Monsoonal moisture is coming, so I decided to go out last night despite there being a lot of Moon to deal with. I actually started out the evening with a little lunar imaging, but I haven’t processed those yet, so I don't know whether they'll be worth posting. I had originally intended to try to image Barnard’s Galaxy, but when I saw how bright the moonlight was I decided to do a brighter, easier target instead. So I chose M8, the Lagoon Nebula, which I haven’t imaged in a couple of years. I see it is also called the Dragon Nebula, which is a cooler, but less-well-known name.
There was little or no wind, and it was quite hot (high 70’s °F when I started). On top of that, last night Mapleton Lateral Observatory was plagued with more than the usual number of little green lacy-winged insects that bite and give off an aromatic smell when smashed, so I was doing battle with them the whole time I was out. I synched on λ-Sag, but the goto was a little off and I had to manually correct by about 1 field diameter. I had trouble focusing, and there was way too much Moon for this to turn out at its best. The chiller was running at 2.5 A, with the CCD at 15.5° down to about 12 °C. I must have had a cable snag during the session so I didn't get much data. Further, I reduced my exposures to 180 s to avoid overexposing the core of the nebula. I had intended to use a focal reducer to capture more of the nebula, but I was set up without it so I went without. Since I'm having "filter envy" (see below), and since M8 is an appropriate target for it, I decided to try and improve contrast by using my UHC-S filter. That definitely enabled me to see detail I haven't seen before. Here’s the result:
Date: 7 Jul 2014
Subject: M8, Lagoon Nebula
Scope: AT8IN
Filter: Baader UHC-S
Mount: CG-5 (Synta motors, PicGoto Simplificado)
Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.3.0 (Win 7 ASCOM)
Camera: DSI IIc chiller at 2.50 A, ~15 down to 12 °C
Acquisition: Nebulosity 3.2.0, no dither
Exposure: 53x180 s
Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack.
Processing: StarTools 1.3.5.279 Crop; Wipe:Color & brightness 79%; Develop 76.08%; HDR:Optimize; Color:Scientific, 200%; Deconvolute auto mask 2.6 pix; HDR:Optimize; Life:Moderate; Track RNC 1.72%; Magic:Shrink 1 pix; Color:Scientific 145%; Color:Scientific 100% cap green to yellow. CS6 Astronomy Tools Astro Frame.
Over last weekend I posted a question on the Stark Labs Astronomy Tools Yahoo forum about using H-⍺ filters with one-shot color cameras. I’d always assumed it would really kill the signal to shoot narrow H-⍺ through a Bayer matrix, and that it wouldn’t be worth trying. On the contrary, apparently a lot of people do it with good results. So now I’m gung ho to shell out $169 for a Baader 7 nm H-⍺ filter. I just have to convince The Boss that this is a reasonable expenditure. It would certainly help my imaging on Moon-lit nights, not to mention piercing the fog of light pollution that shrouds Mapleton Lateral Observatory. Anyone care to guess how long it will take me before the urge to buy becomes irresistible?
No comments:
Post a Comment