M.A.P. : Multi Aster Photometry 

A FREEWARE Photometry Program for the Stars in the Sky. 

Ever wanted a photometry program that can analyse all variable stars of a starfield in one go  ?
Ever wanted a photometry program that is fast, accurate and actually explains what it is doing ?
Ever wanted a photometry program that does the photometry in Real Time while you are observing the stars ?
Ever wanted a photometry program that allows you to vary the apertures and the annulus for every star ? 
Even worse : you do not need to play with apertures and annulus any more, if wanted. 
Here it is ! M.A.P. is the One ! 
The development of M.A.P. started in the automn of 2021 and has been extensively tested as I use it for all my observations, from Exoplanets over HADS stars, close binaries to CV variables.  
Especially the exoplanets observations need ultimate accuracy, with my 25cm Newton at sealevel I go to an accuracy of less that 10 millimagnitudes.
The Real Time module lets you see what is happening at the time of the observation, allowing to intervene on the spot if something surprising happens. Very interesting in case of CV-stars !

Multi Aster Photometry, what's in a name ?

M.A.P. started its carier being called AstroPie. One of the most important Python modules used is called AstroPy. My first name is Pieter, so it was easy to call my program AstroPie.

But, it seems that the pronunciation of AstroPy and AstroPie in English is the same, what would lead to too much confusion.


So, another name was needed. 


The program is still about stars, and about Photometry, and the big differentiator is that it is perfectly possible to do the photometry on multiple stars at once.

So, Multi points to Multiple, Aster is Latin for Star, and then we add Photometry, which gives : Multi Aster Photometry, or M.A.P.

The namechange was decided half of march 2023, so some/most of the printscreens of this help series will still mention the name AstroPie. It will change, bit by bit. 



How to install M.A.P. - Multi Aster Photometry?

See dedicated page : Installation M.A.P.


What are the components of M.A.P ?

 The Dashboard guides you through all the different steps for the Photometry

Default Values : change the default values for your setup. More than one setup is possible : More about Default Values

- Calibration : calibrate your photo's before measuring them : More about Calibration
- Star Groups : define for a field of view what stars have to be analysed. Of course, all stars will be analysed in one single run ! More about Star Groups
- Star Groups : before choosing the directory with the photo's to be analysed, choose the corresponding Star Group. More about choosing a Star Group
- Choose directory with the photo's to be analysed.
Photometry is launched by choosing the folder with the Science Frame (photo's)
- Photometry : the screen with the results, and allowing some extra manipulation.
- Show A Lot Of Graphs : fine details of the photometry, relative flux, total flux, FWHM, background, and many more. About A Lot Of Graphs
- Show A Lot Of Apertures : have a look at the apertures and annulus of the stars. About A Lot Of Apertures
- Show Photo : put the Star Group stars on a photo, and verify exposure times for clipping   Show a Photo
- Real Time : it is possible to do the photometry while observing. Each time a new photo is made, the photometry is instantly done on it. Some people like to look at growing grass, some people like to look at brightness variations of variable stars.

Some General Tricks

- Help is availble through the "?"- buttons on each screen, and on the dashboard
- Each figure can be saved to disk : right click on it and choose where to put it

- Tables : click on the header field of a table and the table will be sorted by that field. Click another time and the sort order will reverse

Is M.A.P. the Absolute Perfection ?


But almost. Well, if you experiment a bit to find the best way to use it.

I started working on M.A.P. because other softwares that were available back then gave results I could not explain. Too many masurements were obviously not completely correct, no explanation could be found why.

Therefore I wrote the subprograms ALotOfGraphs and ALotOfApertures to get a better idea of what happened. It allowed me to add some fine tunings that diminished the inexplicable errors other software gave sometimes.

So Absolutely Perfect

No : one of the remaining problems are hot pixels. When they happen in the background, the problem has been solved, but when they happen inside the pixels of the star, there is something not completely ok. As stated in the AstroPy documentation :
If the object of interest happens to fall on one the bad pixels you may well notice it. In time series photometry this sometimes manifests as a single data point that is well outside the trend in the rest of the data.
Another important remark : when doing photometry with very low SNR it is better to adapt the method of analysis to "radius" instead of "FWHM'". See also the help page about Photometry.
Hint :
Most of the unexplicable errors are due to bad calibration. That can be old darks (warm pixels tend to become hotter by the time), or  bad flats.
More information about that in the Calibration help pages :  More about Calibration

A Lot Of Thanks Go To ...

M.A.P. has been tailored to the needs of my own setup needs for doing photometry. 

But, in order to verify other setups and other needs for photometry I want to thank Hubert Hautecler, Josch Hambsch, Joost Verheyden,Gunther Fleerackers and Franky Dubois !
Tests on thousands of photos with hundreds of stars on one run, tests o nthe logical way of working with the GUI, bug fixing, documenting effects of calibration, and so on...

M.A.P.. is making use of :

- ASTAP : ASTAP website
- AAVSO VSX database
- Vizier UCAC4 and GaiaDR3 databases
- Python : Python website

Door gebruik te maken van onze website gaat U akkoord met ons gebruik van cookies. Wij verzamelen geen gegevens via cookies, er zijn enkel website functionele cookies.