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The C14 is f/11 whereas the C11 is f/10 so for extended objects he is sort of right but only for sensors with the same pixel size.
Even there, since the C14 image will be (more) oversampled, the images could be filtered to match the seeing (which limits the image resolution here) and then other than some extra camera read noise from the larger number of pixels covered, the two images would contain the same information but the C14 would need less exposure time. I could perhaps even argue that with CMOS sensors the increased oversampling with the C14 might give a greater potential for filtering the non stochastic telegraph noise.
StellaMira refractor, 90mm ED triplet, FL 600mm
ZWO – AISI 1600MM Pro (cooled) camera
This gives a plate scale of 1.3 arcsec per pixel unbinned so unless your seeing is particularly poor you would be undersampled with 2x binning
There is a chap on Astrobin who considered this same project. In the end he decided that an MX+ would just not cut it, so he bought an MEII see
Hi Martin,
at the risk of opening an oft opened can of worms, the quote there
“Interestingly enough, although the C11 has only 60% of the light gathering area of the C14, it has a focal length of 2.79m compared to 3.91m for the C14. It is therefore faster and that varies with the square of the ratio of the focal lengths. Therefore I will end up with a 20% higher signal with the C11”
Is nonsense yes ? (you would get more signal from any target with the C14. it is then just distributed differently on the sensor)
Cheers
RobinHi Jack,
I am intrigued to know what the application is with two similar scopes like this on the same mount pointing at the same target
Cheers
RobinIt seemed a bit like a “where’s Wally”. Tonally, it blended into the background or perhaps it is just me.
No I could not spot it either but my wife had no problem seeing it and could not understand what the fuss was about ! As far as I am aware I don’t have defective colour vision but it needed a strong light for me to see it easily.
Yep I am using ANSVR with Windows 10
Have I missed a setting somewhere ?
Yep finally found the unticked checkbox. On to the next step…
The dimmed spectrum divided by the current spectrum (green)
Attachments:
The H alpha emission I mentioned in the VSSC article on RW Cep (and referenced in the paper) has also reduced in the past 3 months as the brightness increased so it looks like it is associated with the dimming.
Cheers
RobinAttachments:
Too low for a spectrum from me but here is one by Christian Buil this morning
https://groups.io/g/Solex-project/topic/101209364
The usual emission bands but not much dust and no obvious sodium despite it being close enough to the sun, at a similar distance to this spectrum of 2020 F3
https://britastro.org/observations/observation.php?id=20200713_224000_2e77e0992eb70386Cheers
RobinAn interesting article on SN 2023ixf. (Well known supernova expert Prof Alex Filippenko was showing people M101 at a star party 11 hours before discovery but did not spot it !)
https://news.berkeley.edu/2023/08/29/releases-20230828-6895045
(Hat tip to Rigel7 on cloudynights for this)Cheers
RobinI managed to squeeze in a high resolution spectrum last night in twilight before it dipped into some trees. The decreasing Equivalent Width of the H alpha emission line reported in ATel #16214
https://www.astronomerstelegram.org/?read=16214
is confirmed by the spectra in the BAA database.Cheers
RobinAttachments:
If it follows the usual IIP type trend I expect it will now continue in a shallow decline dependent on radioactive decay
Robin
I see from the light curve the slow steady decline (~2 magnitudes in V over 70 days) has come to an end and the brightness is now dropping rapidly (~1.5 magnitudes in 12 days) This behaviour is similar to that seen in type II-P supernova following the plateau period so SN 2023ixf may have characteristics of both type II-L and II-P, similar to supernova like 2013by discussed in this paper for example
https://arxiv.org/abs/1501.06491v2Cheers
RobinI guess the noise floor in the signal received at Voyager must be pretty high, aimed so close to the Sun ?
Voyager 2 is currently around 160au away so the Earth is always within 0.35 deg of the Sun
That prompted me to grab a virtual pencil and back of envelope. So to the unaided eye from there the Sun appears star-like (unresolved at just ~12 arcsec diameter) and ~mag -15.7, ~15x brighter than the full moon.
I like the way NASA phrase it as a “Communications Pause”
https://blogs.nasa.gov/sunspot/2023/07/
Though the Independent is reporting that it can still be heard at least
https://www.independent.co.uk/news/ap-earth-nasa-cape-canaveral-california-b2385612.htmlMartin Lewis takes some absolutely superb planetary images with his Dobsonian mounted telescopes. The rings of Uranus and surface detail on each of Ganymede, Mercury, and Venus are among some of his achievements.
But the list is supposed to be the best telescopes for astrophotography. I doubt if you polled astrophotographers (planetary or deep sky) they they would put this scope as the second best for astrophotography (or for that matter the one placed top of the list.)
Does someone get a payment if you click though to amazon on these links ?
It is difficult to know where to start. The website is riddled with misleading nonsense. For example here
https://astroimagery.com/equipment/telescopes/best-telescope-for-astrophotography/#research-what-telescope-would-you-recommend-for-astrophotography
in positions 2 and 7 here you have a Dobsonian mounted scopes which are not suitable for astrophotography and the description does not match the scope.I apologise if I am wrong but the main purpose of this website appears to make money not to inform.
Robin
