[Dr Andrew Smith]

One issue with relative intensity spectra in that where you place the normalisation region significantly effects the plots. 

In effect you force the changes to be other than at that point. I don’t  think the is a simple solution but requires going to absolute flux as described by David Boyd.

Regards Andrew 

[Dr Andrew Smith]

Very modern using nm. Fine observations. 

Regards 

[Dr Andrew Smith]

I have just been reading the new paper and they are relying on the centriod of the spectral line to distinguish PH3 from SO2 in the 0.3 k/s range. While I feel sure they will have corrected for the Earths velocity as that would be standard for stellar work, I can’t  find any reference to correction for the motion of Venus. Does anyone know if this was done.

Also the high wind speed on Venus could shift the line if it did not average out in the measurement. 

Regards Andrew 

[Dr Andrew Smith]

If you have a CMOS camera be aware it has two possible problems with bias frames.  First, amp glow is not linear with time. Two CMOS can have different readout modes for very short exposures such that extrapolating “long” dark frames of different lengths back to zero time does not give the same value as a “short” bias frame.

Regards Andrew

[Dr Andrew Smith]

As always Robin nice work. Looks very good match. Regards Andrew 

[Dr Andrew Smith]

Looks like life is slipping away. I wonder if the same will happen to water on the bright side of the moon?

Regards Andrew 

[Dr Andrew Smith]

It seems the alma data has been withdrawn temporarily while they review the initial calibration. It is not known if this will impact the results.

Regards Andrew 

[Dr Andrew Smith]

Doubt cast on the reliability of the alma signal https://arxiv.org/abs/2010.09761

Regards Andrew 

[Dr Andrew Smith]

I don’t  think there us a simple answer . There are design equations but it depends on the details of the optical design. With  moving mirror focus where the primary moves it can vary considerably. Can you be more specific?  Do you have a particular scope in mind?

Regards Andrew 

[Dr Andrew Smith]

Try launching a second copy. This creates a new .ini file does it have the same issues?

Regards Andrew 

[Dr Andrew Smith]

Did you remove the user files? It is probably a configuration error. Normally in Documents  Software Bisque TheSkyX Professional Edition. Try Renaming the file and installing again. I assume you have not kept up your subscription. 

Regards Andrew 

[Dr Andrew Smith]

Yes Robin, I have used it. Valerie, was kind enough to respond to my questions on what some of the numbers were. It gives similar results but you have to watch the extremes of the data set as when you have low frequency wavelets you need a way of managing the boundary. Visual Spec clearly does this in a simple way and you can get artifacts.

Regards Andrew 

[Dr Andrew Smith]

And a possible geological mechanism https://arxiv.org/abs/2009.11904

Regards Andrew

[Dr Andrew Smith]

Not sure if DUT1 = UT1 -UTC us what your after but look at the International Earth Rotation Service IERS. It may have what you want.

Regards Andrew 

[Dr Andrew Smith]

If you read the “hypothesis paper” you realise that the life would need to be just as exotic, if not more so, than any chemistry to produce PH3.  

A third possibility is the have miss identified the line which given the technical challenges seems possible. I think they too easily dismissed  SO2 as a source of the line. 

Regards Andrew 

[Dr Andrew Smith]

Hi Robin, I had a play with you DN Gem spectra. Filtering confirms the lines you picked out. The noise residuals look good.

[Dr Andrew Smith]

Thanks Paul, I have sent you the data I used in the example as requested by email and I look forward to what you discover. I looked at the Wiki on S-G and will look up D-W.

I am looking for something I can reliably program as I can have a hundred or more spectra per flare to process. The noise profile changes with observing conditions e.g.moon light so as simple and reliable as possible is good.

I used Matlab as I had it from a previous project not tried R but will look at it.

Regards Andrew

[Dr Andrew Smith]

Had a look at the S-G smoothing and like many filtering approaches it requires you to set parameters which I can find no obvious method of fixing other than by eyeballing the results.

While you need to set the number of layers in the wavelet multi spectral approach it uses noise modelling to set the thresholds on the filters at each layer. This together with the visualisation makes it simpler for me to assess the results.

It does seem to be the modern approach, see Astronomical Image and Data Analysis  by Starck and Murtagh.

Regards Andrew 

[Dr Andrew Smith]

No as I had not heard about it. I will investigate. What I like about the multi spectral approach is you can clearly see what is happening at the various levels.

Regards Andrew 

[Dr Andrew Smith]

Not too much of an issue for me as I am not doing serious photometry. Just using it to spot flares. I then calibrate the relevant images and extract the spectra. Thanks for the comment though.

Regards Andrew 

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