THE ASTRONOMER Electronic Circular No 730 1993 Apr 13 19.50UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074 TELEX: 9312111261 Answerback: TA G TELECOM GOLD: 10074:MIK2885 GMH at UK.AC.RUTHERFORD.STARLINK.ASTROPHYSICS STARLINK: RLSAC::GMH GMH at UK.AC.CAM.ASTRONOMY.STARLINK STARLINK: CAVAD::GMH ------------------------------------------------------------------- JUPITER John Rodgers, Director of the BAA Jupiter Section, recently advised us that Terry Platt and Terry Broadbank had independently reported sighting a dark feature in the SEB preceding the GRS. Terry Platt also reported direct to us that his CCD image was recorded on 1993 Apr 9 at 22h55mUT. The dark feature was about half the size of the Great Red Spot, north of its centre and possibly connected to it by a dark streak. As this might represent the re-emergence of the SEB, an e-mail alert was issued appealing for more observations. In response to this appeal, Peter Nelson and Jim Park confirm they also saw the feature on Apr 9 from Ellinbank, Victoria, Australia coordinates: 38d 14m 47.4s S 145d 57' 30.5" E 138m elevation. Peter provides the following comments: "It preceded the GRS (which was very red and prominent) by about 0.5 the width of the spot. The feature was split longitudinally and the SEB preceding the feature had no detail. The feature was fairly prominent. Seeing was excellent at 9. A 0.32-m f/5 Newtonian x 240 was used". SUPERNOVA 1993J IN NGC 3031 J. Blakeslee and J. Tonry, Massachusetts Institute of Technology, communicate: "We have measured the magnitudes of the progenitor of SN 1993J in the V and Kron-Cousins I bands. The images were taken on the night of 1992 May 1 with the 2.4-m telescope (+2048x2048 Loral CCD; scale 0".343/pixel) at MDM Observatory on Kitt Peak. The exposure times were 700 s in I and 300 s in V; the seeing was 1".05 in the I image and 1".14 in the V image. The night was not photometric, but we were able to calibrate the photometry to better than 3 percent by comparing the images to earlier ones, which did not encompass the supernova progenitor, taken under photometric conditions on the Kitt Peak 4-m telescope. Using an aperture of diameter 3".4 to minimize background contamination, we find: V = 20.88 +/- 0.13, I = 19.51 +/- 0.04. Correcting by the psf to an aperture of diameter 10", we find V = 20.79 +/- 0.13, I =19.44 +/- 0.04; these are uncorrected for galactic extinction. The progenitor appears extended north-south as compared to nearby point sources. At least ten stars are visible within 10", with I-band magnitudes ranging from 1 to 3 mag fainter than the progenitor. Most of these are quite red. The nearest is an object with I = 20.4 situated 3".8 to the northwest." IAUC 5758