Central Bureau for Astronomical Telegrams
CBAT "Transient Object Followup Reports"
TCP J18033733-2935266
TCP J18033733-2935266 2025 04 11.7783* 18 03 37.33 -29 35 26.6 12.7 U Sgr 9 5
2024 04 11.965
Position end figures 37s.29, 26.6" measured with Skygems Observatory 0.10m f/5 refractor + CCD, Namibia. J2000, Gaia DR3 positions. Transient position is within 0.17" of Gaia 4050265008973474816 (magnitude 16.35 G). Unfiltered magnitude 12.7. Andrew Pearce, Nedlands, Western Australia
2025 04 11.006
The report prompted visual inspection of the NMW survey's wide-field camera (135mm f/2.0 telephoto lens + unfiltered ST-8300M CCD) images obtained on 2025-04-11.006 UTC, 18.5 h prior to discovery. The images show a faint new source having unfiltered magnitude CV=13.5 +/-0.3 that was not visible in images obtained with the same camera on 2025-04-05.024 (limiting magnitude CV~14). The plate-solved FITS images are available at http://scan.sai.msu.ru/~kirx/img/TCPJ18033733-2935266/ The NMW survey is operating at the Astroverty astrofarm in Nizhnii Arkhyz, Karachay-Cherkessia, Russia http://scan.sai.msu.ru/nmw/ https://astrovert.ru/astrofarm/ ---- Stanislav Korotkiy (Astroverty, Ka-Dar), Kirill Sokolovsky, Vladimir Belousov for the NMW team
2025 04 11.778
Discovered by Tadashi Kojima, Tsumagoi,Gunma-ken, Japan, on three frames(6_s exp) under limiting mag.= 13.5 taken by Canon EOS 6D digital camera + 300mm f/2.8 lens. Nothing is visible at this location taken on 2025 Apr 06.777UT under limiting mag.=14.3 with same instrument.
2025 04 11.7453
I proceeded with the reporting process carefully. Tomoo Kato Shimizu Shizuoka Japan. 2025 Apr 11.7453 UT Mag=12.0 U on three frames (8-s exp. limiting mag 13.2) taken by Canon EOS 6D digital camera + 200-mm lens. https://tomo-kato.jp/large_image.php?file=250412-01.jpg at this location on the frames taken on 2025 Apr. 08.7617 UT Mag<12.8 U by same instrument. https://tomo-kato.jp/large_image.php?file=250412-03.jpg 2025 Apr 11.7679 UT Mag=12.4 U Canon Eos 6D digital camera + 400-mm lens. (10s x 3 exp. limiting mag 14.2) https://tomo-kato.jp/large_image.php?file=250412-04.jpg
2025 04 11.778
This object is the same as AT 2025hfm by Transient Name Server (TNS).T Kojima
2025 04 13.3924
Follow-up photometry results were B =14.24, V =12.72, I =10.31. position end figures 37s.28, 26".4 using 0.51-m f/6.8 Corrected Dall-Kirkham + CCD (T72); remotely Deep Sky Chile. position is almost the same as Gaia EDR3 4050265008973474816. observed by K. Yoshimoto, Yamaguchi, Japan.
2025 05 28.4295
We obtained a spectrum of TCP J18033733-2935266 on 2025-05-28 UT using the Goodman spectrograph on the 4.1m SOAR telescope. The observation was conducted with a 300-second exposure using the 400 l/mm VPH grating and 1.2" slit, covering approximately 3800-7600 A at ~2 A dispersion per pixel. The spectrum shows the characteristic absorption features of a K-type giant with no detectable emission lines. While there is some contamination from a nearby star in the spectrum, it should not affect the spectral classification. The spectrum plot is available at http://scan.sai.msu.ru/~kirx/img/TCPJ18033733-2935266/TCPJ18033733-2935266.png The normal appearance of the stellar spectrum suggests that TCP J18033733-2935266 is likely a gravitational microlensing event. We note that the event was in the TESS field of view (Sector 91). ---- Kirill Sokolovsky (UIUC), Rebecca Kyer, Ryan Urquhart, Jay Strader (MSU)
