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At a conference I am at, some observers from a small university observatory in the Virgin Islands reported visual counterpart observations from a system that is in the 0.5m league – though their sky is rarely below 20.5mag and despite the fact a cat 5 hurricane was about to hit.
They – and several other teams – caught it reasonably quickly via the alert system.
Heres one that might help…
https://www.metoffice.gov.uk/binaries/content/gallery/mohippo/images/migrated-image/2/avgrain1.jpg
Not cloud as such, but associated…
The problem boils down to what do you image/draw/observe.
If its planets then almost anywhere away from a town is good.
If deep sky then choose the dark area on the Philips dark sky map. In addition, you need to start looking at cloud cover figures – I found some on line a year or so ago (do not recall where). I recall Norfolk way being good and having lower rainfall than most the country, but I’m not sure how it did for fog.
We were surprised how much cloud the Welsh borders got when we lived there. Its within the cloud shadow of the Welsh Mountains. Beautiful place to live, but you can get long runs of no blue sky.
Personally I would rather have a couple of really dark clear nights a month than four mediocre one.
There is a great feeling of satisfaction when closing down for the night as the dawn starts to brighten the sky. Though its often accompanied by thoughts like “Arrgh. I’ve got to be at work in 4 hours.”.
In that case, could the ship owners claim salvage rights on the Harrier? That must have been a fair amount.
My copy of Covington’s book suggests that at f/11 and 400ASA/ISO, an exposure of about 1/250th is about right for prominences and 1/15th for corona. Well worth bracketing from 1/1000th down, but how are you mounting the camera? Driven? Undriven. Fixed tripod?
Handheld and without autofocus and stabilisation, the suggested minimum exposure for a half decent photographer in the film days was 2/FL where FL is focal length in mms or, in this case, 1/200th of a second. But a tripod and cable release should improve on that by nearly a factor of 10 I think.
For 1999 I went from 1/1000th to 1/20that 400ASA. Pics were a little soft, but usable.
But really we need an expert like Nick James who has seen total eclipses more times than most. 🙂
A once a month 120s shot of Gyulbudaghian’s nebula would be very welcome in the Deep Sky Section I imagine….
Looked for Mayak with 10×50 bins during the 00:06 pass tonight and saw nothing. Sky was hazy so limiting mag 6.5-7.0 but nothing seen at all. I assume it has yet to deploy.
Has anyone had any luck yet?
Am I reading this right? Its a accumulating signal from a bunch of short exposures, stacking them and then displaying the result on a small screen inside an eyepiece? Quite neat then. Impressive in something so compact.
No different to looking at your laptop screen of course but easier to work with.
“Mayak will stay on orbit for one month. After termination of term of use it will be deorbited and burnt in the atmosphere.”
That was on their website. I take that to mean it will exist as a simple cubesat for a while (a month?) and it will collect data. Then when that mission is achieved it will deploy the sail to deorbit. I imagine a month also gives them a chance to get a good handle on how the orbit would decay without the sail, so that after deployment the change becomes more apparent.
Cubesats can be pretty dim so an up to date TLE, good pointing accuracy and a GPS system setting your system clock are essentials for a tracking system.
It may even be right.
I observed the Canadian CanX-7 satellite which had a smaller solar sail deployed and during one pass it became as bright (for a second) as Regulus – perhaps because it was pretty obviously tumbling at that point.
Should be worth a look. Is there a date yet for when it deploys?
An image of C/2017 k2 at mag 18.9 and 15.9AU from the Sun. As seen through thin cloud (was supposed to be clear but clouded while I was setting up – not exactly uncommon round here) with a 10″ RC and Trius 694 camera.
I additive stacked 120s exposures tracked at star rate only. The variable transparency would have played hell with a median stack.
The position is close to the prediction in RA but – if Astrometry.net is right – not quite right in Dec. My SNR was too poor for a clearer assessment.
The frames need to be aligned on the comets motion for a better result.
That sounds like IRAF. I recall trying to fit a high order polynomial to a dataset and IRAF crashed inelegantly. I had asked for a higher order than the data would permit but, rather than tell me so, it just died instead. Its very powerful, but assumes that those using it don’t do things that are daft.
Its worth learning…
Cannot say whether there was a GUI. You would think so after all these years but professional astronomers are perfectly happy with personalised batch files processing chains akin to a DOS .bat file. Its us Windows users who have gone soft 🙂
I was struck by how obvious the 17th mag SN was, despite being seen against the spiral arm.
Taken with a Starlight Trius 694 and an Altair 10″ RC. 8x 60s exposures centred on 224139UT on 26th May 2017.
Yes, lasers can mess up CCDs – if you dump enough coherent energy into a device it is no big surprise they can fail.
I’m not sure what the energy density required is though.
I assume they are worried that a visual observer who happened to be looking down the barrel of a space based LIDAR laser beam might suffer eye damage if looking directly at it through a large telescope using the naked eye. CCDers would not be under threat.
Afterall, even if you were using a laser of a wavelength generally deemed “eye safe” then the light grasp of a 12″ could massively increase the number of photons reaching your eye.
EDIT: Should have read the very end of the survey. They are indeed trying to model the risk to ground observers.
