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Newbie help

mvln's picture
mvln
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Joined: 2014-07-27

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

standardized magnitude
olichris's picture
olichris
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Joined: 2013-09-21

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

newbie help
HQA's picture
HQA
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Joined: 2010-05-10

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

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484