# VPhot User Guide Suggestions

Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 04/15/2014 - 17:29

If you find errors or omissions, or have suggestions for making the user guide more effective, please enter them in this 'VPHOT User Guide Suggestions' thread.

Thank you,

Mike Simonsen
AAVSO

Affiliation
American Association of Variable Star Observers (AAVSO)
Suggestion from the CHOICE class

From the first CHOICE course on VPhot-

Mike,

In another thread you posted the formula that VPhot uses for SNR and errSNR.  I think it would be very useful to have this in the Users' Guide, if not in the main body at least in an appendix.

Phil

Affiliation
American Association of Variable Star Observers (AAVSO)
VPHOT User Guide Suggestion

I'm trying to find the formulas for calculating the transformed magnitudes for BVRI observations.  Can someone tell me what they are?  It might be nice to have in the manual.

Barbara

Affiliation
Variable Stars South (VSS)
Transformed mags formulae

Hi Barbara,

I don't know about VPhot. These are what I use, showing V and B as examples:

(B-V)var = (B-V)comp +Tbv[(b-v)var – (b-v)comp]

Vvar = Vcomp + vvar – vcomp +Tb_bv[(B-V)var – (B-V)comp]

Then, B = (B-V) + V

v, b = instrumental magnitudes

V, B = catalogue or measured magnitudes

var = variable star, comp = comparison star

Tbv, Tv_bv = TCs

The above were derived algebraically (basic algebra I learned at school 60 odd years ago) from the equations used to determine the TCs.

Roy

Affiliation
Variable Stars South (VSS)
Correction

Sorry,

There is a typo in the above. The correct formula is:

Vvar = Vcomp + vvar – vcomp +Tv_bv[(B-V)var – (B-V)comp]

The error was Tb_bv.

Roy

Affiliation
American Association of Variable Star Observers (AAVSO)
Did VPHOT DISAPPEAR WITH "REVISION" TO WEB PAGE?

WHERE IS VPHOT? I CAN'T FIND IT SINCE WEB SITE WAS "REORGANIZED".

LOST,

Lew

Affiliation
American Association of Variable Star Observers (AAVSO)
It's BACK!!

VPHOT is back in its usual place!! Thanks folks!!!!!!!!!!!!!!!!!!!!!

Grateful,

Lew

Affiliation
American Association of Variable Star Observers (AAVSO)
Suggested Manual changes based on my teaching of CCD1 and VPhot

One suggestion based on teaching both VPhot and CCD1 CHOICE courses. Immediately in major section 2, there should be instructions on how to set up a VPhot account and upload images. I prepared text on how to do this for my CCD1 students and shared it with Phil, who is teaching CCD2. attached is an exampe of a reasonable modification. You can't look at your images before you know how to set up and account and upload images. Right now this information is buried in the back.

Ed

Example extracted from the Manual and modified:

2 AVAILABLE IMAGES PAGE

You can choose to view images uploaded today, the last three days or last week. If you are looking for a specific set of images, choose 'More' to use the image search tool.

Affiliation
American Association of Variable Star Observers (AAVSO)
Suggested Manual changes....

Ed, (Ken, George,)

I think the current VPhot manual is a good, comprehensive guide to the tools available in VPhot organized in a logical fashion.  I see it as a great reference document and class text book, but not as a book designed to get new users started from scratch on their own.

I believe the tutorials in the book are excellent for people who have already gotten a start, but I think there is too much information in these tutorials for raw beginners without the guidance of the class.

I confess I never got very much from the video tutorials when I was trying to learn VPhot.  They jump around too fast for me.  I learned VPhot by taking the course.  I recommend this to anyone who has the time to devote to the class.

For those who want to learn VPhot on their own I think a good complement to the current manual would be a VPhot Quick Start Guide.

I think Ed and I already have a start on this.  As Ed mentioned I use his CCD1 class document on setting up an account and loading images in CCD2.  For the CCD2 course I have several cookbook style step-by-step documents for doing specific tasks.  I try to keep it as simple as possible, but get the student through a full process, i.e. making a user defined sequence, or single image photometry, or submitting data to the AID from VPhot.

I think after someone has gone completely though a task even once that the more detailed discussion in the VPhot Guide  would be more useful.  Also, even without getting a complete understanding of the process, students get a good look at the power of VPhot.  They want to learn more.  Then I think they can use the forum and the VPhot Guide to better advantage.

If there is interest perhaps we could discuss this at the November meeting.

Phil

Affiliation
British Astronomical Association, Variable Star Section (BAA-VSS)