Central Bureau for Astronomical Telegrams
IAUC 2876: TRANSIENT HIGH-LATITUDE X-RAY SOURCE; P/PERRINE-MRKOS; P/WESTPHAL; BPM 30551; NOTICE TO Tlgm SUBSCRIBERS
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Read IAUC 2877
Circular No. 2876
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
TRANSIENT HIGH-LATITUDE X-RAY SOURCE
A. P. Willmore, Department of Space Research, University of
Birmingham, communicates: "The region of the sky containing the
short-lived transient x-ray source MX2348-65 (IAUC 2869) was within
the field of view of the Ariel 5 rotating modulation collimators
around the time of the event. Data from Nov. 16d13h28m to 13h55m
and from 14h13m to 14h46m UT (i.e., up to 2m prior to the event and
from 34m afterwards) accumulated in 32s time bins show no excess
flux comparable with the reported levels, thus setting tighter time
limits on the duration of the event. During the period 11h27m to
13h25m the experiment was in rotating-modulation collimator mode,
and there was a marginal detection of a source within the region.
The significance of the detection is poor (3.5 sigma) but if real gives
a much improved position: R.A. = 23h58m50s, Decl. = -64o06' (equinox
1950.0); the radius of the error circle is 0o.15. This position is
1o.2 from that previously reported. The intensity is 0.15 times
that of the Crab. M. V. Penston has pointed out that CPD -64 4393
= SAO 255625 (mv = 9.0, spectrum M4) lies within the error circle."
PERIODIC COMET PERRINE-MRKOS
E. Roemer, University of Arizona, reports that she has taken
three unsuccessful exposures for this comet with the Steward
Observatory's 229-cm reflector. A 30-min exposure on Aug. 8 covered
the range Delta-T = -0.42 to +0.55 day from the prediction on IAUC 2768,
and somewhat longer exposures on Sept. 12 extended the range to Delta-T
= -1.3 to +1.5 day. No reasonably condensed image appeared near
the line of variation to a magnitude limit of m2 ~ 19.0-19.5.
C. Kowal, Hale Observatories, reports that no trace of the
comet, to m1 ~ 19 and for Delta-T = -5 to +8 days, appears on a plate
taken on Oct. 2 with the 122-cm Schmidt telescope at Palomar.
PERIODIC COMET WESTPHAL
Several observers have reported unsuccessful searches for this
comet also. The ephemeris (IAUC 2770) continues as follows:
For dT = +1d
1976 ET R. A. (1950) Decl. Delta r dR.A. dDecl. Mag.
Jan. 3 22 02.44 +28 32.7 1.214 1.265 +0m08 -48'5 10.4
13 22 26.87 +34 45.0 -0.11 -48.8
23 22 57.00 +40 55.7 1.253 1.322 -0.44 -48.4 10.7
Feb 2 23 34.76 +46 50.6 -0.98 -47.0
12 0 22.16 +52 06.7 1.322 1.434 -1.77 -43.8 11.2
22 1 20.35 +56 11.7 -2.78 -38.0
Mar. 3 2 27.34 +58 33.5 1.459 1.586 -3.78 -29.4 11.8
13 3 36.66 +58 57.6 -4.38 -19.0
23 4 40.48 +57 38.4 1.681 1.763 -4.35 - 9.0 12.6
Apr. 2 5 34.60 +55 09.2 -3.86 - 1.2
12 6 18.94 +52 03.2 1.981 1.955 -3.20 + 4.0 13.4
22 6 55.27 +48 43.8 -2.58 + 7.1
May 2 7 25.59 +45 24.3 2.339 2.154 -2.07 + 8.7 14.2
12 7 51.51 +42 11.7 -1.66 + 9.3
22 8 14.15 +39 08.7 2.727 2.357 -1.34 + 9.4 14.9
June 1 8 34.35 +36 16.2 -1.09 + 9.2
11 8 52.68 +33 33.9 3.120 2.560 -0.90 + 8.8 15.6
21 9 09.50 +31 01.1 -0.74 + 8.3
July 1 9 25.13 +28 36.9 3.497 2.763 -0.62 + 7.8 16.1
m1 = 9.0 + 5 log Delta + 10 log r
BPM 30551
J. E. Hesser, B. M. Lasker and H. E. Neupert, Cerro Tololo
Interamerican Observatory, write: "The magnitude 15.3 DA white
dwarf BPM 30551 (Wegner 1973, Monthly Notices Roy. Astron. Soc.
163, 381) is a complex, low-amplitude (<~ 0.04 maqnitude) variable,
probably belonging to the sparsely populated ZZ Cet class. The
star lies in the region of the two-color plane favored to this
class (Lasker and Hesser 1971, Astrophys. J. 163, L89), and
spectrophotometry suggests log g ~ 8 and T_e ~ 1.3 x 10**4 K. The
character of the variations can change dramatically on a timescale of
one hour. Power spectral analysis of ten long data sets from Oct.
and Nov. 1974 yields periodicities of 606.8 and 744.6 seconds;
periods of 682.7 and 844.6 seconds are often also present. While
these periods offer a relatively good fit to the eighth through
eleventh harmonics of a 1.870-hour fundamental, we find no physical
or observational support for such a model."
NOTICE TO TELEGRAM SUBSCRIBERS
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1975 December 4 (2876) Brian G. Marsden
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