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IAUC 5324: N Sgr 1991; 1991t

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                                                  Circular No. 5324
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


NOVA SAGITTARII 1991
     M. A. Dopita and K. M. Sebo, Mt. Stromlo and Siding Spring
Observatory, communicate:  "Spectra of Nova Sgr 1991 have been
obtained on Aug. 6.43, 8.39, 9.48, and 10.38 UT using the Double Beam
Spectrograph on the 2.3-m telescope at Siding Spring.  These spectra
confirm the extraordinary expansion velocity (6800 km/s FWHM) and
reveal very rapid spectral evolution.  Between Aug. 6 and 8, the nova
made a transition from a cool atmospheric to a hot nebular character.
This was accompanied by the emergence of [Ne III] and [Ne V]
lines, which by Aug. 10 were becoming comparable in strength to H-
beta.  In light of this, it seems very likely that Nova Sgr 1991 is
another member of the O-Ne novae."
     Photometry by A. C. Gilmore, Mt. John University Observatory
(cf. IAUC 5320):  Aug. 10.555 UT, V = 11.98 +/- 0.02, U-B = -0.82
+/- 0.03, B-V = -0.26 +/- 0.02, V-R = +1.29 +/- 0.02.  Further visual
magnitude estimates:  Aug. 12.094 UT, 12.3 (J. E. Bortle, Stormville,
NY); 13.86, 12.8 (M. Verdenet, Bourbon-Lancy, France); 14.89,
13.2 (Verdenet).


PERIODIC COMET HARTLEY 2 (1991t)
     Improved orbital elements from MPC 18598:

                    Epoch = 1991 Sept.21.0 ET
     T = 1991 Sept.11.6542 ET         Peri. = 174.9337
     e = 0.719489                     Node  = 226.0539  1950.0
     q = 0.953285 AU                  Incl. =   9.2561
       a =  3.398382 AU    n = 0.1573243    P =   6.265 years

     1991 ET      R.A. (1950) Decl.     Delta      r       m1
     Aug. 22     5 21.80    +29 32.7
     Sept. 1     6 21.69    +27 00.7    0.822    0.966     8.4
          11     7 13.51    +23 25.5
          21     7 57.44    +19 23.6    0.937    0.963     8.6
     Oct.  1     8 34.71    +15 18.5
          11     9 06.46    +11 23.0    1.060    1.047     9.4

     Total visual magnitude estimates (cf. IAUC 5312):  Aug. 6.33
UT, 9.0 (J. E. Bortle, Stormville, NY, 20x80 binoculars); 10.47, 8.3
(C. S. Morris, Pine Mountain Club, CA, 20x80 binoculars); 12.34, 8.6
(Bortle); 15.00, 9.1 (B. H. Granslo, Fjellhamar, Norway, 0.20-m
reflector).


1991 August 15                 (5324)             Daniel W. E. Green

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