Central Bureau for Astronomical Telegrams
IAUC 2293: 1969i; SUPPRESSED DIGITS IN THE TELEGRAPHIC CODE
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Circular No. 2293
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK
Western Union: RAPID SATELLITE CAMBMASS
COMET BENNETT (1969i)
Dr. R. L. Waterfield, Woolston Observatory, sends the following
precise positions. On July 14 there was a wide, curved, fan
tail 30' long in p.a. 310o. No tail was noted on Aug. 31 and
Sept. 23, these plates being measured by G. H. Rutter.
1970 UT R.A. (1950) Decl. m1
July 14.99546 4 23 34.45 +73 24 40.1 10.5
Aug. 31.89136 4 18 29.21 +81 13 14.6 12.0
Sept.23.86038 1 40 30.09 +83 04 38.3 12.8
SUPPRESSED DIGITS IN THE TELEGRAPHIC CODE
Following the note on IAUC 2275 we have temporarily adopted
the slash (/) to represent a suppressed digit in an astronomical
telegram. On the whole, this choice seems to have been more
satisfactory than previous choices, although trouble has arisen when
a complete group of five slashes has been transmitted. This most
typically happens when supernova reports, where the time (decimals
of a day) of observation is often unspecified. If the time of
observation is not specified, we there propose to omit the whole
group from the telegram: since the second checksum now identifies
the groups containg right ascension, declination and magnitude
information, this omission will not lead to any ambiguity. In the
case of approximate positions the first figure of the magnitude
group is always redundant, and we propose now to use a zero (0) for
this character. For the time being, we propose that the slash
should still be used for suppressed information elsewhere in the
messages: any reasonable alternative would involve transfers between
numeric and alphabetic mode on teletype machines, and this
can cause errors. Telegram subscribers are invited to comment on
this matter of suppressed digits--or any other aspect of the
telegraphic code. Several subscribers have recently requested copies
of a revised code manual, incorporating also the second and third
points on IAUC 2187. Preparation of the revised manual is being
deferred until the suppressed digit problem (which is by no means
new; see, for example, UAIC 765, 772, 792 and 1021) has been
completely resolved.
1970 December 4 (2293) Brian G. Marsden
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