From Pedro Sada Tue May 27 10:12 MDT 1997
We observed the Great Red Spot (GRS) on Jupiter again on May 26th as it was crossing the CM with the 1.5m McMath-Pierce Solar Telescope (NSO/NOAO). Around 12:30 UT seeing was moderate (2"-3") with cirrus clouds present. Video through an OG-570 nm filter was obtained for later digitizing and analysis.
The GRS exhibited little change from our observations two days ago. The bright area to the northeast of the GRS is still present, though it appeared to have grown in size and faded. The north half of the GRS appeared as bright as the South Tropical Zone and the south-west end of the Spot was now clearly distinguished from the STrZ.
Not much more detail could be observed due to the weather. This was our last scheduled night at the telescope.
The weather down here remains erratic, although Don Parker has been able to image the planet during intermittent clear episodes. I have once again taken the liberty to process images of Jupiter obtained by IJW member Isao Miyazaki between May 12 to 24, 1997 using a 40 cm f/6 Newtonian reflector coupled to a Lynxx PC CCD camera. Dr. John Rogers (BAA Jupiter Section Director) in an earlier message stated that the White Tropical Oval (WTO), followed since 1987, was approximately 8 degrees (preceding) from the Great Red Spot (GRS) on a CCD image obtained on April 11, 1997. The WTO was then noted to lie at the preceding edge of the GRS on May 12, 1997 (20h15m36s-16m36s UT), 267.2-267.8(I) 36.3-36.9(II) 21.6-22.2(III), Exp:R60+NR400(0.90s),PO1+NR400(1.40s), B390+NR400(4.00s), refer to Miyazaki image on the left). By May 20, 1997 an image (17h26m43s-28m23s (UT), 347.5-348.5(I) 56.4-57.4(II) 43.8-44.8(III), Exp:R60+NR400(2.10s),PO1+NR400(2.80s), B390+NR400(10.00s), refer to center image) by Miyazaki indicated that the WTO had begun to merge with (or circulate anticyclonically around) the GRS. Miyazaki's latest image obtained on May 24, 1997 (20h25m10s-26m03s (UT), 7.9-8.5(I) 45.4-45.9(II) 33.9-34.4(III), Exp:R60+NR400(1.10s),PO1+NR400(1.50s), B390+NR400(4.00s)) indicates that the WTO material now lies north of the center of the GRS within White Spot Hollow (WSH). It will be interesting to see if the WTO material will remain intact upon arriving at the following end of the GRS whereupon it encounters it's wake. I hope to provide my own observations soon but until then I hope we continue to receive quality observations from IJW members abroad.
Carlos E. Hernandez (A.L.P.O. Assistant Jupiter Coordinator)