P. J. Young, Department of Astronomy, University of Texas at Austin, writes: "This nova was examined visually with the 208-cm Struve reflector at McDonald Observatory on July 6 (coude periscope 500 x) and July 8 (Cassegrain focus 1200 x) with excellent seeing conditions on both occasions. No associated nebulosity as large as 0".1 was observed with either scotopic or photopic vision when the Airy disks, of size ~ 0".05, of the two twelfth-magnitude stars < 1' north of the nova could be seen. Spectroscopic scans by D. L. Lambert at the coude focus of the 270-cm reflector indicate that 10 percent of the luminosity in the scotopic visual band is due to the [O III] emission at 4959 A and 5007 A; this also accounts for 30 percent of the luminosity seen in the photopic band with minor contributions from H-alpha blended with [N II]. The scotopic visual magnitude was 11.20, and photoelectric measurement yielded mean values V 12.00, B-V = +0.51, U-B = -0.25 (on July 8.353 UT; with cooled 8575 photomultiplier tube). The absence of an observed nebulosity is in conflict with the prediction that the gas shell should be ~ 0".4 in diameter, assuming an expansion velocity of 1300 km/s, a distance of 1.4 kpc and a roughly spherically-symmetric ejection." J. C. Kemp, R. J. Rudy and M. V. Sykes, Department of Physics, University of Oregon, report: "Based on 12 cycles observed from 1 July to 25 July 1976 the current light curve has a peak-to-peak amplitude of 0m.20 in unfiltered light (3500-5500 A). The period of variations is currently 0d.1384 with an epoch of the even minimum on 1976 July 16.333 UT. The true orbital period might be twice the period of light variations. The even minima are rounded and symmetrical, while the odd minima tend to show a slow drop and a rapid rise. The difference, if real, is obscured by random variability and by progressive changes. A careful search for the even/odd effect is urged. Power spectra of the rapid flickering (IAUC 2973) show peaks at 122s and 196s, but it has not been established that either of these is a real or persistent period."
International Astronomical Union Circular
- Pub Date:
- August 1976