Central Bureau for Astronomical Telegrams
IAUC 5319: IC 4997; LSI +61 303; N Oph 1991
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Circular No. 5319
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
IC 4997
W. A. Feibelman, Goddard Space Flight Center, NASA; and L. H.
Aller, University of California at Los Angeles, report: "We have
found changes in emission line fluxes of the planetary nebula IC
4997. When high-dispersion International Ultraviolet Explorer data,
obtained on 1991 June 23 and 28, are compared with reprocessed 1980
HIRES data (to adjust the 1980 data for ITF and sensitivity changes),
significant intensity increases by 25-60 percent are detected
for some emission lines. Changes are noted for Si IV 139.3- and
140.2-nm; C IV 154.8- and 155.2-nm; O III] 166.1-, 166.5-, and
232.0-nm; N III] 174.9- and 175.2-nm; [Ne III] 181.4-nm; Si III]
189.2-nm; and some He I lines. He II 164.0-nm is either very weak
or absent. It was believed to be present in LORES (0.7 nm) data in
1981 (Feibelman 1982, Ap.J. 258, 562), but the HIRES spectra clearly
show that the emission is due to O I 164.1-nm, which also increased
in 1991. The corresponding absence of He II 468.6-nm was also noted
on Hamilton echelle spectrograph data obtained with the Lick 3-m
reflector in 1986 and 1990. These echelle spectra showed intensity
increases from 1986 to 1990 for [He III] 386.8-nm, [O III] 436.3-nm,
He I 587.6- and 706.5-nm, and H-alpha 656.3-nm, a trend that is also
apparent on image-tube-scanner data from 1974 and 1977. However,
the IUE [O II] 247.0-nm and Mg II 279.6- and 280.2-nm fluxes
decreased in 1991 relative to 1980. Inexplicably, the (unsaturated)
280.2-nm component of Mg II has the same amplitude for both epochs,
but the FWHM value narrowed in 1991, resulting in a 30-percent
reduction of flux. New Hamilton echelle observations are scheduled
for late August. Additional spectra from other observatories should
prove valuable."
LSI +61 303
Corrigendum. The item on IAUC 5317 should be disregarded; further
observations by Comeron and Marti with the Kapteyn Telescope do not
confirm the optical brightening reported thereon, and they suspect a
misidentification with SAO 12383, which is located 3' from LSI
+61 303.
NOVA OPHIUCHI 1991
Photometry by A. C. Gilmore, Mt. John University Observatory:
Aug. 3.57 UT, V = 14.79 +/- 0.03, B-V = +0.53 +/- 0.02.
1991 August 6 (5319) Daniel W. E. Green
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