N. Aksaker

Emission-Line Fluxes of Northern Planetary Nebulae

We present long slit spectrophotometric emission line fluxes of bright and extended (<5 arcsec in diameter) Planetary Nebulae (PNe) selected from Acker et al. 1992 catalog with suitable equitorial coordinates for Northern hemisphere. In total, 17 PNe have been choosen and observed in 2008--2010. To measure absolute fluxes, broad slit sizes, ranging from 3.5\arcsec to 7.5\arcsec were used and thus equivalent widths of all observable emission line fluxes were also calculated. Among 17 PNes observed, line flux measurements of 12 of them were made for the first time. This work also aims to extend the sky coverage of emission line flux standards in Northern hemisphere (Dopita & Hua 1997 - 52 PNe in Southern hemisphere; Wright et al. 2005 - 6 PNe in Northern hemisphere). Electron temperatures and densities, and chemical abundances of these PNe were also calculated in this work. These data is expected to lead the photometric or spectrometric further work for absolute emission line flux measurements needed for \hii regions, supernova remnants etc.

Optical counterparts of two ULXs in NGC 5474 and NGC 3627 (M 66)

We identified two optical counterparts of brightest ultraluminous X-ray sources (ULXs) in galaxies NGC 5474 and NGC 3627 (M66). The counterparts in Hubble Space Telescope images are very faint, their V magnitudes are 24.7 (MV ≈ −4.5) and 25.9 (MV ≈ −4.2), respectively. NGC 5474 X-1 changes the X-ray flux more than two orders of magnitude, in its bright state it has LX ≈ 1.6 × 1040 erg s−1, the spectrum is best fitted by an absorbed power law model with a photon index ≈ 0.94. M66 X-1 varies in X-rays with a factor of ∼2.5, its maximal luminosity being 2.0 × 1040 erg s−1 with ≈ 1.7. Optical spectroscopy of the NGC 5474 X-1 has shown a blue spectrum, which however was contaminated by a nearby star of 23 mag, but the counterpart has a redder spectrum. Among other objects captured by the slit are a background emission-line galaxy (z = 0.359) and a new young cluster of NGC 5474. We find that these two ULXs have largest X-ray-to-optical ratios of LX/Lopt ∼ 7000 for NGC 5474 X-1 (in its bright state) and 8000 for M66 X-1 both with the faintest optical counterparts ever measured. Probably their optical emission originates from the donor star. If they have super-Eddington accretion discs with stellar-mass black holes, they may also have the lowest mass accretion rates among ULXs such as in M81 X-6 and NGC 1313 X-1.

New Galactic Planetary nebulae selected by radio and multiwavelength characteristics

We have used the Cornish radio catalogue combined with the use of multi-wavelength data to identify 62 new Planetary Nebula (PN) candidates close to the Galactic mid-plane. Of this sample 11 have weak optical counterparts in deep narrow band H

X-RAY SPECTRAL AND OPTICAL PROPERTIES OF A ULX IN NGC 4258 (M106)

\alpha

Emission Lines of Northern Planetary Nebulae

imaging that allows their spectroscopic follow-up. We have observed eight of these candidates spectroscopically, leading to the confirmation of 7 out of 8 as PNe. All but one of our sample of newly detected PNe appear to be of Type I chemistry with very large [NII]/H

A pipeline for the ROTSE–IIId archival data

\alpha

DEFPOS and Its First Results

ratios. This indicates that our selection method heavily favours detection of this kind of PN. Cornish is a low Galactic latitude survey where young objects and Type I PNe (thought to derive from higher mass progenitors) are more plentiful, but where optical extinction is large. The very high success rate in correctly identifying PNe in this zone proves the efficacy of our radio and multiple multi-wavelength diagnostic tools used to successfully predict and then confirm their PN nature, at least in the cases where an optical counterpart is found and has been observed. The study reinforces the effective use of a combination of multi-wavelength and optical data in the identification of new Galactic PNe and especially those of Type I chemistries whose dusty environments often prevents their easy detection in the optical regime alone.

Hα measurements using DEFPOS/RTT150 Telescope:Instrumentation and observations

We study the X-ray and optical properties of the ultraluminous X-ray source (ULX) X-6 in the nearby galaxy NGC 4258 (M106) based on the archival {\it XMM-Newton}, {\it Chandra}, {\it Swift}, and {\it Hubble Space Telescope} ({\it HST}) observations. The source has a peak luminosity of

Intensity calibration of DEFPOS data

L_{\mathrm{X}} \sim 2 \times 10^{39}

Long-term variations and periods of Mira stars from ROTSE–IIId

erg s