ICQ Observation Format Explained

Bellow is the 80-column ICQ observation format that is used for storing and displaying observations at COBS website. This format was established by ICQ in 1995 to accomodate the new designation scheme for comets. Columns were added beyond column 80, beginning 2002 January 1, to add additional information for CCD photometry of comets.


IIIYYYYMnL YYYY MM DD.DD eM mm.m:r AAA.ATF/xxxx &dd.ddnDC &t.ttmANG ICQ XX*OBSxx
         1         2         3         4         5         6         7          8
123456789 123456789 123456789 123456789 123456789 123456789 123456789 1234567890

The first 10 columns are for the comet's identification.

The first three columns are blank for long-period comets. For one-apparition short-period comets, columns 1 and 2 are blank, and column 3 contains a capitalized "P".

In both of these cases (long-period comets and one-apparition short-period comets), the year-and-halfmonth designation goes in columns 4-9 (columns 4-7 contain the year; column 8 contains the capitalized halfmonth letter; and column 9 contains the halfmonth numeral).

Column 11 contains a lower-case letter denoting nuclear components if such exist (even though such letters are usually given in text form as upper-case letters), and this column is so used for all such split comets; in the case of the rare numbered split comets (such as 73P) where more than 26 components were discovered (thus, the components went from "Z" to "AA"), the two letters should go in columns 10 and 11 (if we ever get to the situation where a comet with a year/letter designation spilling over into column 10 has more than 26 components, we will address the problem at that time).

Columns 1-3 are used for "numbered" short-period comets (those seen at two or more returns to perihelion); this number is to be given "flush right".

All comet designations can be found


1     2     3     4     5     6     7     8     9     10     11
^...........^     ^.................^     ^.....^......^......^
SP Comet Code*    Year of Discovery       Desig.**

*Short-period comet code for numbered, multi-apparition periodic comets;
cols 1-3 left blank in case of long-period comets;
place a capitalized "P" in column 3 (with columns 1 and 2 blank) for 1-apparition short-period comets.
**Halfmonth designation (capitalized halfmonth letter in column 8; numeral in column 9;
split-nucleus capitalized letter in column 10); columns 10 and 11 may also be used for minor-planet-designated comets, where letters are given in columns 8 and 9, and 10 and 11 are reserved for digits (to 99, flush LEFT, meaning single digits go in column 10 with no leading zero) -- for minor-planet-designated comets with post-letter digits exceeding 99, use column 10 for letters A, B, C, D, etc., to indicate 100, 110, 120, 130, etc., with column 11 holding the ones digit.


IIIYYYYMnL YYYY MM DD.DD eM mm.m:r AAA.ATF/xxxx &dd.ddnDC &t.ttmANG ICQ XX*OBSxx
123456789 123456789 123456789 123456789 123456789 123456789 123456789 1234567890

YYYY, MM, and DD.DD: are the year, month, and date (to 0.01 day) of the observation in UT. Leading zeroes should be be put in the month and date data.

e (column 26): is for extinction notes and other notes, using the ICQ abbreviations.

M (column 27): is the magnitude method used for the magnitude estimate (e.g.: B = simple Out-Out or VBM (Van Biesbroeck-Bobrovnikoff-Meisel) method; ) A list of all possible magnitude method keys is found here.

mm.m: (columns 28-33, decimal point in column 31): is the total visual magnitude estimate (we do not want estimates of the nuclear condensation alone), given to 0.1 magnitude. Column 28 is the column for a left bracket ([), which represents the comet was not seen and was fainter than a given magnitude. If the magnitude estimate is not very accurate, or made under poor conditions, then a colon (:) is placed immediately after the magnitude (for example, 11.3:).

r (columns 34-35): is the reference or source of comparison stars used for making the magnitude estimate (if more than one source was used, the primary source only must be listed here); here we use a 2-letter code (or 1-letter code in column 34 only). A list of all possible reference catalogue keys is found here.


IIIYYYYMnL YYYY MM DD.DD eM mm.m:r AAA.ATF/xxxx &dd.ddnDC &t.ttmANG ICQ XX*OBSxx
123456789 123456789 123456789 123456789 123456789 123456789 123456789 1234567890

AAA.ATF/xxxx are the specifications concerning the instrument used for the observation. NOTE: If the magnitude estimate is made with one telescope and the tail-length estimate is made with a second telescope, two different lines must be entered!

AAA.A (columns 36-40): is the instrument apertur in centimeters, given to 0.1 cm. An important thing for the recorder to remember is only to use significant figures (example: if the observer reports his telescope aperture as 20 cm, the recorder should not put 20.0 cm, but 20 cm).

T (column 41): is the instrument type, as coded by the 1-letter key. A list of all possible instrumen type keys is found here.

F/ (columns 42-43): is the focal ratio (f/-ratio) of the instrument. The f/-ratio must be rounded (even) to the nearest integer; thus, f/4.5 becomes " 4" and f/3.5 also become " 4". There is no way to include a decimal part of an f/-ratio in this tabulation; decimals must be rounded.

xxxx (columns 44-47): is the power (magnification) used in the case of visual observations or the duration of the CCD or photographic exposure in seconds. Both of these values should be entered FLUSH RIGHT (that is, ones digits go in the right-most column, tens digits in the second column from right, etc.); if a CCD exposure in which the duration is given in seconds, a lower-case letter "a" must be placed in column 44 if the exposure length is less than 1000 seconds; if the exposure duration is 1000 seconds (= 16m40s) or longer (but less than 2000 seconds = 33m20s), an upper-case "A" must be placed in column 44; an upper-case "B" in column 44 indicates an exposure time of 2000-2999 sec (note that the thousands digit is replaced by these letters A, B, C, etc.).

&dd.dd (columns 49-54): is the observer's estimate of the comet's coma diameter in arc minutes at the time of observation. The less-than sign for column 49 indicates the column used for an ampersand (&), which indicates an approximate measurement, or a less-than or greater-than sign. The diameter may be given to 0.01 arcmin, but again only significant figures should be entered (example: when the comet was large, > 10', measurements would probably never even be given to 0'.1, because it would be very difficult to get so exact an estimate when the coma is so large). Do NOT give the coma to 0.1 arcmin if the uncertainty is ± 1 arcmin! (In other words, if you estimate a coma diameter of 8' ± 2', do not give it as "8.0"! Only give it as "8.0" if the uncertainty is ± 0'.3 or better.) CCD photometrists should give here the APERTURE SIZE of the software applied to the comet's coma to yield the tabulated magnitude, with a plus sign (+) in column 49; any larger measured coma diameter than that used for the magnitude should then be given in the descriptive information.

n (column 55): is for a special note describing the physical appearance of the central condensation, described in the July 1995 issue of the ICQ, page 92 (d = faint disk within the coma, D = bright disk within the coma, s = faint "stellar or nearly-stellar condensation, etc.).

DC (columns 56-57): is the degree of condensation of the comet a sestimated by the observer (on a scale of 0 to 9, where 0 is completely diffuse and 9 is completely stellar in appearance). The digit goes in column 56. If an observer estimates DC = 5-6, then a slash (/) goes in column 57 following a "5" (thus: 5/ ). A "5/" means EITHER 5.5 OR 5 to 6; there is no way to denote an approximate DC estimate in this tabulation.


IIIYYYYMnL YYYY MM DD.DD eM mm.m:r AAA.ATF/xxxx &dd.ddnDC &t.ttmANG ICQ XX*OBSxx
123456789 123456789 123456789 123456789 123456789 123456789 123456789 1234567890

&t.ttm (columns 59-64): is the tail length in degrees (to 0.01 degree of arc), with the less-than sign in column 59 indicating the same as column 49 for the coma diameter (see above). Column 59 can be used for either a note or for a second digit if the tail length is 10 degrees or longer. For tail lengths in degrees, a decimal always goes in column 61 and the value can extend to column 63. For tail lengths in minutes or seconds of arc, the lower-case letter "m" or "s" (respectively) is placed in column 64 and the value is given to 0.1 with a decimal point in column 62 instead of 61. Do NOT give the tail to 0.1 unit if the uncertainty is ± 1 unit! (In other words, if you estimate a tail length of 30' ± 3', do not give it as "30.0"!).

ANG (columns 65-67): is the position angle at which the center of the tail is directed (0 = north, 90 = east, 180 = south, 270 = west, etc.). This number is entered flush right *in integer form only* (round even), so that if the p.a. is 56 degrees, a blank is entered in column 65 and "56" is entered in columns 66 and 67. There is no way to denote an approximate p.a. in this tabulation.

RRRRRR (columns 69-74): is the reference for publication (which gets changed upon publication). You should enter "ICQ XX" here.

* (column 75): is the column for a revised observation (use an asterisk here) if the observation replaces one given previously).

OBSxx (columns 76-80): is a 3-letter, 2-digit code to indicate who the observer is. Columns 76-78 give the first 3 letters of the observers last name (family name), and the digits are simply added by ICQ staff in where there are more than one observer with the same first 3 letters in his last name. If you do not know the 2-digit appendage use a temporary code designated to you after you registered to COBS.

Beginning 2002 Jan. 1, the observation record was extended beyond column 80 for CCD observations only (see Oct. 2001 and Jan. 2002 ICQ). New ICQ format for tabulated data to include more CCD information, starting in column 81:


f InT APERTURcamchip SFW C ## u.uu xx.x PIXELSIZE       guideline
         9        10        11        12        13
123456789 123456789 123456789 123456789 123456789 123456789  

f (columns 81-82): if comparison stars are in the same frame as the comet, write "I" in column 81; if comparison stars are in the next field (one instrumental field size outside that of the comet), write "N" in column 81; otherwise, put a two-digit number in columns 81-82 (flush right) indicating the estimated distance of comparison-star field from the comet in whole degrees (with 99 indicating 99 deg or greater; 00 indicates less than 1 deg); write "MA" in columns 81-82 if multiple reference stars are used at multiple air masses around the sky.

InT (columns 83-86): integration time of comparison-star field when the field is outside that of (or different from) the comet exposure (given in seconds, flush right); use identical column format to that used for CCD exposure of comet field in columns 44-47; if multiple fields are used with different exposure times, write down that exposure time that was the longest used for the photometric reduction.

APERTUR (columns 87-93): columns 88-92 hold numerical dimension of photometric-aperture size, with decimal in column 90; column 93 has letter to denote units (d = degrees, m = arcmin, s = arcsec); column 87 gives the shape of the photometric aperture (S = square, C = circular, O = oval). NOTE that this means that only actual, measured coma diameters will appear in columns 50-54 --- and that the plus-sign (+), which indicated an aperture size for electronic photometry, will no longer be used in column 49.

Camchip (columns 94-100): three-character key to specify CCD camera in columns 94-96 (e.g., MCV = Mutoh CV-16II camera). A list of all possible CCD camera type keys is found here.; then three-character key to specify camera's CCD chip in columns 98-100 (e.g., T25 = TC255). A list of all possible CCD chip type keys is found here. Column 97 contains "a" to denote an anti-blooming CCD

SFW (columns 102-104): 3-character key to denote the software package used to derive the magnitudes (e.g., G70 = Guide 7.0; FPr = FitsPro). This is different from the source of comparison-star magnitudes. A list of all possible photometry software keys is found here.

column 106, C:
0 = no correction
1 = correction for bias (bias subtracted)
2 = flat-field corrected (flat-fielded)
3 = 1 + 2
4 = dark-subtracted (and bias-subtracted)
5 = 2 + 4

## (columns 108-109): number of CCD frames taken of comet on same night, for verification of proper identification (flush right); if accurate astrometry was performed and submitted formally to the ICQ/MPC/CBAT for publication, place a "P" for published in column 108 or a "U" in column 108 for either "unpublished" or "publication status unknown" (and, if more than 9 images were obtained on a single night of this comet and astrometry was also reported, simply put a "9" in column 109 in addition to the letter in column 108).

If a number of co-added frames were used for the photometry, then this number should be given in columns 108-109, and place an asterisk (*) in column 110 to denote this fact.

u.uu (columns 111-114): estimated error/uncertainty in magnitude (decimal point in column 112).

xx.x (columns 116-119): magnitude of the comparison star closest in brightness to that of the comet.

PIXELSIZE (columns 121-129): assumed rectangular shape, with one pixel side given numerically in columns 121-124 (decimal point in column 123) and the other (perpendicular) side given numerically in columns 126-129 (decimal point in column 128); column 125 contains the letter that denotes the units (d = degrees, m = arcmin, s = arcsec).