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Heart Nebula - HaSHO


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I have wanted to reshoot the Heart for years.  I Started this project during a 100% Moon.  Now I regret it.  While Ha can provide immediately satisfying results at a time when imaging would otherwise not even be contemplated, the dt is not without compromise.  Fortunately, the Heart is fairly bright as nebulae go.  Other than a mysterious rotation of the frames from night to night (discovered when trying to align a nights framing with previously collected data), the project went well.  I did have to reshoot the SII do to horrific seeing, which was a minor mystery.  Usually when seeing is really bad, my guiding rms errors are large and guiding is erratic.  Not so for the initial SII.  Guiding was good ( .4-.5 rms), polar alignment was normal, focus was typical, there was no wind, and yet FWHM values were 7-8".  Fortunately the next night was decent and I was able to reshoot.  With respect to the rotation issue--I use all threaded connections and they are all very tight.  Every other nut, bolt, and knob is as tight as I can get them.  The rotation seems to be off axis a bit--a star somewhere in the frame will be perfectly aligned, but stars a distance from the aligned star will have been rotated--the subs can still be registered with only minor edge cropping.  The biggest indication that something is not right is the fact that I have never seen this before ( and that subs from opposite sides of the meridian cannot be registered--A stack must be made from east subs and a stack made from west subs and the two stacks registered and combined...certainly not normal).  I try to avoid meridian flips--but they are unavoidable when a target starts the bight close to the meridian.

FSQ 106 with .6x reducer and ASI 1600: Ha 100 300sec; OIII 68 300 sec; SII 81 300 sec.  About 20 hours.



Edited by Rodd
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