[Aavso-photometry] Chart id's

[Richard 'Doc' Kinne]

Folks:

Let me jump in on this a bit. I need to get a bit more of a presence  
on the discussion lists. Aaron, correct me if I say something wrong.

On 21 Jul , 2008, at 10:52, Kate Hutton wrote:
> Wheww ... this system may be easier for the IT staff & I'm sure it  
> is, but
> the user/observer now lacks a basic & intuitive piece of  
> information ... how
> old is the chart I'm using?

That's easily answered, Kate. How old is the chart you're using? When  
did you call it up, or print it out? Literally, that's how old it is!

As Aaron said, there are no set charts anymore. The charts that you  
get are made on the fly from the latest information in the database!  
We're constantly (ask Arne! :-)  ) tweaking and uploading new  
sequences into the DB based on the latest photometric work either  
we're doing, or that we have access to. While this is practically not  
the case, of course, each chart could change on a daily basis - or  
even more often!

At the user's end, you can now call up a chart that is specific to  
both scope, limiting magnitude, or just photometric sequences.

> Does not using the date as a chart identifier uniquely determine  
> the sequence?

Nope.  :-)  Because EVERY CHART IS POTENTIALLY UNIQUE! The chart I  
bring up on SS Cyg this afternoon using an "F" scale and a limiting  
magnitude of 11 is going to be different from the chart you bring up  
tonight of SS Cyg using a "C" scale and a limiting magnitude of 8.  
However, since each chart has a unique ID, we'd be able to replicate  
the chart here in HQ and figure out that Doc had actually transposed  
the magnitude of one of his check stars so, no, SS Cyg has NOT gone  
nova, Doc just needs new glasses.  :-)

At the same time, its possible that between the time when I called up  
the chart and you called up the chart new sequences were uploaded to  
the DB. Does that make past observations invalid? No, since with each  
"chart's" unique ID we can reconstruct the comparison sequence of  
that chart.

> Guess I don't really understand the reason
> for this change.

The reason, simply, as we like to say here at the AAVSO, is that the  
firehose is starting to turn on!  :-) When I first observed variable  
stars (which was not all that long ago!) I remember using charts that  
were 20 years old and based on charts that were hand-drawn. And, 20  
years ago, that was the state of the art. Now, with the survey  
telescopes we have online now, to say nothing of the ones that will  
be coming online in the next 5 years, in order to give you, our  
observers, the correct data YOU need in order to give us the data WE  
need at HQ, we need to keep up with that data flow somehow. And the  
way to do that has been to create an on-the-fly way of creating  
charts for our observers that could change faster than any way we  
could produce charts in the past.
---
Richard 'Doc' Kinne, [KQR]
American Association of Variable Star Observers
<rkinne @ aavso.org>