American Association of Variable Star Observers (AAVSO)
Thu, 07/21/2011 - 09:49


I hava a question about the 'webops (indivitual) submit form',( )

About the first question: What type of observation are you submitting?: *

The possible answers are not all clear to me
Answers (=what i :

So, if you could explain the last 2 in short that would be verry helpful


American Association of Variable Star Observers (AAVSO)
types of observations

Hi Bramjam,

Reduced PEP is using a special single-channel detector called a photoelectric photometer.  Basically, all of the light from a star is focussed onto a single sensor, and you get one digital measurement out.  If you want to measure the light from another star in the telescope field of view, you have to reposition the telescope so that the light from that star falls on the sensor - no "imaging" is possible.

Photographic is where you take an image with, say, a DSLR, and then display that image on your computer monitor.  You then make an eyeball estimate of the brightness of the target star with respect to other comparison stars that are also displayed in the image on the monitor.  It is identical to the method used by astronomers at the turn of the last century when they measured the brightness of variable stars from photographic plates.  This method is rarely used today, as software to get accurate digital estimates of the star brightnesses from a CCD or DSLR image is readily available.

For your DSLR system, and using the Citizen Sky tutorials, you would most likely submit your brightness estimate as "Tri-Color Green" using the WebObs submission tool and the CCD form.  I'm pretty sure the tutorials tell you how to submit data, so read them thoroughly.


Vereniging Voor Sterrenkunde, Werkgroep Veranderlijke Sterren (Belgium) (VVS)
Green channel DSLR


A DSLR measurement is entered in Webobs as Tri-color.

But how do I submit a green channel measurement from a DSLR?

Clear skies, Hubert