Session A: 2008-02-18 13:41MST 2008-02-18 20:41MST I pulled out the PST on an alt-az mount for a quick look at the Sun on Monday, 2-18-2008 13:48MST (2-18 20:48UT). One large hedge type prominence, extending 100 arcsecs from the disk was seen on the east limb at solar lat 40-50 north. Two smaller prominences were seen on the western limb, also in the northern hemisphere at 40-50 north solar lat. A small second hedge was seen on the western limb at 25 north lat. A diagram can be viewed at: 2-18-2008 Solar disk diagram http://gallery.utahastronomy.com/main.php?g2_itemId=10960 I also wanted to confirm the TFOV of the PST using a 12mm Meade reticule ep. With a catalogue listed focal length of 400mm, my calculator was returning a 1.6 deg TFOV, which seemed impossibly large compared to the what was seen in the eyepiece. So, I decided to confirm a rough TFOV measurement by the drift method. The Meade 12mm reticule has an AFOV of about 52 degrees. The reticule is marked in a total of 50 tics. The Sun was at approx. -11degs 23 arcmins. At that declination, my drift rate calculator returned 14.71 arcseconds of drift per second. Although the mount was a simple alt az tripod, using the reticule eas-west centerline, the eyepiece could be rotated parallel to the drift of the Sun. To do this, the centerline is placed along either the north or south pole of the Sun. The reticule is turned until the pole moves parallel to the center line. The scope is then raised to put the disk at the center of the reticule and the disk moved out of the east side of the lens field-of-view. A simple crude watch with a stopwatch function was used to an accuracy of 1-2 seconds. Drift times recorded on one pass were: 0:00 Solar disk appears on east e.p. edge 0:23 50 tic mark grid passed 1:02 40 tic mark grid passed 1:42 30 tic mark grid passed 25 center tic timing missed 2:26 20 tic mark grid passed 3:07 10 tic mark grid passed 3:48 00 tic mark grid passed 4:09 Solar disk contacts west edge A 249 second drift time at a rate of 14.71 arsecs per sec equates to 61 arcmins or approx. 1 deg TFOV at 12mm. The 205 second drift time across the 00-50 grid tics equates to 50.2 arcmins or approx. 1 arcmin per reticule tic mark. A second drift measurement was done with a 15mm e.p. that has no reticule. With the reticule, precise east-west drift alignment was not possible. The drift time was 4:49 seconds, which equates to a 75.7 arcmin TFOV or ~ 1.25 deg TFOV. Based on the tic marking calibration and the larger prominence was about one to two tic marks high, the larger prominence is estimated at about 100,000 kilometers tall. Since the 400mm fl PST did not have a TFOV of 1.6 degs and I concluded that it has a large aperture stop reducing the TFOV to 1 deg. Session B: 2008-02-19 13:46MST 2008-02-19 20:46MST The P1 prominence was seen at the same position, was fainter and looked more like a spray fan today. The other prominences were not visible. Using the protractor grid of the 12mm reticule e.p., the P1 prominence was about two tic marks high at a position angle of 10 degrees east of the eyepiece south from the disk center. That corresponds to about 110,000 kilometers tall and a position angle of 30 degs. 2-19-2008 Solar disk diagram http://gallery.utahastronomy.com/main.php?g2_itemId=10963 - Kurt ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping