here's a geocentric ephemeris at 1-hour intervals computed using the JPL/Horizons system:

Date__(UT)__HR:MN R.A._(J2000.0)_DEC. delta APmag S-O-T /r T-O-M/Illu%
2013-Aug-08 19:00 330.16499 -0.48396 0.00451944808036 16.85 160.7795 /L 171.5/ 3.6
2013-Aug-08 20:00 331.21594 0.92593 0.00412452035453 16.70 159.0540 /L 171.3/ 3.8
2013-Aug-08 21:00 332.48918 2.63193 0.00373421161435 16.55 156.9586 /L 170.8/ 3.9
2013-Aug-08 22:00 334.06193 4.73060 0.00335014571661 16.39 154.3712 /L 169.9/ 4.1
2013-Aug-08 23:00 336.05062 7.36028 0.00297475486812 16.23 151.1142 /L 168.3/ 4.3
2013-Aug-09 00:00 338.63827 10.72104 0.00261180171840 16.07 146.9258 /L 165.5/ 4.4
2013-Aug-09 01:00 342.12663 15.09887 0.00226729605183 15.91 141.4167 /L 161.3/ 4.6
2013-Aug-09 02:00 347.03996 20.87555 0.00195107698942 15.79 134.0220 /L 155.1/ 4.8
2013-Aug-09 03:00 354.33428 28.44048 0.00167926259303 15.75 124.0032 /L 146.1/ 4.9
2013-Aug-09 04:00 5.76705 37.74656 0.00147666178118 15.87 110.7039 /L 133.7/ 5.1
2013-Aug-09 05:00 24.01948 47.16192 0.00137431587382 16.28 94.3722 /L 118.2/ 5.3
2013-Aug-09 06:00 49.73179 52.81176 0.00139452048125 17.09 77.0475 /L 101.7/ 5.5
2013-Aug-09 07:00 75.40457 52.36320 0.00153241948883 18.24 61.5618 /L 86.9/ 5.7
2013-Aug-09 08:00 93.59290 48.35377 0.00176051442929 n.a. 49.3593 /L 75.4/ 5.9
2013-Aug-09 09:00 104.97916 43.76687 0.00204883750195 n.a. 40.2720 /L 67.0/ 6.1
2013-Aug-09 10:00 112.24332 39.73897 0.00237550777400 n.a. 33.5590 /L 60.9/ 6.3
2013-Aug-09 11:00 117.13634 36.44620 0.00272673993981 n.a. 28.5289 /L 56.5/ 6.5
2013-Aug-09 12:00 120.61026 33.79340 0.00309415387650 n.a. 24.6773 /L 53.2/ 6.7
2013-Aug-09 13:00 123.18713 31.64618 0.00347259780716 n.a. 21.6616 /L 50.8/ 6.9

Observation K13P13S, 20130808, Seine and Marne, France

Newton Instrument T300, Focal Length : 1140mm, MPC code : C10/France
Cam. ST8XME, temperature -15°c
Echantillionnage : 1.62"/pixel
No Filter

Pretreatments yes, Mass Air : 2.58 early acquisitions
Unitary integration time : 60s

1 Measuring = Registration 4x60s
Radius opening measures 5", Astrometrica software
Able at the beginning of acquisition

COD C10
CON JEAN-FRANCOIS SOULIER [jean-francois.soulier2@wanadoo.fr]
OBS J.F. Soulier
MEA J.F. Soulier
TEL 0.30-m f/3.8 Newtonian reflector + CCD
ACK MPCReport file updated 2013.08.08 11:52:11 p.m.
AC2 jean-francois.soulier2 @ wanadoo.fr
NET UCAC-4
      K13P13S KC2013 08 08.87584 22 11 30.22 +02 10 52.1 18.7 R C10
      K13P13S KC2013 08 08.87919 22 11 57.34 +02 19 54.8 19.0 R C10
      KC2013S K13P13 08 08.88277 22 12 27.28 +02 29 49.8 19.1 R C10
----- End -----

Time of perihelion passage
T = 2011 novembre 29, 853 35 jours ± 0,00017 TT (jour)
Mean anomaly
M = 117,12797789° ± 0,0000526°
Argument of perihelion
ω = 271,0846088°± 0,0000639°
Longitude of the node
Ω = 147,2857428°± 0,0000657°
Tilt
i = 10,3390644°± 0,0000113°
Perihelion distance
q = 0,8933170 ua ± 0,0000005 ua
Eccentricity
e = 0,1082247 ± 0,0000003
Semi-major axis
a = 1,0017288 ua ± 0,0000009 ua
Mean motion
n = 0,98305727°/jour ± 0,00000135°/jour
Mean sidereal revolution
P = 1,003 ans± 0,0000014 an (0,0005 jour)

Époque 2012 novembre 30.0 TT = JDT 2456261.5
T 2012 novembre 30.02858 TT P. Rocher
q 0.893510224 (2000) P Q
n 0.982789963 Peri 271.0621512 0.51640506 -0.85082728
a 1.001910453 Noeud 147.2573597 0.83960820 0.48075406
e 0.108193530 Incl 10.3368429 0.16847517 0.21205773
P 1.00