All circulars on SN 1997ef through circular 6830, 1999mar05 unless I've missed one somehow. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1) IAUC 6778: Poss. SN IN UGC 4107; N Sco 1997 1997 November 26 (6778) Daniel W. E. Green POSSIBLE SUPERNOVA IN UGC 4107 S. Nakano, Sumoto, Japan, reports the discovery by Yasuo Sano, Nayoro, Hokkaido, of a possible supernova (R = 16.7) on ten CCD frames taken around Nov. 25.582 UT with a 0.28-m f/6.3 reflector (+ R filter). The object is located at R.A. = 7h57m02s.82, Decl. = +49o33'40".2 (equinox 2000.0), which is about 10" east and 20" south of the center of UGC 4107. R. Kushida, Yatsugatake South Base Observatory, provides the following position end figures (measured by Y. Kushida) from an unfiltered CCD image that she obtained on Nov. 26.81 (when the supernova suspect was at mag 16.1) with a 0.40-m f/5 reflector: 02s.87, 41".3. There is no star at this position on the Digital Sky Survey. P. Garnavich, S. Jha, R. Kirshner, and P. Challis, Harvard- Smithsonian Center for Astrophysics, communicate: "P. Berlind obtained a spectrogram (range 370-750 nm) of Sano's supernova candidate in UGC 4107 on Nov. 26.4 UT with the Whipple Observatory's 1.5-m Tillinghast telescope. The spectrum is unusual, showing a continuum with broad (50- to 100-nm) features. The continuum peaks near 510 nm and shows local maxima at 440 and 620 nm. Narrow emission lines from UGC 4107 are also seen and give a redshift of 3400 km/s. The spectrum is clearly not that of a normal star, but from the present evidence, it is not yet possible to conclude that the object is a supernova. The spectrum is available at http://cfa-www.harvard.edu/cfa/oir/Research/supernova/RecentSN.html." %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Circular No. 6783 1997 December 10 (6783) Daniel W. E. Green SUPERNOVA 1997ef IN UGC 4107 J. Y. Hu, Y. L. Qiu, Q. Y. Qiao, and J. Y. Wei, Beijing Astronomical Observatory (BAO), report that the possible supernova in UGC 4107 reported on IAUC 6778 is being monitoring photometrically and spectroscopically at BAO. The object did not appear on CCD images (limiting mag 18.5) taken on Nov. 16. CCD images taken with the 0.60-m telescope show that it brightened from Nov. 28 to Dec. 8; available CCD magnitudes: Nov. 28.70 UT, 16.8; Dec. 7.74, 16.3; 8.72, 16.2. The low-dispersion spectra obtained with 2.16-m telescope on Nov. 28, Dec. 4, and 7, show that the spectra still show the features reported by Garnavich et al. (IAUC 6778), but the peaks are shifted redward. The peak at 510 nm reported by Garnavich et al. shifted to 520, 535, and 545 nm in spectra obtained on Nov. 28, Dec. 4, and 7, respectively. The Na D absorption lines in SN 1997ef show the same redshift as does the H-alpha from UGC 4107, implying that the object is located in the host galaxy. A. V. Filippenko, University of California at Berkeley (UCB), reports that he has examined a spectrum (range 470-1020 nm, resolution 1.5 nm) of SN 1997ef, obtained by E. L. Martin (UCB) on Dec. 10 with the 3-m Shane reflector at Lick Observatory: "The spectrum superficially resembles that of a supernova but in detail is unlike that of any known type of supernova; the features are unusually broad (FWHM 50 nm). The strongest emission line is at rest wavelength 540 nm; if identified with [O I] 557.7 nm, its blueshift is presumably due to obscuration of the object's back side. A smaller peak at 639 nm is then consistent with H-alpha blueshifted by the same amount. Weak peaks are visible at 777 nm (possibly unshifted O I 777.4 nm), 850 nm (slightly shifted Ca II?), and 909 nm (shifted O I 926 nm?). All of the maxima listed by Garnavich et al. (IAUC 6778) have moved substantially to the red. If this offset is applied to their reported peak at 440 nm, the feature would now be roughly consistent with unshifted Mg I] 457.1 nm. Aside from the tentative H-alpha identification (which may instead be unshifted [O I]), the spectrum vaguely resembles what might be expected from a denuded O-Ne-Mg (or perhaps C-O) core. Thus, the object could be a previously unobserved, extreme example of a stripped (type-Ic-like) supernova, though other interpretations are possible. The great breadth of the lines suggests a low mass for the ejecta. Further observations of this unique object are encouraged." Unfiltered CCD magnitude estimates: Nov. 8 UT, [17.5: (W. D. Li, R. R. Treffers, Filippenko, and M. Modjaz, Lick Observatory); Dec. 2.4, 16.5: (Li et al.); 7.98, 16.7 (S. Moretti and S. Tomaselli, Forli, Italy). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 3) Circular No. 6786 1997 December 12 (6786) Daniel W. E. Green SUPERNOVA 1997ef IN UGC 4107 P. Garnavich, S. Jha, R. Kirshner, and P. Challis, Harvard- Smithsonian Center for Astrophysics; and D. Balam, University of Victoria, report: "CCD images of this object were obtained with the F. L. Whipple Observatory (FLWO) 1.2-m telescope by W. Brown and C. Briceno, and with the Dominion Astrophysical Observatory 1.8-m Plaskett telescope, yielding the following V magnitude estimates (relative to the star of V = 17.05 that is 1' to the southwest of UGC 4107): Nov. 28.4 UT, 16.75; 29.5, 16.67; 30.5, 16.57; Dec. 1.3, 16.56; 3.6, 16.55; 12.3, 16.50. The photometry shows a rapid rise in late November, but the brightness has currently leveled out near V = 16.5. Assuming the object is at the distance of UGC 4107 and is unreddened, the absolute V magnitude of the plateau is -17.1 for H_0 = 65 km sE-1 MpcE-1. A series of spectra taken with the FLWO 1.5-m telescope between Nov. 26 and Dec. 8 confirms the trend of increasing wavelength for the broad features that was noted on IAUC 6783. The largest peak near 520 nm has shifted by an average of 1500 km/s per day, covering 513 to 540 nm in 10 days. The flux minimum near 600 nm has become deeper and narrower and now resembles the Si II absorption often found in type-I supernovae. The maximum near 440 nm has strengthened and narrowed and currently peaks at an observed wavelength of 450.1 nm. A spectrum (range 320-850 nm), obtained with the Multiple-Mirror Telescope on Dec. 5, shows no strong interstellar absorption lines of Na I or Ca II at the redshift of UGC 4107, to an equivalent-width limit of 0.02 nm, implying little extinction to this object. The spectrum also shows a sharp drop in flux blueward of 375 nm; this may be due to Ca II absorption out to high velocities, or even to a Balmer jump (but no other signature of hydrogen is clearly present)." %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 4) Circular No. 6797 1997 December 29 (6797) Daniel W. E. Green SUPERNOVA 1997ef IN UGC 4107 J. Y. Wei, J. Y. Hu, Y. L. Qiu, and Q. Y. Qiao, Beijing Astronomical Observatory; and J. S. Deng and J. H. You, Shanghai Jiao Tong University, report the following R magnitudes for SN 1997ef: Dec. 4.8 UT, 16.4; 11.7, 16.1; 12.7, 16.1; 13.8, 16.2; 16.8, 16.3; 22.8, 16.3; 24.7, 16.2; 26.8, 16.2. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 5) Circular No. 6798 1997 December 30 (6798) Daniel W. E. Green SUPERNOVA 1997ef IN UGC 4107 P. Garnavich, S. Jha, R. Kirshner, and P. Challis, Harvard- Smithsonian Center for Astrophysics; and D. Balam, University of Victoria, report: "Recent CCD images of SN 1997ef obtained with the Whipple Observatory 1.2-m telescope by P. Berlind, with the MDM 2.4-m telescope by J. Thorstensen, and with the Dominion Astrophysical Observatory's 1.8-m Plaskett telescope indicate that this object has begun to decline in brightness. Visual magnitude estimates relative to the star (V = 17.05) located 1' southwest of UGC 4107: Dec. 16.3 UT, 16.56; 27.3, 16.84; 28.3, 16.94. Spectra obtained at the Tillinghast telescope by Berlind and L. Macri, and at the MDM 2.4-m telescope by Thorstensen, between Dec. 17 and 27 show that the rapid velocity shift seen in the major spectral features has slowed. After correcting for the redshift of UGC 4107, a number of peaks can now be identified at 397 nm (Ca II), 457 nm (?), 486 nm (H-beta), 547 nm (?), 587 nm (He I), 614 nm (?), and 655 nm (H-alpha). The H-alpha emission peak is rounded, while the unidentified maxima have a triangular shape. Currently, the spectrum appears similar to the peculiar type-Ib supernovae 1988L (Filippenko 1988, A.J. 96, 1941) and 1983I (Wheeler et al. 1987, Ap.J. 313, L69), which also displayed broad maxima near the wavelength of H-alpha. These objects and SN 1997ef appear to be extreme examples of massive stars that have lost all but a small amount of hydrogen through mass loss." %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 6) Circular No. 6809 1998 January 17 (6809) Daniel W. E. Green SUPERNOVAE 1997ef, 1997ei, 1997fb, 1997fc, 1998A A. V. Filippenko and E. C. Moran, University of California at Berkeley, report the results of spectroscopy done on Jan. 17 with the Keck-2 telescope: "SN 1997fb and SN 1997fc (cf. IAUC 6807) are type-Ia supernovae within about 2 weeks past maximum brightness, although the spectrum of the latter appears somewhat peculiar (perhaps due to starlight contamination). Their redshifts are consistent with that of Abell 3301 (0.054). SN 1998A (cf. IAUC 6805, but 40" west, not east, of the galaxy nucleus) is a type-II supernova with well-developed P-Cyg Balmer lines. SN 1997ei is of type Ic (cf. IAUC 6802), not type Ia (cf. IAUC 6796, 6800). A near-infrared spectrum of SN 1997ef (cf. IAUC 6786, 6798) reveals strong, broad Ca II 860-nm emission, but this a characteristic of many supernova subtypes; the exact classification of SN 1997ef is still uncertain." %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 7) Circular No. 6820 1998 February 5 (6820) Daniel W. E. Green SUPERNOVA 1997ef IN UGC 4107 L. Wang, D. A. Howell, and J. C. Wheeler, University of Texas at Austin, report: "SN 1997ef was observed on 1997 Dec. 28 and 1998 Feb. 2 UT with the 2.1-m telescope at McDonald Observatory. The 1998 Feb. data show that SN 1997ef is making the transition to the nebular phase, and the spectrum strongly resembles those of type-Ic supernovae at 1-2 months past maximum (similar to the type- Ic spectrum of SN 1997ei taken on the same night). Broad emission lines of He I (587.6 nm)/Na I (589.0, 589.6 nm), [O I] (630.0, 636.4 nm), O I (777.1 nm), and Mg I] (457.1 nm) were detected. Spectropolarimetry was also obtained, but no polarization was detected down to about 1.5 percent."