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Newbie help

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Last post
mvln
Newbie help

Hi everyone,

I have a few years of data of HADS variables that were used by Patrick Wils. I would like to share this data and enter it into the AAVSO database using the extended file format. I have excel files of all data that have the following format.

T (JD)
Obj1
Ref1
Chk1
Chk2
Chk3
Chk4
Chk5

2456722.284
3.8600
0.0000
1.3210
2.4550
3.2700
3.7520
2.9810

2456722.287
3.8100
0.0000
1.3030
2.4600
3.2260
3.7190
3.0310

2456722.288
3.9190
0.0000
1.2990
2.3890
3.2270
3.7120
2.8710

2456722.289
3.9450
0.0000
1.2990
2.4470
3.1830
3.7360
2.9740

2456722.29
4.0630
0.0000
1.3200
2.4700
3.3130
3.6620
2.9160

where

 
 
RA
DEC
Mag

Object
GSC 3031-0307
13 30 03.22
  43 30 13.0
    13.920 (R)

 
 
 
 
 

Ref1
 GSC 3031-0103
13 30 42.85
  43 30 42.3
     9.880 (R)

 
 
 
 
 

Chk1
GSC 3031-0086
13 30 14.50
  43 24 17.0
    11.150 (R)

 
 
 
 
 

Chk2
GSC 3031-1063
13 30 12.05
  43 35 57.4
    12.410 (R)

 
 
 
 
 

Chk3
 GSC 3031-0129
13 30 34.03
  43 31 42.7
    13.240 (R)

 
 
 
 
 

Chk4
GSC 3031-0171
13 30 28.43
  43 33 44.2
    13.560 (R)

 
 
 
 
 

Chk5
GSC 3031-1088
13 29 34.40
  43 36 35.4
    12.820 (R)

These are differential magnitudes. Can someone explain me how to convert to standard magnitudes ? Can I select 2 check stars to be the CName and Kname ? Where do I figure out what magnitude Cstd is ?

Vstd = (Vins - Cins) + Cstd

tnx for your help !

 

Maarten

olichris
olichris's picture
standardized magnitude

Hello Maarten.

if what you want is the standardized magnitude

Vstd = Vins + (Cstd - Cins)

or also

Vstd = Vins - (0 - (Cstd - Cins))
your putting the magnitudes are transformed, that is another thing. to transform it.

V = v - e * (B-V) - Z

where Z = (0 - (Cstd - Cins))

Now if what you want is about the nature of the transformation, although here long, pretty well explained.

http://reductionism.net.seanic.net/CCD_TE/cte.html

HQA
HQA's picture
newbie help

Hi Maarten,

Your post occurred just before the CCD School, and I was so involved in preparations that I didn't monitor whether someone answered your questions.  Oliver's reply reminded me that there was a void!

Oliver told you how to convert differential magnitudes into standardized ones.  Another source of information is the AAVSO Guide to CCD Photometry, which was just released:

http://www.aavso.org/ccd-photometry-guide

You designate one of your comparison stars as CNAME, use it to standardize the variable's magnitude, and put the CNAME star's instrumental magnitude in CMAG.  Designate another of those comparison stars as KNAME, and put its instrumental magnitude in KMAG.  Unless you are doing ensemble photometry, you can ignore the other comparison stars that were measured.

If you have any other questions, don't hesitate in asking me; I'll forward them to the appropriate person.

Arne

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