COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2490 Konkoly Observatory Budapest 7 March 1984 HU ISSN 0374 - 0676 IMPROVED OUTBURST LIGHTCURVES OF THE NOVAE EY Aql, BC Cas, MT Cen, AND V745 Sco During a stay at the Harvard College Observatory, photographic plates were examined for outburst records of novae, to determine improved positions and to prepare finding charts for a forthcoming catalogue and atlas of galactic novae (Duerbeck 1983). In a few cases, novae could be identified that had been observed and described elsewhere, and some essential points could be added to the existing light curves. Table I. Observations Nova Plate J.D. plate J.D. series 2400000+ m_pg Nova series 2400000+ m_pg EY Aql MF 24761. 10.9 MT Cen MF 26485.3 12.2 " MF 24790. 12.6 " MF 26529.2 11.7 BC Cas AC 25811. ft12. " MF 26530.2 11.8 " AC 25825. 10.7 " MF 26738.5 14.7 " AC 25853. 11.5 V745 Sco B 28645.6 ft14.5 " AC 25856. ft12. " B 28664.6 11.0 " AC 25872. 11.7* " B 28668.6 12.45 " I 25922. 14.0** " B 28670.5 13.0 MT Cen MF 26454.3 ft16.2 " B 28672.5 13.25 " MF 26470.3 14.7: " B 28673.6 13.3 " MF 26474.3 8.35 " B 28674.6 13.4: " MF 26481.3 10.0 " B 28675.6 13.9: " MF 28688.5 14.6: *^ poor plate; defect? " MF 28696.5 ft14.5 **^very good image 1. EY Aql (1926) This nova was discovered by Albitzky (1929) on Simeis plates; it is seen on 5 plates between 1926 September 8 and September 30, it does not appear on a plate taken 1926 August 16 (fainter than 13.6m). Hoffleit (1932) mentions that the nova was found only on two out of 79 Harvard plates, "during the interval of Albitzky's observations". It is indeed seen on two plates of the MF series, taken 1926 September 2 and October 1. The outburst time and the light curve form can be improved. The magnitude scale by Albitzky (1929) is used. The magnitude at maximum was brighter than 11.0m, the t_3 -time about 40 days. The estimates are given in Table I, and the improved light curve is shown in Fig. 1. [FIGURE 1] Fig. 1. The light curve of EY Aql (1926). Circles are Albitzky's (1929) magnitudes, dots are magnitudes from Harvard photographs. 2. BC Cas (1929) This nova was discovered by Beljawsky (1931). Perova and Sharov (1956) list the observations from Moscow (Sternberg) and Simeis plates. Their first plate showing the star was taken 1929 September 4. A Harvard plate shows the object already bright on 1929 July 31, while a plate taken July 18 does not show the star. The Harvard observations are listed in Table I. The improved light curve is shown in Fig. 2. It cannot be decided whether the first Harvard plate was taken on the rising or on the declining branch of the light curve. The magnitude at maximum was certainly near 10m, the t_3-time is between 50 and 75 days. [FIGURE 2] Fig. 2. The light curve of BC Cas (1929). Circles are magnitudes from Perova and Sharov (1956), dots are magnitudes from Harvard photographs. 3. MT Cen (1931) This nova was discovered by Uitterdijk (1934) on plates taken in May, 1931. The rise to maximum is well covered with observations, however, 9 days after outburst, a gap of 411 days follows, after which the nova had disappeared. Some plates of the MF series show the nova. Uitterdijk's (1934) scale is used for the bright phase of the nova. For fainter phases, a scale was established and calibrated from an ESO/SRC J atlas plate, using King et al.'s (1981) magnitude - image diameter calibration. The first Harvard plate shows the nova on the rising branch, more than 6^m below maximum. The magnitude at maximum is 8.35m, the t_3-time is about 10 days. Unfortunately, too few observations are available to classify the light curve. It may be a fast nova of the FH Ser type (Duerbeck's (1981) class Cb). The observations are listed in Table I, the light curve is shown in Fig. 3. [FIGURE 3] Fig. 3. The light curve of MT Cen (1931). Circles Uitterdijk's (1934) magnitudes, dots are magnitudes from Harvard photographs. [FIGURE 4] Fig. 4. The light curve of V745 Sco (1937). Circles are Plaut's (1956) magnitudes, dots are magnitudes from Harvard photographs. 4. V745 Sco (1937) This nova was discovered by Plaut (1958) on plates taken by H. van Gent. It is visible on some B and MF plates. Plaut's (1958) scale is used. The maximum magnitude is 11.0m, the t_3-time is 12 days. The observations are given in Table I, the light curve is shown in Fig. 4. Finding charts and accurate positions of the novae will be given in the forthcoming catalogue. Acknowledgments: I thank Dr. M. Liller for the permission to use the plate collection of the Harvard College Observatory, and for her advice. I also thank the Deutsche Forschungsgemeinschaft for a travel grant (Du 107/4-1) that made the stay at the HCO possible. H. W. DUERBECK Observatorium Hoher List der Universitats-Sternwarte Bonn 5568 Daun, F. R. Germany References : Albitzky, V., 1929, Astr. Nachr. 235, 317. [BIBCODE 1929AN....235..317A ] Beljawski, S., 1934, Astr. Nachr. 243, 115. [BIBCODE 1931AN....243..115B ] Duerbeck, H.W., 1981, Publ. astr. Soc. Pacific 93, 165. [BIBCODE 1981PASP...93..165D ] Duerbeck, H.W., 1983, Astrophys. Space Sci. 95 (in press). Hoffleit, D., 1932, Harvard Bull. 887, 9. [BIBCODE 1932BHarO.887....9H ] King, D.J., Birch, C.I., Johnson, C., Taylor, K.N.R., 1981, Publ. astr. Soc. Pacific 93, 385. [BIBCODE 1981PASP...93..385K ] Perova, N.B., Sharov, A.S., 1956, Per. Zvezdy 13, 317. Plaut, L., 1958, Leiden Ann. 21, No. 3. [BIBCODE 1958AnLei..21..217P ] Uitterdijk, J., 1934, Bull. Astr. Inst. Netherl. 7, 176. [BIBCODE 1934BAN.....7..176U ]