Software Programs for Variable Star Observers

Last update : July 10th 2020

Two software programs here presented could help the Amateur Variable Star Observers in their activities.

LesvePhotometry is an automatic photometry tool.
PeriodicVSOplanner helps you in the observation planning of periodic variable stars.

They are provided as Freeware programs and do not require any registration key. My aim is to improve them and they will remain free in the future but your contribution will be greatly appreciated.

Click next button if you prefer to pay in Euros

Click next button if you prefer to pay in USD

The old discussion group on Yahoo is transfered to


Quick links

Getting started
LesvePhotometry Download Page
LesvePhotometry User guide
FAQ page


LesvePhotometry is based on differential photometry, the more common photometry method used by amateurs. In differential photometry, we compare the amounts of light from the target star (variable star) and comparison stars.
The different steps to measure the magnitude of star from a CCD image are :

  • detection of target and comparison stars on the CCD image
  • calculation of the average pixel values in a circular apertures around the star and in annulus (to measure the sky background)
  • calculate the magnitude of the target star from
    - the aperture measurements
    - catalog magnitudes of comparison stars

With common photometry programs, the user has to select manually the target and comparison stars (on the first image of a series) enter the catalog magnitudes of comparison stars. He has to repeat these operations each time a new photometry is launched. In LesvePhotometry, following data are provided once by the user and stored in a database:
target star
- Name
- Right Ascension, Declination
- Names of comparison stars
- an other parameters
comparison stars
- Name
- Right Ascension, Declination
- Catalog star magnitudes for B, V, R and I filters
- an other parameters

Each time a photometry is launched, the program automatically :
- retrieves the needed data from the database
- solves the image by astrometry
- locates stars and positions the aperture circles
- calculates the magnitude of the target star

The results are provided in three reports: AAVSO format, CBA format and Excel file with a chart. The program provides an easy human interface for the star database maintenance.

Installation information

The database engine (SQLite.Net) is integrated in the program and all the needed files are included in the setup program. An example of database is included in the setup program.

The locations of target and comparison stars on each image plates are obtained with PinPoint astrometry engine.
To use PinPoint astrometry engine, you need the appropriate license ($149) from

Note for MaximDL users

The PinPoint "Light Edition" included in Diffraction Limited's MaximDL does not support scripts and will not work with LesvePhotometry. If you have MaximDL you have to upgrade to the "full" PinPoint license. Additional capabilities are available with the full version of PinPoint, which are also compatible with MaximDL.

Besides the normal "LesvePhotometry" version using PinPoint astrometry engine another version "LesvePhotometry-ansvr" is using Astrometry.Net engine instead of PinPoint. But with this "LesvePhotometry-ansvr" version, the speed of execution is slower by a factor of 5 to 10 and some features are disabled. See the LesvePhotometry-ansvr Download Page section for details.
It's strongly recommended to use the standard version using the PinPoint engine.

The ASCOM platform (version 5.5 or higher) is required by PinPoint and LesvePhotometry, free download at

The .NET Framework 4 must be installed, free download from Microsoft website.

The photometry results are also presented in an Excel file, Office Excel version 2003 or later is required.

LesvePhotometry program has been tested on WindowsXP,Windows7 and Windows10 operating systems.

Two directories are used for installation :

C:\Program Files\Common Files\DPP Lesve\ (for XP)
C:\Program Files(x86)\Common Files\DPP Lesve\ (for Win7/10)

contains the program and needed files (don't modify them)

C:\Documents and Settings\yourUserAccount\DPP Lesve\ (for XP)
C:\Users\yourUserAccount\Documents\DPP Lesve (for Win7/10)

contains a working copy of the database (VS_Database.db3)

If you are curious, the user parameters are stored in a General Driver of ASCOM Profile (use the ASCOM Profile Explorer to inspect the parameters)

C:\Documents and Settings\All Users\Application Data\ASCOM (for XP)
C:\ProgramData\ASCOM\ (for Win7/10)

Known issues

For an unknown reason, the DPP_AstroFunctions.dll is not always registered correctly.
You will find in the directory

C:\Program Files\Common Files\DPP Lesve\Utilities
C:\Program Files(x86)\Common Files\DPP Lesve\Utilities

two batch files to register the dll file in both OS (XP or Win7/10):
Run the appropriate .bat file. Under Win7/10 you have to run this file as Administrator.


The next link is not a full user guide but provides the basic information to use the program : LesvePhotometry User guide

You will also find interesting information in the FAQ page : FAQ

Getting started

This page explains the first settings you have to perform.


Click the following links to access to the LesvePhotometry download page : LesvePhotometryDownloadPage


This program help you in the observation planning of your periodic variable stars, it calculates on night basis the stars having their maxima or minima. In an Excel file you specify the list of your stars (name, maximum/minimum epoch, period, Right Ascension and Declination).
For each nights, it selects the stars having a maximum and provides the Time of Maximum, Azimuth, Elevation, Sun and Moon Distances, a.s.o
The planning results are presented in another Sheet of the same Excel file.
At a glance, you have the selection of interesting stars for a night and the needed information to plan your observation night.


which contains two sheets
contains examples of RR Lyrae stars. For each star you have to introduce
Maxima/Minima epoch (in Julian Days),
Period (in days),
RightAcension (Ra in hours)
and Declination (De in degrees).
You have also to update the "Site coordinates" for you location.
You must preserve the column layout inside the green box, but you can add rows and columns outside the this box. You can also insert new lines in the green box for additional stars. The program will search for the cell containing the word "VariableName" to locate the box. So don't use the word "VariableName" in other cells. The program stops when it reach a blank star field.
will contain the results of the observation planner.


Horizon.xls file contains definition of your horizon. Column A contains 360 cells with horizon elevation. One cell per Azimuth degree (1 to 360).
Don't forget to update this Horizon.xls file to your environment. My horizon has been used as the default horizon.

These two files, saved in, "My Documents\DPP Lesve" will not be modified when you reinstall the program or install a new version. They will not be erased during program uninstallation.


PeriodicVSOplanner Setup.exe
dated December 11th 2018
- The Times of Maxima are also provided in local time format.

PeriodicVSOplanner Setup.exe
dated December 1st 2011
- In previous versions, the "Star rise UT" and "Star set UT" were calculated for an altitude defined in the main form. Now these values are calculated from your local horizon (defined in the "Horizon.xls" file) and the "Minimum Star Altitude (Rise/Set)". This minimum star altitude is very convenient if you have a very low local horizon and nevertheless you don't intend to observe a star below this minimum altitude.

PeriodicVSOplanner Setup.exe
dated November 2d 2011
- You have to observe a minimum of time (e.g. 1 hour) before and after the Maximum to cover correctly the Maximum. Now you can define this time in the main form. The program will calculate the Start and Stop observation times in JD and the corresponding Altitude and Azimuth at those times. If at the Start or Stop observation times, the star is below your custom horizon the Start of Stop observation times will be displayed in red.

PeriodicVSOplanner Setup.exe
dated December 8th 2010