[Aavso-photometry] HD37605 data request

[Jean-Luc]

Hi Aaron,

I still have data to provide for HD 37605. Since I am not used to this 
level of precision I would like to make sure I will submit data properly.

Here is what I have done :
0/ I used AAVSO (e) chart,  86 (8.58) as comp star and 99 (9.89) as 
check star
1/ I took a set of 10 exposures (20 sec + V filter) every 10-15 minutes 
between Dec 28 - 21h00 UT and Dec 29 00h00 UT
2/ For each image of the set I substracted a master dark. I then 
combined the 10 of them (with MIRA) in order to get an averaged (mean) 
image.
3/ My SNR is good enough to have 2 millimag precision for HD 37605 and 3 
millimag for the Check Star.
4/ At this point I got 17  Vmag values for HD 37605
5/ The average value of these 17 Vmag over 3 hours is 8,626 with Stdev 
0,009.
5/ I calculated Airmass (between 1.51 and 1.36) and Scintillation (0,004 
- 0,003) for each of the measures.

Now my questions are :

a) I don't know the Kv coefficient for my location, so I cannot correct 
my data for first order extinction.
    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)).
     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.
>
>  
>