The Gaia-FUN-SSO pipeline provides information on a daily basis upon the new Solar System Objects detected by Gaia.
The goal is to help observers to retrieve these objects and to validate these detections.
For information on the how the processing is performed, and on the functionalitites of the dissemination pages,
please check out the FAQs page.
However, since some observers are not familiar with astrometry of moving targets,
we describe the methodology to apply for successful observations here below.
A timescale in Universal Time is required for astrometry of Solar System Objects. The images in FITS format must be dated with at least 1 second of accuracy. The exposure time is chosen as a a balance between the time required to achieve a good Signal to Noise ratio and a time short-enough to avoid spreading the signal on too many pixels due to the asteroid velocity. Very fast moving faint objects require specific tunings which are not described here.
We employ sophisticated algorithms to predict the sky search areas for each observer (in red in the star map plots). The new asteroid could be anywhere withing the computed region. However, due to the uncertainties inherent to the system, a detection just outside it cannot be ruled out and should be reported. Several exposures are required to detect motion, hence identify moving objects. Two exposures are the bare minimum, 3 to 5 are well adapted for comfirmation. The easiest way to detect the motion is to blink between images (animate them as a movie). Most imaging softwares for astronomy provide tools for that.
For each moving object detected in your frame, you should check if they are already known or not. Gaia discoveries are unknown at the time of their releases, although observations from the ground quickly after can lead to registration. Two very convenient tools are available:
Anytime you observe an alert, we kindly ask you to provide feedback. In case of a positive detection, attach to your report your message sent to MPC. The report shall be submitted by using:
You are in charge to report to the Minor Planet Center the astrometry of the objects measured in your images. Please note that:
Astrometric measurements can be performed with many to different tools.
Astrometrica is one of the most popular, but several other tools exist.
A recent astrometric pipeline, the GBOT pipeline provides
excellent results. The choice of the reference stellar catalog is crucial and we recommend to use of Gaia data release
(currently DR1. DR2 is expected for April 2018).
Many softwares offers the astrometric measurements in MPC format. This format is required by MPC to submit data to
obs@cfa.harvard.edu.
See the MPC pages for more details.
See below the report on a new object transmitted to the MPC:
COD 511
CON W. Thuillot, Coordinator of Gaia-Alert at Haute Prov. Obs.
CON Paris Observatory-IMCCE-SYRTE and OCA Nice, FRANCE
CON [thuillot@imcce.fr]
OBS W.Thuillot, F. Taris
OBS S. Bouquillon, B. Carry, P. David, M. Delbo, M. Dennefeld, P. Tanga
MEA W. Thuillot, S. Bouquillon, F. Taris, T. Carlucci, C. Barache
TEL 1.20-m f/6 reflector + CCD
NET GAIA-DR1
BND R
COM On behalf of Gaia-FUN-SSO
ACK OHP Observations
AC2 William.Thuillot@obspm.fr
g1L008 * C2017 03 27.91989 09 24 28.12 -16 55 18.1 20.5 R 511
g1L008 C2017 03 27.92166 09 24 28.21 -16 55 17.7 20.2 R 511
g1L008 C2017 03 27.92343 09 24 28.04 -16 55 16.3 20.7 R 511
.../...
Archive your data if you can. In case of disagreement, the astrometry may be reprocessed. If you cannot archive over a long period, 6 months appear to be a standard duration.