[Aavso-photometry] Reporting Data, Guidelines for a new person?

[Jim Jones]

Hmmmm

Something strange going on.  I sent  my answer via aavso-photometry.  
Guess I should have "replied to all" instead just to the list.

Jim Jones

Richard Huziak wrote:

>Here you go, Ed :-)
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>rick
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>Jim Jones wrote:
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>>Hi Ed
>>
>>Welcome and glad to see you made it over here.
>>
>>Since Miras don't change very fast, I normally take enough images so 
>>that after I get done stacking to get the SNR that I want, I have 5 
>>stacked images to analyze.
>>Then I report the average of the five as the magnitude (a single value) 
>>and the standard deviation of the 5 as the error.  Just like reporting 
>>double stars.  The 1/SNR error is probably one of the least accurate 
>>methods to calculate error but sometimes that is all you have.  Having a 
>>good SNR isn't a guarantee that a particular image might not have a 
>>problem that gives you a flyer.
>>
>>As far as flyers are concerned, I always plot the check star.  If you 
>>have a flyer, it usually will show up in the check star.  Sometimes you 
>>get an observation that is out in left field even though the check star 
>>looks good.  If it is really out in left field, I throw it away (talking 
>>about Miras).  If it is just a little out, I include it in the average 
>>and take a hit on the error.
>>
>>Many of the comps on the Mira Charts are not very accurate.  So I 
>>sometimes also use a comp that another CCD observer has used (assuming I 
>>am satisfied with the other observer's choice of comps).  Probably no 
>>good reason except that it tends to make a "prettier" light curve ;>}.
>>
>>Time series error is more complicated.  I'm sure you will get lots of 
>>comments and suggestions.  There is also a bunch of stuff in the 
>>Aavso-photometry archives on this subject and it is probably worth going 
>>back and reading it.  As I remember, you are using Canopus...doesn't it 
>>calculate an error for you?
>>
>>Beware, variable stars are at least as addictive as double stars.  You 
>>are you going to wind up observing all night and analyzing data all day.
>>
>>Jim Jones
>>
>>Ed Wiley wrote:
>>
>> 
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>>>I am just getting into variables. I am starting with CCD V-filter photometry
>>>on some selected Miras that have recent observations that I can use to
>>>compare my results. (So far, so good or at least reasonable!).
>>>
>>>My regular work is with neglected double stars, where I report the average
>>>of four observations (position and angle) and the standard deviation.  
>>>
>>>However, I understand that (and why) the AAVSO needs single observations
>>>with one comparison star for standardization. I am now taking a minimum of
>>>3-4 images. So, a bit of advice would help me considerably.
>>>
>>>1. Consulting Quick Look I have not found a case of more than one
>>>observation reported for the Miras I am following. Does this mean that the
>>>usual protocol is a single CCD image? I would feel a bit strange if I was
>>>the only person who was posting, say, say, three V magnitude estimates taken
>>>at 5 minute intervals. But, I will not feel strange at all if this is the
>>>correct protocol.
>>>
>>>2. If I have an obvious "outlier," perhaps due to a hot pixel or some such
>>>thing, should I drop that measure, given that it does not agree with the
>>>other 2-3 measures.  For example, of three measures I took of RCom, one
>>>deviated considerable: 13.51, 13.50, 13.42, but since all have excellent
>>>SNR, the "errors" were all small.
>>>
>>>3. Any standard way of measuring accuracy error for a series. For example,
>>>computing standard deviation using pairs of companion stars?
>>>
>>>4. If so, should I put comments like "series of four images, SD +/-..." in
>>>the comments section.
>>>
>>>5. I am taking a "monkey-see-monkey-do" attitude towards picking companion
>>>stars. I have noted in playing around that V-mag estimate can vary
>>>considerably by picking different comparison stars, even those close in
>>>magnitude (no doubt due to color differences). So, I am going with what
>>>seems to be what others have picked for the stars I am measuring. I assume
>>>this is a good thing.
>>>
>>>Many thanks for any advice and answers!
>>>
>>>Ed Wiley
>>>Remote Astronomical Society Observatory
>>>http://www.remote-astronomical-society.org/
>>>
>>>
>>>
>>>
>>>------------------------------------------------------------------------
>>>
>>>_______________________________________________
>>>
>>>Aavso-photometry mailing list
>>>Aavso-photometry at mira.aavso.org
>>>http://www.aavso.org/mailman/listinfo/aavso-photometry
>>>
>>>   
>>>
>>>      
>>>
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