Supernova 1999cl in M88

Supernova 1999cl occurred in Virgo Cluster spiral galaxy M88 on May 28, 1999 and was discovered one day later at magnitude 16.4. It reached magnitude 13.4..13.5 on June 12, 1999.

As this is a type Ia supernova, and situated in the Virgo Cluster of Galaxies, it may be of great interest in gauging this galaxy cluster's distance, and thus also the scale of our intergalactic neighborhood, and the whole observable universe.

If our assumed relative distance scale should be correct, one can make a preliminary estimate: Both supernova 1999cl and 1998bu in M96 are of same type (Ia), and thus should be of same absolute luminosity. Therefore, as M96 is a factor of about 1.6 closer to us than the Virgo Cluster and presumably M88, SN 1999cl should stay a factor of about 2.5 times, or one magnitude, fainter than SN 1998bu. As 1998bu became magnitude 11.8..11.9, the new supernova should be expected not to exceed a magnitude of 12.8..12.9. Otherwise, either M88 would be closer to us than the 60 million light years assumed here, or 1999cl was brighter than 1998bu - and thus probably not of the same type.

This supernova was discovered by the Lick Observatory Supernova Search team on May 29, 1999. Later Jeff MacQuarrie found that he had obtained a pre-discovery image of SN 1999cl one day earlier.

The image in this page has been obtained by Martin Germano with a 14.5" f/5 Newtonian, exposed 80 minutes on hypered Tech Pan 2415 (find more of Martin's images here).

.. more to come soon ..

Hartmut Frommert
Christine Kronberg
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Last Modification: August 11, 2005