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Have you downloaded the complete GCVS? If so a preliminary selection based on a minimum Dec, a plausible range of RA and a type of EA, EB, … will give you an initial range of candidates.
What do you consider high-cadence? Minutes, seconds or milliseconds?
My 0.4m telescope (located only about 100km from El Teide) could manage a very few millimags precision (unfiltered CCD, so approximately Gaia G band) down to mag 11.5 with a cadence of around a minute as demonstrated with an observation of an exoplanet transit.
In fact, why don’t you try for an exoplanet transit? Not only do you get your differential timing data, you also add to our knowedge of exoplanets. The minimum may be wide but the ingress and egress events are short-lived and it’s generally possible to observe both in a single session.
Would you like me to join in perhaps, weather permitting? It’s been unusually cloudy in these parts of late. I also need to get the new camera commissioned first but I hope that doesn’t take too long.
I thought it was just me until your post. It appears under Chromium, the free version of Chrome, on this Ubuntu system. Not yetchecked with Firefux under Ubuntu.
I hope long time Usenet afficionados here recognize the Subject line It’s quite a while since I last saw it on a net posting but these days nostalgia doesn’t seem like it used to be. Such cultural references should be preserved IMHO.
That is seriously bad news from my point of view. Can you point me to sources of information about the incompatibility of these two components please?
If it’s seriously the case it will be much easier for me to continue with Win7 and insert an old PC configured as a nailed-down firewall between the observatory and the interweb thingy.
Added in edit: just found https://www.cloudynights.com/topic/515833-windows-10-and-maxim/ — opinions seem mixed. Some had serious troubles, others had none.
Thanks Eric.
In my case I’ve a bunch of additional cards in the PC, serial ports mostly, which may not work in a new system so I’m averse to swapping the hardware given that it appears to be working well.
I wasn’t sure whether to revive this thread or start a new one but then plumped for this. Background: today is the re-awakening for my W7-Ultimate observatory controller. Windoze Update just brung over 66 updates (it’s been asleep since April 2 after all) and a dire warning that security updates will not be available after January 14 2020. Actually, Enero 14 2020 because it’s a Spanish install but we know what it means.
The material posted above indicates that W10 home should work fine but it isn’t clear whether that is through a fresh install or after upgrading from (presumably) W7. Can anyone set my mind at rest please? The hassle of re-installing everything anew is daunting so I’d much prefer to upgrade.
Thanks, Paul
I have that book but it never occurred to me that the lunar maps were the ones under discussion. They are indeed beautiful and practical, not that I ever look at the moon through a telescope any more.
Added in edit: I forgot to mention that I have the French translation.
Andrew has turned down my offer of free hosting for the BAA, including power, internet and tech support.
The pad is still available, either to a private individual (in which case I would charge the same as Kevin now pays and would provide the same service) or for at most a peppercorn rent to the BAA if the observatory were to be used for charitable purposes.
We’re flying out in 36 hours time. LP isn’t as easy to get to as GC or TF, I fully agree, but it aint that difficult either. There are direct flights once a week from MAN and LGW. On this occasion, all the flights LGW->SPC were fully booked. From where we are in Cambridge, STN is a much nicer option anyway, so we are taking Ryanair STN->LPA and then Binter for the LPA->SPC hop. Really not that difficult.
Don’t know whether it is relevant, but I have a spare concrete pad in La Palma. It’s 4m square, around 20cm thick and has been used by a European university physics department as the site of a robotic telescope. Power and ethernet are laid on but there is no other infrastructure right now. A Google maps image is available at https://www.google.co.uk/maps/@28.6419037,-17.8677037,123m/data=!3m1!1e3 which shows the orange circle painted on the slab. To its left is Kevin Hills’ robotic observatory and to its right is mine.
Musk has already stated that they’re looking at darkening the satellites. Unfortunately, painting them matt black will end up cooking the electronics by solar heating.
The LSST software stack has an implementation in Python. I installed the stack a couple of weeks ago — a not entirely trivial exercise but that’s another story. The learning curve is going to be a hard climb. The tutorial is good but limited.
There a number of ways. A common way is to estimate the background noise at each pixel after defect, dark and flat processing. A (relatively) simple way is to tile the image with a number of sub-images, (say 64×64 pixels by way of example) and compute the pixel histogram of each tile. Assuming that the majority of the pixels are sky and a minority are stars, discard the top 10% or so (which are presumably the stars) and fit a Gaussian to what remains (presumably the background). That Gaussian determines the sigma of the background at that point. Then interpolate (by whatever means, by a biquadratic fit, perhaps, or with cubic splines) to estimate the sigma at each pixel. The weight map is then 1/(sigma^2).
(Typo alert: undersampled to be precise…)
See also https://en.wikipedia.org/wiki/Drizzle_(image_processing)
“Drizzle has the advantage of being able to handle images with essentially arbitrary shifts, rotations, and geometric distortion and, when given input images with proper associated weight maps, creates an optimal statistically summed image.” and “Results using the DRIZZLE command can be spectacular with amateur instruments.”
Richard Hook and I were at Oxford together. He recently retired from ESO and we’re in frequent email contact.
A quick searcn turns up one for which I only have the abstract as the full text is behind a paywall.
Optimal Addition of Images for Detection and Photometry, Authors: Fischer, P ; Kochanski, G P, In: Astron. J. 107 (1994) 802-810
Abstract:
In this paper we describe weighting techniques used for the optimal coaddition of CCD frames with differing characteristics. Optimal means maximum signal-to-noise (s/n) for stellar objects. We derive formulae for four applications: 1) object detection via matched filter, 2) object detection identical to DAOFIND, 3) aperture photometry, and 4) ALLSTAR profile-fitting photometry. We have included examples involving 21 frames for which either the sky brightness or image resolution varied by a factor of three. The gains in s/n were modest for most of the examples, except for DAOFIND detection with varying image resolution which exhibited a substantial s/n increase. Even though the only consideration was maximizing s/n, the image resolution was seen to improve for most of the variable resolution examples. Also discussed are empirical fits for the weighting and the availability of the program, WEIGHT, used to generate the weighting for the individual frames. Finally, we include appendices describing the effects of clipping algorithms and a scheme for star/galaxy and cosmic ray/star discrimination.
Two much more recent papers I have read in full are https://arxiv.org/pdf/1512.06872.pdf and its sequel https://arxiv.org/abs/1512.06879 which specifically treat optimal co-addition.
Sigma clipping destroys photometric accuracy. If all I want is a pretty picture I tend to use median stacking but for scientifically useful images that’s only an option for astrometry.
I use 30s subs, so bad images can be discarded with out losing too much data, but need to use arithmetic mean co-addition for the great majority of my work.
