LASCO participated in the coronal holes/streamer boundary study of UVCS/SUMER/CDS during May 17th through 23rd. It introduced only slight modifications to the LASCO synoptic observation plan: For C2: 6 hr cadence in orange filter pB (02:54 - 08:54 - 14:45 - 20:54 UT) For C3: 12 hr cadence in orange filter pB (10:42 - 22:42 UT) Now, again Nominal. SOHO Telemetry Submode changed to Submode 5 on 2004/04/13 at 16:00 UT (SUMER began observing on 2004/04/14). SUMER campaign runs until 2004/06/17. In other words, LASCO synoptic observation plan cadence remains the same but the EIT CME watch images will be reduced to half-resolution (512x512) during that period.
05:50 UT WN West Asymmetric loop front in the trailing material (southern leg) of event reported to start at 23:26 UT on previous day. It fades close to the inner edge of C3. 12:26 UT N East Narrow and faint ragged front. It fades throughout C2. 18:50 UT N Pole Extemely faint loop front, developing slightly toward NNE. It fades throughout C3. 19:27 UT ES East Faint ragged front. It fades throughout C3.
00:26 UT ES East Ragged spray-like front that fades throughout C2. 01:27 UT N East Another narrow and faint ragged front that fades throughout C3. 04:26 UT N West Ragged and diffuse loop front. It fades close to the inner edge of C3. 06:50 UT S West Very faint (though wide) loop front, barely visible in C3. At 07:27 UT a bright and narrow fan-like front develops. It fades close to the inner edge of C3.
11:06 UT W Limb Bright and wide ragged loop front. By 12:50 UT faint extensions surround completely the C2 occultor. The event is first seen in C3 at 11:42 UT, the C3 occultor being completely covered by 15:18 UT. EIT Fe XII running difference images show a huge signature of a backsided CME above the W Limb starting at 11:00 UT. Material is swept away toward N and S as the event develops. The event has therefore been determined as a 'full' (asymmetric) halo CME, backsided. 15:26 UT ES East Very faint asymmetric loop front. 15:50 UT W Limb Diffuse and ragged loop front with apparently twisted trailing material. By 16:26 UT a diffuse loop front starts developing to S. They both fade throughout C3.
05:06 UT W Limb Very narrow ragged front. 07:27 UT S East Ragged loop front. 12:10 - 20:15 UT Temporary DSN Data Gap.