Guide to Minor Body Astrometry
This guide is intended for those observers interested in undertaking an astrometric CCD-observing program of minor planet and/or comets.This document was last updated 2010 April 1.
The following questions will be posed, then answered:
- What equipment do I need? [Updated 2003 Jan. 23]
- What sort of CCD should I use?
- How do I make measurements?
- Where should I obtain my comparison star coordinates? [Updated 2010 Mar. 1]
- What corrections should I apply to the derived positions?
- How do I obtain an accurate time? [Updated 2010 Mar. 1]
- What do I report?
- Are there any recommendations regarding e-mail? [Updated 2004 Feb. 4]
- What if I use spam-blocking systems? [Added 2005 Oct. 31]
- What are some common mistakes?
- Can I report approximate or preliminary measures?
- The observation format requires an observatory code. I don't have a code. How do I get one? [Updated 2007 Dec. 29]
- Does my observatory code move with me? [Added 2002 Dec. 12]
- Are there any restrictions on my observatory's name?
- How do I begin? [Updated 2004 Nov. 7]
- How many observations should I make of each object?
- What objects should I be observing?
- What quality of measurements should I aim to produce?
- Do I need to identify objects? [Updated 2005 Oct. 31]
- When should I use a discovery asterisk? [Added 2009 Dec. 18]
- How do I know that the Minor Planet Center has received my observations? [Updated 2003 Aug. 2]
- What about batches containing observations from two or more observatory codes? [Added 2005 Oct. 31]
- A message to the MPC bounced. Do I need to resend it? [Added 2004 Oct. 1]
- I think I have something new. How do I get a provisional designation assigned to it? [Updated 2010 April 1]
- What is the difference between reporting two-nighter and single-nighter new objects? [Updated 2010 Apr. 1]
- Who gets credit when single nighters are linked? [Updated 2010 April 1]
- What objects go on to the NEOCP?
- How long does it take to assign a new provisional designation? [Updated 2005 May 20]
- How do I understand the designations the Center sends me? [Clarified 2005 Feb. 28]
- What's the best way to follow-up a new discovery?
- What about coverage on a single night? [Updated 2009 Dec. 11]
- What if I can't follow-up a new discovery?
- Should I separate my comet and minor-planet observations when submitting them? [Updated 2002 Nov. 27]
- Should I check my observations before reporting them to the Center?
- How quickly are observations processed by the MPC?
- What's the best way to get my discovery numbered? [Updated 2008 December 29]
- When can I name my discovery?
- What names are acceptable?
- How do I write the citation and submit the name? [Added 2000 Jan. 29]
- How long does it take for the name to be approved? [Added 2000 Dec. 2]
- What happens to accepted observations?
- What is the purpose of the contact details?
- What (p)recovered objects get MPECs? [Updated 2002 December 26]
- I'm interested in photometry... [Added 2003 Aug. 13]
What equipment do I need?
Almost any type of telescope will do (reflector or refractor). You will need to know the focal length of your telescope and the physical size of your CCD's pixels to calculate the pixel scale. Your setup should be such that the pixel scale is no greater than 2"/pixel (preferably) or 3"/pixel (at worst). In practice, your optimal pixel scale is something that you will have to determine for yourself, taking into consideration the capabilities of your telescope and CCD and the seeing at your site. If your pixel scale is much larger than the values quoted above, then the quality of the astrometry will suffer. If your pixel scale is too low for your local setup, then the signal-to-noise of the images may be low as each image is spread over a large number of pixels.You will also need a computer to capture the images and software to perform the reductions. Most astrometry software packages use the Guide Star Catalogue, so a CD-ROM drive is also required. Various software packages are advertised in popular astronomy magazines:
- Herbert Raab's Astrometrica
- John Rogers' CCD Astrometry
- Project Pluto's Charon
- Bob Denny's PinPoint
- BdW Publishing's Canopus
- Prism
- Software Bisque's TheSky + CCDSoft
- Circe
- fitsblink
An accurate clock/watch set to Coordinated Universal Time (UTC) is a must and this must be checked regularly (as a minimum, at the start of each observing session) against a reliable standard.
Access to e-mail is also important, both for reporting observations to and receiving designations from the Minor Planet Center (MPC).
What sort of CCD should I use?
It is not our place to recommend specific brands of CCDs. A look through any popular astronomy magazine shows that there are a variety of CCDs available. The CCD that is right for you depends on your computer system and on how much you want to spend.How do I make measurements?
The exact details of how you will make measurements on your images and perform the reductions will depend on the software package you are using. In broad terms, you will determine pixel x,y for the centers of a number of comparison stars of known position (at least three comparison stars, preferably as many as are on the image) and the minor bodies in each image. Using these x,y measurements (determined to a fraction of a pixel) and the comparison star coordinates (taken from a suitable reference catalogue [see below]), the program should then do a least-squares plate-constants (LSPC) solution to derive the unknown coordinates of the minor bodies. Be suspicious of any package that does not do a proper LSPC solution!You must not attempt to derive positions by overlaying charts on your images or by estimating positions by eye. The accuracy of these positions will not be sufficient.
Where should I obtain my comparison star coordinates?
Most CCD fields tend to be rather small (a few tens of arcminutes wide) and this has in the past precluded the use of traditional standard astrometric catalogues. Fortunately, the situation is now much improved and most astrometric software allows suitable catalogues to be queried over the network (e.g., from sources such as Vizier) or from a local copy.It is the recommendation of the Minor Planet Center that observers who are still using the GSC or USNO-Ax catalogues as their reference catalogue should migrate to the USNO-B1.0, unless their field-of-view is large enough to contain sufficient UCAC 3 stars.
The following sources MUST NOT be used for comparison-star coordinates:
- The World Coordinate System information in the FITS headers for images in the Digital Sky Survey (whether accessed via the Web or via the highly-compressed CD-ROM version).
- Any B1950.0 star catalogue (e.g., SAO Catalogue).
What corrections should I apply to the derived positions?
None! No corrections should be made by the observer for parallax and no attempt should be made to correct the UTC times of observation to Terrestrial Time (TT), the uniform timescale used in orbit computations.How do I obtain an accurate time?
If you have a Java-enabled frames-capable Web browser you can obtain current UTC from the U.S. Naval Observatory's Time Service Department. This link also contains information on programs that you can use to automatically set your computer's clock, as well as the Network Time Protocol. Note that due to the unpredictable delays in Internet transmission such programs should be used in preference to the in-lined clock displayed by your browser when accessing this site.Various radio stations around the world transmit UTC. The following table of stations is reproduced from the British Astronomical Association Handbook by kind permission of Max White.
Station Call Transmission Time of Details of Sign Frequencies Transmission Signal /KHz Mainflingen, Germany DCF77 77.5 continuous Second marker 100 ms Minute marker 500 ms 59s omitted Prangins, Switzerland HBG 75 continuous Markers interruptions of carrier wave. Second marker 10ms; minute marker double pulse; hour maeker triple pulse Moscow, Russia RWM 4996 continuous Except 08 & 38m past hour 9996 Morse ID 09 & 39m 14996 Fort Collins, U.S.A. WWV 2500 continuous Second marker 5 ms pulse (29s and 59s omitted) 5000 Minute marker 800 ms pulse 10000 Male voice announcement 52s-60s 15000 20000 Kauai, Hawaii WWVH 2500 continuous Second marker 5 ms pulse (29s and 59s omitted) 5000 Minute marker 800 ms pulse 10000 Female voice announcement 45s-52.5s 15000 20000 Ottawa, Canada CHU 3330 continuous Second marker 01s-28s 7335 30s-50s 14670 Minute marker 500 ms pulse 51s-59s Long hour marker Puncheng, China BPM 5000 continuous Second marker 10ms; minute marker continuous 30m. 10000 continuous Call sign in Morse and voice at 29-30m and 59-60m. 15000 0100-0900 UTC time signals give out at 00-10, 15-25, 30-40, Z tranmsission 45-55m. Chung-Li, China BSF 5000 continuous Second marker 5ms; minute marker 300ms 15000 except 35-40m Taejon, S. Korea HLA 5000 continuous Second marker 20 ms Minute marker 800 ms at 1000 Hz tone Hour marker 800 ms at 1500 Hz tone Voice announcement 52s Nazaki, Japan JG2AS/ 40 continuous Second marker 500ms; 59th second 200-ms JJF-2 interruption of carrier wave. Morse call sign at 15 and 45m. Buenos Aires, LOL1 5000 1700-1800 Morse ID; voice 04, 09. Then every 5m Argentina 10000 2000-2100 past hour 2300-2400 Caracas, Venezuela YVTO 6100 continuous Second marker 100 ms pulse 52s-57s voice announcement of time Minute marker 500 ms pulse 30s marker omitted
What do I report?
There is a special format for reporting astrometric observations. Please read this document carefully and report the observations in the correct format (noting that the UTC time of observation should be reported to 0.00001 day, the R.A. to 0s.01, the Decl. to 0".1, and that magnitudes should not be reported more precisely than 0.1 mag.). The reduction packages mentioned in question 1 should produce this format automatically.Observations of both minor planets and comets, formatted as specified in the link above, must be reported via e-mail to mpc@cfa.harvard.edu.
Do not report more than one position for each time of observation!
When there is no trailing of the minor planet image (or you are measuring the middle of a trail) the time of observation is the mid-exposure time. If you are measuring both ends of a trail, then one end is associated with the start of the exposure, the other with the end. Alternatively, if the trail is very short, you can simply report the mid-point. However, you must not report both a trail-end and mid-point measures from the same trail.
Note that reported magnitudes must be derived from the individual frames: do not obtain a magnitude from one frame and then copy it on all the other observations! Also, ensure that you report the magnitudes with the astrometry: do not say "Photometry to follow"!
Always report positions for every moving object in your images. Do not assume that just because an object is numbered that continuing observations are not important. The inclusion of well-known objects, particularly when there are also observations of unidentified objects, serves as a useful check of the quality of your measurements.
Are there any recommendations regarding e-mail?
The following guidelines should be noted with regard to any e-mail submission of observations:- Observations must be reported as plain ASCII files. Do not send, e.g., UUENCODE'd or BINHEX'ed files! This is important if you are using e-mail attachements.
- Please ensure that your mailer does not split the 80-column observation records--many mailers, such as PINE, will automatically break a line at about 72 characters. In PINE you can avoid this problem if the observations you wish to send are in a separate file by including the file using CTRL-R, rather than by using cut and paste.
- If you are using a mailer that can send HTML mail, please disable the
inclusion of the HTML version. Inclusion of the HTML version more than
doubles the length of the e-mail and the repetition of material is
completely useless. In addition, the inclusion of HTML text may trigger
the MPC's antispam e-mail filters, causing your message to be flagged
as spam.
Information on disabling HTML e-mail for users of Outlook Express is available. Information on disabling HTML e-mail for users of many different mail clients is also available. - Never send any kind of word-processor/DTP file! If you use a word processor or DTP package to prepare your observations, ensure that you use the package's `Save as ASCII' option.
What if I use spam-blocking systems?
If you use any sort of spam-blocking system to sift your incoming e-mail, you are warned that it is your responsibility to ensure that e-mail from the MPC is passed unimpeded. The list of e-mail addresses that must be allowed through are autoack/mpc/autodes/des/(initial.surname) at cfa.harvard.edu. If e-mail from any of these addresses is blocked, you may not get ACKs or designation files. Bounced messages will not be resent.Note that "Allowed Sender" systems will not work with our automated routines that send out information as e-mail returned to certain addresses will bounce.
What are some common mistakes?
A: Incorrectly-Identified Objects
If you try to identify objects, ensure that the identifications are correct and that you used the packed forms of the designations in the appropriate columns of the observational records. If in doubt, use temporary designations.B: Incorrect Times of Observations
Ensure that the mid-points of your exposures are timed and reported correctly! The most common error by observers (and one of the trickiest to correct if the observation has already been published) is incorrect observation times (or occasionally even dates!).C: Non-ASCII Submissions
Ensure that you send only plain ASCII e-mails. Encoded attachments will be ignored by the automated processing routines.D: Incorrectly-Specified Observer Details
If you do not include an observational header before the observations, the e-mail message will not be recognized as containing observations.
Some observers specify observer details in the form used in the MPCs. These details are usually nicely formatted, but the observation processing routines will ignore them. Observer details must be formatted in the proper format.Can I report approximate or preliminary measures?
No. Approximate measurements will be ignored and you will not be credited for any discovery for which you report approximate positions. Only report final astrometry--don't report preliminary measures and then improve them. It can be time-consuming to replace the preliminary measures, particularly now that observations get published in the mid-month Minor Planet Supplements (MPS) that are issued weekly.The observation format requires an observatory code. I don't have a code. How do I get one?
An observatory code is assigned upon receipt of acceptable observations. Codes are intended for permanent observing sites. If you continually move your telescope around, you are advised to choose a permanent site before undertaking an astrometric program. It is a waste of an observatory code if only a handful of observations are ever obtained there.The observation format has been extended to allow the concept of "Roving Observers", for use by observers at temporary sites. The format is documented elsewhere.
The first time you submit astrometric observations (see Q. 15 for details on what observations your initial batch must contain), you must report:
- A snail-mail address (used as a contact address on the observatory headers in the Minor Planet Circulars);
- An observatory name and site name;
- Longitude, in degrees, minutes and seconds (not decimal degrees)
E of the Greenwich meridian, in the WGS-84 system.
To avoid any possible confusion, avoid using negative longitudes. Give a
longitude as either:
- a specific number of degrees E or W (being sure to state which direction) of the Greenwich meridian (avoid the use of negative quantities);
- a specific number of degrees E of Greenwich (according to the IAU convention). If a site is just west of the Greenwich meridian, give the longitude as a quantity near 360°, not as a negative quantity.
- Latitude, in degrees, minutes and seconds (not decimal degrees) N or S of the equator, in the WGS-84 system;
- Altitude (in meters above sea-level);
- The source for the specified coordinates (e.g., Google Earth, named map, etc.);
- Details of your telescope setup.
The longitude and latitude must be specified to an arcsecond or better. A useful tool for determining your site's coordinates is the Google Earth package: you should quote your long. and lat. to a precision of 0".1 or better. Note that we now use Google Earth to check out the given coordinates. If we have a query as to the location, we may ask for clarification based on our description of the environment shown around the given coordinates in Google Earth.
If you do not use Google Earth, it is important to note that the longitude and latitude that you supply must be geographic coordinates, not geocentric coordinates.
It is also important that you specify COD XXX in the observation header for your initial batch. Do NOT use, for example, COD 000 or COD 999, as these are assigned codes and may cause your initial batch to be processed as if it contained observations from the code you used. Neither should you attempt to use a currently-unused code.
A convenient way to supply the above information in a form that is preserved by the automated processing routines is to use the COM keyword. E.g.:
COM Long. 239 18 45 E, Lat. 33 54 11 N, Alt. 100m, Google Earth
Note that if you request an observatory code during MPC preparation time, you will experience a longer than usual delay before an observatory code is assigned.
If you fail to supply sufficient observations in your initial batch, you will experience a longer than usual delay before an observatory code is assigned.
Does my observatory code move with me?
No, your observatory code does not move with you since observatory codes (with the exception of the "Roving Observer" and artificial satellite codes) are tied to a specific site relative to the center of the earth. If you move your observing site you have to apply for a new code. If you go and observe at a friend's observatory, you must use his/her observatory code (applying for one if necessary) rather than using your own.Are there any restrictions on my observatory's name?
Yes and No.No, in the sense that we cannot dictate what you choose to call your observatory.
Yes, in the sense that we don't have to use your observatory's name in the MPCs.
However, we are fairly liberal in the observatory names that we allow into the MPCs. At least two amateur-owned sites have names with connections to the popular TV show Star Trek: The Next Generation. Where is the dividing line between acceptable and unacceptable? This is determined on a case-by-case basis. Using a popular character from the well-known TV series The X Files as an example, "Scully Observatory" would probably be acceptable, but "ScullyIsAGoddess Observatory" wouldn't.
How do I begin?
If you are new to astrometric observing, you should observe a number of low-numbered minor planets each on pairs of nearby nights. If weather interferes, the two nights can be some weeks apart. Report two or three observations of each object from each night: do not report single positions per night. We will check these positions and advise you on their quality. As a general rule we advise you NOT to observe very low-numbered objects--e.g., (1), (2), (51), etc.--but objects with numbers in the range (400) to (40000). In addition, you should try and observe objects of various brightnesses. If your site does not have an observatory code, one will be assigned upon acceptance of your initial submission. Note that it is important that your initial batch contains two nights of observation of more than one numbered minor planet. If you submit only single-night measures or two-night measures of a single object, your initial batch will not be processed until further observations are forthcoming.You should not start by observing fast-moving objects! It is important that you gain experience by observing "routine" objects before attempting to observe "unusual" objects. We also expect you to prove that you can produce good astrometry of known objects before you begin to discover new objects.
Even if you interested only in comets, it is advisable that you follow these guidelines for your initial batch. In general, comets are harder to measure than minor planets. If we have a new observer reporting comet observers of bad or indifferent quality we do not know if it is simply a problem due to the comet (big, bright difficult-to-measure image) or a problem with the measurement/reduction process. If we have received minor planets from a new observer in the initial batch, we will have already have determined that the measurement/reduction process is acceptable.
How many observations should I make of each object?
It is most efficient to make two or three observations (over a period of an hour or so) per object per night. Observations of specific objects are best made on pairs of nearby nights as the accuracy of isolated single-night observations can be difficult to judge. By observing on pairs of nights any ambiguity is removed.You should not make only one observation of each object per night. Neither should you make many more than three observations per objects per night--it is a waste of your time and rarely helps the orbit solution.
However, to make observations of a new discovery in groups many hours apart on a single night can be useful, particularly in the case of an newly-discovered object that may be close to the earth.
For multi-opposition objects the preferable regimen of observing is observations on pairs on night in each dark run around each opposition until the object is numbered.
What objects should I be observing?
Those observers who wish some guidance on what objects to observe are advised to check out the monthly lists of unusual objects, comets and critical-list numbered minor planets that appear on the Minor Planet Electronic Circulars.Some observers have set up their own web pages, generally to encourage follow-up their own discoveries. Such sites are collected together here.
Ephemerides for minor planets can be generated using the Minor Planet Ephemeris Service.
What quality of measurements should I aim to produce?
Astrometry is a field where bad measures are generally of little or no use. It is important that observers can consistently produce observations with a consistency of <1" for observations using the same comparison stars, and a night-to-night consistency limited only by the comparison star catalogue.Do I need to identify objects?
Strange as it may sound, no. The checking procedures of the MPC are most efficient when observers do not try to identify objects, except as described in the following sentence. Note that observations of NEOCP objects must always be tagged with their NEOCP designations and observations of designated NEOs and comets should be tagged with their provisional or permanent designations, as must the initial observations made in support of an observatory code request.However, every reported observation must have a designation. If you don't know the designation of a particular object, or are not bothering to identify objects, use an observer-assigned temporary designation.
- Observations of the same object on different nights must be given the same temporary designation only if they reported in the same message and you are absolutely positive that all the nights refer to the same object. Correspondences of observer-assigned temporary and MPC-assigned provisional designations will be reported back to the observer via e-mail.
- Observer-assigned temporary designations should be unique--don't call everything `X'!
- Observer-assigned temporary designations should be six characters or less long, and begin in column 6 of the observational record.
- Observer-assigned temporary designations must not be of the form of the packed or unpacked designations used by the MPC. Note that this now includes the form single letter followed by four digits.
- Do not continue to use your observer-assigned designations once official provisional or permanent designations have been assigned.
When should I use a discovery asterisk?
Discovery asterisks are placed in column 13 of the observation record to indicate the discovery observations of an unidentified object. It is premissable for there to be no discovery asterisk, in which case the MPC will assume that the chronoloically earliest observation is to be treated as the discovery observation. There must not be more than one discovery observation per object (a common error is put a discovery asterisk on every observation on the discovery night).Discovery asterisks on submitted observations must only appear on observations with observer-assigned temporary designations. They must never appear on submitted observations with MPC-assigned designations.
How do I know that the Minor Planet Center has received my observations?
Upon receipt of a batch of observations, we send an automatic acknowledgement back to you. E-mail is not perfect and messages do sometimes get lost. If you do not receive the acknowledgement within 24 hours you should resend the original message, noting in the subject line that the message is a retransmission (ensuring your subject line contains `RESEND' is a good way). Further communication will only occur if we need to send you designations or there is a problem with your observations. Information on how to personalize the acknowledgement is available.The acknowledgement now contains a 'junk' rating for the message that was submitted. The junk rating is the percentage of the submitted message that was not useful (i.e., material that was not observational records, observational header or e-mail header). Many messages arrive with junk ratings of more than 50 percent (in some cases, more than 90 percent!). If you get a poor junk rating, you should examine what you are actually sending and try and cut out some of the junk that some PC mailers seem to insert.
Note also that the acknowledgement is automatic and simply informs you that we have received your message. It says nothing about the formatting of the observations contained therein or their quality.
What about batches containing observations from two or more observatory codes?
If you want to submit observations from two or more observatory codes in the same message, you must group each site's observations under an observational header appropriate for the site. A representation of an example follows:COD 608 OBS ... MEA ... ... Rest of header ... Observations from code 608 COD 644 OBS ... MEA ... ... Rest of header ... Observations from code 644
Failure to format the message as shown above will result in the batch being rejected by the automated routines.A message to the MPC bounced. Do I need to resend it?
Perhaps yes. Perhaps no.It all depends on the source of the bounceback message. mpc@cfa is an e-mail alias that forwards incoming messages to five different user accounts: four are personal e-mail accounts of MPC staff members; the fifth is the e-mail account for the AUTOACK procedure (the automated routine that sends out acknowledgements and that extracts messages into the processing queues).
You should resend your message if the bounceback indicates that autoack@scully or mpc@cfa is the source of the failure. If the mpc@cfa address has failed, you should resend your batch to autoack@scully.cfa.harvard.edu.
You do not need to resend your message if the bounceback comes from any other e-mail address.
I think I have something new. How do I get a provisional designation assigned to it?
New provisional designations are assigned to newly-reported objects that cannot be identified with a known numbered, multi-opposition unnumbered or recently-discovered one-opposition (with or without a general orbit) minor planet.New designations are assigned upon the receipt of observations from two nights, not necessarily from the same observer. The two nights should be fairly close together, certainly within a week of each other. See the note on the required coverage on each night. You may use the on-line New Object Ephemeris Generator to generate ephemerides to enable you to find the object after the first night.
If there are a number of observers involved at a particular site and assignment of credit for the discovery of particular objects is important, ensure that the observer-assigned temporary designations reflect the names of the discoverers. For example, at a particular site there are three observers--Byers, Frohike and Langly. Objects discovered by Byers alone are reported with temporary designations beginning By (e.g., By0001), objects discovered by Byers and Langly jointly by designations beginning BL or ByLa (e.g., BL0001 or ByLa01). Similarly, designations beginning FrLa indicate objects discovered by Frohike and Langly.
It is preferred that discoveries are made by a single individual, although discoveries by pairs of discoverers are accepted. Claims for discoveries of specific objects by three or more discoverers are treated as site discoveries, where no individuals are named as the discoverer. An exception to this is allowed for discoveries of TNOs, where up to four individuals may be listed, recognizing the difficulty of obtaining sufficient observations of these (typically very) faint objects.
If your new object (observed on two or more nights) can be matched to an earlier undesignated one-night stand, that one-night stand does not have priority (see the next question for a situation where this priority does not apply) and you will receive the credit for the discovery. If your new object can be matched to an earlier designated one-night stand (generally this will be a redesignation from a published two-night object), your new object will also have priority.
What is the difference between reporting two-nighter and single-nighter new objects?
There is no difference between submitting single night or multiple nights of observation of a "new" object. It is therefore recommended that you report observations of potential new objects nightly, ensuring that each object has a unique designation on each night.Who gets credit when single nighters are linked?
The credit for the discovery is given to the chronologically earliest observation that is identifiable at the time the designation is to be assigned. If earlier undesignated observations are subsequently located (these will often be isolated observations), the discovery credit does not change.Note that this linking process requires the earlier observations be on a different night (at least 12 hours separation) and to be of good quality (the automated routines currently reject linkages where one or more observations appear to be off by 1".5 or more).
What objects go on to the NEOCP?
The objects that go on to the NEO Confirmation Page are those objects which, on the basis of their motion or orbit, appear to be NEOs. Objects that are suspected of being comets also appear.When removed from the NEOCP, the inner-solar-system objects that get put on to MPECs are as follows:
- Any object with perihelion distance less than 1.3 AU
- Any object with an perihelion distance beyond 5.5 AU
- "Main-belt" objects with eccentricities above 0.5
In the past, objects with perihelia beyond 1.3 AU and eccentricities between 0.4 and 0.5 and/or inclinations above 40 degrees might appear on an MPEC if there was not much activity. This was deemed to be somewhat arbitrary (particularly in light of the fact that the major surveys were counting how many discovery MPECs they had!).
If it turns out that an NEOCP object is identical to an object that has already received a provisional designation that has been published in the MPCs and the MPSs (i.e., the permanent publications), the observations that have already been published are not republished on the MPEC announcing the object (i.e., a temporary publication). Such cases are indicated by the lack of a discovery asterisk amongst the listed observations and the use of 'Additional observations' as a heading, rather than 'Observations'.
How long does it take to assign a new provisional designation?
The time delay between your submission of "new" objects and your receipt of the designations corresponding or newly-assigned to your objects is variable. If things are relatively quiet at the MPC, you may receive designations back within a matter of minutes. In other cases, it may be more than 24 hours or more before you receive anything.Note that objects that are placed on the NEO Confirmation Page will not be assigned designations until they are removed from the page.
If observations are received at the MPC before 4 p.m. local time, we try, but cannot guarantee, to assign new designations that same day.
Note that all newly-assigned designations are provisional: they are only finalised when the observations are published in the next MPS batch. Each month a number of newly-assigned designations are retracted before the observations are published: such designations are flagged as being "omitted".
How do I understand the designations the Center sends me?
If you have `new' objects you will receive a list matching your temporary designations to official provisional or permanent designations. Here is a (ficticious) sample assumed to have been sent in Feb. 1999, showing most of the probable forms:By0001 (03244 ByLa01 J99A18T ByLa02 (J81U78A By0004 (By0003 By0003 (J99A08H
This may be interpreted as follows: By0001 is the numbered object (3244); ByLa01 is a new object 1999 AT18 that is credited to Byers and Langly; ByLa02 is the known unnumbered object 1981 UA78; By0003 and By0004 refer to the same object, now designated 1999 AH8, which is a recent discovery by another team.In short, provisional and permanent designations not prefaced with `(' are your discoveries. Note that if you are mining data from some source other than your own setup (e.g., SkyMorph), the lack of `(' indicates only that the designation is newly assigned, as credit for the discovery lies with the producer of the mined data (e.g, NEAT in the case of observations measured from SkyMorph data). Provisional and permanent designations will be in the packed form, as used on the observation record.
New designations are not assigned to objects observed on only one night, although you may receive designations if such objects can be identified with already-known objects.
Observers with at least one discovery credit may request the (roughly) monthly receipt of a DISCSTATUS report, which lists their discoveries, as well the current disposition of each object. Requests to be added to the mailing list for DISCSTATUS reports must be made to the normal submission address (subject line must be "DISCSTATUS" and the message must indicate to which e-mail address the report is to be mailed).
What's the best way to follow-up a new discovery?
After the initial two nights, wait for a week or ten days, then obtain another pair of nights a day or two apart (ephemerides can be generated using the Minor Planet Ephemeris Service. There really is no point in following a new object night after night. Further observations can then be made between fifteen and twenty days after discovery (if the Moon permits). Further pairs of nights of observations can be obtained in following months for as long as the object is visible and remains unidentified.What about coverage on a single night?
You should always supply at least two observations of each object on each night. If you are observing objects in dense starfields, you should plan your observing session with this recommendation in mind.Note that for new objects, it is imperative that you get at least 30 minutes of coverage on each of the nights. As a general rule, the MPC will not assign designations to MB objects observed on only two nights where the coverage on one or both nights is less than 30 minutes.
If you are stacking images, try and ensure that you produce at least two stacks (remembering that the stacks have to be independent, so an image cannot be used in more than one stack). If you can produce only one stack, ensure that the observation is marked as a stack ("K" in column 14). If you produce more than one stack, mark the observations as stacked unless there is another note you wish to use (such as "F" or "V"). If you are observing at a site that uses codes to distinguish between different programs, the "K" should appear on the submitted observation, but will be replaced by the program code during processing.
What if I can't follow-up a new discovery?
If you observe an object on one night and are not able to obtain a second night within a week or so, you should report these "One-Night Stands".The observations will be subject to the normal checking procedures of the Minor Planet Center but will be published only if they can be identified with some already-designated object. They are then checked against recent one-night stands. If a match is found the object can receive a designation. The discovery will be credited to the earlier observation: if earlier undesignated observations are then identified, the discovery credit does not change. If no match is forthcoming, the one-night stand observations are filed. These files are checked regularly against new orbits and matches are extracted and published under the already-assigned designation.
If you wish someone else to follow-up your new discovery, you may use the New Object Ephemeris Generator to generate ephemerides to enable your colleague to find the object after the first night.
If someone does follow-up for your new objects, you will get credit for the discovery even if you have obtained only one night's observations. However, there is nothing preventing your colleague from getting two nights on your new object and then reporting it to us as a new object. In such a case, credit will be given to your colleague. For this reason, you should not distribute observations of the new object and you should only send ephemerides to colleagues that you trust.
Should I separate my comet and minor-planet observations when submitting them?
The automated processing routines now in use at the MPC have recently been rewritten. The assignment of different types of objects to various queues for processing is automatic and based on the orbit corresponding to the designation assigned to each observation. Observations of different types of objects may now be freely mixed.It is recommended, however, that if you are reporting a possible new NEO, that you include "NEOCP" in the subject line of your e-mail (alternatives are "NEO" or "FMO"). Possible new comets (that are not on the NEOCP) should have "COMET" in the subject line. Similarly, use "TNO" or "SAT" for batches containing observations of potential new TNOs or natural satellites.
Should I check my observations before reporting them to the Center?
Observer checking does not need to be anything more than checking that what you actually send is what you meant to send! Checking of designations, observation dates and times, positions and the format is advisable. We do not recommend that you check the residuals of your observations before submitting them.If observers decide to check the residuals for known objects prior to submission, they are advised to use the consistency of the residuals (particularly night-to-night), rather than the size of them, as the discriminator for rejecting observations.
A careful observer with normal equipment is quite capable of obtaining nightly measures that are consistent to within a few tenths of a second of arc.
How quickly are observations processed by the MPC?
In general, observation batches are processed by the MPC as soon as resources are available, in the order in which the observation batches were received. In order to utilise the resources of the MPC in the most efficient manner, different priorities are attached to the processing of different classes of observation. Processing priority is in the following order:- "New" FMOs, comets and potential NEOs/unusual objects, suitable for posting on the NEO Confirmation Page.
- Follow-up observations of NEOCP objects.
- Other NEO observations.
- Survey observations from last night and recent non-survey material.
- Older non-survey material.
- Survey observations from before last night.
Observations that are not submitted in the proper format are subject to delay.
Note that the different processing classes are dealt with at different rates. This should not affect the order in which "new" objects are processed.
What's the best way to get my discovery numbered?
The first requirement for getting your discovery numbered is to ensure that the observations at the discovery opposition cover a sufficient arc to enable recovery at a subsequent or previous opposition.Once identified (or recovered as a result of a direct search), observations should be made on pairs on nights in each of two dark runs at each opposition until the object is numbered. For main-belt objects this can occur after the object has been observed at four oppositions (although this depends on the number and distribution [preferably two nights in each of two dark runs in at least three of the oppositions] of the observations as well as their quality); NEOs can receive a number after two or three well-observed oppositions. In addition, objects to be numbered require the uncertainty parameter, U, must be less than or equal to two. Note that newly-identified multiple-opposition objects are not eligible for numbering: numbering of such objects can only take place after the first multiple-opposition orbit has appeared in the MPCs and after further observations have been reported (these can be at the latest opposition, or at an earlier or subsequent opposition).
The selection of objects for numbering is an automatic process performed just before the preparation of each batch of MPCs. There is no need to ask us "What do I need to do to get such-and-such numbered?". Simply follow the guidelines above and the object will be numbered when it is ready.
When can I name my discovery?
Names for minor planets are proposed by the discoverer of a specific object after the object is numbered. Proposals are accompanied by a brief citation explaining the reasons for the naming.Proposed names are judged by the fifteen-member Committee on Small Body Nomenclature (CSBN) of the International Astronomical Union. Except in very unusual circumstances, new names may not be assigned until a minimum of two months have elapsed since the objects were numbered. If the CSBN has objections to the name or the accompanying citation, this process can take much longer.
Names become official when they are published in the Minor Planet Circulars. Note that the CSBN condemns the preannouncement of names, even if any such preannouncement indicates that a name is only a proposal.
When several provisional designations belong to the same numbered minor planet, one of these provisional designations is defined as the prinicipal designations (this is decided when the object is first identified) and it is the discoverer of this principally-designated object that is defined as the discoverer of the numbered object.
An alphabetical list of current minor planet names is available. A list of the discovery circumstances of the numbered minor planets is available.
What names are acceptable?
There are prohibitions against suggesting names of individuals, places or events with military or political connections unless at least 100 years have passed since the individual died or the event occurred. This means that names from the 20th century's two World Wars are not yet acceptable. Names that are offensive are also disallowed.Other than those restrictions, almost any other type of name is acceptable.
Names should not be too similar to an existing name. In order to check whether your proposed name (or one very similar) has been used already, consult the the alphabetical list of minor-planet names and use your browser's 'Find' facility.
Names should preferably be one word. For individuals, use the surname (family name) if possible. If you run two or more parts of a individual's name together to make the name, do not use mid-word capitalization. Proposers should remember that names of minor planets are not the same as the names of people. Ideally, if a name is to honor a person, it should simply "suggest" that person, in a manner that is as unobtrusive as possible.
Please remember that the purpose of naming minor planets is for identification, not commemoration.
How do I write the citation and submit the name?
Each new name proposal from a discoverer of a numbered minor planet is accompanied by a brief citation, describing why the particular name is being bestowed. Citations must be brief and to the point. A four-line limit (as printed in the MPCs) on the body of each citation has been imposed. Avoid making political, controversial or posturing statements in the citation.Note that the CSBN reserves the right to edit the citation for publication.
There is a special format for submitting names. This format is necessary to expedite processing of the proposal. The first line consist of an "index entry" containing the proposed name, the number of the object to which the name is to be applied and a very short summary of the citation. Then follows a blank line. Then the citation in the form that it will appear in the MPCs. Single name proposals or batches of proposals must be e-mailed to mpc@cfa.harvard.edu.
The index line can extend to column 80, but the other lines must not go beyond column 78. Lines must have ragged-right margins (i.e, do not right-justify the lines), neither should words be hyphenated across line breaks. Submitted files must be plain ASCII: do not send any kind of WP/DTP/HTML file! Diacritical marks must be indicated in the TeX format.
This is best illustrated with a couple of examples from the batch of names in the 2000 Jan. 24 batch of MPCs (the column ruler at the top is simply to show you where the entries in the index line fall: e.g., the index description begins in column 31 and the number ends in column 27):
1 2 3 4 5 6 7 8 12345678901234567890123456789012345678901234567890123456789012345678901234567890 Flagsymphony 6582 Flagstaff Symphony Orchestra (6582) Flagsymphony = 1981 VS Discovered 1985 Nov. 5 by E. Bowell at the Anderson Mesa Station of the Lowell Observatory. The Flagstaff Symphony Orchestra is celebrating its 50th season in 1999-2000. It is considered by many to be the best symphony orchestra in a small community in the U.S.A. Baton Rouge 11739 Louisiana state capital (11739) Baton Rouge = 1998 SG27 Discovered 1998 Sept. 25 by W. R. Cooney, Jr. and M. Collier at Baton Rouge. Baton Rouge, the Louisiana state capital, is located on the banks of the Mississippi river and derives its name, French for ``red stick'', from an Indian marker at the site seen by a French expedition in 1699. The city is home to the Highland Road Park Observatory, where this minor planet was discovered.When printed in the MPCs the example citations above took up 2.2 and 3.8 lines, respectively.It there are multiple names being proposed at the same time, each index-citation block is separated from other blocks by a blank line, as in the example above.
Submitted citations are subject to editing.
How long does it take for a name to be approved?
Typically, new batches of minor-planet names appear in alternate batches of Minor Planet Circulars (MPCs). Batches of new name proposals are sent to the CSBN every two months. All accepted names from the batches sent to the committee will appear in the next batch of MPCs. There is no set deadline for submitting names. If you want a name to appear in a particular MPC batch you should submit the name at least ten weeks in advance. Note that appearance in any particular batch cannot be guaranteed, especially if there are problems with the name or citation.What happens to accepted observations?
Observations are published in the monthly Minor Planet Circulars (MPCs) (and on the occasional Minor Planet Electronic Circulars). Early observations of new comets may be published in the International Astronomical Union Circulars.From time to time, the question arises as to whether inclusion of observations in the MPCs can be construed as publication in the `refereed' astronomical literature. The Minor Planet Center stresses most emphatically that astrometric observations of comets and minor planets submitted for publication in the MPCs are indeed subjected to close, critical study, and that erroneous observations are returned to their authors for amendment. Particular care is taken to ensure that all observations presented are correctly identified. The MPCs are designed specifically to handle the publication of astrometric observations of comets and minor planets and there is no need also to publish in other journals.
What is the purpose of the contact details?
The contact details as published in the MPCs for each observatory code are intended as a contact point for persons with queries regarding a specific program. The contact address does not have to be the street address of the observatory. For professional programs it should be noted that the contact details are NOT intended to be a list of P.I.s on the project.The contact details MUST include:
- the name of a person connected with the program (who is willing to answer queries about the presented observations)
- a snail-mail address for that person (this can be a P.O. Box)
- an e-mail address for that person
Information on how to specify the contact address (as well as names of observers and measurers) is available.
What (p)recovered objects get MPECs?
In order to qualify for a special MPEC, (p)recovered NEAs must have been observed on two or more nights. Single-night (p)recoveries will simply appear on the next DOU MPEC (assuming that the observations actually fit).Precovery refers to the identification of images of a single-apparition object at an earlier opposition.
I'm interested in photometry...
A good guide to minor planet photometry is available from Brian Warner.
