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The Restoration of HST Images and Spectra II
Space Telescope Science Institute, 1994
R. J. Hanisch and R. L. White, eds.
FOC Observations of SN 1987A: The Movie
Peter Challis
Harvard­Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138
Abstract. HST has now observed SN 1987A six times over the past 3 years with the FOC
as part of the Supernova Intensive Study program. To help visualize the evolution of the
debris and circumstellar matter, a movie was created from these observations. The movie
provides a unique perspective on the history of SN 1987A covering the epoch 1278 ± 2424
days since explosion.
The movie consists of 5 sequences each showing a particular aspect of SN 1987A. For each
sequence, 100 images (or one every 11 days) were created by interpolating between the observations,
using a cubic spline. The images were then shown in succession at a rate of 66 days/second using
the animation software in IDL.
The ®rst sequence shows the raw FOC F/96 F501N [OIII] observations centered on the debris
and with a ®eld of view of 2: 00 2. The fading of the circumstellar ring and debris is quite dramatic. The
entire ring fades surprisingly uniformly. The Richardson­Lucy algorithm was used to deconvolve
the F501N images to create the next sequence. A nearby bright star in each image was used as the
PSF. Since we have low S/N nebular data we stopped the iterations at a relatively low number of 30.
The deconvolved images show convincingly that the structure of the ring is clumpy, that the clumps
are all about the same size, and that the debris is extended. The third sequence shows the step
by step iteration of the deconvolution. This is followed by a comparision between a raw and ®nal
deconvolved image. This comparision provides con®dence that the deconvolved images restore the
raw images without creating false structure.
The fourth and ®fth sequences show the raw and deconvolved images of only the central debris
from the FOC F/96 F275W observations with a ®eld of view of 0: 00 56. The expansion of the debris
is striking. Both sequences show some asymmetry and possible extension in the N­S direction.
It will be interesting to compare the recent deconvolved images of SN 1987A with the COSTAR
improved images. This method of interpolating and animating provides a visual tool to aid in the
understanding of time sequenced data.
References
Panagia, N., Baxter, D., Gilmozzi, R., Macchetto, F., Adorf, H.­M., Jakobsen, P., & Kirshner, R. P.
1993, in Science with the Hubble Space Telescope, P. Benvenuti & E. Schreier, eds., 175
White, R. L 1993, in Restoration Newsletter, R. J. Hanisch, ed., Space Telescope Science Institute,
1, 12
249