NOT/ALFOSC classification of microlensing BH candidates
ATel #15689; E. Paraskeva (University of California, Davis), M. Gromadzki, L. Wyrzykowski (Astronomical Observatory, University of Warsaw), P. Zielinski (Nicolaus Copernicus University in Torun), Z. Nagy (Konkoly Observatory, Budapest)
on 17 Oct 2022; 20:08 UT
Credential Certification: Mariusz Gromadzki (marg@astrouw.edu.pl)
Subjects: Optical, Microlensing Event, Transient, Variables
We report on recent spectroscopic observations of 9 candidates for microlensing events detected by the Gaia Science Alerts program (http://gsaweb.ast.cam.ac.uk/alerts). The observations were performed with the 2.56 m Nordic Optical Telescope equipped with ALFOSC instrument and grating no. 4 (range 350-950 nm; resolution 1.6 nm FWHM) within observing program P65-034 (PI: E. Paraskeva). Spectra were reduced using ALFOSC pipeline v3 (http://github.com/crangus/ALFOSC_Pipeline_v3). The results of classification are summarized in the table below. The spectra are available on IAU's Transient Name Server.
Gaia Name | IAU Name | RA (J2000) | Dec (J2000) | Discovery date | Discovery G mag | Spectrum date | Class
----------|-----------|-------------|---------------|----------------|-----------------|---------------|---------------
Gaia22ang | AT2022bvc | 20:49:10.29 | +44:32:46.72 | 2022-02-08 | 15.00 | 2022-08-22 | Be star(1)
Gaia22atd | AT2020dcn | 19:11:04.50 | +10:36:32.47 | 2022-02-22 | 14.82 | 2022-04-09 | Be star(1)
Gaia22atp | AT2022ddy | 18:42:20.19 | +02:45:26.96 | 2022-02-23 | 17.71 | 2022-04-09 | Be star(1)
Gaia22awp | AT2022eot | 01:56:41.86 | +62:28:06.85 | 2022-02-28 | 14.33 | 2022-08-22 | Be star(1)
Gaia22ayk | AT2022ewn | 20:43:59.62 | +38:03:15.55 | 2022-03-04 | 13.39 | 2022-08-22 | B star(2)
Gaia22daf | AT2022pny | 23:00:05.39 | +63:48:02.30 | 2022-07-21 | 17.51 | 2022-08-23 | Be star(1)
Gaia22dti | AT2022trk | 06:01:49.99 | +22:22:12.86 | 2022-09-05 | 14.53 | 2022-09-22 | Be star(1)
Gaia22dve | AT2022uag | 06:30:45.39 | +09:01:09.41 | 2022-09-09 | 17.86 | 2022-09-22 | M-type star(3)
Gaia22dym | AT2022vhf | 19:44:54.39 | +35:14:40.31 | 2022-09-19 | 16.57 | 2022-09-22 | K-type star(4)
Notes:
(1) spectrum shows significant reddening caused by extinction and Halpha in emission.
(2) spectrum shows blue continuum and Balmer , He I and DIBs lines in absorption..
(3) spectrum shows strong TiO absorption bands and faint Halpha in emission.
(4) absorption lines visible only, late-type spectral class. It is a microlensing event.
Acknowledgements. We thank Nordic Optical Telescope staff for help with observations. Observations were carried out under the P65-034 program (PI: E. Paraskeva). This project has received funding from the EU Horizon 2020 research and innovation programme under grant agreement No. No 101004719, as well as Polish NCN DAINA grant 2017/27/L/ST9/03221. We acknowledge ESA Gaia, DPAC, and the Photometric Science Alerts Team (http://gsaweb.ast.cam.ac.uk/alerts).
