[Aavso-photometry] HD37605 data request

[Radu Corlan]

On Sat, 1 Jan 2005, Radu Corlan wrote:

> > > a) I don't know the Kv coefficient for my location, so I cannot correct 
> > > my data for first order extinction.
> 
> Jean-Luc,
> 
> One more thing: you may be able to determine the extinction coefficient 
> from your data. you have to plot the instrumental magnitudes of your comp 
> star againt airmass. The plot should slope down, with a slope equal to 
> your extinction coeff. 

oops - that should read "sloping up".

> The only catch is to first see if the exctinction 
> was stable during the time. The spread of the values around the 
> downsloping line should be of the order of your total SNR (poisson plus 
> scintillation). If this is the case, you can safely use the slope of the 
> plot as your extinction coeff. 
> 
> Radu
> 
> 
> 
> > >     Is it OK to report my data without applying the extinction 
> > > correction - and provide the uncorrected data with Airmass instead ?
> > > 
> > > b) I am not sure how to calculate Scintillation error impact on my data. 
> > > I read in a previous thread that the err should be calculated as follows :
> > >     err = SQRT(1/NetCountVar + 1/NetCountComp + 2*SQRT(Scintillation)).
> > 
> > 
> > Jean-Luc,
> > 
> > the above should be:
> > 
> >      err = SQRT(1/NetCountVar + 1/NetCountComp + 2*SQR(Scintillation)).
> > 
> > (note sqr instead of sqrt). This gives a total contribution of 0.006 from 
> > scintillation, and a total error of 0.007 (which is consistent with the 
> > 0.009 standard deviation you obtained) - and i may add, a pretty good 
> > figure overall.
> > 
> > Radu
> > 
> > >      If  I do so, the err which was in the 0.002 range jumps to 0.3xx 
> > > ... just because of the Scintillation factor.
> > >      What does it mean ? Is Scintillation of 0,004 that bad ? 
> > >      Since it does not make any sense to try to detect a 0,02 gap with a 
> > > 0,3x error...what error should I report  ?
> > >      What is your recommendation to calculate / include scintillation 
> > > error ?
> > > 
> > > c) A lot of things are told about about error reporting  and I am a bit 
> > > confused. Is there an AAVSO recommendation to calculate error ?
> > >     The CCD Manual is giving SNR and Stdev as starting points but many 
> > > emails I read on this list tend to say that it is not enough.
> > >      Is there a commonly agreed procedure/formula to calculate error 
> > > when submitting data ?
> > >     (And especially for high precision measurement like for this campaign ?)
> > > 
> > > Many thanks for your advices,
> > > Best,
> > > 
> > > Jean-Luc
> > > 
> > > 
> > > Aaron Price wrote:
> > > 
> > > > I was wrong about Arto's data set, it does not include the estimate
> > > >ingress time if Gary's event is indeed an egress. If anyone has
> > > >observations of HD 37605 anywhere from JD 2453367.2 - 2453367.4 (16:48
> > > >-  21:36: UT on December 27, 2004) please submit them as soon as you
> > > >can as this is when the ingress should have occured. Thanks.
> > > >
> > > >  
> > > >
> > > 
> > > 
> > > 
> > > _______________________________________________
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> > > Aavso-photometry at mira.aavso.org
> > > http://www.aavso.org/mailman/listinfo/aavso-photometry
> > > 
> > 
> > 
> 
> 

-- 

-------------
Radu Corlan       Snail Mail: Bucuresti sect. 1, 
rcorlan at pcnet.ro  str. Argentina nr. 28, Romania

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