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Hi all, I wonder whether it is meaningful to capture the well known "WitchHead Nebula" (NGC1909 in Eri) from a light polluted area with the Antlia Triband RGB Ultra filter? All colorful nebulae in nearby Orion work fine, as expected. I fear, though, NGC1909 will rather turn invisible ... !? Anyone share his experiences? |
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| High light pollution = No Witch, no matter the filter. |
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Yes, worked. See my result from last week Bortle 5: Witch-Head Nebula, Orion ( Markus Selbach ) - AstroBin It makes sense to only shout it +/- 1.5 hours of meridian whem it's higher in the sky. You will hardly see it on a single sub, so you have to use Rigel for framing. But after stacking it comes clearly visible. |
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| B5 hardly counts as high light pollution. So it actually depends on what the OP situation is. |
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andrea tasselli: andrea tasselli: nope, it still has. I used hyperstar c8 before with 533mm, i can see it clearly. |
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When I started AP three years ago, with an unmodified Canon EOS 5D4 and the Samyang F=135mm f/2.0, I captured the WitchHead Nebula (NGC1909) by coincidence, not even knowing it was there. When you read the details, it was only 1h20' total integration time ... but the WitchHead is clearly visible. Two nights ago I gave it a second try with the same lens and my ZWO ASI533MC Pro ... and The Antlia Triband RB Ultra. Fog rushing into our valley like the tides at the ocean stopped the fun after 1h20' - coincidently the same as three years ago. But this time I can barely see any hint of the WitchHead at all. Thus I asked ... it may be the very damp air, the incoming fog or whatever. Glad to read from @Markus he had good luck with the same filter and a similar setup. |
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Hi, if I understand IC2118 correctly, it is a diffuse reflection nebula, whereas the Antlia Triband RGB Ultra filter as I understand it (being 'narrow-band') is recommended for emission nebulae... Then from being discouraged to not being able to do it is another matter.... It would also be to understand how light polluted the area is and how high the subject actually is. BUT from what I understand there are so many variables to consider. I'd try it on principle anyway (I'm someone who likes to bang my head against a wall even if it's advised against!) and at worst throw away a night's worth of data and a day's worth of processing.  I'm a newbie so I could probably be wrong! Greetings, CS! F.T. |
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Hi, if I understand IC2118 correctly, it is a diffuse reflection nebula, whereas the Antlia Triband RGB Ultra filter as I understand it (being 'narrow-band') is recommended for emission nebulae... Thanks for your reply @FilippoTib, unfortunately good deep sky nights here in our valley in the Alps are rare. The Alps being the European weather divide, are a great barrier between south Europe and central/north Europe where the big weather systems collide and mix, yielding strong and gusty winds, wind shears and severe turbulences. Also humidity is often 80-90% ... these days 90% thus often yielding fog and/or low cloud covers as can be seen in this animation. Despite having acceptable light pollution in our valley (Bortle 4), we thus suffer severe limitations indroduced by our local micro climate. Having said this, good nights are rare and precious. It can take weeks waiting for another good night. Thus it hurts to leave such a night unused or "abused" for experiments. ~ * ~ Concerning the Antlia Triband RGB Ultra I cite from the maker's website:
So I expected (read: "hoped") it would work as advertised with NGC1909 / IC2118 and it does work. I choose this filter because our atmospheric conditions are unreliable and change fast. It would be a pain to collect Ha for some hours in one night and OIII in the next good night after weeks. I could simply not collect enough photons yet because of this: Every single day an night tidal clouds rush in and out and in again ... I live in the valley shown in the upper third of the image. It's a wonderful landscape and I love beeing here ... but it's not easy to capture DeepSky images. All the best to everyone, CS Frank |
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| Given you are in B4 zone there is no advantage in using such a filter. If anything I'd opt for a wider pass-band such as offered by the latest Optolong L-Quad (see :[2023 NEW] Optolong L-Quad Enhance Filter (L-QEF) quad bandpass light pollution suppression filter-Optolong Optics Co.,Ltd. ) |
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unfortunately good deep sky nights here in our valley in the Alps are rare. The Alps being the European weather divide, are a great barrier between south Europe and central/north Europe where the big weather systems collide and mix, yielding strrong and bumpy winds, wind shears and severe turbulences. Ah, I see. Then yes, a wasted night is not a great idea. Concerning the Antlia Triband RGB Ultra I cite from the maker's website: As for this, I had looked at the site of artesky.it, an Italian dealer, as a reference. t states Consigliato per: Ridurre l'inquinamento luminoso, Aumentare il contrasto per le nebulose ad emissione, Risparmiare tempo di elaborazione" which translated to "Recommended for: Reduce light pollution, Increase contrast for emission nebulae, Save processing time'. It was my mistake not to check the manufacturer's website directly! CS! F.T. |
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| @firstLight : for your location and with B4 I would prefer to shout witchhead without an aggressive filter like the triband. It‘s narrow bands need much more integration time, and as clear skies are THE limiting factor here in Germany, you could have more usable data in the same time. To add some more Ha (there is only a bit in the background) you could use a duo narrowband on a night were nothing else is possible because of the moon and combine the channels. |
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Hi all, just a proof of concept for the use of the Antlia Triband RGB Ultra filter on the WitchHead nebula. This is only 1h20' integration time. In addition damp and foggy air flowed in, as obviously visible at the big star Rigel. So I can answer my own question which I posted to start this thread: The Antlia Triband RGB Ultra is capable to capture reflection nebulae like the WitchHead nebula. This result is .... well ... rather ugly. I hope to collect at least 4 hours of photons from this target to hopefully get a more pleasing result. This image was taken with the ZWO ASI533MC Pro + Samyang 135mm @ f/2.0 + 34x180s + Gain 100 + Bias 1 + -10°C. CS Frank  |
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Half of the Witch Head two nights ago in New Mexico twenty miles east of Albuquerque, Bortle 4/5. About 2-1/2 hours using an ASI533MC on my Askar 103 APO through an Antlia Triband filter: |
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I am not sure of your conditions, but I just photographed this from my Bortle 3/4 zone. My problem is that it is low in the Southern sky, and I have hills that obscure my Southern Horizon. This led to less integration time than I would like. I did use an IDAS LPS D3 filter which may have similar bandpass characteristics as the Antila Tri-Band. Give it a try, and see what you come up with. I would recommend 5-minute guided and dithered subs, and possibly 3 to 10 hrs of integration time. Here is a link to my image. https://www.astrobin.com/rkk3z7/ |
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Jon Bryan: Beautiful detail in the WitchHead. Of course I cannot even get close to this resolution with the tiny 67.5 mm aperture the Samyang 135mm f/2.0 provides. OTOH, I get a nice wide field with the whole nebula plus the star Rigel which illuminates it - see above! |
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Timothy Straub: I looked up your place (Prosser) in Google Earth 3D out of curiosity: Prosser is at ~46°N (200m MSL) with dry hill barrier (~500m MSL) in the south, on top and behind of which are extended dry lands. My place is at 47.5°N at 680m in an alpine valley, which is only about 1+ km wide and surroundet on three side with mountains up to 2968 m. The mountains are covered with extensive mixed forests (deciduous and coniferous) up to an altitude of 1850m. There are many alpine meadows, torrents from the mountains and a river in the valley. It is so green here for a reason: All weather systems (esp. low pressure zones with clouds, storms, rain / snow) from SW > W > NW > N > NE crash against the Alps and all precipitation falls here. I love my home, here in the mountains: climbing, hiking, paragliding, mountain biking, rafting, skiing, cross country skiing ... there are endless options to have beautiful times outdoors. ~ * ~ For (deepsky) AP this ist certainly not a very good place: Very limited horizon due to surrounding mountains and usually very high humidity - mostly 80%-90% - which yields bad seeing, together with wind shears where the three valleys meet and gusty, turbulent winds due to our local micro climate. >>> See this tidal cloud / fog animation at my place <<< and mind the timestamps! In winter nights, the WitchHead nebula is in view from Az=160° at Alt=32°, with an altitude of 34° in the meridian and only 28° two hours past the meridian. Then the mountains on the western side of our valley come into the imaging field. So, at best I could capture NGC1909 for ~3 hours ... if a good night would decide to stay clear and cloud- / fogless. :-) |
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I live in Tucson, Arizona, USA close to Steward Observatory at the University of Arizona. I am in a Bortle 5 zone and I use the L-eNhance filter since there is not a BIG difference from the Tri-Band. I have tried imaging this target for quite some time and finally concluded that the answer is integration. I shot this image for eight hours as a test to see if it would be worth doing a mosaic. The answer is, of course, yes. I know that a dark sky would help tremendously but I am unable to travel because of my medical condition. To see an example of what I can do with a 102mm Apo in polluted skies check out my page at https://www.astrobin.com/pvd1bb/C/ Clear Skies my friend.  |
