Article: Transit of Mercury - Observing/Imaging Guide
Hi all
Dennis has written a fantastic article on preparing for the Transit of Mercury on the 9th November 2006, called Transit of Mercury, 2006 - Observing/Imaging Guide.
Anyone wishing to observe or photograph this event should read this article, as it contains loads of practical tips and considerations to help you out.
You can find the article on the IceInSpace Projects page (under Astronomy & Observing), or directly by clicking on the link below:
Here is the FOV for the C9.25 at F10 (Prime Focus) with my Pentax *ist DS DSLR.
I have also been trying to compare the imaging performance of the C9.25 with a full aperture solar filter and my Vixen ED102S 4” F9 refractor with a full aperture solar filter. Due to clouds and time constraints, I haven’t been able to image through both systems on the same day, at the same time.
However, here is a C9.25 F10 Prime Focus image from 24 Oct (2350mm fl) compared to a Vixen 102mm f9 with x2 Barlow image from 25 Oct (1840mm fl). Both were taken with the Baader Astrophotography Solar Film (3.8) and the Philips ToUcam. I estimate that the seeing was around 4 to 5 out of 10 for both images.
The C9.25 was difficult to focus and the image on the screen never really looked sharp during the avi capture.
Finding focus with the Vixen refractor with x2 Barlow was markedly easier and there were several fleeting moments of reasonable clarity during the avi capture.
I would like to take side-by-side images with the C9.25 at F10 (2350mm) and the Vixen 102mm with my x2.5 Powermate (2295mm) and compare the results. But – there are no sunspots on the Sun right now…..
So, based on this single sample, it does appear that the 102mm refractor out performs the C9.25 during mediocre seeing in the day time. I know there are other factors to consider, such as “was the C9.25 perfectly collimated", "was the seeing the same", etc, but interesting early results I would say.
The last transit of mercury i had seen was way back in 1993 at Tebbutts Observatory at Windsor, NSW.....i remember looking through the 8"SCT they had there and it was bloody hot in that lead-lined dome!
Very nice it was though, and i can still smell the place! Had a beeswax smell about it......
What sort of result would I achieve using the ToUcam at prime focus in the 9.25???
Many thanks
Hi Matt
I just re-read your question…correctly this time…
The C9.25 + ToUcam (2350mm fl) will have a similar FOV as the Vixen 4" + x2.5 Powermate + ToUcam (2300mm fl), so have a look at Figure 2 in the article as a comparison. The FOV will be approx 6 x 7 arc mins, compared to the Sun’s diameter of 32 arc mins.
Update 02 - Some images from 6th Nov 2006, Brisbane.
Hi
Image 1:
It’s a bit ugly, but here is a 2 pane mosaic of Sunspot 921 from today, 6th November 2006. Images taken from Brisbane using a Vixen 4 inch refractor, Televue x5 Powermate, full aperture Baader solar filter and Philips ToUcam 840K. The seeing was quite awful and the little detail I was able to rescue is a testimony to Registax’s capabilities. I have estimated the apparent size of Mercury based on the following calculations:
FOV of a single pane is approx 3x3 arc mins = 180x180 arc secs.
Mercury = 10 arc secs in diameter.
Image 2:
The next image is with the same ‘scope and ToUcam, but using the x2.5 Powermate.
Image 3:
The final image was taken through a WO 80mm f7 ED Triplet with a Pentax *ist DS DSLR and a x2 photo teleconverter.
Images captured between 9:30am and 12 noon, in between cloud cover.
Cheers
Dennis
Today’s lessons:
Be prepared for clouds and poor seeing. So don’t forget to enjoy the paltry crumbs that may come your way, rather than regret what may have been.
If you plan to be observing/imaging from 5:00am to 10:00am, PLEASE have some shelter nearby – a parasol, sun tent or something to give you respite from the heat.
Daytime Paul, and I agree Dennis's examples are a really good example of sharp imaging! image 3 could hold a clue for the timing paul
Whoops - I edited the post in response to Paul's question re timing, but the edit status did not change? Oh well, at least we know Paul's not got a bad head as well as a bad back! Get better soon Paul.
Article: Transit of Mercury - Observing/Imaging Guide
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