------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 3074 2015 Apr 23 15.59UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074 INTERNET: GUY@TAHQ.DEMON.CO.UK Backup: gmh@wdcc1.bnsc.rl.ac.uk WORLD WIDE WEB http://www.theastronomer.org ------------------------------------------------------------------- COMET C/2015 H1 (BRESSI) T. H. Bressi reports the discovery of a comet with a diffuse extended centre on CCD mosaic images taken with the Spacewatch 0.9-m f/3 reflector at Kitt Peak (discovery observations tabulated below): 2015 UT R.A. (2000) Decl. Mag. Observer Apr. 20.46356 21 35 25.72 + 4 54 51.2 18.2 Bressi 20.48713 21 35 24.43 + 4 55 23.3 18.0 " The MPC's WWW alert prompted other CCD astrometrists to confirm the cometary appearance. A. R. Gibbs notes that images of Apr. 21.5 UT with the Steward Observatory 1.0-m reflector at Mount Lemmon show a round coma 6" in diameter and a short fan tail 6" long in p.a. 260-310 deg on four 30-s exposures. H. Sato (Tokyo, Japan; ten stacked 60-s exposures taken with a 0.61-m f/6.5 astrograph + luminance filter at the Sierra Remote Observatory near Auberry, CA, USA, on Apr. 21.50 UT) finds the comet to be strongly condensed with a round coma 10" in diameter, w-band magnitude 17.7 as measured within a circular aperture of radius 5".0, and a hint of tail 10" long toward p.a. 315 degrees. The available astrometry, the following preliminary parabolic orbital elements by G. V. Williams, and an ephemeris appear on MPEC 2015-H100. T = 2015 Apr. 8.3782 TT Peri. = 27.6910 Node = 326.4655 2000.0 q = 1.941464 AU Incl. = 141.2590 >From 56 observations 2015 Apr. 20-22 Ephemeris (MPEC): Date TT R. A. (2000) Decl. Delta r Elong. m1 2015 03 24 21 48 51.2 -03 45 59 2.6716 1.9507 35.7 18.5 2015 04 08 21 43 55.4 +00 35 27 2.4173 1.9415 50.5 18.3 2015 04 16 21 39 04.2 +03 16 32 2.2645 1.9437 58.8 18.2 2015 04 22 21 33 59.3 +05 30 19 2.1449 1.9487 65.1 18.1 2015 04 23 21 32 59.8 +05 53 50 2.1247 1.9498 66.2 18.0 2015 04 24 21 31 57.6 +06 17 43 2.1044 1.9510 67.3 18.0 2015 04 30 21 24 41.0 +08 49 23 1.9828 1.9597 73.9 17.9 2015 05 08 21 11 34.5 +12 35 47 1.8235 1.9755 83.1 17.8 2015 05 23 20 31 55.3 +20 55 06 1.5609 2.0176 101.1 17.5 NOVA OPHIUCHI 2015 Further to TA E-Circular 3071, U Munari relays further news of spectroscopic study. Intensive monitoring of the evolution of Nova Oph 2015 since its discovery, obtaining UBVRI photometry and Echelle spectroscopy with ANS Collaboration telescopes, low resolution spectra with the Asiago 1.22m telescope and high resolution Echelle spectra with the Asiago 1.82m telescope. Our photometric observations show that the He/N-type classifications reported in CBET #4086 and ATel #7339 were obtained before Nova Oph 2015 passed through the pre-maximum halt. The nova is only now passing through maximum brightness, at the usual ~2 mag brighter than pre-maximum halt. Our latest spectrum was obtained with the Asiago 1.22m+B&C+CCD spectrograph on Apr 11.094 UT and it is a textbook example of a FeII-type nova at maximum brightness rather than 'He/N' type nova. Guy M Hurst