Central Bureau for Astronomical Telegrams

CBAT "Transient Object Followup Reports"

TCP J17374270+4915116

TCP J17374270+4915116   2024 12 21.1440*  17 37 42.70 +49 15 11.6  12.4 U             Her       9 0

2024 12 21.1440

The 12.4 mag. transient is visible in three 20 sec. images captured around 2024-12-21.1440 UT using the NMW survey's ( http://scan.sai.msu.ru/nmw/ ) second wide-field camera (135mm f/2.0 telephoto lens + unfiltered SBIG STL-11000 CCD) operating at the Astroverty astrofarm in Nizhnii Arkhyz, Karachay-Cherkessia, Russia ( https://astrovert.ru/astrofarm/ ). The unfiltered magnitude zero-point was set using V magnitudes of Tycho-2 stars in the field. The transient position uncertainty is ~10" due to the camera's 13.8"/pix scale. A blue (g= 21.02 +/-0.06, r= 21.07 +/-0.03) Pan-STARRS1 object 167102644265414180 is located at 17:37:42.37 +49:15:10.5 J2000, which is 3.4" from the transient. The discovery images, finder charts and animations may be found at http://scan.sai.msu.ru/~kirx/img/TCPJ17374270+4915116/ ---- Kirill Sokolovsky, Ekaterina Saveleva, Stanislav Korotkiy (Astroverty, Ka-Dar)

2024 12 23.72

Trabacchin.N, Andreoli.V and Ochner.P report the classification of TCP J17374270+4915116. Low resolution spectrum was obtained with 1.22-m telescope + B&C spectrograph (with dispersion 2.25 Ang/pix) located in Asiago (Italy) on 2024-12-23.722. Spectrum shows a blue continuum consistent with the photometry obtained (see below) and broad absorption of Balmer lines (mean FWHM 3300 km/s) except for Hα (6562.8 Ang) probably filled up by the disk, He I 4471; 4026 Ang is also weakly present. We also obtained BV photometry with 0.4m DK telescope + Moravian G4 CCD full frame located in Novezzina (Italy) on 2024-12-23.77 with results: B:13.3 ± 0.1 V:13.5 ± 0.1. These characteristics are typical of dwarf novae. We propose to classify this object as a CV. (you can find the spectrum at the link: https://photos.app.goo.gl/HWaQoUebQUo3NfLB6)

2024 12 21.627

Astrometry and photometry with the 50-cm robotic telescope (Astrosib RC500 with ZWO ASI6200MM Pro CMOS camera) at the Kislovodsk Observatory of the Institute of Astronomy of the Russian Academy of Sciences: 17:37:42.37 +49:15:10.4 +/-0.1 J2000 relative to Gaia DR3, 2024-12-21.627 UT B=13.14, V=12.94, R=13.02, I=13.51, 2024-12-22.097 UT B=13.31, V=13.11, R=13.17, I=13.64. The photometric uncertainty is 0.01 mag for BVR and 0.02 mag for I band. The magnitude zero-point was calibrated using APASS stars in the field. ---- Alexander Tarasenkov (Institute of Astronomy RAS), Kirill Sokolovsky (UIUC, SAI MSU), Stanislav Korotkiy (Astroverty, Ka-Dar)

2024 12 19.1165

The transient is visible at an individual frame obtained with the NMW Camera-1 (135mm f/2.0 telephoto lens + ST-8300M CCD) on 2024-12-21.0650 UT, about two hours before the discovery observation, having CV= 12.7. Our latest pre-outburst image of the field was obtained with the NMW Camera-2 (135mm f/2.0 lens + STL-11000M CCD) on 2024-12-19.1165, two days before the discovery, with no object brighter than 13.5 CV visible at the location of the transient. ---- Kirill Sokolovsky, Ekaterina Saveleva, Stanislav Korotkiy (Astroverty, Ka-Dar) for the NMW survey team