H-alpha emission from extragalactic nova candidate M81N 2019-10a
ATel #13243; A. Kurtenkov (Institute of Astronomy and NAO, BAS, Bulgaria), A. Valcheva (Department of Astronomy, Sofia University, Bulgaria)
on 30 Oct 2019; 13:43 UT
Credential Certification: Kiril Stoyanov (kstoyanov@astro.bas.bg)
Subjects: Optical, Nova, Transient
We report photometric detection of H-alpha emission from the recent nova candidate M81N 2019-10a discovered by Hornoch et al. (ATel #13237).
We imaged M81 in Cousins R and narrowband H-alpha filters with the FoReRo2 focal reducer at the Rozhen 2-meter RCC telescope in Bulgaria. Photometric calibrations were obtained using field stars included in the SDSS DR12 catalog. Their Sloan r and i magnitudes were converted to Cousins R by applying the transformations from Jordi et al. (2006) available on the SDSS webpage. The R magnitudes were then used as references for both the R and H-alpha bands with a precision of 0.01 and 0.03 mag respectively. Aperture photometry after subtraction of the M81 galactic background yielded the following results:
# Date,UT Filter Exposures Magnitude Error
2019-10-29.123 R 7x120s 21.0 0.1
2019-10-29.139 Hα 5x300s 18.48 0.03
The utilized H-alpha filter has a FWHM of 3 nm. The result is consistent with a M81 nova.
The magnitude estimate of 20.0 on Oct 27 reported in ATel #13237 could have been influenced by the brighter source located 4" north of the nova or by the non-uniform background as it seems unlikely that it faded that rapidly since. Our images were obtained at a 1.5" seeing and sampled at 0.5"/pix. We used both 1.3" and 1.8" radius apertures.
This work was supported by the Bulgarian Ministry of Education and Science under the National Research Programme "Young scientists and postdoctoral students" approved by DCM #577/17.08.2018.
Processed R and H-alpha images of the M81 nova
