SXT support of SOHO JOP 059

(This is only a rudimentary page to show target locations and representative images. Don't expect much in the way of analysis.)

18-May-98 update

This is a summary of SXT coverage during the JOP:

UT Dates, Times	Target	SXT resolution	SXT cadence	Notes
6-may, 22:00 to 7-may, 15:20	AR 8216	Full	2.5 min
7-may, 15:41-16:09	AR 8216	Full	32 sec
7-may, 16:11-16:37	AR 8216	Half	64 sec
7-may, 17:00 to 9-may, 15:56	AR 8216	Full	5 min	Poor tracking?
9-may, 16:16-16:44	AR 8217	Full	32 sec	Also some dark frames
9-may, 16:45-17:09	AR 8217	Half	64 sec	Also some dark frames
9-may, 17:50-18:27	AR 8217	Full	32 sec	Also some dark frames
9-may, 18:29-18:48	AR 8217	Half	64 sec	Also some dark frames
9-may, 19:33-21:49	AR 8217	Full	128 sec
9-may, 22:45 to 11-may, 15:00	AR 8217	Full	128 sec	Poor tracking?
11-may, 15:00 to 12-may, 17:00	AR 8217	Full	128 sec
12-may, 17:07 to 13-may, 17:20	AR 8219	Full	128 sec
13-may, 18:50 to 14-may, 15:42	AR 8218	Full	128 sec	After JOP 080
after 14-may, 15:45	full Sun	Half

13-May-98 entry

Beginning at 17:07:00 on 12-MAY-98, SXT has been observing the active region NOAA 8219. The cadence is 128 seconds, and the exposure is 5.34 seconds for each image. An example from this morning's run is shown below (click for a larger image).

We will continue these observations until approximately 17:20 on 13-May, when we begin making observations for JOP 080. The southern active region NOAA 8218 has been chosen as the target for that JOP; at the completion of JOP 080, JOP 059 will continue with NOAA 8218 as its new target. SXT's support of JOP 059 on 8218 will probably be in the form of 2-minute cadence observations, as no uplinks will be possible between the end of JOP 080 and the end of JOP 059.

10-May-98 entry

Beginning at 16:16 UT on 9-may-98, SXT is making observations of active region NOAA 8217. The image shown in yesterday's entry on this webpage (below) displays the location and field of view of the SXT images. This table summarizes the observations made on 9-may:

UT Times	SXT resolution	SXT cadence
16:16:29-16:44:35	Full-res	32 sec
16:45:43-17:09:11	Half-res	64 sec
17:50:19-18:27:41	Full-res	32 sec
18:29:11-18:48:23	Half-res	64 sec
19:33:55-21:49:55	Full-res	128 sec
After 22:45:47	Full-res	128 sec

Between 17:57:23 and 17:59:01 SXT observed a localized transient brightening. The images below show the location of this brightening and its light curve (click to see a larger image).

9-May-98 entry

Due to a network problem (the source of which is still uncertain), the SXT uploads scheduled for UT date 8-may 15:39 and 8-may 17:21 were not performed. As a result, the fast-cadence run was not carried out. Furthermore, the pointing was not updated and the target region AR 8216 has begun to drift out of the field of view. (Click here for an image.) This situation will be remedied at our next upload opportunity, 9-may 15:56 UT. At that time, assuming the network is back up, we will point the SXT partial-frame images towards the new target AR 8217. We plan to make a series of 5-second exposures, with a cadence of approximately 32 seconds, from 16:00 UT to 19:22 UT (two Yohkoh orbits). The region selected for this high-cadence run is depicted in the image below: we will run in the intervals 16:00 to 17:39 and 17:50 to 19:20.

Unfortunately this is not precisely the same region being targeted by TRACE and CDS -- they're pointing further south. It was judged that due to the faintness of X-ray emission closer to the limb, SXT would not be able to make contributions of any real value at that location. (Click to see a larger version.)

8-May-98 entry

First, here is a full-Sun image to show what region SXT is looking at. The box gives the size and location of the partial-frame images made on 7-may-98. (Click for larger image.)

Next, here's a representative image from the fast-cadence run. The run resulted in two sets of images: a set of full-resolution (2.5 arcsec) images at 32-second cadence from 15:41:57 to 16:09:47 UT, and a set of half-res (4.9 arcsec) images at 64-second cadence from 16:11:19 to 16:37:11 UT. The full-res images are made with an exposure length of 2.7 seconds. (Click for larger image.)

The smaller image has been decompressed, exposure normalized, and dark-current subtracted. Peak brightness in the northern set of loops is about 125 DN. The bright spot in the southern set of loops is an artifact.

David E. McKenzie