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Help request from a new member

maxgaspa's picture
maxgaspa
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Joined: 2011-06-09

Dear all,

 

I'm a new user of the AVVSO website (or better a member) and I need some help to report correctly my observations.

 

I'm using a Celestron C8 XLT with a B/W CCD (Meade DSI PRO II) using a Johnson V filter.  I did some test with my CCD using the following process.

 

1) Get the image

2) Get the dark (10 avaraged), bias , flat (10 median) and darkflat (10 averaged)

3) Using AstroArt I corrected the image with the dark and flat

3) I'm using AstroArt to make photometry, I think is the "aperture" photometry measurement. I get a photometry table from AVVSO in which there are several (three) references. I used those references to "calibrate" the photometry relation and I've got the magnitude of the variable star with an estimation of the error.

First question. Is that process correct? Any advice?

 

Now  I'd like to submit the report to AVVSO but I have some question on how to fill it.

Using "Enter Observation Individually" and type = CCD I don't know how to fill:

Check this box if your magnitude is transformed. -> Should I select this or not.? My guess is yes

Check this box if your magnitude is differential. -> Shuold I select it or not? My guess is no!

Comp Label : I didn't use any comparison star or, weel, more than one. Should I fill it with the chart label? Photometric table label ? Or what else?

Comp Mag: Did I make an "ensemble" photometry or not? What should I write in this field?

Check Star and Check Magnitude : Shuold I leave this fields empty?

 

Any help or suggestion will be very appreciated.

 

Regards

 

Max

help request from new member
HQA's picture
HQA
Online
Joined: 2010-05-10

Hi Max,

Welcome to the variable-star world!  Here are the answers to your questions:

Using "Enter Observation Individually" and type = CCD I don't know how to fill:

Check this box if your magnitude is transformed. -> Should I select this or not.? My guess is yes

use "no".   Transformed magnitudes require knowledge of how your Johnson V filter compares with the standard V filter.  You would need to know the color of your variable star and your transformation coefficient.

Check this box if your magnitude is differential. -> Shuold I select it or not? My guess is no!

use "no".  Differential means that you just report (variable - comp).

Comp Label : I didn't use any comparison star or, weel, more than one. Should I fill it with the chart label? Photometric table label ? Or what else?

use "NA" since you are doing a crude ensemble with 3 comparison stars

Comp Mag: Did I make an "ensemble" photometry or not? What should I write in this field?

use "ENSEMBLE"

Check Star and Check Magnitude : Shuold I leave this fields empty?

This one is a bit trickier.  For now, I'd go ahead and leave the fields empty.  The correct way to do this is to use a fourth "comparison star" and use your 3-star ensemble to determine its magnitude too.  Then report the star's ID and the determined magnitude in the check star fields.

Help request from a new member
maxgaspa's picture
maxgaspa
Offline
Joined: 2011-06-09

Thank you very much for your help and for all information!

 

Max

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