Trapezium – the journey from ugly duckling to beautiful swan?
Hello,
Here is a series of images of the Trapezium in Orion captured at 1:00am on 16th October 2007, showing the processing steps from single raw frame through to finished product.
Takahashi Mewlon 180 F12 with Vixen x2 Barlow.
DMK 21AF04.AS CCD camera.
The target was approximately 40 degrees above the horizon, with the seeing estimated to be between 5 and 6/10.
The (heavily) processed version looks nicer than the single raw frame and to my eye, retains much of the fidelity of the original data. Maybe beauty is in the eye of the beholder?
Theta 1 Ori, Magnitude: 5.13
AB: 5.13+6.35 mag, PA 312° Sep 12.87"
AC: 5.13+7.2 mag, PA 56° Sep 13.12"
AD: 5.13+7.49 mag, PA 342° Sep 16.87"
AE: 5.13+6.4 mag, PA 134° Sep 135.30"
EF: 6.4+7.5 mag, PA 92° Sep 52.50"
Thanks Dave. Next time, I’ll save myself a lot of bother and just take a photo, in a coal cellar, at midnight, of 6 white dots of varying sizes judicially placed on a black velvet background – seems a lot less trouble and so much easier!
I try to avoid blooms in the first instance as I find them very hard to get rid of. When I do get them, they are usually minor and the de-bloom function in Maxim DL seems to do a reasonable job, although the worse cases also require a manual touch up in CS3 on a per star basis.
It seems there is no such thing as a free lunch in CCD imaging!
Ok, (insert deep sigh) that's what I figured, try to avoid them and save data. How effective (from a signal/noise ratio perspective) is taking multiple Track and accumulate images and then combining them as compared to trying to get multiple long exposure as long possible before blooming and then combining them?
I’d always choose the self guiding option over Track & Accumulate, and run some test exposures to establish the blooming threshold, and then select an exposure just shy of that.
T&A is very nice, but you will get gradual drift and sometimes I encountered streaks when applying Darks to T&A images.
Once you’ve had a go at self-guiding, it becomes quite easy, especially as you have the TC237 chip. I only have the meagre TC211.
I'm still to take the plunge with self guiding Dennis. I'm actually cheating a bit with the T&A, I'm still relying on the trusty ol' ToUcam and K3CCDTools to autoguide while I experiment with the imaging side of the SBIG. In fact I'm still using CCDOPS rather than CCDSoft (too scary for me atm. I know I'm a woose ) I'll take your advice onboard next time and see how I go with the long exposure shots.
Your image is a very good illustration of the differences in light gathering capabilities of differing Focal Ratio systems. With the Mewlon operating at F24, and a frame rate of 5fps, I did not pick up G and H, even though the DMK is more sensitive than your unmodified ToUcam.
Assuming your GSO 12” dobsonian has a Focal Ratio of say, F5, this makes it a more “sensitive” system as F5 is “faster” than F24, irrespective of the differences in aperture of the scopes. So, it is not the 12” of glass that works here, but the faster Focal Ratio, enabling you to easily capture the fainter components E, F, G & H.
Your image is a very good illustration of the differences in light gathering capabilities of differing Focal Ratio systems. With the Mewlon operating at F24, and a frame rate of 5fps, I did not pick up G and H, even though the DMK is more sensitive than your unmodified ToUcam.
Assuming your GSO 12” dobsonian has a Focal Ratio of say, F5, this makes it a more “sensitive” system as F5 is “faster” than F24, irrespective of the differences in aperture of the scopes. So, it is not the 12” of glass that works here, but the faster Focal Ratio, enabling you to easily capture the fainter components E, F, G & H.
Cheers
Dennis.
Dennis, it isn't only a matter of f ratios and sensitivity with Trapezium. It is also a BIG matter of timing.
A & B are eclipsing binaries
'A' drops to mag 7.65 every 65 days
'B' drops to mag 8.65 every 6 days
G, H, and I are all variables. In the image above (the best I could get over many months) I was unable to image 'I' as it must have been at its weakest intensity.
I attempted for months to get all 9 stars, but as I saw 'I' appear, 'B' had slightly faded, and 'H' was completely gone and 'G' was very very faint.
It's a mathematical game that I gave up on after many months
One day I hope to get all 9, but I think it will be a timing fluke
Here’s a nice reference site for anyone who wants to have a go at this beautiful multiple star system.
Cheers
Dennis
PS - Great photo too Bojan!
Thanks..
This was actually a preparation for my attempt to record some of those runaways (http://arxiv.org/pdf/astro-ph/0506002), and I still think it is possible, considering my Qcam is modified (it uses TC237 CCD chip without any filters, so it is IR sensitive)
Of course, it was not a success that time, but maybe sometimes in the future it may happen, with longer exposure (this one was 5x10sec only).
Thanks..
This was actually a preparation for my attempt to record some of those runaways (http://arxiv.org/pdf/astro-ph/0506002), and I still think it is possible, considering my Qcam is modified (it uses TC237 CCD chip without any filters, so it is IR sensitive)
Of course, it was not a success that time, but maybe sometimes in the future it may happen, with longer exposure (this one was 5x10sec only).
Hi Bojan
Thanks for the link. I Googled the “Jones & Walker Catalogue” and ended up at the ADC/CDS Standard Document for Catalog: /journal_tables/AJ/113/1733/ where I read:
“Approximately 50% of the ~3500 stars identified to date within ~2.5pc of the namesake Trapezium stars are optically visible,”
Well, with ~3500 stars optically visible, I have a long way to go!
I was originally after a “pretty picture” of the 6 main stars in the Trapezium, A B C D E & F. After seeing Ken’s “pumped” version, I went back to the 2 AVI’s I had captured and re-processed them to see what was lurking in the data.
In doing so, I managed to locate stars G & H which are shown on both AVI’s, lessening the chance that they are noise or processing artefacts. Thanks for the nudge Ken!
Excellent work Dennis, I always enjoy viewing the Trap area and I like how you've presented it here.
Also thanks for the link.
I was lucky enough to view it through Rod's 20" which blew us away last Saturday night and also though Astropolak's (Joe) Binoviewer on his 10" Meade LX200R which looked like it was in 3D.
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