Long Weekend of Deep Sky Observing
Posted: Fri Mar 15, 2024 4:33 am
My mate Phil @scribbly came up for the weekend last weekend. It was a long weekend in Canberra so Phil stayed Friday, Saturday, and Sunday nights. I organised clear weather for all three nights.
On Friday night the transparency was quite poor (an understatement). Fires in three equally distributed directions, pollen and other vegetation detritus was so thick floating through the air that my flashlight clearly illuminated it. On Saturday night the air was clearest and on Sunday night, like an orchestra reaching a crescendo, the transparency was quite superb.
Equipment
I set up my 6" f7 Newt and 18" f5.5 Dobsonian.
Phil brought his Takahashi TSA120 and a Hansen Optical Genstar 10" f5 ultralight ultracompact Dobsonian previously owned by Alan Dyer.
Eyepieces:
Joe: 31mm 17mm Nagler, 21mm & 14mm Denkmeier, 10mm Pentax XW
Phil: 22mm Nagler, 21mm Denkmeier, 14mm Denkmeier, 11mm Nagler
My reported observations below are mainly through my 18 inch f5.5. I have avoided describing views through Phil's scopes to afford him the opportunity to report his own observations at a later date. Phil also added my Televue 0.8X focal reducer/flattener to his TSA120 on the 2nd and third nights to do some astrophotography while we observed with the two large reflectors, both of which have optically quite superb mirrors. I deliberately do not read the documented descriptions of new objects. I record my observations using voice recognition to text using my iPhone's "Notes" application and record my visual impression and attempt to identify the object from unbiased visual observation only. The best way, IMO to avoid "averted imagivision."
After setting up the scopes, I collimated my 18 inch with my 2” Howie Glatter and matching Tublug. Phil collimated the 10” f5 with his 1.25” Kendrick laser collimator. We also collimated my 6” using the laser. Both scopes only have 1.25" focusers. Something went wrong and early evening I could see from a star test that the collimation of my 6" was way off. I suspect that the spring loaded brass pull tubes in my focuser may not have held the laser straight. The laser collimated Phil's 10" fine. With three other scopes set up, I didn’t worry about it, as the light required to visually collimate would have caused an observing hiatus. At f7, I have always found it very easy to do a straight daytime visual collimation. I forgot to do that on Saturday but I did it on Sunday evening during twilight.
We started off each night (predictably) with a quick tour of deep sky gems:-
Orion Nebula (faint rust colour observed in parts of the nebula)
Crab nebula – fibrous texture observed on surface.
M78
Horsehead nebula faint outline just visible in 18”
Tarantula Nebula took a 3D spacewalk using my remarkable 14mm Denkmeier
NGC4755 (Jewel Box)
NGC 3532
NGC 3372 (Eta Carina)
M65, M66,NGC 3628 (Leo Triplet)
M104 (Sombrero)
NGC3242 (Ghost of Jupiter)
NGC 2392 (Eskimo Nebula)
NGC 5236 / M83
M100 bright spiral galaxy in Virgo Cluster
Markarian’s Chain
Omega Centauri /NGC 5139 (bright globular cluster 10M stars)
NGC 104 / 47 Tucanae (bright globular cluster 10M stars)
NGC 5128 / Centaurus A (bright galaxy with prominent dark lane through core)
Then we went prospecting for “gold,” concentrating on a swathe of objects in the constellation of Dorado, many of them, galaxies in the Dorado Group.
NGC 1672 : moderately large, barred open spiral, bright star in core.
NGC 1566 large diffuse face on spiral w diffuse core
NGC 1553, bright condensed face on spiral, I could see two other companion galaxies in the 0.9 deg field of the Nagler 31 on the 18”. One similar in appearance (NGC1549), the other, a much fainter surface brightness, edge on spiral or possibly an irregular galaxy.
NGC 1515. Low surface brightness edge on spiral.
NGC 1533. Observationally, I identified it as a faint face on spiral, possibly barred. In preparing this report, Starry Night ID’s it as an elliptical. Wikipedia describes it as
NGC 1947. Mv 11.65 Appeared to me to be a faint face on spiral not much structure visible. (Actually, listed as a faint elliptical)
NGC 2100 small, low condensation, globular in the Large Magellanic Cloud just beneath the Tarantula Nebula.
ESO 56-73, faint but nicely condensed glob.
NGC1850, 1855, 1856, and 1858 group of four clusters in 0.9 deg field. 1850 and 1858 are open clusters, split in the middle by a globular clusterNGC 1855. 1856 off to the side is another open cluster. All 4 fit easily in the 0.9 degree field.
Comet Kushida 144P: I observed this comet on February 4 with my 6" f7. Fascinating, the visual appearance seemed nearly identical to February through my 18" f5.5. Very nice view albeit slightly fainter through Phil’s 10”. The comet has faded by exactly the same amount as the difference in light gathering between the two instruments.
This is a composite and incomplete summary of three great nights observing. I only recorded the observation of new objects in Dorado and not the visits to many old friends.
We were both feeling quite tired each night, Phil from a long week at work and me from a couple of nights of poor sleep. Knowing we had 3 clear nights, we didn’t overdo it and each night we wound up by around 1:00am-2:00am and spent the last little while sitting in comfortable camp chairs just watching naked eye or using binoculars. There were numerous meteors, many leaving vapour trails. I see a lot of vapour trail meteors out here. think perhaps that vapour trails are common but you need the dark transparent skies and dark adapted eyes to see the trails and you have to be looking up not into a telescope or at a camera display or monitor to see them.
On Sunday afternoon, I washed the 18 inch mirror, in situ without removing it from the scope as described in my DIY section post:
https://theskysearchers.com/viewtopic.p ... 75#p267560
On Friday night, the poor transparency absorbed much of the light from the Orion Arm Milky Way. On Saturday night, transparency seemed to be very changeable on very short timescales. Possibly high very thin cloud. There were also many particulates floating through the air. Large areas not associated with the bright band of the Milky Way would suddenly go from bland and empty to being alive with a sea of faint stars. On the third night, the sky was so transparent that we both noticed that the backyard was much less dark than the first two nights, illuminated by the bright glow of the Milky Way. At the end when we were just sitting in the dark, I was sure I could see with averted vision, one of the outer arms of the Large Magellanic Cloud extending the apparent size of the object to about 7 degrees. Phil disagreed with this. We recognise that though our ages are similar, our eyesight sensitivities and degradation are different. Through a telescope, Phil sometimes sees colour when I don’t, indicating his photopic (colour) vision is more sensitive to low level illumination than mine and perhaps a little sharper at resolving detail. When observing naked eye, my scotopic (low light) vision may be more sensitive perhaps because my distance vision and hence ability to focus light from long distance is better.
All in all, a very satisfying weekend of deep sky observing.
Joe
On Friday night the transparency was quite poor (an understatement). Fires in three equally distributed directions, pollen and other vegetation detritus was so thick floating through the air that my flashlight clearly illuminated it. On Saturday night the air was clearest and on Sunday night, like an orchestra reaching a crescendo, the transparency was quite superb.
Equipment
I set up my 6" f7 Newt and 18" f5.5 Dobsonian.
Phil brought his Takahashi TSA120 and a Hansen Optical Genstar 10" f5 ultralight ultracompact Dobsonian previously owned by Alan Dyer.
Eyepieces:
Joe: 31mm 17mm Nagler, 21mm & 14mm Denkmeier, 10mm Pentax XW
Phil: 22mm Nagler, 21mm Denkmeier, 14mm Denkmeier, 11mm Nagler
My reported observations below are mainly through my 18 inch f5.5. I have avoided describing views through Phil's scopes to afford him the opportunity to report his own observations at a later date. Phil also added my Televue 0.8X focal reducer/flattener to his TSA120 on the 2nd and third nights to do some astrophotography while we observed with the two large reflectors, both of which have optically quite superb mirrors. I deliberately do not read the documented descriptions of new objects. I record my observations using voice recognition to text using my iPhone's "Notes" application and record my visual impression and attempt to identify the object from unbiased visual observation only. The best way, IMO to avoid "averted imagivision."
After setting up the scopes, I collimated my 18 inch with my 2” Howie Glatter and matching Tublug. Phil collimated the 10” f5 with his 1.25” Kendrick laser collimator. We also collimated my 6” using the laser. Both scopes only have 1.25" focusers. Something went wrong and early evening I could see from a star test that the collimation of my 6" was way off. I suspect that the spring loaded brass pull tubes in my focuser may not have held the laser straight. The laser collimated Phil's 10" fine. With three other scopes set up, I didn’t worry about it, as the light required to visually collimate would have caused an observing hiatus. At f7, I have always found it very easy to do a straight daytime visual collimation. I forgot to do that on Saturday but I did it on Sunday evening during twilight.
We started off each night (predictably) with a quick tour of deep sky gems:-
Orion Nebula (faint rust colour observed in parts of the nebula)
Crab nebula – fibrous texture observed on surface.
M78
Horsehead nebula faint outline just visible in 18”
Tarantula Nebula took a 3D spacewalk using my remarkable 14mm Denkmeier
NGC4755 (Jewel Box)
M65, M66,
M104 (Sombrero)
NGC3242 (Ghost of Jupiter)
M100 bright spiral galaxy in Virgo Cluster
Markarian’s Chain
Omega Centauri /
Then we went prospecting for “gold,” concentrating on a swathe of objects in the constellation of Dorado, many of them, galaxies in the Dorado Group.
“NGC 1533 is a barred lenticular galaxy with faint spiral structure in the constellation Dorado. The seventh-brightest member of the Dorado Group and 1°[3] off the group's center,[2] it is surrounded by a vast arc or ring of H I which is connected to IC 2038 and IC 2039.[2]”
ESO 56-73, faint but nicely condensed glob.
NGC1850, 1855, 1856, and 1858 group of four clusters in 0.9 deg field. 1850 and 1858 are open clusters, split in the middle by a globular cluster
Comet Kushida 144P: I observed this comet on February 4 with my 6" f7. Fascinating, the visual appearance seemed nearly identical to February through my 18" f5.5. Very nice view albeit slightly fainter through Phil’s 10”. The comet has faded by exactly the same amount as the difference in light gathering between the two instruments.
This is a composite and incomplete summary of three great nights observing. I only recorded the observation of new objects in Dorado and not the visits to many old friends.
We were both feeling quite tired each night, Phil from a long week at work and me from a couple of nights of poor sleep. Knowing we had 3 clear nights, we didn’t overdo it and each night we wound up by around 1:00am-2:00am and spent the last little while sitting in comfortable camp chairs just watching naked eye or using binoculars. There were numerous meteors, many leaving vapour trails. I see a lot of vapour trail meteors out here. think perhaps that vapour trails are common but you need the dark transparent skies and dark adapted eyes to see the trails and you have to be looking up not into a telescope or at a camera display or monitor to see them.
On Sunday afternoon, I washed the 18 inch mirror, in situ without removing it from the scope as described in my DIY section post:
https://theskysearchers.com/viewtopic.p ... 75#p267560
On Friday night, the poor transparency absorbed much of the light from the Orion Arm Milky Way. On Saturday night, transparency seemed to be very changeable on very short timescales. Possibly high very thin cloud. There were also many particulates floating through the air. Large areas not associated with the bright band of the Milky Way would suddenly go from bland and empty to being alive with a sea of faint stars. On the third night, the sky was so transparent that we both noticed that the backyard was much less dark than the first two nights, illuminated by the bright glow of the Milky Way. At the end when we were just sitting in the dark, I was sure I could see with averted vision, one of the outer arms of the Large Magellanic Cloud extending the apparent size of the object to about 7 degrees. Phil disagreed with this. We recognise that though our ages are similar, our eyesight sensitivities and degradation are different. Through a telescope, Phil sometimes sees colour when I don’t, indicating his photopic (colour) vision is more sensitive to low level illumination than mine and perhaps a little sharper at resolving detail. When observing naked eye, my scotopic (low light) vision may be more sensitive perhaps because my distance vision and hence ability to focus light from long distance is better.
All in all, a very satisfying weekend of deep sky observing.
Joe