October 24, 2008

IC1805 Heart Nebula, with new Baader 35nm Ha filter

One of the issues with imaging with the Hyperstar @ f/2 is that the wavelengths all get shifted by ~6nm, so doing narrowband with it can cause some real issues. A 13nm filter would appear to be OK, but in fact by the time (for example) Hydrogen Alpha is shifted by 6nm, its in the 30% or less bandpass section of the filter.

Then Baader released their new range of filters, including an oddity… a 35nm Ha filter. Is it a wide Ha or a narrow red? Who knows, but its use on the Hyperstar was obvious to me, keeping the peak Ha emision line well above the 90% transmission. It also seem to cope really well with the full f/2 shift at the outer egdes of the QHY8 APS size CCD. The only small downside is that because of the wide bandpass, its not quite as “contrasty” as you would expect from a narrowband filter.

So, here goes:

OTA: NS8GPS @ f/2 (Hyperstar v3)
Guiding: William Optics ZenithStar 66 SD + DSI-C + PHD
Imaging: QHY8 + MaximDL, 24×600s, Baader 35nm Ha
Stacked: DeepSkyStacker
Post Process: ImagesPlus + PSCS2 + Noel Carboni’s AstroTools

(Click on image for larger version)

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