General Observing Practices: Minor Planets and Comets

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EDITORIAL NOTICE.

General Observing Practices

The number of observers submitting astrometric observations to the MPC has risen rather dramatically in the past year. This has been accompanied by a rather worrying and troublesome increase in poor observing practice, with many sub-standard quality observations reported to the MPC.

Observers should strive to provide the best quality observations to the MPC. Poor quality observations cause the MPC significant extra work and reflect badly on the observer.

Some good practice advice follows:

• Observe each object at least three times over the course of an hour or so on each night. If the object is a known object, this can be relaxed to 30 minutes or more, as long as the motion of the object in that period is significant.
• Provide two nights of observation for "new" objects, obtaining three to six observations on each night, with at least one hour of coverage on each night.
• If you have a suspected new NEO, more than six observations may be useful if they are obtained over the course of several hours.
• In following-up interesting objects, provide good coverage of at least one hour.
• Never, under any circumstance, provide a single, isolated observation on a single night. A single observation shows no evidence of motion and there is no guarantee that the observer has not measured an image defect, a star or a variable object (star, nova or supernova).
• Stacked observations should always be marked as such and the individual images should be stacked so as to provide two observations, noting that an individual image can appear in only one stack. In very rare cases, a single stack may be all that is available: such situations will be handled on a case-by-case basis.
• Observations of "new" objects in support of discovery claims should be spaced by at least one and no more than five nights.

It is hoped that self-regulation by observers will be sufficient. If this does not prove to be the case by the end of this month, we will implement additional filters to reject automatically entire batches that contain single observations or new objects with insufficient nightly coverage.

"Corrected" Observations

Observers are informed that batches submitted with "corrected", "correction", "remeasured" or "remeasurement" in the subject line or ACK line are treated as being corrections to observations published previously and are filed by the automated routines for manual examination by MPC staff. The processing of such batches may be delayed.

It is also worth remarking that resubmission
of observations or batches that were rejected by the automated AUTOACK routines do not need to be indicated as resubmissions, as the MPC has no internal record of the original, rejected batch.

Observations of Dual-Status Objects

A number of objects are designated as both minor planets and comets. Examples include (2060) Chiron = 95P/Chiron and (4015) Wilson-Harrington = 107P/Wilson-Harrington. Astrometry of dual-status objects must be reported under the minor-planet designation, with the magnitudes reported in the asteroidal form. If observations are reported under the comet designation the AUTOACK routines will change the designation into the minor-planet designation. If there are "nuclear" or "total" magnitudes reported on the observations this causes problems further down the processing pipeline because minor planets cannot be marked with "N" or "T" magnitudes.

Observing at Remote Sites:

Observers who use multiple remote observing sites are requested to be extra vigilant in indicating where the observations were made. A number of observations have been received recently when, at the time of observation, the object was below or the sun was above the local horizon at the observing
site.

Indication of Observers, Measurers and Telescope Details

In anticipation of the short-term plans for automatic MPEC preparation by the MPC, we remind observers that information given with the OBS, MEA and TEL keywords in the observational header must conform to the formats described at http://www.cfa.harvard.edu/iau/info/ObsDetails.html. Observers who do not adhere exactly to these instructions will find that their observations on automatically-prepared MPECs will not be credited in the way they intended.
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Reference:

EDITORIAL NOTICE from 2009 DEC. 2 MPCs batch