| Comm. 20 Discussion Forum | Mon, 19 Jun 2000 10:58:45 +0200 |
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Dear Colleagues, The present subject for the Discussion Forum is the printed ephemerides in Ephemerides of Minor Planets (EMP) and the Opposition Data in Minor Planet Circular (MPC). The problem is to reduce the size and improve the content. How long time the printed data shall survive depends on their convenient form and content of information. By a small change of the Opposition Data in MPC positions may be provided to an accuracy of 2' (2 minutes of arc) in a 70-days interval without increasing the present size of one line per object. This is done by fitting Chebyshev polynomials to the 8 10-days standard ephemeris dates. The idea is illustrated by 1999 CQ14 on MPC 40734: The right ascension in hours is given by 18.312 -0.441 -0.018 +0.024 and declination in degrees by -4.49 -0.58 -0.78 +0.01. The 8 standard dates are 2000 May 16.0 to July 25.0 which corresponds to the time-parameter X=-1 and X=+1 respectively. If we want the position July 15.0 the parameter is X=25/35=0.7143 and the Chebyshev polynomials (T(0), T(1),... ) are 1.0000, 0.7143 (=X), +0.0204, -0.6851 The last values are found by recursion: T(n) = 2 X T(n-1) - T(n-2). Multiplying these polynomials with the coefficients above and adding gives 17.980 hours and -4.93 deg. The respective errors in the position are only +0.1' and +1.2' . The present form with a single position and the daily motion corresponds to and gives the same work as including only the two first terms above. The maximum error in our example is 0.78 deg in declination due to the ignored term. Several examples give an r-m-s error ½ deg. in the entire 70-days interval. This may suffice for planning and is better than the present opposition position and daily motion. The place for the small coefficients ( -18, +24, -78, +1 in last figure) may be obtained by deleting the repeated opposition dates ( 2000 06 24.8 ) which are redundant and deleting the minimum phase angle (6.9/25.7 ) which seems not used as much as intended. The 4. and 5. standard dates are June 15 and 25, and the 4 pages (MPC 40731-734), each with 102 lines, have opposition dates in this interval. The 8 standard dates or the central date (June 20) may be used as the header for ca. 400 objects. The EMP ephemerides can be given with 6 coefficients. Taking into account that in the present form full accuracy may require interpolation with third differences the work in obtaining a position is not much larger. Several examples shows that the above example is the normal one. A few unusual objects may require more space, - as it is the case at present. Are there better solutions to this problem ?? Best regards, | |
| Leif Kahl Kristensen | |
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| ToR, sorry for the delay... | Fri, 16 Jun 2000 13:45:45 +0200 |
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Dear Alan, Pushing your logic to the limit would make me adjust survey parameters in the following fa shion: - Set my detection threshold to one sigma or less. - Cover as much sky as I can once a month (strictly once, not 3 times once). I would then subtract a reference image, and publish immediately anything that does not show on a reference map as a potential object, letting others deal with all my false detections, variable stars, cosmic ray hits, and potential scientific discoveries, knowing that in all the crap I publish, I will get discovery credit for everything that I was able to observe first. Your nice criteria would be all fullfilled. Now it is easy to imagine two different scenarios: - I am the only one to work like this and pretty quickly I show up on the top of the list of "individual discoverers" thanks to the efforts of my colleagues. - Everybody works like me and the number of orbits produced in a given year go down by at least an order of magnitude, having several orders of magnitude of computing power wasted to sieve through all the published crap. You seem to forget that there is a difference between an astrometric position, a preliminary set of observations (i.e. typically the set obtained during a single night, from 3 to 5 observations depending of the observatory, which for many do even not assure that the object is a real one), a set of astrometric positions which provides assurance that the object is real (see the number of "lost" objects on the NEO confirmation page alone), and the final set of observations which allow us to obtain what we all strive for, i.e. orbital elements of good quality. Personally, I find the current system quite optimised toward this goal, being the result of a long evolution, whereas I find your suggestion would just bring chaos in an otherwise correctly working system (i.e. the MPC and its current operation, and the current quality of the existing database). Cheers, Alain | |
| Alain Maury | |
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| ToR, sorry for the delay... | Fri, 16 Jun 2000 13:45:45 +0200 |
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Dear Hans, There is a saying which goes like "if it ain't broken, don't fix it". In this context, and in the recent history of the MPC, I don't see the point of your proposed Terms of Reference (ToR), unless it is to satisfy a minority of known complainers, to the disadvantage of the _vast_ majority of MPC users. This is true whether "users" are counted as individuals, or by observatory codes, or in proportion to the number of astrometric measurements provided to the MPC (including or not the dreaded One Night Stands; ONS), or in proportion to the number of orbits derived from their observations. If the IAU were an employer of the MPC personnel, and if these personnel were working with adequate means (i.e. 35 to 40 hours a week), such a document (the existence of the document, not its current content) could be considered as a valid concept. However, if I am right, the IAU does not pay the salary of the MPC personnel (NASA and the SAO do). These personnel are known to work much more than 40 hours a week, and their dedication and competence have made it possible to absorb the recent explosion in data submission since the last GA in quite an impressive manner. In this context, the least the IAU could do is to congratulate the MPC for its achievements, not offer it rigid terms describing its operation, without (it seems) any discussions with it. The current system, based on the good relations between scientific colleagues, is working well and has shown quite well, most notably in the last few years, its ability to evolve. On the problem of the ONS, let the colleagues who _claim_ they can use them in a useful manner demonstrate that it can be done efficiently. Many surveys (Catalina, LONEOS, ODAS to name a few) have their data, including ONS, available upon request. So a paper or two showing case studies where the ONS could indeed most of the time lead to valid orbits would do more to _convince_ the community that today's faster computers, or better programs, or whatever that these data (today considered by most observers as unpublishable junk) has now such value that after a given delay they should be made public. Amicalement, Alain | |
| Alain Maury | |
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| MPC ToR | Wed, 14 Jun 2000 16:48:41 -0700 |
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Dear Hans, I have read the various e-mails and postings on the Comm. 20 discussion page relating to the MPC Terms of Reference. I regret to say that I cannot support the latest draft. I share two of the concerns expressed by Bob McMillan in his communications, but from there I diverge with him diametrically. My points of agreement are that the latest draft is only little changed from the previous one, and certainly does not go far in addressing my concerns which I expressed following that version circulated in February. I also agree that laying out a detailed recipe for the conduct of the MPC should be unnecessary and it is demeaning to the staff of the MPC to do so. Following Bob's lead, I offer below my own proposal for a Terms of Reference. I believe we should limit ourselves to simply affirming basic principles which are common to all scientific endeavors, followed by a few comments indicating how these principles apply to the protocol of the MPC. The guiding principles are: (1) Any scientific result must be reproducable. To reproduce a result, one must have access to the underlying data. That includes not only data that were used, but all data that were not used as well, so independent judgements can be made of the validity of choices made. (2) Credit for a scientific discovery is granted according to the time a claim is publicly made, not the time the underlying observations were made. (3) To receive credit, a discoverer need not confirm the claim, (s)he need only be right, as confirmed by others. Below is my draft proposal. I request that you post it, along with this message, on the Comm. 20 discussion page. There is a tendency to reduce wisdom to "sound bites." Andreas Doppler has done this, paraphrasing Cato the Censor (ca. 180 BC -- the sound bite has been around a long time): "Ceterum censeo observationes noctium singularium edendas esse." Best regards, Alan Harris -------------------------------------- IAU MPC TERMS OF REFERENCE Proposed by A. W. Harris 14 June 2000 The duties of the Minor Planet Center are divided into three categories listed according to priority: 1. To receive, catalog and make publicly available all observations submitted. 2. To correlate observations by object, assigning designations and eventually numbers. 3. To produce a variety of data products, such as orbital elements, ephemerides, and other observing aids. The first category activity is simple but most essential. The collection and archiving of data cannot be limited or delayed by any form of "checking" of data. By their fundamental nature, observations often cannot be declared unequivocally valid or invalid. Such judgement depends on the intended use, on subsequent observations, and a host of other imponderable factors. Thus a data bank must "accept all deposits" without initial judgement, and make all deposited data immediately available to anyone and everyone. The second category activity does necessarily involve some measure of "checking." This activity should be carried out as rapidly as possible in order to confirm claimed discoveries of new objects, as distinct from re- observations of already known objects and observations that cannot be confirmed or correlated with any other observations. However, "confirmation" shall not be a criterion for inclusion in the public data file, nor a reason for delay in public posting of observations as received. In assigning discovery credit, two universal principles, which are fundamental to all scientific investigations, must be observed. First is that the discoverer is not required to confirm a claimed discovery in order to receive credit. (S)he only needs to be right. That is, the discovery claimed must be confirmed, but not necessarily, indeed preferably not, by the "discoverer." Independent confirmation is to be far preferred. The second principle is that credit is due according to the time of public disclosure of the discovery claim. Thus an observer may withhold reporting of observations pending confirmation, but does so at the peril of losing priority for the discovery. If an observer enters into an agreement with the staff of the MPC to pre-check data, it must be clearly understood that such an agreement is outside of the terms of reference of the MPC. Care must be taken to keep such activity separate from the official duties of the MPC, and it must be understood that discovery credit will be determined according to the moment of public posting of the observations, not the time the observations were made, or private consultation with MPC staff. Category three activities are the only ones that represent "intellectual property" of the MPC, and are the only products that should be subject to copyright or sale. It remains desirable to offer these services freely, but if budget limitations require compromise, it could be acceptable to sell these products by subscription, transfer the production of them to other centers, or take other measures to cut costs to the MPC. | |
| Alan W. Harris | |
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| Spacewatch response to MPC Terms & Conditions | Tue, 13 Jun 2000 23:02:32 -0700 (MST) |
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Dear Colleagues, This message concerns the draft for _Terms of Reference for the IAU Minor Planet Center_ dated 2000 Feb 18 17:15 UT and distributed by Mike A'Hearn. I have written this in consultation with Tom Gehrels, Jeff Larsen, and Jim Scotti, but take full responsibility for its content. To the extent that it might be considered necessary that there be an "official" Spacewatch position on this issue, I hope this will begin discussion that will lead to such a position. Spacewatch has enjoyed an effective, informal, and collegial relationship with the MPC since 1983. Stability of the MPC is of paramount importance to us, especially in regard to personnel, data submission protocol, discovery rights, data formats, and their software. Without disruption or discontinuity of service, we have witnessed a steady expansion and acceleration of its capabilities and services. These enhancements resulted largely from the resourcefulness, dedication, and talent of Gareth Williams in response to the increasing data rate as well as requests from observers and healthy competition from colleagues who have begun to provide some parallel services. Therefore, even in the absence of controversy, I would question the need to redefine their mission, especially if that is a change from adaptive evolution driven by need to that of rule by committee. In the present climate, a formal, overarching document such as these proposed _Terms_ has to be scrutinized especially carefully for potential misunderstandings, inadvertent omissions, and unexpected contingencies and implications, a burdensome task with uncertain reward. Would these _Terms_ supersede the "incremental resolutions" by Comm. 20 that cumulatively define the role of the MPC, or incorporate them by reference? It would be helpful to see those original resolutions, and even better, a synopsis of what is being omitted, changed, and added. With all due respect to this distinguished company, the introduction of an additional committee (MPCOC) to control the MPC is troubling to me; almost all of the recommendations made by review panels to Spacewatch have been worthless. I would be more comfortable with these new _Terms_ if I knew of examples of improvements in the MPC to date that resulted from recommendations from the Comm. 20 Organizing Committee, the WGNEO, or the MPC/ITA Consulting Group. What is the process of appeal if the MPC does not agree with the demands of the MPCOC? How would these _Terms_ interact with the contract(s) that currently fund the MPC and the contracts of employment of its personnel? What will be the consequences of dispersal of MPC services to subordinate institutions or the relocation of the MPC itself? In other words, do we really know what we are doing with these _Terms_, or is the mission of the MPC, like the British Constitution, best left to precedent? Shouldn't we always strive toward the collegial approach to solving problems, treating the MPC as a small group of professional colleagues instead of a commodity service organization? As an employer of many long-term technical workers, I know that people need latitude to be creative and take initiative. With the high salaries outside of astronomy nowadays, respect for the dignity of colleagues and employees is more important than ever. What requests for information or technical support that were made privately and politely to the MPC have ever been denied? I expect that approach has been as effective for others as it has been for Spacewatch. Those who make strident demands in public risk appearing as if they are trying to embarrass, humiliate, demoralize, and/or undermine the reputation of the MPC, with the apparent object to build a case to take over some of the functions of the MPC, instead of progressing with their own research. Many years ago, Spacewatch convinced the MPC to reverse their policy and accept the incidental astrometry (IA; otherwise known as "one-night stands") of all moving objects detected in our scans. This was a very prescient suggestion on Tom Gehrels' part, but it was on the condition that the MPC check those measurements and release them when the MPC was convinced they are valid, not merely when there was no reason to believe they were flawed. Given the history of this agreement, I am bemused that some in the asteroid science community somehow view access to IA as an entitlement. At the very least, we need there to be a delay between our submission of IA and their release to the world, if only to preserve our discovery rights. Otherwise, our IA submission process would have to include filtering out of potentially interesting objects, putting an additional burden on our staff. As the employer of many observers, some who are new and still in training, I also need the MPC to act as a buffer of peer review between a sleep-deprived solo worker and the outside world. If our emailed IA were released by the MPC automatically without validation, I would have to delay our email to the MPC until a second worker in the daytime could do quality control. Limitations of staffing could cause delays of several days. Such is the invaluable service being performed by Gareth Williams. Bob Robert S. McMillan Principal Investigator Spacewatch Project Dear Colleagues, 2000 June 14 05:56 UT Since the statement above was written in February, I have received no official response directed specifically at its content, and no answers to any of the questions I raised in it. Drs. A'Hearn, Andersen, and Rickman distributed a message on March 21 notifying us of their decision that there would be new ToR for the MPC (thus rebuking the pleas of some of us not to tamper with it) and that they "welcome further SPECIRIC [sic] recommendations for IMPROVING the Terms of Reference". Subsequently, on May 31, Dr. Rickman distributed another draft with no significant differences from the one in February. Therefore, some colleagues and I have drafted an alternative ToR that has the approval of the MPC. I append it below, and as a new member of Commission 20, humbly offer it as a substitute to the draft that has been so controversial. It contains all the requirements for ToR without micromanaging or using the ToR as a vehicle to make changes in policy. I urge the leadership to adopt it. Respectfully yours, Bob Robert S. McMillan Spacewatch University of Arizona _Terms of Reference for the IAU Minor Planet Center_ Draft of 2000 June 13 04:00 UT Preamble Several activities related to the orbits of the small bodies of the solar system are carried out on behalf of the International Astronomical Union (IAU) by the IAU's Minor Planet Center (MPC). Until the adoption of these _Terms or Reference_ (ToR), however, the existence and operation of the MPC as an entity of the IAU were described only by a series of incremental resolutions by Commission 20 spread over many decades. In order to establish a clear basis for the continued operation of the MPC in a rapidly expanding field, including the provision of adequate financial support, it is appropriate to establish ToR for the MPC. Rationale for an IAU Minor Planet Center Ready access to up-to-date reliable orbits and ephemerides of the known solar-system small bodies, together with some information on the accuracy of the data, is necessary both for the astrometric observers who continue to track the objects and for the observers and theorists wishing to undertake physical and dynamical studies, respectively. The study of potentially hazardous (Earth-threatening) objects requires access to original astrometric data as well as reliable orbital data for such objects. Astronomers, as well as the world at large, need a definitive set of designations and names for the small bodies of the solar system. The IAU delegates the MPC to coordinate the nomenclature of minor planets and (in collaboration with the Central Bureau for Astronomical Telegrams, CBAT) comets. Scope of the Minor Planet Center The MPC is charged with considering astrometric and orbital data for the small bodies of the solar system, including asteroids, comets, near-Earth objects, Centaurs, and Trans-Neptunian objects, optionally including Pluto and Charon and the outer satellites of the giant planets. This activity includes the receipt and prompt processing of astrometric observations from professional and amateur astronomers around the world, and verifying, insofar as is possible, the reliability of those data. The processing also includes associating observations with previously designated objects. Depending on their urgency, recently processed observations shall be published, together with appropriate documentation, by the MPC. The MPC is also charged with archiving the reliable astrometric data and with ensuring their maintenance and availability. The MPC is charged with the computation and publication of orbital elements, as well as ensuring the maintenance and availability of a database of orbital elements, including some indication of their quality. For small bodies that might be of particular or immediate interest to observers, the MPC is also charged with ensuring the dissemination of ephemerides. The MPC is charged with co-ordinating both the official catalog designations (and numbers) and the names of asteroids and (in collaboration with CBAT) comets, using the systems established by IAU Commissions 20 and 6. The actual assignment of names is undertaken with the Small Bodies Names Committee (SBNC) of IAU Division III. The full spectrum of tasks in this scientific field has grown so large that in the future several institutions may be involved in their execution. The MPC may collaborate with other suitable institutions to cover its responsibilities. Establishment and Organization of the MPC The MPC is established by Agreement between the host institution and the IAU, upon the recommendation of IAU Commission 20 and with the approval of the Executive Committee. The Agreement will specify the amount of financial support provided by the IAU. Support may be: (a) run until notification of termination or substantial revision of the Agreement is given by one of the parties, or (b) concluded for a specified period, renewable by mutual agreement. Termination or revision will take effect at the next IAU General Assembly and require notification at least one year in advance. Any such action from the IAU side will be undertaken upon the recommendation of the IAU MPC Advisory Committee (MPCAC) established by IAU Commission 20 (see below). The Director of the MPC is appointed by the host institution in consultation with the IAU General Secretary, upon the recommendation of the IAU MPCAC, Commission 20, and Division III. Other sources of funds for the MPC may include, but are not limited to, contributions from the host institution and from such other national and international sources as are possible and appropriate. The choice of institution to host the MPC is based on the institution's ability to provide the following services: -- qualified staff with scientific and practical expertise in astrometry and celestial mechanics -- full-time availability of sufficient personnel for day-to-day operations -- sufficient computational capability -- internet connections of adequate bandwidth -- ability to remain operational 24 hours a day IAU Commission 20 appoints an IAU MPC Advisory Committee (MPCAC) of four to eight members, following the IAU rules for the appointment of Working Groups. It is essential that both astrometric observers and orbit computers be represented on this Committee, with regular astrometric observers represented by at least half of the members. The MPCAC has the responsibility to monitor the services and performance of the MPC, and it advises the MPC Director and the IAU (through Commission 20 and Division III) on the suggested future development of the services of the MPC. The MPCAC may also advise the MPC regarding the suitability of agreements with collaborating individuals or institutions to provide some of the services of the MPC, and may receive appeals from observers or orbit computers regarding the handling of their data by the MPC. | |
| Bob McMillan | |
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| MPC Terms of Reference of May 31 | Tue, 6 Jun 2000 10:07:56 -0700 (MST) |
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Dear Colleagues, I regret that it is impossible for me to support the proposed Terms of Reference for the Minor Planet Center distributed on May 31, for it seems to me that such a detailed prescription of requirements is entirely inappropriate. It would be a mistake to try to micromanage an operation that has served the community well and faithfully over many years. Indeed to force on an honorable operation such a prescription has the potential to destroy the MPC without the possibility of a workable replacement. Who would want to work as slaves to masters who are so uncomprehending? The current version of the ToR essentially ignores the responses, particularly of observers, to the draft circulated to a limited group last February. It is unclear to me how the new demands placed on the Minor Planet Center would be supported financially. To this point, the IAU has never contributed more than a token amount, and subscription charges have been essential. Indeed, I believe that some of the proposed new demands are unwise, e.g., the immediate release of "one night stands", the validity of which cannot be established. This suggests to me that the authors of the current version of the ToR do not understand the constructive interaction between observers and the MPC that leads to improvement of the quality and reliability of astrometric data. Does somebody want to try to link one-night-stands with each other and then send observers on wild goose chases to try to sort out which are valid? The name MPC "Oversight" or "Overview" Committee implies a license that I believe to be not appropriate. I much prefer a more neutral and collegial name, such as "MPC Advisory Committee". I perceive the present situation to be so serious and potentially so damaging that I urge withdrawal of the current version of the ToR for fundamental reworking. Its adoption without a major change of philosophy would be a grave mistake. To make clear the depth of my concern over the damage that I believe likely to follow implementation of such poorly conceived and dictatorial ToR, I state here with deep regret that I would support a motion of "no confidence" in the present leadership of Commission 20 if anything like the present version of the ToR is to be submitted to the IAU Executive Committee for further action. | |
| Elizabeth Roemer | |
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| New input! | Wed, 7 Jun 2000 10:05:37 +0100 |
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Dear Commission members and consultants, the forum will now concentrate for a while on the MPC Terms of Reference, but I still invite views on all matters concerning our Commission. Entries for this forum can be submitted to me by email. The address is: hans@astro.uu.se. Looking forward to hearing from you! | |
| Hans Rickman | |