Forum Replies Created
-
Posts
-
I’m curious as to how you make a weight map. Are they looking at the darks, flats and defect maps or doing something more sophisticated? Drizzle normally works best though with large numbers of oversampled images doesnt it?
What does that do to the photometry? Doesnt drizzle interpolate values with a bicubic spline or something?
Thanks for that. I shall have a look at it. The appendices sound the interesting bit.
I have always felt people are careless with median stacking. Transparency changes can have a huge impact on the results – simply normalising the backgrounds isnt enough, normalisation of the signal received is necessary too if you want to do things thoroughly (so some sort of gain correction is necessary). I tend to avoid really long exposures and median stack images in sets of ~10 and then coadd all the resulting frames.
Thanks. Will give that a go when we get a clear night – though the forecast in Salisbury is cloudy for a most of the next 3 days.
Are they really ready for operations that fast that they are already ion driving? Thats a pretty quick shakedown.
So you give it an externally sourced template/reference to aim for? Isnt that dangerous?
Can understand running the process and getting an improved result and using what that processing generated as your template/reference for an iterative process.
But using imagery from some other source means the result is not led by the data itself.
I would imagine the impact of the noise varies depending upon how the wavelet transform is implemented in Registax. A large chunk of the image being replaced with a single value would certainly change the frequency spectrum and has reduced the total dynamic range within the image.
The pixels on the planet will still contain readout/sky noise, but that is a lot less obvious when on top of the brighter background provided by the planet.
My first inclination would be to wavelet first and apply any threshold afterward, but I’m probably over cautious.
Hi Chris,
Any chance of seeing one of your SQM from a clear moonless nights? Would be curious to see the shape it takes.
Grant
I used a Meade LS-8 a couple of years ago. That was a case of shove it on the tripod, put tripod outside, plug in and flick switch. It handled all the leveling, north finding, GPS location/time and pointing refinement with an attached built in webcam. Failed 1 in 10 times and took about 10 mins.
You can take image of up to about 30s (threw away about 25% of pics) before field rotation trails the stars and its fine for planets. Got some quite nice pics with one using a Starlight H18.
Worth considering. Its doesnt get any easier – unless you go for a permanent set up. Richard Miles has an impressive solution…
I imagine whether it is bad news depends upon who buys it.
In recent years it had become a pale shadow of its former self.
Theres at least one USB relay on Amazon that can be run via a simple serial port command (but which plugs into USB). If not done in Python its only a few lines in VB6 to create an executable that opened or closed the relay. It even has a small LED on it so you can see the relay status.
I must admit I too was tempted until I saw it was in York. Its just too far away for me. About 5hrs continuous traffic-jam-free driving or 4.5hrs on the train. Could stay for the weeknd but have other commitments.
Britain is big and, in the past, meetings have too often been in the south, so I am certainly not complaining.
Looking forward to enjoying the videos from a comfy chair.
Is that real football or the other sort?
Perhaps play it safe and measure in perch, rods and chains*?
* For those unfamiliar with the joys of the archaic Imperial units. A chain is the same length as a cricket pitch 🙂
Isnt his raising an objection at this late stage a conflict of interest?
Also,someone not far from here and had a Meade LX200 in his observatory – which was in a conservation area. He appears to have got round it by making the observatory walls out of stone and flint (local materials) and making the roof dark.
