Central Bureau for Astronomical Telegrams
IAUC 2265: SECOND DISCONTINUITY IN PERIOD OF CRAB PULSAR; 1969i
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 2266
Circular No. 2265
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
SECOND DISCONTINUITY IN PERIOD OF CRAB PULSAR
Dr. R. N. Manchester, National Radio Astronomy Observatory,
communicates: "A second discontinuous change has been observed in
the period of the Crab pulsar (PSR 0531+21). Observations at 1-day
intervals from 1970 Apr. 17 to 26 showed that between Apr. 21d20h
UT and Apr. 22d20h UT the period decreased by a factor of 5 x 10**-8.
This change is approximately 20 times larger than the discontinuity
observed by Boynton et al. (IAUC 2179) and by Richards et al. (IAUC
2181) in October 1969. Observations subsequent to the discontinuity
cannot be fitted assuming a constant period and period first
derivative. It is possible that the period oscillated about its
new mean value with an oscillation amplitude of about 2 x 10**-8 and
period of about 4 days."
COMET BENNETT (1969i)
The following precise positions have been reported:
1970 UT R. A. (1950) Decl. Mag. Observer
Feb. 24.73021 22 42 08.84 -49 11 08.6 Bruwer
24.73299 22 42 09.01 -49 11 09.8 "
Mar. 19.11322 22 04 05.88 -18 56 49.9 "
Apr. 26.07668 0 08 53.33 +57 03 13.2 Debehogne
26.09728 0 08 59.70 +57 04 03.7 "
27.00789 0 18 09.65 +58 13 30.2 "
27.03942 0 18 18.36 +58 14 28.0 "
30.05391 0 27 55.39 +59 20 09.9 "
30.06988 0 28 00.03 +59 20 41.8 "
May 2.91195 0 41 19.99 +60 41 31.7 Codina
2.93070 0 41 25.51 +60 42 00.3 "
5.04216 0 51 09.03 +61 34 40.2 Debehogne
5.06990 0 51 16.61 +61 35 19.0 "
5.87813 0 54 56.97 +61 53 56.3 6 Muller
6.05606 0 55 45.68 +61 57 59.3 Debehogne
6.07753 0 55 51.48 +61 58 27.0 "
6.13345 0 56 07.15 +61 59 44.7 Muller
7.03948 1 00 11.00 +62 19 26.9 Debehogne
7.06925 1 00 19.71 +62 20 05.9 "
9.05494 1 09 07.47 +63 00 27.5 "
9.06810 1 09 11.56 +63 00 43.7 "
13.90927 1 29 51.39 +64 24 43.2 Codina
13.91622 1 29 53.31 +64 24 49.5 "
21.03715 1 58 12.91 +66 01 18.8 8 Muller
26.91034 2 19 41.36 +67 04 45.8 Codina
26.92388 2 19 44.48 +67 04 58.8 "
June 1.89067 2 39 54.48 +67 59 21.8 "
1.91706 2 40 01.20 +67 59 39.9 "
1.96944 2 40 10.33 +68 00 06.1 9 Muller
3.07153 2 43 43.79 +68 09 24.1 9 "
6.06736 2 53 06.31 +68 33 59.5 9 "
10.96046 3 07 35.90 +69 11 43.6 Codina
10.98546 3 07 41.25 +69 11 59.4 "
J. A. Bruwer (Republic Observatory Annexe, Hartbeespoort).
Franklin Adams telescope.
H. Debehogne (Royal Observatory, Uccle). 40-cm double astrograph.
Reduced by G. Roland. Communicated by J. Dommanget.
J. M. Codina and Torras (Fabra Observatory, Barcelona). Computed
by Torras and Vera.
P. Muller (Paris Observatory, Meudon).
Continuation to the ephemeris on IAUC 2234:
1970/71 ET R. A. (1950) Decl. Delta r Mag.
Sept.21 2 06.5 +83 10.8 2.868 3.113 17.2
26 1 21.6 +82 54.6
Oct. 1 0 41.2 +82 15.8 2.900 3.237 17.4
6 0 08.4 +81 17.5
11 23 43.8 +80 04.0 2.943 3.358 17.6
16 23 26.2 +78 39.4
21 23 14.0 +77 06.8 3.001 3.478 17.8
31 23 00.9 +73 47.3
Nov. 10 22 57.3 +70 20.2 3.175 3.713 18.2
20 22 59.31 +66 55.9
30 23 04.65 +63 41.6 3.437 3.942 18.6
Dec. 10 23 12.13 +60 43.0
20 23 20.97 +58 03.3 3.783 4.165 19.1
30 23 30.73 +55 44.3
Jan. 9 23 41.09 +53 46.5 4.191 4.384 19.5
19 23 51.83 +52 09.2
29 0 02.81 +50 51.2 4.632 4.597 20.0
Feb. 8 0 13.90 +49 51.0
18 0 25.02 +49 06.7 5.075 4.806 20.3
28 0 36.10 +48 36.6
Mar. 10 0 47.08 +48 18.9 5.493 5.012 20.7
The magnitude, calculated from 10.0 + 5 log Delta + 10 log r, refers to
the central condensation. The total magnitude should still be
about 13 in September.
1970 July 21 (2265) Brian G. Marsden
Read IAUC 2266
Our Web policy. Index to the CBAT/MPC/ICQ pages.
