ATel #16314: Optical spectroscopy and optical-NIR photometry of the black hole transient SWIFT J1753.5-0127

ATel #16314 (1 Nov 2023): V. V. Neustroev, T. A. Laaperi, E. S. Leskinen, R. J. Liimatainen, L. V. Ruotsalainen (University of Oulu), S. Moran, G. Fedorets, T. Kangas, E. Kankare (University of Turku)

The black hole X-ray binary Swift J1753.5-0127 entered a new optical outburst on 2023 September 28 (ATel #16262). On October 1, the transient was detected in soft X-rays (ATel #16272, ATel #283), and subsequently in the radio (ATel #16281) and hard X-rays (ATel #16308). Here, we report our optical and infrared observations performed on October 24, 25, and 27 with the Nordic Optical Telescope (NOT).

On October 24 and 25, we observed the transient with ALFOSC (the Alhambra Faint Object Spectrograph and Camera). On October 24, we obtained 10 spectra with a total exposure time of 70 min with grism #7 and a slit width of 1 arcsecond which provide a spectral resolution of R~650 in the spectral range 3650-7110 Angstrom. On October 25, we obtained 3 spectra with a total exposure time of 15 min, using grism #4 which provides a lower resolution of ~360 but a broader wavelength coverage of 3200-9600 Angstrom.

The spectra show a blue continuum but no emission lines are seen even in the average spectrum (S/N~70 at Halpha and ~50 at Hbeta). However, in addition to telluric and interstellar absorption lines (e.g. the Na D doublet), the spectrum exhibits a weak sign of broad absorption features at the wavelengths of Hbeta, Hdelta, and possibly Hgamma lines, but not Halpha.

We note that during the previous outburst of SWIFT J1753.5-0127 which began in 2005, the emission lines Halpha and HeII 4686 were observed only at the very beginning of the outburst (ATel #551, #566). The lines disappeared a month later (Cadolle Bel et al. 2007, ApJ, 659, 549) and after that, the object showed a rather featureless spectrum (Durant et al. 2009, MNRAS, 392, 309) until 2013 when the broad emission lines re-appeared again (ATel #5307; Neustroev et al. 2014, MNRAS, 445, 2424).

To check the current photometric state of Swift J1753.5-0127 during our spectroscopic observations, we additionally obtained multicolour photometric data. These observations were performed on October 24 with ALFOSC through the SDSS g’, r’, i’, and z’ filters, and on October 27 with NOTCam (the Nordic Optical Telescope near-infrared Camera and spectrograph) through the J, H, and Ks filters. These observations gave the following magnitudes: g’=16.86+/-0.02, r’=16.73+/-0.01, i’=16.50+/-0.02, z’=16.51+/-0.02, J=15.61+/-0.02, H=15.31+/-0.05, Ks=15.01+/-0.07.

The average spectrum of Swift J1753.5-0127

The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT.

Bookmark and Share

Tags: ,

This entry was posted on Wednesday, November 1st, 2023 at 16:45 and is filed under Astronomy, Observations, Publications, Work. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

Comments are closed.