#1
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ASTRO: NGC 5496
A low surface brightness galaxy imaged through the Sacramento light
dome. I could not find any scientfic papers on this galaxy. The green channel was synthesized from the red/blue channels. The Astrodon-I green filter is not a good match for the scope/camera generating a large reflection in the Mewlon. NGC 5496 Virgo Penryn, California May 2009 M 250 @ f 9.3 (ag, ST-4) ST-10XME LRGB 10 minute subs NGC 5496 is classified as SBcd, surface brightness is 14.6, distance is 82 Mly. |
#2
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ASTRO: NGC 5496
On 4/30/2010 10:26 AM, Glen Youman wrote:
A low surface brightness galaxy imaged through the Sacramento light dome. I could not find any scientfic papers on this galaxy. The green channel was synthesized from the red/blue channels. The Astrodon-I green filter is not a good match for the scope/camera generating a large reflection in the Mewlon. NGC 5496 Virgo Penryn, California May 2009 M 250 @ f 9.3 (ag, ST-4) ST-10XME LRGB 10 minute subs NGC 5496 is classified as SBcd, surface brightness is 14.6, distance is 82 Mly. I like this one. I've never been able to make pseudo green work for me. I have several shots with poor green data and tried that but I still got better results using the bad green. Your results look good. My used camera came with Astrodon 1 series I filters that are very close to 1:1:1 at the zenith. I need to compensate as I get lower in the sky but they easily work with the same exposure time. But they have bad reflections in Blue and pretty bad ones in green but not to the extent as blue. So I was surprised by your green being the problem filter. A friend here with a ST-10 so very different response curve uses old CSI filters. I tried those with the same result. Blue and green reflections were even worse. Even with the shorter exposure times I needed for them to compensate for red. Today's filters are far better coated. Baader's are supposed to be well matched to the interline chips so am thinking of blowing the budget to see if they have less reflection issues. Everyone tells me they are far better than the old Astrodon's I now have and are cheaper than new Astrodons. I'm getting tired of large blue halos around bricht K and M stars. They are a pain. Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
#3
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ASTRO: NGC 5496
Hi Rick -
I ordered the Astrondon filters and received the set with the green missing, the company I ordered from had Astrodon contact me directly (they're located about 20 miles away) and after collecting serial numbers and what not, they shipped me a green filter. One wonders if the green filter was from a different batch). I use Noel Carboni's photoshop actions to generate the green channel. I find it works quite well. I tried sky flats for the green channel to no avail. On a different subject - I located my NGC 4395 data. Looking at the raw data there is not any dust motes, etc in the area of the object in question and a stretch of the raw data does show something there. (9 hours of luminance data was collected over a 4 night period) Going back to the list of objects plotted in SIMBAD for NGC 4395 there is an object WR468 listed as PoG (part of galaxy) at the approximate coordinates (Disclaimer - I don't have TS6 on my home computer so don't have a means of doing accurate measurements - forecast is for a clear sky tonight so will play around with the data on the observatory computers and see if I can get an accurate plot) 4395 is not in a favorable position for imaging (It's close to the zenith and will soon be behind a "heritage Oak" which is protected by both law and my wife. Next spring I'll put the ST-10XME on the FS-128 and reshoot 4395 On Fri, 30 Apr 2010 12:19:44 -0500, Rick Johnson wrote: On 4/30/2010 10:26 AM, Glen Youman wrote: A low surface brightness galaxy imaged through the Sacramento light dome. I could not find any scientfic papers on this galaxy. The green channel was synthesized from the red/blue channels. The Astrodon-I green filter is not a good match for the scope/camera generating a large reflection in the Mewlon. NGC 5496 Virgo Penryn, California May 2009 M 250 @ f 9.3 (ag, ST-4) ST-10XME LRGB 10 minute subs NGC 5496 is classified as SBcd, surface brightness is 14.6, distance is 82 Mly. I like this one. I've never been able to make pseudo green work for me. I have several shots with poor green data and tried that but I still got better results using the bad green. Your results look good. My used camera came with Astrodon 1 series I filters that are very close to 1:1:1 at the zenith. I need to compensate as I get lower in the sky but they easily work with the same exposure time. But they have bad reflections in Blue and pretty bad ones in green but not to the extent as blue. So I was surprised by your green being the problem filter. A friend here with a ST-10 so very different response curve uses old CSI filters. I tried those with the same result. Blue and green reflections were even worse. Even with the shorter exposure times I needed for them to compensate for red. Today's filters are far better coated. Baader's are supposed to be well matched to the interline chips so am thinking of blowing the budget to see if they have less reflection issues. Everyone tells me they are far better than the old Astrodon's I now have and are cheaper than new Astrodons. I'm getting tired of large blue halos around bricht K and M stars. They are a pain. Rick |
#4
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ASTRO: NGC 5496
Neither SIMBAD or NED show anything at the position of your mystery
object. WR 468 is a good 5 minutes from that area. Use SIMBAD's Aladin to find it on the DSS plates. Just go to the object in SIMBAD http://simbad.u-strasbg.fr/simbad/si...04699631&Name=[BKD2008]%20WR%20468&submit=submit Then click on the Aladin applet. It will load the POSS 1 red plate and center on the object. Many others will be shown as well. If you load the NED database even more will show. Rick On 4/30/2010 1:52 PM, Glen Youman wrote: Hi Rick - I ordered the Astrondon filters and received the set with the green missing, the company I ordered from had Astrodon contact me directly (they're located about 20 miles away) and after collecting serial numbers and what not, they shipped me a green filter. One wonders if the green filter was from a different batch). I use Noel Carboni's photoshop actions to generate the green channel. I find it works quite well. I tried sky flats for the green channel to no avail. On a different subject - I located my NGC 4395 data. Looking at the raw data there is not any dust motes, etc in the area of the object in question and a stretch of the raw data does show something there. (9 hours of luminance data was collected over a 4 night period) Going back to the list of objects plotted in SIMBAD for NGC 4395 there is an object WR468 listed as PoG (part of galaxy) at the approximate coordinates (Disclaimer - I don't have TS6 on my home computer so don't have a means of doing accurate measurements - forecast is for a clear sky tonight so will play around with the data on the observatory computers and see if I can get an accurate plot) 4395 is not in a favorable position for imaging (It's close to the zenith and will soon be behind a "heritage Oak" which is protected by both law and my wife. Next spring I'll put the ST-10XME on the FS-128 and reshoot 4395 On Fri, 30 Apr 2010 12:19:44 -0500, Rick wrote: On 4/30/2010 10:26 AM, Glen Youman wrote: A low surface brightness galaxy imaged through the Sacramento light dome. I could not find any scientfic papers on this galaxy. The green channel was synthesized from the red/blue channels. The Astrodon-I green filter is not a good match for the scope/camera generating a large reflection in the Mewlon. NGC 5496 Virgo Penryn, California May 2009 M 250 @ f 9.3 (ag, ST-4) ST-10XME LRGB 10 minute subs NGC 5496 is classified as SBcd, surface brightness is 14.6, distance is 82 Mly. I like this one. I've never been able to make pseudo green work for me. I have several shots with poor green data and tried that but I still got better results using the bad green. Your results look good. My used camera came with Astrodon 1 series I filters that are very close to 1:1:1 at the zenith. I need to compensate as I get lower in the sky but they easily work with the same exposure time. But they have bad reflections in Blue and pretty bad ones in green but not to the extent as blue. So I was surprised by your green being the problem filter. A friend here with a ST-10 so very different response curve uses old CSI filters. I tried those with the same result. Blue and green reflections were even worse. Even with the shorter exposure times I needed for them to compensate for red. Today's filters are far better coated. Baader's are supposed to be well matched to the interline chips so am thinking of blowing the budget to see if they have less reflection issues. Everyone tells me they are far better than the old Astrodon's I now have and are cheaper than new Astrodons. I'm getting tired of large blue halos around bricht K and M stars. They are a pain. Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
#5
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ASTRO: NGC 5496
Very good image Glen. This galaxy is new to me.
Stefan "Glen Youman" schrieb im Newsbeitrag ... A low surface brightness galaxy imaged through the Sacramento light dome. I could not find any scientfic papers on this galaxy. The green channel was synthesized from the red/blue channels. The Astrodon-I green filter is not a good match for the scope/camera generating a large reflection in the Mewlon. NGC 5496 Virgo Penryn, California May 2009 M 250 @ f 9.3 (ag, ST-4) ST-10XME LRGB 10 minute subs NGC 5496 is classified as SBcd, surface brightness is 14.6, distance is 82 Mly. |
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