Hi everyone,
This my first image posted here, I have been taking quite a few shots with a Meade LPI on my 150mm Reflector.
This image was taken in March of this year, at f/15 and is composed of 100 shots at 1 sec and stacked in Maxim DL 5.
I visually slpit this hard double last year around the time Jonathan Bradshaw from AAQ captured the split with his scope and imaging equipment. I don't think any body believed me that I got the split with a 150mm Reflector...well here is proof..
Without knowing too much about your equipment, field of view, set up for this image etc., at face value, the smaller star looks far too bright to be a candidate for the Pup, Sirius B? With the 150mm F5 at F15 (using an x3 Barlow?) you’ll be shooting at 2250mm?
Just for comparison, here are a couple of images I took. The 1st one shows Sirius A & B at an effective focal length of 8640mm and the 2nd one is a prime focus exposure through my Vixen 4” at F6.3 showing some brighter field stars.
If you can establish your field of view and measure the separation between Sirius A and the brighter star in your image, it might give some insight into what you have managed to capture? The current separation is approximately 9 arcsecs.
Not trying to rain on your parade, especially given that you’re a Queenslander, but the secondary in your image looks awfully bright!
Hi Dennis,
Well I can not be positive that this was taken at f/15 it could be f/25 as I was also using two barlows in conjunction on the same night. I didn't record any specificates of the equipment I used for the shot, just the date, I will have to learn to record my information of my shots for future reference.
So I am uncertain as to the focal length used but I have split this visually twice now in this instrument on extremely clear nights so I do believe this is the pup, the photo has been enhanced quite a bit in Maxim DL 5. When the photo was in its raw state the pup was not visible in the shot and only appeared after tweeking it quite a bit.
If it is not the pup then what is it???? any ideas. I know of no stars this bright next to Sirius?
My 150mm has a focal length of f/5 and the Meade LPI has a approx focal length of 6mm, combine this with a 3xbarlows and a 2xbarlows.
I have not calculated the field of view of the LPI, but when this dust storm (cough cough cough)moves on I will check it out and let you know.
Rod
When I first saw your image, what struck me was the brightness of the secondary star and what appear to be diffraction spikes on that same star.
So, as I’m just at a computer screen looking at a 2D B&W image, that’s about all I can really say as I wasn’t there on the night, so I really don’t know. What I have written is just my guesswork and some speculation but gee, I’d be so very happy for you if that were the Pup!
I guess one approach would be to establish the apparent field of view and we can do this at F15 and also F25 and plug the numbers in, assuming you were using the Meade LPI, and this is the full frame. The FOV would be something like the following, based on a chip 640x480 with 7.5 micron pixels:
150mm F5 with x3 Barlow giving 2250mm at F15:
FOV is 7.3 x 5.5 arcmin at 0.69 arcsec/pixel.
150mm F5 with x5 Barlow giving 3750mm at F25:
FOV is 4.4 x 3.3 arcmin at 0.41 arcsec/pixel.
So, using a separation of 8.75 arcsecs for Sirius A & B;
At F15 the Pup would be some 13 pixels from Sirius A,
At F25 the Pup would be some 21 pixels from Sirius A.
Hope that helps and mate, thanks for not spitting the dummy ; as I previously wrote, my comments are pure speculation and only my best guesses, and thus do not detract from your work at all.
Hi again Dennis,
Thanks for the info, all is welcome and I have no problems with any comment, we are all here to learn and understand, if I'm mistaken, well, I will learn from the mistake.
I myself am a member of AAQ and have posted this image there as well. David Odriscoll replied soon after and advised me that you know your stuff ....... He also recommended that I keep more accurate records which I thouroughly agree with....still learning the ins and outs of this wonderful Science even at the age of 52.
He feels that the best judge of the image would be Jonathan Bradshaw who has previously imaged this split last year.
I will still try and work the field of view out at the time of the shot, hopefully I will get an accurate idea of the seperation in the image. If it turns out not to be the split I was hoping on then I will try again.
But just a piece of interesting info on my first split of last year of Sirius. I was using both a 150mm Reflector and a Meade 8" LX10. I could not see the split in the Meade LX10 because of the bright defraction rings that you get in excellent seeing, the pup was totally washed out by the rings, but in my reflector I had deliberately turned the tube so that the spikes where not in the apparent position of the pup and not cover it, I feel this was one of the main reasons I was able to get the split besides the excellent seeing condition at the time. I found out this method from one of the issues of Aus Sky & Telescope last year when they had an article on how to split
Sirius, not to sure what issue? It was implied in the article that a 150mm scope should have no problems spliting it but it was the brightness of the primary that made the split extremely hard.
I helped with the resolution survey that Tim Munn of the AAQ last year conducted on double stars, and I did split a few that I should, by rights, have been extremely hard with the 150mm but not impossible, a lot, as you know depends on the seeing and the colmination of your scope, I keep my 150mm extremely tight in the colmination area, and check it every night before use. So far I have not had the seeing conditions like the ones I did when I splt Sirius, the condition where unbelievably still and clear, and amazing.
Once I work the field of view out I will post the results here under this post.
.....soon after and advised me that you know your stuff .......
Rod
Hi Rod
Whilst I know some stuff, it is only stuff related to my own gear and how it behaves, which is why it can be challenging to comment on the work of others and also why I try to tread carefully and with respect!
I just copied and pasted your image into CS3 and enlarged the region around Sirius to measure the separation and came up with a distance of approx 13 to 15 pixels. So, if this is the Pup, it would suggest you were using the x3 Barlow.
I’m still really puzzled by the brightness of the candidate star, as well as the diffraction spikes around it?
Oh well, the measurement indicates that the Pup should indeed be at this distance, assuming the 150mm F5 with x3 Barlow and Meade LPI, according to my calculations.
I’d certainly be very interested in the observations and analyses of others too, it all adds to our collective knowledge.
Hi Dennis,
I really do appreciate all your help on this, obviously I have to keep more accurate records in future. As for using the 3x Barlows lens for the shot, that would make sense as this is my first choice for Double on this instrument. I did tweek the image in Maxim DL but I think I only used a little bit of wavelet filter which made it brighter? but beside strech (brightness/contrast), that was it, I have not touched it in photoshop CS3 yet as I didn't think it needed it.
The only other double I have imaged over the months like this is Antares but I checked all these images and they don't match the date or time of this shot.
Next time Sirius is up and I'm up and the skies are clear I will get another few more shots, one good colour RGB shot would be nice.
Rod
When I first imaged Sirius and the Pup (feb 08 I think) it was met with some scepticism in the double satr world as it was largely thought to be impossible. I have to add, that I made the observation purely by chance as I was stuffing around with my telescope and had just swung it on to Sirius as a conveniant bright thing.
I think the scepticim was justified as there had been many claims (I was to discover) that were totally bogus - and they are still out there!
Even though I could reliably repeat the observation, I still needed to rigorously justify the method - something I did by taking reference images of canopus - a bright non-double, and taking images at differnt times of night to show the rotation caused by my alt-az mount.
It certainly taught me to make an log of observations as I always do now. And I think that the riggor is justified too.
In Rod's case, the image is as I would expect which is a good thing. It will be a even better when he repeats the exercise in the next few months. 'Onya Rod
For those tuning into this thread the separation in 2010 season is now so large that it will be a much easier target photographically, and possibly visually. I expect to see lots of great images cropping up. It is 24 years since the separation was this great - way before digital imaging.
Hi Dennis,
As for using the 3x Barlows lens for the shot, that would make sense as this is my first choice for Double on this instrument.
Rod
Hi Rod
I’ve imaged Sirius A and B through my Tak Mewlon 180mm and Celestron C9.25 and those results produced a much fainter Sirius B, albeit at the much longer effective focal lengths I was operating at.
However, I must confess that although I have heard about the wonderful images to be had from quality, well collimated Newtonians, I’ve never owned or looked through one; hence I might just be guilty of being blinded by my experiences limited to the Tak Mewlon and Celestron SCT? Hmm, methinks a good quality Newtonian might well be my next ‘scope!
Based on the image measurements, FOV calculations and assumptions I have made, plus your obvious skills and experience, located at a distance of 13 to 15 pixels you have an excellent candidate for having recorded the Pup. It certainly is by far the brightest recording I have ever seen, hence my initial uncertainty.
Congratulations, and please accept my apologies for my initial, probing uncertainty.
Hi again,
Thanks for your imput Jonathan, and your use of a standard to compare the split is an extremely valuable bit of science. I should know better as I come from a chemistry field, lab work etc where we use standards or Media Blanks as we call them, something to reference against. I will do this next time to check for any aberations or reflections from the barlows.
Dennis you have been great with this and I really appreacited the input and and the help. I have found that SCT scopes can produce extremely bright diffraction rings on bright stars on nights of good seeing (the Meade 8" LX10 showed me this), and hiding any faint secondary. Where with a straight colminated Newt that the tube can be turned in the mount rings, So the spider that causes the spikes don't hide the secondary. An excellent trick, and found very effective a number of times when previously the spike would hide the secondary.
Generally I will not check the current position (angle/seperation) of any double prior to trying to get the split, so if I get it I generally check what I get with what it is suppose to be. If I don't get the split I try and turn the tube to make sure it's not covering it's supposed current position and try again. As I knew where the approx position of the pup was from my previous observation I made sure the diffraction spike wouldn't cover it.
I'll hopefully get some more imaging of this wonderful double with a comparison image (standard) in the next few months.
I'll post what I get here, as Jonathan said there should be a few such images starting to appear when the Dog Star rises in our skies over the next comming months.
Rod
Well, I’m now left wondering if I have been going down the wrong path after seeing yours and Jonathan’s images?
I chose to use a x4 PowerMate to give me a longer effective focal length to provide a "greater" separation between Sirius A & B, based on the much increased image scale. This approach has certainly recorded the Pup as a much dimmer object in my images so I’ll attempt the split gain, but at the native focal length of 2160mm of my Mewlon 180 and see what I get.
This has been a very insightful and enjoyable investigation and discussion – thanks! I might even break out the 4” Vixen and give it a go with that, as I have successfully split Antares visually and using my Meade LPI with the 102mm aperture.
Gentlemen, a very interesting thread indeed and as it seems congratulations are in order to Rod.
I found the 2 sites below of interest and thought I would share them as they provide some useful information, the first has a nice reperesentation of the position of the Pup in relation to Sirius over a 50 year period. It is also interesting to note how the authors sought and received an opinion from the USNO in relation to their 2002 image.
PeterM. http://www.integram.com/astro/Sirius.html http://scott-logan.org/SkyWatch.php?ArticleID=221
Hi eveyone,
I have some bad news for you for, especially Dennis, you were right to query the brightness of the pup in the image, I found out there is another object that's accidendently aligned over the top of the pup....
The story is (this is hard ) when I was imageing earlier in the year I was very in experianced with this device and more importantly with the after processing of the captured images.
At the time of this shot I did not truely understand the concept of the RGB fits files and combined all the best images regardless of there RGB designation into one Black & white image.
It was not till a bit later that I woke up to the use of these in combining them into coloured images.
I also was not up on the stacking and alignment process and was still teaching myself this process and didn't understand what was happening especially with auto star matching.
Since then I do have a lot more understanding of what can happen as I have seen some very strange and weird results, which I usualy scrap.
Anyway to make this clear about the photo below... I went looking for the original fits files but looks like I deleted them, all I have left (not anymore :x ) are four previously stacked images which the header says are composed of 37 stacked images.
I am quite surprised I didn't see this in the stacking process but when I looked at some of these individual files with the screen streach up this what I got........ http://www.rodroger.com/rr/images/as...us_stuffup.jpg
I swear to you all that I did not do this on purpose, this is something Maxim DL 4 has done. To me it looks like it has some how decided to overlay some of the frames (which didn't have the pup?) over the pup, effectively overlaying the primary over the fainter seconday. What the @#%^%
This why it is so bright, but makes this shot of the split worthless. I feel like a real idiot, truely shows my inexperiance what a learning experiance this has been.
Oh well I am going to have to go back and image this again. Pitty I can't find the original fits as I know now I can fix this stupid stupid mistake.
I am so embarressed by this - SORRY GUYS , what can I say.
Rod
Last edited by rodroger; 24-09-2009 at 02:40 PM.
Reason: image not showing in post
I am so embarressed by this - SORRY GUYS , what can I say.
Rod
Hi Rod
Mate, no apologies needed and thanks for the update – your investigation and subsequent report is an excellent example illustrating how difficult it is to be certain about what we record and importantly, how re-visiting the data can often help to provide alternate conclusions.
I think that this has shown how fabulous Ice In Space can be for collaborating in this manner, sharing our experiences, thoughts and assumptions, liberally sprinkled with our best guesses too!
The brightness of the candidate star and its diffraction spikes really did trouble me but when I weighted this “personal opinion” against the “measured data” of some 13 to 15 pixels separation, I decided to come down on the side of the data which just goes to show how difficult these investigations can be.
That you remained open, honest and willing to have another look at the data is a true credit to you Rod and in my opinion this shows real character and integrity – well done.
I’m sure that next time, you’ll nail the Pup! Rod, it has been a pleasure discussing this topic with you and I also learned much by going over my old data and looking at yours. No harm done and we are all the wiser, how good is that!
Hey Rod,
An even more interesting thread - a process started, opened to the IIS community, a hiccup it seemed, then through trial and error a resolution came about, and everyone has learnt something, now that's what I call great work. I thought you had bagged it. Congratulations are definitely in order for your determined investigating, your follow up and the update.
Dennis is right you are among friends here.
PeterM.
Hi,
I am overwelmed by everbodies support, thats what I love about Astronomy, it's not just the science, it's also the lovely people you encounter.
I still do not really underatand why Maxim DL 4 decided to align the image like this??
I have seen some weird alignments but this takes the cake. What possed it to do this I don't know unless the pup was in the image and its decided align some images I had missed that where not very good, and decided that it was the fainter seconday.
Anyway I have here some images I have processed that are more accurate in the alignment situation.
The first is the jewel Box Cluster taken with my 150mm @ f15.
on the 4/06/2009 and is composed of approx 55 red, 55 green & 55 blue frames combined into the coloured image and sharpened and then tweek in Photoshop CS3. http://www.rodroger.com/rr/images/as..._150mm_f15.jpg
The next image is of NGC6231 in Sorpio 150mm/f5, on the 29/04/2009
The fishes Mouth - part of M42 inculding the famous four - 150mm f5. This was taken a around feb 2009, I have cropped the image and enhanced it with wavelet filtering and has treated with Lucy-Richardsons deconvolution.
This is a mosaic of last thursday imaging of Jupiter 17/09/2009 @21.40
203mm Meade LX10 f50 Meade LPI and is composed of aprox 90RGB images. I used wavelet filtering and Lucy-Richardson Deconvolution after combing the R G B seperately in there RGB groups, I then colour combined then, exported and tweeked in photoshop CS3. I then made the mosaic in Paintshop Pro 7. The Blue looking one at top left was from a seperate exposure where I used a Ultra High Contrast Filter for effect.
The various examples are different methods of combination, sum, average, SD Mask, Median & Sigma Clip. I won't list them here unless you are interested but have recorded this data.
Nice work Rod. I’ve still got my Meade LPI which launched me into Lunar & Planetary imaging. I still have fond memories of how (relatively) easy it was compared to the more complex and computer intensive processes when using my DMK cameras, Registax, Photoshop, etc!
Sirius split with my 150mm Reflect
; as I previously wrote, my comments are pure speculation and only my best guesses, and thus do not detract from your work at all.
Whilst I know some stuff, it is only stuff related to my own gear and how it behaves, which is why it can be challenging to comment on the work of others and also why I try to tread carefully and with respect!
) when I was imageing earlier in the year I was very in experianced with this device and more importantly with the after processing of the captured images.
what a learning experiance this has been.
