supernova

July 2, 2020

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Time Sensitive Alerts: https://www.aavso.org/2020nvb-possible-supernova-131-mag-ngc-4457
- Cataclysmic Variables: https://www.aavso.org/sn-2020nvb-ngc-4457

Observers are encouraged to participate in the AAVSO forums listed above for this event, and to visit the AAVSO CV Section webpage.

November 3, 2007: The Central Bureau for Astronomical Telegrams (see CBET 1114) has announced the discovery of supernova SN 2007oc in the southern galaxy NGC 7418A. The galaxy was discovered at magnitude 13.6 on November 3.06 UT (approx JD 2454407.5). The supernova has since been detected on an image taken October 23.09 (approx JD 2454396.6) at magnitude 13.3, and is therefore in its declining phase.

The J2000 coordinates of the supernova are given as

RA: 22 56 41.77    Dec: -36 46 22.3

October 17, 2007: Further to AAVSO Special Notice #73, "SN 2007le in NGC 7721", a comparison star sequence has now been added to the AAVSO Variable Star Plotter (VSP). The sequence by A. Henden was obtained at SRO based upon a single night of data; the calibration is estimated to have a zero-point accuracy of approximately 0.03 magnitudes.

October 15, 2007: SN 2007le was discovered in the galaxy NGC 7721 on October 13, 2007 by L.A.G. (Berto) Monard of Pretoria, South Africa (CBET 1100, Monard). The supernova has since been classified as a type-Ia, approximately 7-10 days prior to maximum (CBET 1101, Silverman et al.).

The coordinates of the supernova are:

RA: 23:38:48.41 , Dec -6:31:21.3 (J2000)

September 13, 2007

August 16, 2007: As published in CBET 1034 by D. Madison and W. Li, Supernova 2007gr was discovered at magnitude 13.8 by KAIT on August 15.53 UT, and is currently at magnitude 13.5 on August 16.47. It is located in the bright spiral galaxy NGC 1058, approximately 30 arcseconds northwest of the nucleus.

The coordinates of the supernova are (J2000):

RA: 02:43:27.98     Dec: +37:20:44.7

August 19, 2007: Data for SN 2007gr can now be submitted to the AAVSO using the following Harvard Designation and/or name: 0237+36B SN 2007GR

Latest report from Martin Nicholson is that the SN is at V=12.83 and continuing to rise. The two prior SNe in NGC 1058 both reached a peak brightness about this level, so SN 2007gr may not get much brighter.

December 19, 2007: A.J. Drake et al have reported in A.Tel #1337 on the detection of a bright optical transient in one of the spiral arms of the Antennae Galaxies (NGC 4038/VV 245). The object [SN 2007sr] was at magnitude 12.9 on 2007 December 18. The transient is located at the following coordinates (J2000):

RA: 12:01:52.80 , Dec: -18:58:21.72

They note the object is on the edge of one of the spiral arms, and the brightness is consistent with a supernova at the known distance of the Antennae.

March 28, 2008