PICARD observes a new partial Sun eclipse

     
Partial Sun eclipse on 01/08/2011 at 21h59, 22h02, 22h05, 22h07, 22h10 and 22h14 at 535 nm

The six images above have been taken on June 1st, 21h59, 22h02, 22h05, 22h07, 22h10 and 22h14 (Universal Time UTC) at the wavelength of 535 nm.
They enable to observe the transition of the Moon between the Earth and the Sun.

Otherwise, scientists pursue their analysis and interpretation work of the enormous volume of data collected.

PICARD observes the partial Sun eclipse

   
Partial Sun eclipse on 04/01/2011 at 8h25, 8h26, 8h27 and 8h28 at 782 nm

The four images above have been taken on January 4th, 2011 at 8h25-8h26-8h27 and 8h28 (Universal Time UTC) at the wavelength of 782 nm while the satellite flew over Greenland.
They enable to observe the transition of the Moon between the Earth and the Sun.
The Sun image is gradually shifted from the center of the image, due to the satellite driving principle which points towards the gravity center of the lighted part of the Sun.
From a scientific point of view, the interest of this observation is limited because the eclipse is partial. Nonetheless, by using SOVAP and PREMOS instruments measurements, the consequences of the darkening of the center-border of the Sun on the total and spetral radiation can be studied.

Otherwise, scientists pursue their analysis and interpretation work of the enormous volume of data collected.

Scientific Mission Center delivery to its operator

The delivery key point (hand over) of PICARD CMS took place on November 23 and 24, 2010, in Brussels with representatives from CNES, which was the prime contractor for this development, from B-USOC which is its operator, from Belpso, which funds the development and the operations and from IASB which hosts it.
The CMS-P was developed by the Belgian company Spacebel.
After the key point, the CMS-P was accepted without reservation by its operator. The operations responsibility, conducted in coordination with the Mission Operations Preparation Group (scientific group) and its maintenance switches from CNES to B-USOC.
These last delivery and responsibility change conclude the passage of PICARD system to routine operation mode.

CNES and B-USOC responsibles working

Bruno Millet PICARD system responsible with Dominique Fonteyn, Belspo Director

Definitive opening of SOVAP right shutter

SOVAP instrument was victim, since July 26, of a dysfunction of the entry shutter of the right cavity. Faced with this issue, the instrument responsibles decided to let this shutter permanently open; however the different commands sent to this objective failed until November 18 when the opening manoeuvre succeeded. The shutter will now stay open until the end of the mission, enabling the instrument to ensure its scientific mission.

Entry in eclipses period

The 6h00-18h00 orbit choice is dedicated to minimize the eclipses periods during the year, interrupting the continuous observation of the Sun. This period is thus limited to a few weeks around the winter solstice.
It begun on November 12 and the eclipses duration will gradually increase to reach the value of 20 mn on December 20.
The eclipse entry and exit go with a period during which the Sun is seen through the atmosphere, which refracts its rays: the Sun image is thus distorted and seen in a different direction than the real one.
During this absorption period, the satellite stay guided as long as possible by its solar ecartometry sensor, in the Sun direction. The scientific instruments continue the acquisition of measurements in order for SODISM, to study the distortion of the limb through the atmosphere, and for the radiometers, to analyse the impact of the atmosphere on the spectral repartition of the solar radiation.
At the beginning of the eclipse, the pointing is realised by star sensors.
At the end of the eclipse, the satellite stay pointed in the theoretical direction of the Sun until the solar ecartometry sensor receives enough solar flux to enable a correct pointing. This period is used by SODISM to try to evaluate the impact of the temperature variation of its front part (it was notably cooled during the eclipse) on the instrument metrology.

The graphic above represents the variation (expressed in arc second) between the direction aimed by the satellite and the direction of the Sun. Two eclipses periods can be observed with an important variation during the beginning and the end of the eclipse (effect of the switch between the star sensor and the solar ecartometry sensor) and a decreased pointing performance when the satellite is driven by the star sensors instead of the solar ecartometry sensor.

PICARD declared ready for duty

The in-flight commissioning operations successfully ended on October 8.
The system was declared ready to begin the exploitation phase after the in-flight commissioning review.
The Calibration Validation phase, dedicated to the last tuning to reach the system ultimate performances thus begins.

New images of the Sun taken by SODISM instrument

SODISM instrument continu its regular acquisition of images of the Sun (one each minute). The 5 images below have been taken at 5 wavelength of SODISM instrument SODISM. They have been obtained after application of a processing to correct the main optical and radiometric defaults of the raw images.

Image at 535 nm taken on 04/09/2010 at 13h31	Image at 607 nm taken on 02/09/2010 at 04h04
Image at 782 nm taken on 03/09/2010 at 09h04
Image at 215 nm taken on 22/09/2010 at 03h53	Image at 393 nm taken on 22/09/2010 at 04h23

The images at 535 nm, 607 nm and 782 nm are mainly used to measure the Sun's diameter and the study of its shape.
The images at 215 nm and 393 nm are mainly used to study the solar activity.

All these images enable to visualise several sun spots. These images confirm the increase of the solar activity.

High resolution AVI format ~26,5 Mb High resolution MOV format ~23 Mb Low resolution AVI format ~2,4 Mb Low resolution MOV format ~2,7 Mb

This video is a series of images taken at the wavelength of 393 nm between August 5 and 31, 2010. It shows a nearly complete rotation of the Sun.
These images have been obtained after processing to correct the main defaults of the instrument.

First stellar pointing

During the in-flight commissioning operations, PICARD successfully realised its first stellar pointing sequence.
During this particular operation, the satellite doesn't point towards the Sun, but towards a couple of stars which angular distance is near the value of the solar diameter, located in the opposit direction from the Sun. The image taken by SODISM serves to compare the distance between the stars as measured by the instrument to the distance foretold by Hipparcos catalogue, to calibrate, in the absolute, the measurement function of SODISM.

First image of the Sun taken by SODISM instrument on July 22, 2010 at 16h12. It is a raw image, level L0, thus obtained before processing, at 607 nm wavelength in a very narrow band of 0.5 nm width.

Several solar spots can be seen in the lower left part. These spots appear at high solar lattitude then move slowly towards the solar equator, their number increasing with the solar activity.

First image of the Sun taken by SODISM instrument on July 22, 2010 - Wavelenth 607 nm

The 607 nm wavelength enables to measure the shape (diameter, flatening) of the solar disk at the photosphere level.
SODISM also has filters at 215, 393, 535 and 782 nm, enabling to study the active regions (sun spots, facula) as well as the Sun internal structure interne (heliosismology).
The CCD has 4 Millions pixels.

PICARD payload is also composed of 2 radiometers measuring the total and spectral solar irradiance. PICARD is a solar metrology mission, not an imaging mission. The wealth of the mission is in the continuous observation of the Sun during several years to get very precise measurements of characteristics such as the diameter and the emitted power, their variations (with a precision of about 10^-6) and their relations during all the increasing phase of the 11 years solar cycle.

End of the first operations to bring the payload to operational configuration: the 3 instruments are now functioning, all their parameters are nominals.
SODISM is in decontamination mode, at the mean temperature of 25°C; dark current images are regularly acquired.
All the system componants (satellite and payload, control center, network, mission center) are fonctioning nominally.

Evolution of SODISM temperatures during its passage in decontamination.

Successful launch of PICARD satellite together with the Swedish satellites PRISMA, in a DNEPR launcher.

(MP4 format ~6.5 Mb)