The results of the Phemu15 campaign of observations of the mutual events of the satellites

of Jupiter

J.E. Arlot(1), E. Saquet(1,2), N. Emelianov(3)(1): IMCCE, Paris observatory

(2): Institut Polytechnique des Sciences Avancées

(3): Sternberg Astronomical Institute, Moscow

EPSC, Nantes, September 2015

3

Equinox on Jupiter: the jovicentric declination of the Earth and the Sun is close to zero

Sun

Earth

Mutual events occur when this declination is smaller than

one degree. 2015 is very favorable especially for the

northern hemisphere. Unfortunately, the meteorological

conditions were bad in the north.

Summary of observational campaigns

Number of

observations

Number of sites

of observation

Number of

observed

events

Number of

observable

events

Jupiter

1973 91 26 65 176

1979 18 7 9 60

1985 166 28 64 248

1991 374 56 111 221

1997 275 42 148 390

2003 361 42 116 360

2009 523 68 206 237

2015 (429) (~50) (~200) (~400)

Note: for 2015, only the reduced events are included in the table

J3 occults J2 on Dec. 12, 2014 J1 occults J2 on Feb. 5, 2015

J1 eclipses J2 on April 10, 2015 J2 occults J1 on April 19, 2015

Examples of observations

annular

grazing

J4 eclipses J2 on Feb. 4, 2015before and after photometric reduction

the absorption of the sky when Jupiter is close to the horizon must be corrected

Examples of observations

7

Correction of the photometric observation (absorption, sky background)

The interest of 2-D CCD images:A constant reference object may be observed together with the occulted or eclipsed satellites

8

IoEurope1

9

IoEurope2

10

IoEurope3

11

IoEurope4

12

IoEurope5

13

IoEuropeS

Méthode de réduction

Photometric function

24

P() - the integrated albedo of the satellite

The photometric function depending on the central meridian

The first astrometric results

The observations of the eclipses of the inner satellites

• Observations made (1m telescope of Pic du Midi observatory in Methane filter):

– Eclipses of Amalthea

• 4E5 on 07/01/2015 (E. Saquet, F. Colas and V. Robert)

• 3E5 on 07/04/2015 (E. Saquet, F. Colas and A. Vienne)

• 2E5 on 08/04/2015 (B. Christophe and O. Dechambre)

– Eclipses of Thebe

• 4E6 on 07/01/2015 (E. Saquet, F. Colas and V. Robert)

Jupiter is under the filter

Amalthea

Thebe

Raw image of Amalthea (left) and the flux (at right)

The background (left) and the polynomial fit of the background (at right)

The image of Amalthea after substracting the background (left) and the final flux of Amalthea (at right)

J4 eclipses J5 on January 7, 2015

Comparison to ephemerides

4E5

J4 eclipses J6 on January 7, 2015

Comparison to ephemerides

4E6

Conclusion • The number of observations is sufficient for

astrometric purpose: results will be published soon

• The events implying Amalthea and Thebe would becompared with direct imaging astrometry

• We organize a workshop on astrometric and photometric observations after Gaia

next October 14-18; see:

www.imcce.fr/hosted_sites/phemu