[Dr Andrew Smith]

Hi Paul, I would advise you look at what the best images use in the categories you mention.

I am not an expert but a few points.

Modern CMOS cameras can quickly download large numbers of pixels with USB 3

Nyquist does not really apply to area detectors like CCD and CMOS cameras and greater oversampling is needed.

If I remember correctly planetary imagers go for about 0.1as.

Regards Andrew 

[Dr Andrew Smith]

It is a while since I had a Lhires but I would check that the slit is in focus of the doublet.. It is too easy to get it out of focus when focusing the camera.  You will need to do this on the bench with the grating removed.

I don’t see how moving g the mirror will have  much effect.. 

Regards Andrew 

[Dr Andrew Smith]

Opps I got the contamination the wrong way round thanks for pointing this out. I realise the 0 order is not photomericaly clean but in your result it certainly showed an increase. I will try various strategies as as long as I get a signal it is ok as I will save past spectra over a period long enough even if the trigger is a bit late. I am planning to use my past experience of control charts to spot the signal.

Thanks again and for offering to seek out the raw data..

Andrew

[Dr Andrew Smith]

Hi Robin if you still have the raw fit images of your event would you share the  with me then I could try my detection strategy  on them ? I would of cause credit you as an when

Regards Andrew 

[Dr Andrew Smith]

 Hi Robin first idea is to use the zero order flux increase but initially I will just save it all and process off line until I am sure it is robust. The drive on the obs PC is large an fairly empty.

Some late M dwarf stars flare quite often so I will start with them.

Reading up on the flares it seems the flux increase is higher in the U then B etc. going down to low in R.

I will use an IR cut filter to get as far as I can into the U band without contamination. Although  IR cut filters seem to cut UV as well!

Regards Andrew 

[Dr Andrew Smith]

Andy and Eric why do you use both Maxim and the Sky X? Don’t they overlap in functionality? 

Regards Andrew 

[Dr Andrew Smith]

You know what you achieved. Well done.

Regards Andrew 

[Dr Andrew Smith]

I am out of date! A simulation of a WD Type Ia explosion was achieved in 2007.

See here https://crd-legacy.lbl.gov/DOEresources/2008highlights/ASCR_accomplishment_Flash_Center.pdf

[Dr Andrew Smith]

Hi Andy, I think the issue with WD is stopping the accreting  material doing a hydrogen flash on the surface before the mass builds up to the limit. I need to research this area again though to be sure.

Regards Andrew 

[Dr Andrew Smith]

The last time I looked at this in detail we could not get any models of supernova to explode! The art of 3D supernova modeling may have solved this issue but I am not sure. We still have a way to go to pin  this all down.

Regards Andrew 

[Dr Andrew Smith]

Both measurements of H0 the current value if the Hubble parameter rely on physical models which have a fair degree of room for uncertainty. It is fun to conclude new physics maybe required but there is still room for them to converge within our current understanding. 

Regards Andrew 

[Dr Andrew Smith]

” Surely other way round? (longer exposures stabilise against seeing)? I use between 4 and 9 secs…” indeed but…

…  to clarify I have to take short exposures to stop the guide camera saturating. I then use a low gain to prevent chasing the seeing.

By setting the guider aggression quite low it essentially needs to integrate up several exposures corrections before a sizable move is built up. Thus random excursions due to seeing get averaged out by only causing a series of small insignificant corrections. All the guider is doing is correcting for the slow drifts as the Paramount ME II with Protract does a good job on its own.

I agree a slit with it’s bipolar lobes is more difficult a guide challenge than the “hole” presented by a fibre. One reason I never felt happy with a Lhres III  on a Barlowed Newtonian.  

Regards Andrew

[Dr Andrew Smith]

Kevin, there is no magic in pulling the target onto the slit or hole. I just use the standard The Sky X autoguider. I set the center of the hole as the guide star position. Then once the star is placed close to the “hole” by the finding process the autoguide is set going. It assumes the closest object is the guide star and guides it on to the hole.

I am looking at “bright” stars so they are always the only bright object in the guide field. I have to take very short exposures so set the guide settings very “loose” so as not to chase the seeing.

Regards Andrew

[Dr Andrew Smith]

When I started down the road to spectroscopy automation I had and still have the main controlling PC in the observatory and a keyboard and mouse extender over an cat 5 cable to a room in the house. While the main PC ran a script I could interact directly if need be. This worked well when doing a search for possible Be stars looking at one every few minutes.

I also have a cat 5 cable onto my LAN hub and could link via wi fi to any PC in the house using Radmin. 

I now have fully automated the finding and capture process and do longer exposures without the need to inspect in real time. So I run a Python script that does all the work while I do other things. I keep a weather eye on it via a laptop via wi fi but I do find it drops out once a night on average.

Lamp switching is via a USB relay controlled by Python. All else is via two instances of The Sky X.

I think the video of the talk I gave on this at the joint BAA/AAVSO meeting is still available on this site.

Regards Andrew

[Dr Andrew Smith]

I used to lust after the Unitron refractors that were advertised on the back cover in the good old days.

Regards Andrew 

[Dr Andrew Smith]

I assume you mean now as the answer is time dependant.

Regards Andrew 

[Dr Andrew Smith]

No you should not, anymore than I should disregard your advice as it was free!

[Dr Andrew Smith]

Grant , I don’t want to make a big issue of this but I apply Richard Feynman saying:

Have no respect whatsoever for authority; forget who said it and instead look what he starts with, where he ends up, and ask yourself, “Is it reasonable?”

rather than what it cost me.

Regards Andrew

[Dr Andrew Smith]

Grant , 

“I have no doubt it also has a percentage of observers who manage to “see” rather more than their instrument actually delivered and enjoy the immediacy of the applause available.”   a trait shared with Percival Lowell!

Also “clearly just plain biased in favour of stuff they had owned” a passion shared on SGL by a recent President of The BAA and Takahashi!

Of course it’s a forum that does not seek peer reviewed posts and us such needs care in deciding what to take as accurate. However, to condemn it as the worst without justification is committing the offence it is accused of.

There are many fine images posted there and discussions which myself, Robin Leadbeater and other BAA members have contributed to. It does not seek to replicate the BAA but engages a wide audience interested in astronomy. In my view it is better to participate and improve such a form than sit on the sidelines sniping.

Regards Andrew

[Dr Andrew Smith]

Owen as a BAA and SGL contributor, I was interested in how you justify your comment on SGL being “the least credible source of any observational material known” ? Have you done a study or can you provide a credible reference? 

On a different tack, I suspect visual acuity is as important as telescope  aperture, seeing and other sky conditions to observations of the Pup.

Regards Andrew 

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