1. Home
  2. Forums
  3. Variable Star Observing
  4. Photometry

DSLR observation submission form question

Carl Knight
Affiliation
British Astronomical Association, Variable Star Section (BAA-VSS)
Mon, 07/22/2013 - 01:53

When entering the comparison and check magnitudes the help says:

"Comparison Star Magnitude

The instrumental magnitude of the comparison star that you used. A decimal point is required.

...

Check Star Magnitude

The instrumental magnitude of the check star that you used. A decimal point is required."

I have presumed (correctly I hope) that the "instrumental magnitude" as referred to elsewhere is the instrumental magnitude obtained by the photometry software (Iris in my case) and NOT the transformed magnitude for the Comparison and Check stars (using the derived coefficient)  - correct?

Thanks in advance.

- Carl.

Roger Pieri
Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 07/22/2013 - 11:27
DSLR reporting

Hi Carl, all,

Interestingly this is different from the Citizen Sky form ! In any case we should use an "ensemble" process with DSLR. This is the way developed at CS with Brian and the best to determine the actual transform and extinction gradient across our large FOV. Then an "instrumental" value for the check has little meaning in our case. In most it can't be used to make a "back" check. Best to qualify the observation would be to report the sigma of the "ensemble" fitting, this is what I do for my own. Then I report the full processed check mag including DSLR, extinction gradient, atmospheric chromatism compensations (important for guys under urban skies, we do not observe at Paranal !) All this using my VSF technique.

Maybe we should put in the comment a note saying the check is processed ? 

Clear Skies !

Roger

   

Carl Knight
Affiliation
British Astronomical Association, Variable Star Section (BAA-VSS)
Mon, 07/22/2013 - 22:11
Summary of my understanding...

Hi Roger,

Firstly, thanks again for responding.

So using the DSLR observation (http://www.aavso.org/webobs/individual - Observation Type = DSLR) entry page:

  • Magnitude is of course the fully transformed variable star magnitude.
  • Check box options beneath "Magnitude", check the "...magnitude is transformed" option.
  • Filter: I have been entering "Tricolor Green", should this be "Johnson V" in conjunction with the "...magnitude is transformed"?
  • Comparison Star Label: I am using the CS data reductions spreadsheet for beginners so I should be specifying "ensemble" and then leaving the "Comp Mag" blank?
  • Check Label and Check Mag are the AUID and fully transformed (not Iris "Instrumental") magnitude for the check star.

Clear skies.

- Carl.

FRF
Affiliation
Magyar Csillagaszati Egyesulet, Valtozocsillag Szakcsoport (Hungary) (MCSE)
Tue, 07/23/2013 - 11:04
If transformed then Johnson V

[quote=Carl Knight]

  • Magnitude is of course the fully transformed variable star magnitude.
  • Filter: I have been entering "Tricolor Green", should this be "Johnson V" in conjunction with the "...magnitude is transformed"?[/quote]

In case you submit transformed magnitudes then is should be "Johnson V".

TG is for untransformed magnitudes.

Clear skies,

Robert