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Galaxy Filters for the Backyard

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#251 SeanStaresatStars

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Posted 11 June 2021 - 01:51 AM

This thread has had me really interested in joining in on the topic, especially with most of my observing being done from a light polluted balcony, and a new UHC filter on it's way (Baader Neodymium). I've been using the NASA/IPAC Extragalactic Database to get some idea if any of the galaxies on my list might have stronger emission lines in the regions favored by what filters I have. Especially, in the hopes of seeing more spiral structure. Trying to bank on the hope that spiral arms often have more star formation going on, and therefore might behave more like nebulae. Tonight was a pretty decent night, so, I went after some of the aforementioned galaxies to see how they did. Here's my report:

 

Equipment used: Skywatcher 250p Classic Dob. Explore Scientific 82deg eyepieces: 8.5mm, 14mm, and the ES68 24mm. Svbony UHC filter, and Orion Ultrablock. 

 

Conditions: Bortle 6, NELM: 4.5, TLM: 11.8. Seeing: 2.5/5.

 

NGC 3310: 21:48hrs, Directly visible in 24mm as moderately bright round disk brighter towards center, averted vision shows another dimmer halo around that. Same in 14mm and 8.5mm, however 8.5 would show a slight hook to one side of central disk in moments of good seeing. 

                       8.5 w/ UHC: Brighter Nucleus, outer disk appears uneven and mottled in averted vision, hook to central disk more apparent

                       8.5 w/ Ultrablock: dimmer overall, however, may appear slightly elongated, hard to tell with wind.

 

NGC 4111: 22:25hrs. Bright stellar core that "blinks" when looking directly at it. Core surrounded by faint, thin ellipse, core offset to south of this oval region. 8.5mm shows this central oval region best. 

                      8.5 w/ UHC: slight increase in contrast of core region, stellar core is steady. 

                      8.5 w/ Ultrablock: Significantly dimmer, still visible with averted region: central oval much smaller. 

 

NGC 4244: 22:43hrs. Undetectable in 24mm, in 14mm averted vision reveals thin line of mottled light. 8.5mm still visible only in averted vision, center of thin section shows slight bulge. All filters at all magnifications render target undetectable. 

 

 

M66 and M65: (forgot to log time): easily seen in 24mm, bright cores surrounded by fuzzy patches, thinner for M65, more round for M66. with UHC filter both central regions easier to see, more so on M66, extra "bump" visible in averted vision with filter on 8.5mm. M65 seen as long, thin, ellipse. 

 

That's as far as I got before conditions started to go downhill pretty fast. Just enough to get me curious about using filters more from home. 


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#252 brentknight

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Posted 11 June 2021 - 07:11 AM

Thanks for your post Sean.

 

This topic has gotten pretty long, and I know there have been quite a few galaxies mentioned that seem to do well with a UHC type filter, but I don't recall them all right now.  I'd really like to give these ones a try myself - maybe this weekend will cooperate.

 

Most of my recent successes in detection have been with the broadband filters that allow more of the starlight to pass than the UHCs do.  But I don't mind trying the narrowband filters for more details in the brighter galaxies too.


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#253 Starman1

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Posted 11 June 2021 - 09:21 AM

This thread has had me really interested in joining in on the topic, especially with most of my observing being done from a light polluted balcony, and a new UHC filter on it's way (Baader Neodymium). I've been using the NASA/IPAC Extragalactic Database to get some idea if any of the galaxies on my list might have stronger emission lines in the regions favored by what filters I have. Especially, in the hopes of seeing more spiral structure. Trying to bank on the hope that spiral arms often have more star formation going on, and therefore might behave more like nebulae. Tonight was a pretty decent night, so, I went after some of the aforementioned galaxies to see how they did. Here's my report:

 

Equipment used: Skywatcher 250p Classic Dob. Explore Scientific 82deg eyepieces: 8.5mm, 14mm, and the ES68 24mm. Svbony UHC filter, and Orion Ultrablock. 

 

Conditions: Bortle 6, NELM: 4.5, TLM: 11.8. Seeing: 2.5/5.

 

NGC 3310: 21:48hrs, Directly visible in 24mm as moderately bright round disk brighter towards center, averted vision shows another dimmer halo around that. Same in 14mm and 8.5mm, however 8.5 would show a slight hook to one side of central disk in moments of good seeing. 

                       8.5 w/ UHC: Brighter Nucleus, outer disk appears uneven and mottled in averted vision, hook to central disk more apparent

                       8.5 w/ Ultrablock: dimmer overall, however, may appear slightly elongated, hard to tell with wind.

 

NGC 4111: 22:25hrs. Bright stellar core that "blinks" when looking directly at it. Core surrounded by faint, thin ellipse, core offset to south of this oval region. 8.5mm shows this central oval region best. 

                      8.5 w/ UHC: slight increase in contrast of core region, stellar core is steady. 

                      8.5 w/ Ultrablock: Significantly dimmer, still visible with averted region: central oval much smaller. 

 

NGC 4244: 22:43hrs. Undetectable in 24mm, in 14mm averted vision reveals thin line of mottled light. 8.5mm still visible only in averted vision, center of thin section shows slight bulge. All filters at all magnifications render target undetectable. 

 

 

M66 and M65: (forgot to log time): easily seen in 24mm, bright cores surrounded by fuzzy patches, thinner for M65, more round for M66. with UHC filter both central regions easier to see, more so on M66, extra "bump" visible in averted vision with filter on 8.5mm. M65 seen as long, thin, ellipse. 

 

That's as far as I got before conditions started to go downhill pretty fast. Just enough to get me curious about using filters more from home. 

Baader makes a broadband filter called the UHC-S, and they make a neodymium glass filter called the Moon & Sky Glow, which has a few notches taken out of the spectrum.

They do not make a neodymium glass filter called the UHC, however, so it is not clear which filter you used.

Could you clarify?



#254 SeanStaresatStars

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Posted 11 June 2021 - 09:28 AM

I do not have the Baader filter, yet. I was using a Svbony UHC when I made these observations.

The Baader that is on its way is the Moon and Skyglow filter. It is a birthday present so I didn't pick it out myself, but I'm excited to see how it does.

#255 Starman1

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Posted 11 June 2021 - 10:48 AM

That filter is enough different from your Svbony UHC that it will be interesting to hear your comments.


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#256 Jon Isaacs

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Posted 11 June 2021 - 12:31 PM

That filter is enough different from your Svbony UHC that it will be interesting to hear your comments.

 

I have one. It hasn't helped me with galaxies. I think my skies are split between too bright for it to be effective and too dark to be needed.  

 

But it does make a noticeable difference with nebulae, improving the contrast noticeably on objects like the Veil and the North American.   I should measure the filter's sky darkening with the SQM-L.  I measured the O-lll at about 3 magnitudes, thr Ultrablock at about 2.3 magnitudes, these more or less agreed  with my calculations based on bandwidth.

 

Looking at the pass band, it looks like it's about 60nm which suggests more than 1 magnitude of darkening, definitely significant and about what I see. 

 

https://www.amazon.c...B079BWDRFC?th=1

 

Jon



#257 Starman1

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Posted 11 June 2021 - 01:17 PM

I have one. It hasn't helped me with galaxies. I think my skies are split between too bright for it to be effective and too dark to be needed.  

 

But it does make a noticeable difference with nebulae, improving the contrast noticeably on objects like the Veil and the North American.   I should measure the filter's sky darkening with the SQM-L.  I measured the O-lll at about 3 magnitudes, thr Ultrablock at about 2.3 magnitudes, these more or less agreed  with my calculations based on bandwidth.

 

Looking at the pass band, it looks like it's about 60nm which suggests more than 1 magnitude of darkening, definitely significant and about what I see. 

 

https://www.amazon.c...B079BWDRFC?th=1

 

Jon

You're talking the Svbony UHC.  I was talking about the Moon & Sky Glow filter he's getting.



#258 SeanStaresatStars

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Posted 11 June 2021 - 02:03 PM

That filter is enough different from your Svbony UHC that it will be interesting to hear your comments.

It was well reviewed and I liked what I researched when I was told it was on the way. I keep checking the tracking data way more than I should be, I should get it Monday. Very excited to see how it fits into a growing quiver of filters. I think line filters will be next. 



#259 RLK1

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Posted 13 June 2021 - 03:42 PM

This thread has had me really interested in joining in on the topic, especially with most of my observing being done from a light polluted balcony, and a new UHC filter on it's way (Baader Neodymium). I've been using the NASA/IPAC Extragalactic Database to get some idea if any of the galaxies on my list might have stronger emission lines in the regions favored by what filters I have. Especially, in the hopes of seeing more spiral structure. Trying to bank on the hope that spiral arms often have more star formation going on, and therefore might behave more like nebulae. Tonight was a pretty decent night, so, I went after some of the aforementioned galaxies to see how they did. Here's my report:

 

Equipment used: Skywatcher 250p Classic Dob. Explore Scientific 82deg eyepieces: 8.5mm, 14mm, and the ES68 24mm. Svbony UHC filter, and Orion Ultrablock. 

 

Conditions: Bortle 6, NELM: 4.5, TLM: 11.8. Seeing: 2.5/5.

 

NGC 3310: 21:48hrs, Directly visible in 24mm as moderately bright round disk brighter towards center, averted vision shows another dimmer halo around that. Same in 14mm and 8.5mm, however 8.5 would show a slight hook to one side of central disk in moments of good seeing. 

                       8.5 w/ UHC: Brighter Nucleus, outer disk appears uneven and mottled in averted vision, hook to central disk more apparent

                       8.5 w/ Ultrablock: dimmer overall, however, may appear slightly elongated, hard to tell with wind.

 

NGC 4111: 22:25hrs. Bright stellar core that "blinks" when looking directly at it. Core surrounded by faint, thin ellipse, core offset to south of this oval region. 8.5mm shows this central oval region best. 

                      8.5 w/ UHC: slight increase in contrast of core region, stellar core is steady. 

                      8.5 w/ Ultrablock: Significantly dimmer, still visible with averted region: central oval much smaller. 

 

NGC 4244: 22:43hrs. Undetectable in 24mm, in 14mm averted vision reveals thin line of mottled light. 8.5mm still visible only in averted vision, center of thin section shows slight bulge. All filters at all magnifications render target undetectable. 

 

 

M66 and M65: (forgot to log time): easily seen in 24mm, bright cores surrounded by fuzzy patches, thinner for M65, more round for M66. with UHC filter both central regions easier to see, more so on M66, extra "bump" visible in averted vision with filter on 8.5mm. M65 seen as long, thin, ellipse. 

 

That's as far as I got before conditions started to go downhill pretty fast. Just enough to get me curious about using filters more from home. 

Thanks for your report. I note you also had a positive filter response on NGC 3310 with the svbony UHC filter; similar to my own. I had hoped to view it under dark sky conditions this past week with and without the filter but my plans changed due to interior decorating in my home.  Nevertheless, I did view it again under highly transparent skies with good seeing Saturday night (6-12-21)  in front of my light polluted home. ( I just can't deal with Mt Pinos on a Saturday night anymore).  I could discern the milky way from Cygnus extending a bit southward towards Sagittarius along with a few of the rifts within it. With my 16" and a 10mm Ethos/ Celestron Baader LPR UHC filter, I could penetrate easily to 13 magnitude and views of M27/M17 approached those seen from a dark sky site, especially with an 0111 filter. I noted the Siamese twins in Virgo appeared reasonably bright in the Ethos/LPR UHC combo despite the general low contrast of these galaxies and I could also discern the overall length of the hockey stick  with the same combo with averted vision. Although I had decent views of M13, including the propellor with the aforementioned combination along with good views of M92, M3 and M53, I couldn't, for some unknown reason, locate and observe NGC 5466 in Bootes. Although the latter globular cluster is 9th magnitude and my DSCs were accurate throughout the evening, the object eluded me completely. I could, however,  see the brightest galaxy in Bootes, 10th magnitude NGC 5248, but the 9th magnitude globular was invisible despite multiple attempts to locate it. Those attempts included viewing with and without a filter and varying eyepiece focal lengths as well.  

My observing stint lasted from about 9:30pm to 2:00am and was aided greatly by excellent transparency coupled with good seeing and even Saturn looked impressive despite being quite low in the horizon with my  16" f4.5 dob nearly horizontal. Despite high ambient lighting, I was able to observe most of the galaxies I went after that were magnitude 11.5 or brighter and I credit the use of the filter as being a key to my success...


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