M88 is an Sc-type, spiral galaxy in the constellation Coma Berenices and is a bright member of the Virgo Cluster in which a supernova was discovered on 29 May 1999.  This galaxy is oriented at approximately 30-degrees from the edge-on position.  It was estimated to reside at a distance of approximately 60 million light years, although recent data indicates the galaxy may be on the order of 40 million light years distant.   More information and additional images of this galaxy can be found at the Messier Index - M88.  


M88 (NGC 4501) with Supernova 1999cl clearly visible to the left of the galaxy's center on 4 June 1999.  This image appeared in the October 1999 issue of Astronomy Magazine.

(15.75 minute composite of 63, 15-second exposures)

The Supernova and a small, faint (magnitude 18.7) galaxy (PGC 169501) which can be seen in the 4 June image are identified below.


4 June 1999 image with Supernova 1999cl

(Negative version with SN1999cl and PGC169501 identified)

M88 9Jun99 SN1999cl

9 June 1999 image

(13.25-minute composite from 53, 15-second exposures, stacked using a percentile linear stretch)

 M88 28 May Prediscovery

28 May pre-discovery image

(13.5-minute composite from 54, 15-second exposures)

Shortly after taking the above image early on 28 May 1999, I was notified that a Supernova had been discovered in this galaxy on 29 May 1999.  The announcement from UC Berkeley reads:

"M. Papenkova, A. V. Filippenko, and R. R. Treffers, University of California at Berkeley, on behalf of the Lick Observatory Supernova Search (cf. IAUC 6627, 7126), report their discovery of an apparent supernova in an unfiltered image taken on May 29 UT (mag 16.4) with the 0.8-m Katzman Automatic Imaging Telescope (KAIT). The object was confirmed in images taken on May 30 and 31 (mag 16.2 and 15.3, respectively). Images from May 21 and 22 do not show the object, to a limiting magnitude of 18.6."

KAIT Discovery Image of SN199cl in NGC4501 (M88)

29 May KAIT discovery image of Supernova

Weidong Li from the UC Berkeley Supernova search indicated in an e-mail to me on 3 June, that my image below (negative version)  possibly contained an early pre-discovery view of the Supernova.

M88 SN1999cl 28 May Negative

Negative version of  28 May pre-discovery image

For more images of this and other Supernovae along with a wealth of information, visit David Bishop's Bright Supernova Page.  For information on the physics of supernovae, visit the following sites:

High Energy Astrophysics Science Archive Research Center (HEASARC) Supernova Page

Royal Observatory Greenwich, "What is a Supernova?"

Imagine the Universe - Supernovae

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