ULTRAVIOLET EXPLOSION!!

The title does not refer to the actual explosion of a star or the ultraviolet emission that results, but the recent, dramatic increase in ultraviolet (UV) observations of supernovae (SNe) over the past several years.

The launch of the Swift spacecraft in late 2004 enabled a ten-fold increase in the number of SNe observed each year in the UV utilizing the UltraViolet/Optical Telescope (UVOT).  Interestingly, the Hubble Space Telescope (HST) has observed more SNe in the UV during the Swift era than it did previously.  These high quality spectroscopic observations complement nicely the well sampled photometric UV light curves and low resolution UV spectra from Swift.  There are likely many SNe missing from this plot, in particular from XMM which likely observed in the UV simultaneous to the primary X-ray observations.  The list is posted here, and you can alert me to any missing SNe by e-mailing me at uv dot supernova at g mail dot com.  Likewise for the Swift SNe, I used the same list as for this website, so please let me know if I am missing any (in particular, PTF and other project designated transient objects may not be listed unless I have found out it was a SN). 

Strictly speaking, the plot shows the number of observations of a SN from a given year as opposed to the number of observations that year.  The spike from SN1987A results from the hundreds of UV observations made by IUE and HST over the subsequent years.  I first envisioned a plot like this years ago but dropped the idea when I saw exactly how many UV observations of 87A and how it dwarfed the number of Swift observations.  We have now passed that amount both cumulative and for a single year (thanks to SN2011fe and 2011dh and other notables of that year).  Of course, not all observations have the same scientific weight, but judging importance is hard to put in an automated script.