Is anyone contributing observations to Sissy Haas’ Uneven Double Star Project?
Sissy launched this project a few years ago with the objective of determining by observations only, the minimum apertures that will resolve specific combinations of separation and magnitude differences for double stars. It is an observation based project to find the answers, not a theoretical/formula based approach. Sissy wrote an update to this project in the Australian Sky & Telescope in Jan ’16 in which she provided the table of target test pairs and progress to date. Many of these doubles are in our southern skies and from the article and results to date you can see that Sissy is seeking more observations from the Southern Hemisphere.
I have been contributing observation for the test pairs over the last two years. I have found it a rewarding project as it fully extends one’s observing skills given one is seeking to observe at the resolution limits of the scope being used.
I have been able to contribute positive observation reports for 11 of the test pairs to date using my Vixen ED103S. It has been slow progress waiting for the test pair to be in a favourable position and for weather and seeing conditions to cooperate. The most challenging observations to date have been psi Ori (3.0” separation and magnitude delta 4.0), h3874 Pic (2.5” separation and magnitude delta 3.5), kappa Lep (2.0” separation and magnitude delta 2.5) and Dun39 Car (1.5” separation and magnitude delta 1.0).
There are four test pairs remaining on the list that are potentially resolvable by the ED103. They are: 3 Mon (2.0” separation and magnitude delta 3.0), Struve 1171 Cnc (separation 2” and magnitude delta 3.5), theta Gru (1.5” separation and magnitude delta 2.0) and Struve 2303 Ser (separation 1.5” and magnitude delta 2.5). I am just waiting for the test pairs to be as close as possible to culmination and the right seeing conditions to see if I can bag these.
Four of the test pairs in the 1” separation category are targets for southern observers and I am seeking to split these test pairs using my NA140SS. These test pairs, in increasing order of difficulty, are Hrg 47 Car (delta mag 1.5), 41 Oph (delta mag 2.5), 42 Ori (delta mag 3.0) and 8 CMa (delta mag 3.5). Again, am just waiting for the right conditions.
Anyhow, just interested to know if any other double star enthusiasts are targeting these test pairs and reporting their results to Sissy Haas.
Sissy Haas' every publication and project seem to draw as much enthusiasm as scorn. The theoretical and practical limits of double star observing are apparently a perennial hot topic.
I'm all for empirical evidence, in the end that's the sword by which scientific theories live or die.
The months since I've done any double star observing myself are now numbering in the double digits. I'm grateful for any mention of the subject
Sissy Haas' every publication and project seem to draw as much enthusiasm as scorn. The theoretical and practical limits of double star observing are apparently a perennial hot topic.
I'm all for empirical evidence, in the end that's the sword by which scientific theories live or die.
The months since I've done any double star observing myself are now numbering in the double digits. I'm grateful for any mention of the subject
Hope that you do get back in to double star observing Steffen , your contributions would be very welcome.
It seems also that a lot of measurements can be inaccurate and have indeed been ( even some by none other than William Herschel ), if done by inexperienced observers; who would first need to train their eyes to estimate star separations , resolution exit pupils needed etc.- so I think these sorts of contributions should best be left to very experienced observers like Steve and perhaps yourself.
This endeavour requires enormous patience, which I don't possess and you must have in abundance Steve!
It would be great to hear of others who have done their seeing homework on how to actually use their scopes and EP's for this task and not just the things I highlighted in another thread, there's so much more to being a capable observer for this; in short it requires a lot of skill and patience.
Knowing what the Airy Disk and Diffraction Rings will look like in one's scope setup: the correct Exit Pupil and magnification needed : determining your diffraction limit in one's scope: Dawes Limit: the effect seeing will have on all this etc, etc.
I hope others with young eyes will do just this and take up this challenge.
This endeavour requires enormous patience, which I don't possess and you must have in abundance Steve!
It would be great to hear of others who have done their seeing homework on how to actually use their scopes and EP's for this task and not just the things I highlighted in another thread, there's so much more to being a capable observer for this; in short it requires a lot of skill and patience.
bigjoe.
Yes, in my mind it is all about patience, persistence and practice.
My observing experience for each of the difficult test pairs that I referred to earlier, e.g. kappa Lep (2.0” separation and magnitude delta 2.5- actual delta 2.4) maybe of interest, as I guess it reflects patience and persistence.
Initial observation was negative. At this point I cycled through available higher powers (re-focusing carefully each time) to see if there are any signs that a different magnification would be better. After settling on a target magnification, I settled in for some patient observing to see if any transient improvement in seeing and/or transparency revealed anything. I did not record the time spent, but I doubt that I would have spent more than 30 minutes waiting and observing. At some point I saw a possible sighting of the secondary. From then on I have focused on this and waited for further sightings. Seven regular brief sightings of the secondary occurred in moments of better seeing in a relatively short period of time. At this point I have ceased observing the target to record the event and have then moved onto my next observing target.
In cases of difficult targets my personal discipline is to seek 7 sightings before I record it as a successful observation, just to minimise averted imagination.
A couple of other things in my mind that are important for success, that build on the things you have highlighted:
Accurate focus is everything. I have a home made, soft touch 17:1 fine focus on each of my scopes. It allows for very accurate focusing.
Rock solid, smooth mount that just “gets out of the way”. In my case, a TRex with home made long flexible manual drive cables.
Observing chair and warm clothing. One sees more when sitting steadily at the eyepiece. Plus one needs to be comfortable to observe patiently for extended periods at the eyepiece.
Knowledge built up over time of the apparent visual separation for different actual separations for each eyepiece.
So much depends on (a) the observer and (b) the type of scope used that I would regard this project as a waste of time. Sissy has seems blissfully ignorant of these factors. Andrew James did this topic to death decades ago - there a table by Robert Atkins which lists this.
So much depends on (a) the observer and (b) the type of scope used that I would regard this project as a waste of time. Sissy has seems blissfully ignorant of these factors. Andrew James did this topic to death decades ago - there a table by Robert Atkins which lists this.
There is also a formula for unequal doubles, she's not doing anything original.
Maybe not a waste when the advancements in optics are considered: Fluorite Lens, Triplets as well as better reflectors available compared to home ground mirrors some decades ago.
Then, there are EPs to consider.
Nah, projects like this are never a waste and if they are... well there is no harm as everybody is giving their time freely and increasing their own knowledge during the project.
The laws of optics haven't changed, Bob. There's nothing special about modern scopes compared to ye-olde refractors at f/15.
I like the idea of longer focal lengths myself...but, they not always either available or practical.
Some years back I stopped down a 6" F8 reflector to 30mm (off axis, off course), which effectually made it F40. I split Epsilon Bootes so was very impressed. The other notable feature was that the depth of focus at this F Ratio was incredible; it seemed to be in sharp focus when I racked the EP in & out for over 5mm.
I often thought this was worth investigating further, but so far, have not....
[QUOTE=Tropo-Bob;1235043]I like the idea of longer focal lengths myself...but, they not always either available or practical.
Some years back I stopped down a 6" F8 reflector to 30mm (off axis, off course), which effectually made it F40. I split Epsilon Bootes so was very impressed. The other notable feature was that the depth of focus at this F Ratio was incredible; it seemed to be in sharp focus when I racked the EP in & out for over 5mm.
I often thought this was worth investigating further, but so far, have not....[/lengt
So much depends on (a) the observer and (b) the type of scope used that I would regard this project as a waste of time. Sissy has seems blissfully ignorant of these factors. Andrew James did this topic to death decades ago - there a table by Robert Atkins which lists this.
There is also a formula for unequal doubles, she's not doing anything original.
I think you are over complicating Sissy’s original objectives for this project and it's intended use. Sissy was well aware of the issues you raised and the many other potential variables, in her original briefing materials and I don’t recall any claims from Sissy that this would be original work.
Irrespective of whether Sissy is able to draw useful conclusions from the data sets obtained, it has been a worthwhile exercise for myself.
It has provided a useful set of test pairs that has helped me systematically develop my observing skills at close to the resolution limits of the scopes being used. I am gaining a much clearer picture of the capabilities of the equipment that I am using and, of course, the many factors that affect that performance. Plus, I now have a much better visual appreciation of what to expect at varying combinations of separation and magnitude differences for my scopes and magnification options for the eyepieces I have.
In fact last Saturday night I managed to successfully split two further test pairs on the list. These have got me a step closer to the resolution limits for my scopes and my eyes. First was Hrg 47 (Car) at 1.2” separation and magnitude delta 1.6 and second was 3 Mon at 1.9” separation and magnitude delta 3.0. Both observations were with a 140mm refractor.
I think you are over complicating Sissy’s original objectives for this project and it's intended use. Sissy was well aware of the issues you raised and the many other potential variables, in her original briefing materials and I don’t recall any claims from Sissy that this would be original work.
Irrespective of whether Sissy is able to draw useful conclusions from the data sets obtained, it has been a worthwhile exercise for myself.
It has provided a useful set of test pairs that has helped me systematically develop my observing skills at close to the resolution limits of the scopes being used. I am gaining a much clearer picture of the capabilities of the equipment that I am using and, of course, the many factors that affect that performance. Plus, I now have a much better visual appreciation of what to expect at varying combinations of separation and magnitude differences for my scopes and magnification options for the eyepieces I have.
In fact last Saturday night I managed to successfully split two further test pairs on the list. These have got me a step closer to the resolution limits for my scopes and my eyes. First was Hrg 47 (Car) at 1.2” separation and magnitude delta 1.6 and second was 3 Mon at 1.9” separation and magnitude delta 3.0. Both observations were with a 140mm refractor.
Steve.
I totally agree with Steve, this project has been the best fun and a terrific opportunity to learn and hone observational skills.
I think the highlight for me is that thanks to training myself to split pairs of stars with uneven brightness helped me to see my first ever supernova. The one recently in Centaurus A which was close to a foreground 8 magnitude star. That was way cool.
Another benefit, I have finally come to appreciate angular separation at various magnifications. A very useful skill.
Why not help someone with their endeavours (crazy or not) if you're having fun and learning things.
I would certainly urge everyone to have a go at it.
I like the idea of longer focal lengths myself...but, they not always either available or practical.
Some years back I stopped down a 6" F8 reflector to 30mm (off axis, off course), which effectually made it F40. I split Epsilon Bootes so was very impressed. The other notable feature was that the depth of focus at this F Ratio was incredible; it seemed to be in sharp focus when I racked the EP in & out for over 5mm.
I often thought this was worth investigating further, but so far, have not....[/lengt
+1 for depth of focus from long focal length
bigjoe
Yep, another added bonus. When I first tried to contribute observations to the uneven doubles project all I had were a 10" and 14" dob. Sissy actually suggested stopping down the 14 with aperture masks. I never thought of it myself. Anyways, after a few very fun hours doing arts and crafts with my 5year old, I had a mask cut out of cardboard giving me 150mm and another 10 smaller masks to go on top of the big one to stop down further in 10mm increments. Please see attached photos.
The significance here is that if you have a big bore dob, you can participate as well.
By way of example, with HRG47 I was able to see the faint companion down to 120 mm direct and 110 mm with averted vision. For 3 Monoceros direct vision down to 130 mm, averted 110. Between 100 and 90 I call it a ghost zone where I think I see the fainter star, but not sure. By 80mm the faint companion is invisible for certain.
Like I said, lots of fun. Admittedly if you have a goto/tracking scope it helps a lot as you can play around with different apertures eyepieces etc.
Wow, seeing the Centaurus supernova is quite a feat. Well done. It is well beyond the reach of my scopes.
Steve
Thanks Steve. All I can say is that aperture wins every time. Oh yes, and a dark sky.
Had to drive with the 14" an hour outside of Brisbane to see it. I didn't go out deliberately for it. Much to my shame I didn't even know about the supernova. It was one of our regular dark sky trips with the Brother in law. Luckily he knew about it and we gave it a go. I could only perceive it now and then and only with averted vision. Nevertheless when we looked at the photo online after to confirm our sightings, there it was. Awesome!
I will confess that my dedication to the uneven doubles has its limits. I'm happy to do it from my suburban backyard, but i don't spend precious dark sky observing time on it.
The laws of optics haven't changed, Bob. There's nothing special about modern scopes compared to ye-olde refractors at f/15.
Oh, I don't know about that... I m probably skating on thin ice here (I'm still a relative newbie) but here goes anyway:
22 years ago I had the privilege of looking through Percival Lowell's 24" F/16 refractor. The guides had it pointed at Jupiter that night for us tourists. It was awesome, but the views I get through my 14" F/4.6 dob are amazing.
Ok, yes it was 22 years ago but I'm blown away by just how much detail I can see in my humble dob. For example, I can always easily see the GRS when it's facing us, I know that's obvious, but it's all the little details like the white band around it separating it from the main belt and also the vortices in the main southern belt trailing the GRS.
I can't deny that at the high ( probably too high) magnifications I like to look at the planets I will only get 5-10 seconds of clear seeing for every 30 seconds before the "syncan" nudges the dob again. But those 5 seconds are so worth it!
For what it's worth I reckon the combination of fast dobs and the super glass like Televue and ES has really changed visual observing for the better.
