Central Bureau for Astronomical Telegrams
IAUC 3243: OPTICAL OUTBURST OF Aql X-1 (4U 1908+00); CH Cyg; 1977m
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Read IAUC 3244
Circular No. 3243
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
OPTICAL OUTBURST OF AQUILA X-1 (4U 1908+00)
F. Walter, P. Charles, J. Thorstensen and S. Bowyer, Space
Sciences Laboratory, University of California at Berkeley, report
that the Thorstensen et al. (1978, Astrophys. J. 220, L131) optical
counterpart of the flaring x-ray source Aql X-1 is currently also
in outburst (cf. IAUC 3235). Plates taken on June 29 and 30 UT
with the Leuschner Observatory's 76-cm reflector show the counterpart
to be at B ~ 16.5, approximately 3-4 magnitudes brighter than
its quiescent level of B ~ 20. The source should remain at or near
this level for 1-2 weeks. Continuous monitoring at all wavelengths
during the remainder of this active period is urged.
J. van Paradijs and R. Remillard, Massachusetts Institute of
Technology, observed Aql X-1 with the McGraw-Hill Observatory's
132-cm telescope during June 25d06h17m-25d10h25m and 26d06h13m-26d10h31m
UT. Spectra obtained during these times with the image-tube
scanner showed no strong emission features, but weak interstellar
Na D lines were present.
R. C. Puetter and H. E. Smith, University of California at San
Diego, observed Aql X-1 with the Lick Observatory's 305-cm Shane
telescope on June 30 and July 1 UT. Spectrograms (resolution ~ 8
A) covering the range 3500-5000 A clearly show weak (equivalent
width ~ 1-2 A) emission features at C III-N III 4640-4650 A and He
II 4686 A. A spectrogram taken in the red displays no emission
features, but it does show the weak Na D lines.
F. J. Vrba, U.S. Naval Observatory, Flagstaff Station, reports
that unfiltered photoelectric photometry of Aql X-1 with the 100-cm
reflector on July 2 UT shows variability of order 0.05-0.15 magnitude
on timescales of 2-4 min. This activity decreased on subsequent
nights, observations on July 4 UT showing very little (< 0.02
magnitude) rapid variability. Magnitudes and colors were as follows:
1978 UT V B-V U-B
July 3d07h42m-03d07h48m 15.6 +/- 0.1 +0.93 +/- 0.03
4 07 19 -04 07 26 15.6 +/- 0.1 +0.76 +/- 0.03
6 06 28 -06 06 41 15.9 +/- 0.1 +0.51 +/- 0.03 -0.49 +/- 0.03
S. Tapia, University of Arizona, reports photoelectric photometry
of Aql X-1 with the Lunar and Planetary Laboratory's 154-cm
reflector that is consistent with the values given above. On July
5 UT unfiltered photometric variations of as much as 0.2 magnitude
on timescales of 1-2 min were seen. Polarization measurements
yielded an upper limit of (1 +/- 0.6) percent to linear and circular
polarization in the object.
CH CYGNI
Tapia also reports that variations in the linear polarization
of CH Cyg since the recent outburst (IAUC 3101) suggest the appearance
of dust grains in the shell of this star. The percentage P
and position angle theta of the linear polarization, observed with the
Minipol photopolarimeter on the 154-cm reflector, were as follows:
1977 Sept. 9.1 UT 1978 July 5.3 UT
Band P theta P theta
(N) 1.53 +/- 0.08 163o 1.97 +/- 0.04 154o
U 1.05 +/- 0.03 162 1.86 +/- 0.03 155
B 0.28 +/- 0.01 153 1.08 +/- 0.03 156
V 0.12 +/- 0.01 134 0.79 +/- 0.09 154
R 0.29 +/- 0.01 90 0.36 +/- 0.02 162
I 0.26 +/- 0.01 88 0.08 +/- 0.05 174
The spectral band (N) is centered at 3400 A and has halfwidth 400 A.
Polarimetry with higher spectral resolution is needed to study the
shell structure and evolution.
COMET KOHLER (1977m)
The following precise positions have been reported:
1977/78 UT R. A. (1950) Decl. m2 Observer
Oct. 4.84343 16 35 52.68 +17 36 39.6 Benishek
5.77643 16 38 49.80 +17 07 20.7 "
6.77921 16 42 03.00 +16 35 23.7 "
7.76392 16 45 16.53 +16 03 11.4 "
8.77642 16 48 38.61 +15 29 31.1 "
18.74447 17 25 03.19 + 9 15 41.7 "
18.78129 17 25 11.66 + 9 14 12.5 "
27.71600 18 03 00.84 + 2 30 35.8 "
28.72433 18 07 35.45 + 1 41 09.4 "
Jan. 6.40319 0 13 09.26 -34 08 08.2 Gilmore
6.41008 0 13 10.97 -34 08 06.1 13.4 "
Mar. 4.37630 3 09 25.03 -24 29 29.0 "
4.39854 3 09 28.13 -24 29 11.5 "
12.36322 3 27 47.76 -22 58 42.3 15.2 "
12.38492 3 27 50.87 -22 58 27.5 "
31.35302 4 08 14.83 -19 47 07.8 "
Apr. 8.32443 4 24 06.41 -18 38 44.2 15.5 "
8.35336 4 24 10.00 -18 38 29.0 "
V. Protitch-Benishek (Belgrade Astronomical Observatory).
A. C. Gilmore (Carter Observatory). 41-cm reflector. Measurer:
P. M. Kilmartin. The single image on Mar. 31 is of doubtful
appearance.
1978 July 12 (3243) Brian G. Marsden
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