Dear friends,

Using my private system scraping MARS ( https://mars.lco.global ), I've just found ZTF21achzkjo out as a CV candidate from the public ZTF data. Its amplitude is > ~ 6.0 mag (assuming the limiting mag of PS1-g is 21.6). (I'm sorry if someone has already discovered and reported it elsewhere.)

Lasair: https://lasair.roe.ac.uk/object/ZTF21achzkjo ALeRCE: https://lasair.roe.ac.uk/object/ZTF21achzkjo MARS: https://mars.lco.global/?objectId=ZTF21achzkjo

According to ALeRCE, the position is (RA, Dec) = (20:51:40.411, +32:02:24.42)

Last non-detections by ZTF: r > 19.9806 on 2021-10-15.20 (ZTF, 'difference mag' via ALeRCE) g > 19.8502 on 2021-10-15.22 (ZTF, 'difference mag' via ALeRCE)

First detections by ZTF: r = 15.862 +/- 0.030 on 2021-10-17.16 (ZTF, 'difference mag' via ALeRCE) g = 15.531 +/- 0.027 on 2021-10-17.20 (ZTF, 'difference mag' via ALeRCE)

The result of ASAS-SN Sky Patrol: https://asas-sn.osu.edu/sky-patrol/coordinate/23aa601d-22a4-42f6-b93d-24c201... It looks a nearby star is contaminating, so it cannot confirm the current outburst.

No known minor planets are found by the Minor Planet Checker ( https://www.minorplanetcenter.net/cgi-bin/checkmp.cgi ).

Best Regards and Clear Skies, Kenta