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IMSNG: Light curve analysis suggests SN 2017ein as a young SN at the time of the discovery

ATel #10481; Myungshin Im, Changsu Choi, Sang-Yun Lee, Gu Lim, Seongyong Hwang (Seoul Nat. Univ.), Davron Milzaqulov, Bahadir Khafizov, Otabek Burhonov, Shuhrat A. Ehgamberdiev (UBAI), Coyne A. Gibson (McDonald Obs.), Tae-Woo Kim, Wonseok Kang (DOAO), Hyung-Il Sung (KASI), on behalf of a larger collaboration
on 10 Jun 2017; 13:10 UT
Credential Certification: Myungshin Im (myungshin.im@gmail.com)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 10485

NGC 3938 has been monitored nearly every night during mid-May through early-June of 2017 as a part of the Intensive Monitoring Survey of Nearby Galaxies (IMSNG) program. The images (B, V, and R) taken at various locations in Korea, Uzbekistan, and USA show that SN 2017ein was visible on UT 2017-05-25, but not visible in the images on UT 2017-05-24 and before. Furthermore, it has brightened to R=14.7 mag at UT 2017-06-08 since our first detection at R=17.7 mag. This suggests that SN 2017ein was discovered shortly after the explosion rather than at near the peak as suggested earlier by Xiang et al. (ATel #10434). Furthermore, SN 2017ein is yet to approach its maximum brightness (images). Follow-up observations are encouraged. We thank the staffs of each observatory for their support of our program.

The preliminary magnitudes are reported below for a selected sample of our data. The magnitude error is about 0.2 mag, considering that the results are based on quick-look analysis.

UT Date        R mag    Observatory
2017-05-23.77    >19.9    Maidanak
2017-05-24.63    >18.4    DOAO
2017-05-25.77    17.7    Maidanak
2017-05-29.30    15.9    LOAO
2017-06-04.53    15.1    DOAO
2017-06-08.58    14.7    SOAO

Madanak: Maidanak observatory 1.5m telescope (Uzbekistan)
DOAO: Deok-Heong Optical Astronomy Observatory 1m telescope (Korea)
LOAO: Mt. Lemmon Optical Astronomy Observatory 1m telescope (USA)
SOAO: Sobaeksan Optical Astronomy Observatory 0.6m telescope (Korea)