[Grant Privett]

Had a look at the last two papers. It all looks pretty straightforward – though the devil will be in the detail as they themselves admit, care is needed to ensure the implementation is robust against residual defects, cosmic rays and artefacts. Would be fairly easy (though fiddly) to implement in something like Python – shame some of the commercial packages go for the simple solutions only – its not as if CPU and memory is expensive anymore.

It was surprisingly familiar as I saw similar methods presented at an SPIE conference in 2003 or 2005 (cannot check as work went “smart working” a year or two back and lots of conference proceedings got thrown out when we lost book shelves) where there was a session on dim source tracking techniques. 

Will have a look at the other paper on Tuesday and report back.

[Grant Privett]

Hells teeth!

[Grant Privett]

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?

[Grant Privett]

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. 

[Grant Privett]

Thats interesting. Is there a paper you could refer me to on that?

[Grant Privett]

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. 

[Grant Privett]

Are the TLEs on Heavens Above yet?

[Grant Privett]

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.  

[Grant Privett]

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.

[Grant Privett]

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

[Grant Privett]

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…

[Grant Privett]

Weather down south also looks poor. Moon will be full too.

[Grant Privett]

Personally, I would go with mending the dome. Better solution long term.

[Grant Privett]

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.

[Grant Privett]

Does the measurement depend on how you look, or where you look? They are quite distinct things.

[Grant Privett]

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.

[Grant Privett]

Whats a bus in furlongs?

[Grant Privett]

That does look rather nice.

[Grant Privett]

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.

[Grant Privett]

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 🙂

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