Gaia Follow-Up Network Circulars

We provide here below the circulars sent to the network since 2012.

Dear colleagues of the Gaia-FUN-SSO network,

Gaia discoveries need you! Since October 2016, the short term processing of Solar System Objects by Gaia is up and running. Since January the 1st, 2017, about 600 candidates discoveries have been published on the Gaia-FUN-SSO Web pages:
So far, it seems that very few have been followed up. Remember that we do not send emails for each discovery pending confirmation. All the alerts visible from your location and within your observing criteria (limiting magnitude and maximum search area) are accessible on the pages:

Feedback please ! For each attempt to observe an object listed on the Gaia-FUN-SSO pages, we invite you to provide feedback, regardless of the outcome: successful detection of the new Gaia discovery, or not. This can be done either by:

  • using the link in the column "Report" of the alert list at the corresponding line;
  • using the "Report observation" button in the detail page;
  • using the selection page for former alerts if the alert you observed is no longer active (expired): (link accessible from the alert list).
In the case of positive recovery of the target, please provide a copy of the message you sent to MPC in the report page. Also, please remember to cite the Gaia-FUN-SSO in your message to MPC, for example by using a comment line like: COM On behalf of Gaia-FUN-SSO

Help page We have added specific information for helping those who are not familiar to the astrometric observations of the Solar System Objects. A description of the Gaia-FUN-SSO system and pages are also available. Please refer to it ( and do not hesitate in contacting us if you need more support.

Dear colleagues of the Gaia-FUN-SSO network,

Gaia SSO pipeline: Gaia SSO alerts are daily triggered through the pipeline We are still improving this pipeline to help you in finding the objects on sky. We encourage you to register, to define your observing sites, and to set up your instruments if this has not been done yet. You will then be able to get topocentric information. Note that if you register with a new observing site not yet in our list, alert information will not be immediately available. It will be necessary to wait for the next alert update for getting the alerts regarding this site. We have recently posted a help page at some basic information. Do not hesitate to request complementary information to be added on this page.

We need your feedback! In case of a positive observation of a Gaia alert, we ask you to send us back this information and a copy of the astrometry data that you sent to the Minor Planet Center. We have already received several positive observations related to the Gaia alerts. In your message to MPC, please add a special line citing Gaia-FUN-SSO, for example a comment line like this one: COM On behalf of Gaia-FUN-SSO
We have also received some requests for improvement or information regarding bugs in the pipeline. We are taking them into account. Note for example that we will soon introduce an estimate of the apparent velocity of the objects.

ESA announcement: On last Tuesday, ESA has published an announcement regarding the validation of the Gaia SSO alerts. See This announcement enhances the visibility of our activity and will hopefully attract more observers for confirming Gaia alerts!

Last minute news: Among the ground-based detections on alert, one new object has been observed on January, the 3rd and the 4th, from Haute Provence Observatory and registered as 2017 AD17 in the MPC database. The first detection by Gaia previously occured on 29 December 2016. We have been able to fit all the data together in a very consistent way. This is the first orbit, hopefully from a future long list, computed using both Gaia and ground-based data.

Dear colleagues of the Gaia-FUN-SSO network,

Gaia-FUN-SSO is back...! After a long period of silence and a hard work by all the team, we are happy to announce that the Gaia alert system for SSO is validated : alerts are produced on a daily basis, and available online at The main problems that we had to overcome concerned discrimination between many stellar/spurious sources and moving objects (i.e. SSO/Solar System Objects). This has been now solved thanks to a drastic filtering. Despite this aggressive filtering strategy, all alerts have to be validated and verified by ground-based observations. Contaminants or missed identifications of known asteroids could still be present and generate false-positive alerts, although hopefully in a very minor fraction.

Gaia SSO alerts: Note that the primary goal is to validate the discovery of a new asteroid by Gaia, thanks to ground-based confirmation and follow up. For the dissemination of these alerts, we have developed a tool, the Gaia FUN SSO pipeline, accessible at the address This is the unique access point to get the Gaia SSO alerts. More than 70 persons have already registered. Only registered users can obtain the full predictions tailored for their site and instruments (including topocentric ephemerides and sky maps). If you have not registered, please do, and enter your telescope data and site coordinates. Check the web site regularly when you have telescope time available, as the alert list can evolve anytime, depending upon the arrival time of input data. In general, a typical 1-m telescope should always have a few alerts to choose from, with 1 or 2 possible candidates per night. We have been able to validate the first Gaia alerts in October, during the test phase.

Report policy: In case you successfully observe an asteroid we ask you to fill in and send us the form labelled "Observation report" that can be accessed from the object list or the "List of currently active alerts" page. We remind that we aim at giving to follow-up participants the maximum visibility for this activity. Besides sending the report back, we recommend that you submit your astrometry to MPC by using the provisional object name g0#### that is provided on the Gaia-FUN-SSO site. A rare exception to this naming, is for asteroids that could appear as alerts on the web page, but are in fact known to MPC. If you find a clear, unambiguous match to a known asteroid, you should then use the official asteroid name in your MPC communications. However, especially in this first phase, we are very interested to receive a feedback from you, on any related aspect (alert page issues, failed attempts, doubts and comments...).

More details: astrometry, discovery opportunities, limitations: The astrometry of candidate new asteroids obtained by Gaia are currently derived from a preliminary astrometric reduction using approximate (daily) attitude data. As such, it is not currently transmitted to MPC.
We plan to improve this aspect soon and to send Gaia astrometry to MPC directly. However, following the MPC policy the discovery will be officially attributed, for the time being, to the first observer submitting the astrometry. So, right now you have now the concrete possibility of discovering asteroids, just by following Gaia's "suggestions".
Further limitations are due to the way our filtering works, and should be kept in mind by the observers. As it is aggressive, our alert stream is not "complete", in the sense that faintest detections, corresponding to real alerts, or slowly moving objects, can be absent. Also note that the alert stream feeding the web pages can be temporarily suspended without notice for different reasons, independently from the alert processing itself (delays in the upstream data processing, technical problems...). In general, such interruptions should not be longer than a day or so.. We will keep you informed in case of longer breaks.
And now... let's go to the telescope and observe Gaia asteroid alerts!

Dear colleagues of the Gaia-FUN-SSO network,

Gaia SSO alerts: The Gaia mission is in the operating mode since several months now but the Solar System Objects alerts are not yet available...This delay is mainly due to the complexity of the short term process which identifies moving objects among millions of stars, discriminates the known and unknown objects, identifies the possible bound observations, and computes the bundles of probable orbital elements before triggering alerts. But, we are in the verification phase and we do hope to be able to solicit observers soon. Stay online!

Gaia-FUN-SSO tool: As mentioned in previous circulars, the only tool for receiving Gaia-FUN-SSO alerts is accessible at Therefore your registration on this page is necessary, even if you already sent us a registration sheet before...the reason is that you need to define your login/password and we need to know the characteristics of your location, your telescope and so on, in order to automatically prepare topocentric ephemerides and sky charts. We ask you to pay attention to this registration and to not forget the registration of these characteristics. Please complete your registration at Our ancient tool, the Gaia-FUN-SSO wiki, is now used only for dissemination of general information.

Collaboration with GBOT: new asteroid alerts! The positionning of Gaia required the set up of a specific task, the Ground Based Optical Tracking activity (GBOT, web accessible at, which regularly provides astrometry of the probe itself. During the analysis of the data currently provided by this task, the GBOT team is able to extract astrometry from moving objects. It appeared that GBOT can detect many asteroids and in particular several non yet identified ones! These objects are in the field of view of Gaia, toward the L2 point, therefore at their opposition. GBOT is not able to monitor these objects and the confirmation of detection of new objects, along with their complementary astrometry measurement, can be a task assigned to the Gaia-FUN-SSO network. We encourage the Gaia-FUN-SSO participants to contribute to this validation.

All necessary specific information related to the GBOT asteroids can be accessed at Recent unknown asteroid observations are available at: On this page, you can get the MPC formated astrometry and you can use it for computing ephemerides with one of the following tools:

Results must be sent to the MPC...

Dear colleagues of the Gaia-FUN-SSO network,

I forward you a message from M. Micheli & E. Perozzi (ESA-SSA-NEO) which recommend the observation of two newly discovered asteroids with short windows of observability (see below). At this date, on our side we are shifting from a "wiki" mode to a "pipeline" mode of distribution of data. We are not yet ready to push the data related to these asteroids in our new system. I suggest that you access to the ESA-SSA-NEO website for ephemerides.

But we will be able to post the possible astrometric data (MPC format) on our Gaia-FUN-SSO wiki. Therefore, if you succeed, please send me copy of these data. Thank you.

Message from M. Micheli, E. Perozzi and colleagues (ESA-SSA-NEO): Dear colleagues, here at the ESA NEO Coordination Centre we recently noticed a couple of newly discovered asteroids, 2014 WU200 and 2014 WX202, which may significantly benefit from additional observations in the next few days.

We would therefore like to ask if any of you would be interested in collaborating with us to obtain astrometric and/or physical observations of these asteroids. The two objects will go into solar conjunction around December 11 and December 9 respectively, and the observability window is therefore quite limited. From the point of view of physical characterization, anything ranging from lightcurves to colors and/or spectra would be extremely valuable, since almost nothing exists in the literature for objects of this size range. Given the reasonably faint magnitude of both objects (V=19 at peak), only moderately large telescope can probably obtain valuable physical data on these targets.

From an astrometric perspective much smaller apertures can still be very useful. The most important goal in this case would be to obtain a few detections (no more than 3-4 per observatory) on any of the upcoming nights. Since the accuracy of the astrometric reduction is essential in this case, we would be happy to support you in the measurement process, to ensure the highest quality positions are reported to the MPC (we would obviously properly credit you for any information we would extract from your data). In this case please let me know, and we can make the necessary agreements.

More information on the targets, and why they are interesting, is given below. Please let us know if you have any question, or need any help to prepare or optimize the observations. We will be happy to provide you with observatory-specific ephemerides, or any other information you may need to achieve the best results. Thank you in advance for anything you can do.

Marco Micheli on behalf of the ESA NEO Coordination Centre

Why are they interesting?

Both objects are in the H=29 size range, corresponding to diameters of a few meters, and will have a close approach with our planet next week. Despite the very small size, they are both particularly interesting for a variety of reasons, such as:

  • They are both "virtual impactors", meaning they have non-zero impact probability in the next century. Although an impact from an object of this size will have negligible consequences on Earth, it is nevertheless interesting to test our impact monitoring tools on such objects.
  • Both asteroids have peculiar Earth-like orbits, making them easily accessible by spacecraft from Earth (low DeltaV).
  • The small size, together with their accessibility, puts them in the right size regime for retrieval missions such as the one currently under study at NASA (ARRM).
  • The size regime of these targets is also particularly interesting because it directly represents the most common Earth impactors.

Dear colleagues of the Gaia-FUN-SSO network,

News from Gaia alerts: As already mentionned, last news from the Gaia mission are available on the blog at You will see there that the photometric science alerts have begun in validation mode on October 13. No Solar System Objects are concerned but other transient objects such as supernovae are. In case you are interested by these alerts, you can access to a selection of Gaia photometric detections at this address: In addition, you can access the presentations given during the 5th Gaia Science Alerts meeting in Warsaw at this address: The goal of our network itself is the astrometric observation of Solar System Objects (SSO) on alert. Tuning the Gaia data processing for these SSO alerts appears to be a more difficult task than foreseen and we hope that we will soon start receiving SSO alerts for diffusion, although no date is planned at the moment. Nevertheless, we must be ready for this and this is why we organized the last training campaigns, why a new workshop is held in Paris this month and why we ask to the network members to become familiar with our baseline tool for alert diffusion (see next sections).

Important: the tool for SSO alerts: The Gaia-FUN-SSO wiki will be no more used now for some observing campaigns and it cannot be used for the monitoring of alerts. It will remain open as an information repository. According to our project to distribute a large amount of SSO alerts each week, we have developed a new tool in order to automatically filter the data on the basis of the local constraints of each observatory. This pipeline will propose the list of alert, together with graphical visualization of sky maps with the probable zone where a newly detected object could be retrieved from the ground. This tool will be soon open to all the network participants. The first important steps required from the participants are:

  • to register
  • to enter your telescope and site properties and your personnal preferences in a menu
Therefore we invite all the Gaia-FUN-SSO observers to connect at and to perform these steps. In case of difficulty or for suggestions, let us know at

3rd Gaia-FUN-SSO Workshop: On November 24, 25 and 26, a 3rd Gaia-FUN-SSO workshop is held in Paris Observatory. 29 communications are scheduled and 49 participants will attend. The program can be accessed here. As for the previous workshops, we will post the talks at this address too and the proceedings will be also available.

Dear colleagues of the Gaia-FUN-SSO network,

2014 HQ124 triangulation campaign: Taking the opportunity of a close approach of the NEO 2014 HQ124 on 8 June, we propose a special very short campaign of observation. The idea is to experiment a triangulation measurement thanks to coordinated observations. This will not be an observing mode really adapted to the Gaia observation alerts but it will be interesting here, as a new training campaign, to apply this method which can give us an improvement of the positioning and, therefore, of the orbital parameters of this object recently discovered. This will probably not be an easy observation again. More information on this experiment is available in the attached text. Note that this will be probably the last "training" campaign before the real observations on alert since the operating mode of Gaia will begin soon. Further information about that will follow. Depending on the results, that kind of campaign could lead to communications or article and all the observers will be associated to them.

Dear colleagues of the Gaia-FUN-SSO network,

Campaign of observation of 2007 HB15 in close approach: The asteroid 2007 HB15, a potential impactor with small diameter (9 m) discovered in 2007, will have a close approach from Earth on April 28. Its orbit is not precisely known since it is based on only 24 observations spanning a short arc of 1.2 day. This close approach could be the opportunity to improve the orbital model. Due to its faint magnitude (around 22) these observations are challenging and will be reserved for the largest diameters of the network, with large field of view if possible.

Analysis of the NEA 2013 TV135 observations: Many observations of this asteroid have been performed in end of 2013.

Gaia SSO alerts: The commissionning of Gaia is still ongoing. The first alerts for Solar System Objects will probably not be triggered before mid June. A new pipeline for the dissemination of the Gaia alerts has been developped. It will be soon accessible. Further information to come.

3rd Workshop Gaia-FUN-SSO: a third Gaia-FUN-SSO workshop will be held on November 24-26 in Paris Observatory. Announcement will be diffused soon.

Dear colleagues of the Gaia-FUN-SSO network,

Launch of Gaia: The launch of Gaia will occur very soon: Thursday 19 December 9:12:18 UTC. The launch will be visible online in a webcast at this address:

Training campaign for the NEA 2013-TV135: Many observations of this asteroid have been performed during the last weeks.

New tool for the dissemination of the Gaia alerts next available: A new pipeline for the dissemination of the Gaia alerts has been developped. It will be soon accessible. Further information will be diffused in January.

Dear colleagues of the Gaia-FUN-SSO network,

New training campaign for the NEA 2013-TV135: The asteroid 2013 TV135, about 400 meters in diameter, has been discovered at the Crimean Astrophysical Observatory on October 8, after its close approach to the Earth on September 16. Due to its high eccentric orbit, its magnitude will decrease drastically in a few weeks for a long time. However this NEA is right now at the level 1 in the Torino scale (see / and presents a probability of impact in 2032 of 1:63000. Further observations are required during the next weeks for a better knowledge of its orbital characteristics.

Launch of Gaia delayed: The launch of Gaia has been delayed from November 20, previously planned, to the first date of the next launch window: December 17.

Dear colleagues of the Gaia-FUN-SSO network,

A new training campaign of observation for the NEA 2012 GT: The NEA (163 249) 2002 GT is one of the targets of the space mission EPOXI and a better characterization is needed. There is, for example, a suspicion of binarity which has to be solved before the arrival of the probe...At the actual period, the magnitude of this asteroid is 16 but it will become fast a faint object not observable before 2020. We propose to the Gaia-FUN-SSO network to observe 2002 GT during the next weeks according to the fact that the observational conditions are quite similar to those of possible detection by Gaia starting in 2014: magnitude down to 19 (rather low for 1m class telescopes) and low Solar elongation. The ephemerides, accessible with the link below, show that this observation will be difficult,...even impossible, from several observing sites...please check it. Other sites will certainly be able to provide some astrometric or photometric measures useful for the preparation of this mission.

Proceedings of the Gaia-FUN-SSO workshop 2012: They will be available on line starting from June 18 here.

The launch of Gaia is foreseen around September19....the network will be certainly involved in validation of SSO detections starting from January 2014.

OR#3: during the period from August 28 to September 6, the DPAC consortium will operate a special training activity (Operations Rehearsal #4) for testing the data processing through simulations. Simulated detections of Solar System Objects will be provided and will be triggered toward the Gaia-FUN-SSO network. More information will be provided later.

Dear colleagues of the Gaia-FUN-SSO network,

A meeting on the Gaia Follow-up (not only SSO...) is organized in Marseille, France, on April 11th. This is focused on the French participation, in particular from the Haute-Provence Observatory. But, this meeting is open to everybody (who is able to come in Marseille...). Let us know at if you intend to attend.

(99942) Apophis: We have now collected a large amount of images of 99 942 Apophis. The involved stations have the MPC codes: 71, 89, 119, 300, 511, 585, 910, A84, B04, B17, C01, D20, Z20 and the Lijiang station. Several more (MPC code 188 and 586) are still awaited. This represents more than 3200 measures. The analysis is in progress and we are confident to reach interesting results upon the dynamics of this PHA. We are still interested by collecting more observations. Do not hesitate to send them to us, we intend to submit a collective article to a journal on this topic. Collecting your images is important in order to provide an homogeneous analysis. I will give you a mean to upload them on our ftp if you are concerned.

A message by Lukasz Wyrzykowski informed us that the 4th Gaia Science Alerts Workshop will be organized in Paris by the Gaia Science Alert Working Group, probably in June. More information will appear soon at

Dear colleagues of the Gaia-FUN-SSO network,

2012 DA14: We have collected several astrometric measures we remain interested by collecting more...

(99942) Apophis: We have collected a rather large amount of astrometric measures of 99 942 Apophis. The measurements by the observers, jointly to all the new MPC collected measures, allowed us to fit a numerical model of the motion of the asteroid. This work leads to statistics of the observing stations and to the determination of new orbital elements. We are still interested by collecting more observations. Do not hesitate to send them to us, we think that we can provide a collective article to a review on this topic. For this goal, we are also interested by collecting your images in order to provide an homogeneous analysis. I will give you a mean to upload them on our ftp if you are concerned.

Dear colleagues of the Gaia-FUN-SSO network,

Need for 2012 DA14 observations! Southern hemispere : before the close approach on approach !

As announced before, we propose to perform new training astrometry campaigns. There is right now the need for astrometric measurements of 2012 DA14. As you probably know, this PHA has been discovered on February 2012 at the Observatorio Astronomico de Mallorca - La Sagra - in Spain, after its approach from Earth at 2.5 million kilometers. This year on February 15 at 19:24 UT it will pass much closer to the Earth, since it will cross the zone of geosynchronous satellites and pass at a distance of 27 700 kilometers from the Earth surface. Before this date it will be observable only from the Southern hemisphere and after this date it will be observable only from the Northern one. This asteroid is about 45m in size and its magnitude is generally faint. During the next close approach, the magnitude will change very fast, down to 7.7, and observations become accessible to small telescopes, but the apparent velocity will be very large (from 43'/min to 4'/min). Astrometry of this object is important since most of the observations used for the orbital model are based essentially on the 2012 approach observations, and this object is flagged as a virtual impactor by the JPL Sentry. The ephemerides given on the wiki are 1h step ephemerides. Observers are invited to compute their own ephemerides with smaller stepsize if needed. Besides, we encourage observers to perform some observations at the exact times given in the ephemerides because simultaneous astrometric measurements could be analyzed and lead to a new observational constraint: an accurate estimate of the distance of the asteroid. Note that in case of observations of a very fast moving asteroid, it is possible to acquire several positions in only one frame by using a shutter occulting periodically the camera during a certain time interval (perhaps several seconds) and by identifying exactly the corresponding time of the exposures when the shutter is open.


The PHA 99 942 Apophis is still observable and astrometry is still interesting for the improvement of the orbit. Note that, for all these campaigns, besides the interest of the astrometric measurements themselves, it is important that the observing stations involved in Gaia-FUN-SSO be well visible. The number of stations involved in such a campaign is important. No need for systematically numerous measurements, but need of large participation.

Dear colleagues of the Gaia-FUN-SSO network,

As announced before, we propose to perform new training astrometry campaigns. The Potentially Hazardeous Asteroid (PHA) (99942) Apophis is coming back and is now observable for several months. We propose this target for the first campaign in the period 9/12 - 1/3. The conditions will not be so good for the beginning of the period but you will be able generally to find some possible time slots for observations. The wiki pages (at have been updated and you will find in particular topocentric ephemerides for preparing some runs in your observing site depending on the local conditions that you will read in them. As usual, some recommendations are given in the wiki and we stay available to answer to some questions if needed. We would appreciate that you send us your astrometry measurements at (by specifying wether you also sent them to MPC or you let us do that).

Dear colleagues of the Gaia-FUN-SSO network,

We come back to you for giving some last information from the Gaia-FUN-SSO central node.

In last September we had an interesting Gaia-FUN-SSO workshop in Paris, in particular for organizing the new period before the launch of the Gaia mission in Autumn 2013. A large part of the talks given during this workshop are accessible on the web at this address. If you were a participant of this worshop, as you know you can access to these talks. If you were not, you can nevertheless access them as member of the Gaia-FUN-SSO network. The login / password are : gaiafun / 20gaia12. On the other hand the proceedings are being collected and will be gathered and published by 2013 February.

We are now in a rather short prelaunch period (less than one year from the launch and almost 15 months from the operating period) where we can try to be more in the conditions of the Gaia alerts. Due to the parallax effect between the L2 point where Gaia will observe and the Earth, the retrieving of a new object can be rather difficult. We are now preparing new material for supporting these observations by the network. In the following months, you will receive more information upon that.

We think that now it will be important to have again new training observations of interesting targets. In another message, we will send you more information upon that. All the data will be once more accessible on the wiki page at the address During the next months, we wish to diffuse a series of such a circular, hoping we will keep in touch...but if you wish to unsuscribe let me know too.