Needs to be updated!Draft Guidelines for Comet Discoveries

General discovery procedures

If you think you have found a comet, first wait and see if it moves – most suspect objects don’t! A single observation of a fuzzy object with no evidence of movement is not sufficient to claim a possible comet. Beware of clusters of faint stars, which can often appear diffuse under low magnification, and ghost images of bright objects. You must check that no previously discovered cometary object matches your potential discovery (check the CBAT web page). You must also check that there is no deep sky object in the position of your object (use for example Megastar, Guide or the Digital Sky Survey). Once you are reasonably certain that you have found something new, contact the Assistant Director or the Director. For visual discoveries an accurate sketch is essential and independent confirmation is a help. For any discovery you must provide the dates, times and positions of the object. Failure to provide this information means that you will not be credited with the discovery, though you may be credited with a pre-discovery observation. You should also include the rough magnitude, coma diameter, DC and details of any tail. NB: In the majority of cases it is up to the discoverer to provide sufficient confirming information. If you only suspect motion and bad weather prevents further observation report the available information as soon as possible.

If you are not worried about gaining credit for your possible discovery, just supply what information you have. This will be logged for future reference, but follow up will be made only in exceptional circumstances. Reports of objects found on single frames of film exposed some time in the past will not be followed up.

If you discover that an already known comet is much brighter than expected, first check that there is no deep sky object near the position and that the comet is not exactly on top of a bright star. If it is then clear that the comet is in outburst report the fact without delay to the Assistant Director (Observations) or the Director.

Visual discoveries

An object that is clearly a comet (for example a diffuse object showing clear motion or a tail) should be reported to the Assistant Director or the Director without delay. You should make a sketch of the field showing the object and its motion. This can be submitted after any telephone or email reports. Less obviously cometary objects will require observation on a second night to confirm the motion and its direction.

Photographic discoveries

A single image is not sufficient to claim a discovery as various photographic flaws, stray light or ghost images of bright stars can cause comet like images. Bright stars in the field of a camera lens can create fuzzy comet-like objects, usually in the opposite quadrant and perhaps 5 – 6 magnitudes fainter. They will therefore appear on more than one exposure and can on occasion show motion, for example when photographed using an altazimuth platform. You must provide at least two images that are sufficiently separated in time to show clear motion.

CCD discoveries

A single image is not sufficient to claim a discovery as various CCD flaws, stray light, ghost images of bright stars and very red stars can cause comet like images. Bright stars in the field of a camera lens can create fuzzy comet- like objects, usually in the opposite quadrant and perhaps 5 – 6 magnitudes fainter. They will therefore appear on more than one exposure and can on occasion show motion, for example when imaged using an altazimuth platform. You must provide at least two images that are sufficiently separated in time to show clear motion and include these with your email report. If possible reduce the images to provide precise astrometric positions.

Satellite discoveries

Cosmic rays and charged particles near the Earth can make satellite data very noisy. At least four frames are therefore required to obtain a confirmed detection of a comet. In exceptional circumstances two or three frames may be sufficient, for example a clear tail with consistent motion. You should check that the motion is consistent by plotting your measured X and Y positions against time and this should show a smooth track. For most objects motion is usually obvious and you should then email the leader of the group that operates that particular instrument with details of the positions and a rough estimate of the magnitude of the object, and contact the Director and Assistant Director. For potential discoveries on SOHO LASCO images first view the discovery guidelines, then if you are certain that you have found a comet email Karl.Battams at nrl.navy.mil. For possible objects found in SWAN imagery you should contact a suitable amateur observer to try and obtain ground-based confirmation, and inform a member of the SWAN team.

False discoveries

Observers who do not follow the above guidelines risk being blacklisted. If you report more than two possible discoveries in a twelve month period, which turn out to be false and where you clearly have not followed the guidelines you will be blacklisted. In these circumstances you risk loosing the credit for any discovery that you may report.

You can also refer to the CBAT guidelines on comet discovery procedures.

Updated 2009 August 10

Published by Jonathan Shanklin