Discovery certificate for object 1999gz
TNS Astronomical Transient Report No. 33378 [ 2019TNSTR.611....1N ]

Date Received (UTC): 2019-04-22 08:49:55
Sender: Mr. Richard Nowell
Reporting Group: None     Discovery Data Source: None

R. Nowell, A. Drummond report/s the discovery of a new astronomical transient.

IAU Designation: AT 1999gz
Coordinates (J2000): RA = 11:57:31.944 (179.383098308) DEC = +00:48:59.85 (0.81662625)
Discovery date: 1999-03-20 07:09:39.000 (JD=2451257.7983681)

Potential host galaxy: SDSS J115731.45+004901.6
Host redshift: 0.06227

Remarks: This transient was first discovered on the Galaxy Zoo website in a discussion started by Averil Drummond here: Christine Macmillan, Sam Deen and Ine Theunissen also took part in the discussion.


Discovery (first detection):
Discovery date: 1999-03-20 07:09:39.000
Flux: 20.35 ABMag
Filter: r-Sloan
Instrument: SDSS-Spec
Telescope: Sloan Digital Sky Survey

Remarks: The r-band Apparent magnitude was calculated by Richard Nowell using APT. The star used as a reference is: SDSS J115737.32+004925.7

Last non-detection:
Archival info: SDSS
Remarks: In SDSS, this transient is called J115731.94+004859.8 (J115731) and is listed as TYPE=GALAXY with a photometric redshift of z=0.933 ± 0.1103. Having calculated the Apparent and Absolute magnitudes using SDSS redshift values, it became clear that an Absolute magnitude value of near -22.91 for J115731 must be wrong. After some debate on the Galaxy Zoo website, it was concluded that J115731 is a likely Supernova with an Absolute magnitude of -16.91 within the host galaxy SDSS J115731.45+004901.6. Also, J115731 is not visible in later surveys by DECaLS and Pan-STARRS.

Details of the new object can be viewed here: