David's Astronomy - Notes 2011-01-20 (S00449)

Start-Up Gremlins Unusual start-up problems were encountered at beginning of session where double dot stars images and vertical streak trails where intermittently encountered. (see below) Switching off and restarting the ST10-XME camera seemed to fix the problem. (There has been no reoccurance of the problem in the followimg imaging sessions)
Example Image showing double dot / trail problem

CCD Images (cropped, 150% size) 5s exposure (single frame), 3x3 binning, C Filter, (#449002) 12" LX200R (at f/9.7) + ST-10XME

Problem Observations / Analysis
- Vertical streaks (trail lines) don't have the usual sharp digital character of blooming streaks - Vertical lines are more like the trails one might get if the equatorially mounted telescope was still slewing/correcting or was jogging in Dec whilst recoding the image. However the sequence of frames (see below) makes this improbable. - Double dot feature appears for faint stars as well as bright stars - On brightest stars there is a faint 3rd and 4th dot (look closely at image below) - Brightness of trail line seems dependant on the brightness of the star - Star trails are roughly straight and or are not obviously curved - No double dot/star trail problem is noted with the V filter. - Is the problem related to Filter Wheel itself or the Camera's Control of the Filter Wheel ?

Sequence of frames
		1) Slewed to Lyr TZ Locate Frame, 5s, C, (#449001) Cloud? Single double dot star & weak trail/line. Target aborted.

		2) Slewed to Cyg SS Initial Locate Frame 5s, C, (#449002) Double dot star & strong trail/lines. Secondary star dot is the same brightness as the primary star image.

		3) Jogged 1 arc min West Final Locate Frame 5s, C, (#449003) Double dot star & strong trail/lines. Any star trail (if any) at this point should be a E-W trail and not a N-S trail.

		4) Taking BVR Frames 15s, B, (#449004) No stars visible Clouded out ? Continuing to next frame

		4a) V Frame 5s, V, (#449005) Normal Image (No double dots or trail lines)

		4b) B Frame 15s, B, (#449006) Cloud, with few stars Double dot star & weak trail lines

		4c) B Frame 15s, B, (#449006) Cloud, with few stars Normal stellar images ? (No double dots or trail lines ?)

		4d) R Frame 3s, R, (#449008) Double dot star & strong trail lines returned (rules out the problem being star trails from jog/slew or ghost trails from a pevious slew.

		4e) B Frame 15s, B, (#449009) Double dot star & weak trail lines Secondary star dot is much weaker than primary star image.

		4f) V Frame 5s, V, (#449010) Normal image (No double dot star or trail line) Partially Clouded ? (cloud edge very sharp ! ) One might suspect a filter wheel or a camera shutter problem but two stars are still visible in the clouded region.
		Following frames clouded out R, B (#449011-12). Target Imaging Aborted
		5) Slewed to RX And, First Locate Frame First Locate Frame without visible stars (cloud ?) 5s, C, (#449013)

		5b) Second Locate Frame 5s, C, (#449014) Double dot stars with trail lines on brightest stars. Secondary star dot is much weaker than primary star image. Aborted Target Imaging.

		6) Restarted Camera. Took Image Slewed to Cyg SS 5s, C, (#449015) Normal Image (no double dot stars or trail lines) From this image onwards the session was normal
CCD Image (50% size) Single Frames, 3x3 binning, various filters (#449001 to #449015)

This Web Page:	Notes - Session 449 (2011-01-20)
Last Updated :	2015-05-15
Site Owner :	David Richards
Home Page :	David's Astronomy Web Site

	2011-01-20
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David's Astronomy Pages Notes - Session 449 (2011-01-20)

Start-Up Gremlins

David's Astronomy Pages
Notes - Session 449 (2011-01-20)