[AZ-Observing] Re: Astroman Site

>Jeff,
>    Thanks for visiting my web site.  Let me know if you find any dead links,
>ok?
>   Nicola Tesla was no doubt the most significant electrical engineer of the
>20th century, without whom the industrial revolution would have been
>impossible.  If you need to know anything about him or his work, don't
>hesitate to ask me.
>   When you say, "less accurate CCD data", I assume you are aware that every
>single professional observatory worldwide is now using CCD's in favor of
>outdated photomultiplier tubes.  Your fine book and research
>notwithstanding, you of course would know this. Vast strides in CCD
>technology have taken place since 1990, (the copyright on your book, which I
>have in front of me.)  I can only guess at the reason for it.  Perhaps you
>can shed some light on this?
>   As for "real" data acquisition and publishing, as you have read my
>website, I can only figure you haven't reached the part about my membership
>in the AAVSO, and the GCN.  Credit for data is routinely given AAVSO members
>in professional journals, and it is routine also for AAVSO observations to
>trigger satellite observations through "TOO's"-Targets of Opportunity. 
>Satellites which use CCD's, btw.  In case you don't know, the GCN takes the
>detection of gamma ray bursts from satellites and distributes them to a
>network of mostly amateur astronomers in the hopes one of them will be in
>position to look for early optical transients of the event.  Photometric
>measurements are taken and volumes of data are used in conjunction with
>later professional data to give a complete picture of the event.  Pros are
>almost completely unable to image GRB's at the drop of a hat, unlike
>amateurs such as myself.  Timing is everything in the GRB world, and only my
>aperture and location on the planet stands in the way of even lowly me
>taking the next GRB discovery image.  If I happen to be in the observatory
>at the time of an alert, even my small scope and "less accurate CCD" could
>have enormous value.
>   Kindly temper your condescending tone.

Hello Steve,

Thanks for your response.

Tesla was indeed a most interesting man and actually far more 
important than the more popular Edison.

Much has changed since 1990 and much has remained the same. While CCD 
photometry has become popular is also has drawbacks, one of which is 
accuracy and the other is wavelength. BTW, PMTs are not outdated! 
They still can detect a single photon and are used extensively in 
high energy physics.

I belonged to both the AAVSO and IAPPP for many years. I also have a 
list of over 3 dozen publications, many of which are in professional 
astronomical journals.

I have a copy (.pdf) of the AAVSO CCD Photometry Handbook. If you 
don't have a copy and would like one I can send it to you or you can 
just get it off of the AAVSO site. I also have several other CCD 
publications that may be of interest.

It is readily acknowledged that CCD photometry can be accurate to 0.2 
m and with some work 0.1m and with lots of work maybe 0.01 m. Typical 
PEP differential photometry easily exceeds 0.01 m and very often 
exceeds 0.001 m. I know, I have hundreds of observations. Some were 
collaborated by a friend in Norway with data taken near the same time 
as mine with differences less than 0.001 m.

The other problem with CCD photometry is wavelength. Most variable 
stars are typically stated as UBV and in recent years extended into 
the infrared region. The solid state detectors shine in the IR band, 
but are fairly insensitive in the B and not sensitive in the U bands. 
There are many very interesting things that can be learned about a 
star with U and B data. Unless you are willing to spend a great deal 
of money and effort, you will not get a CCD camera that works in the 
U band and is very sensitive in the B band. Note B work can be done, 
but sensitivity and accuracy will suffer.

I have not been involved with the GRB project. I would think that 
accuracy and the shorter wavelengths would be most important to the 
project, however.

So, I don't feel my tone was condescending, but accurate. :-)

Are you interested in some photometry collaboration with Stan and me? 
I think Gene Lucas may get involved too. CCD photometry is most 
welcome and perhaps I will learn some new things.

Jeff




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                                      Jeff Hopkins
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